Hip replacement navigation system and method

Abstract

Hip navigation systems and methods are provided. In some embodiments, the systems and methods described herein determine a table reference plane that approximates the anterior pelvic plane. In some embodiments, the systems and methods described herein measure pre-operative and post-operative points. In some embodiments, comparison of the pre-operative and post-operative points corresponds to changes in leg length and joint offset. In some embodiments, the systems and methods described herein determine an adjusted plane. In some embodiments, the adjusted plane adjusts for tilt by rotating the anterior pelvic plane about the inter-ASIS line. In some embodiments, the adjusted plane improves correlation between the navigated cup angle and post-operative images.

Description

[Technical field]

[0001] INCORPORATION BY REFERENCE TO PRIORITY APPLICATION Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet filed with this application, including U.S. Provisional Application No. 62 / 471,185, filed March 14, 2017, and U.S. Provisional Application No. 62 / 521,097, filed June 16, 2017, are each hereby incorporated by reference in their entirety under 37 CFR 1.57.

[0002] This application is directed to the field of hip joint replacement and, inter alia, to surgical tools and methods for establishing a reference plane. This application is also directed to surgical tools and methods for calculating leg length and joint offset. [Background technology]

[0003] Hip replacement surgery is common and is becoming more and more common each year. One persistent problem with hip replacement is poor seating of the cup and ball components of the artificial hip joint. For example, the cup is optimally seated in a specific abduction and anteversion orientation. An acceptable window of deviation from optimal abduction and anteversion angles has been observed in clinical practice, but for several reasons, an unacceptably high percentage of patients have artificial hip cups that fall outside of this window.

[0004] Unfortunately, malalignment can lead to dislocation of the hip joint as soon as one year after the implantation procedure. This is especially problematic because recovery from a hip procedure can take many months. Patients who undergo correction too soon after initial implantation will certainly be dissatisfied with their treatment and undergo additional redundant surgery. Naturally, all surgical procedures carry some degree of risk. These unsatisfactory outcomes are frustrating for patients and surgeons, and inefficient for the health care system as a whole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Serial No. 10 / 864,085 [Patent Document 2] U.S. Pat. No. 8,057,479 [Patent Document 3] U.S. Patent Application Serial No. 11 / 182,528 [Patent Document 4] US Patent Application Publication No. 2010 / 0076505 [Patent Document 5] U.S. Patent Application Serial No. 12 / 557,051 [Patent Document 6] U.S. Patent Application Serial No. 12 / 509,388 [Patent Document 7] U.S. Patent Application Serial No. 13 / 011815 [Patent Document 8] U.S. Patent No. 8,118,815 [Patent Document 9] U.S. Patent Application Serial No. 13 / 115,065 [Patent Document 10] U.S. Patent Application Serial No. 14 / 399,046 [Patent Document 11] U.S. Patent Application Serial No. 14 / 401,274 [Patent Document 12] U.S. Patent Application Serial No. 13 / 800620 [Patent Document 13] U.S. Patent Application Serial No. 14 / 643864 [Patent Document 14] U.S. Patent Application Serial No. 15 / 550,564 [Patent Document 15] US Patent Application Publication No. 2016 / 0242934 [Patent Document 16] US Patent Application Publication No. 2014 / 0052149 [Patent Document 17] US Patent Application Publication No. 2010 / 0137871 [Patent Document 18] U.S. Patent Application Serial No. 14 / 639758 [Patent Document 19] U.S. Patent Application Serial No. 14 / 639784 Summary of the Invention [Problem to be solved by the invention]

[0006] There is a need for improved systems and methods for providing proper alignment of hip components with a patient's anatomy during a hip replacement procedure. This may involve the use of a table coordinate reference system. This may involve the use of a vertical reference plane. This may involve the use of a reference plane that approximates the anterior pelvic plane. This may involve providing the user with additional information related to the anatomy including leg length and joint offset. [Means for solving the problem]

[0007] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include establishing a vertical plane with a measuring device. The method can include positioning a probe to contact a point. The method can include recording a position of the probe when the probe is contacting the point before replacing the joint. The method can include recording a second position of the probe when the probe is contacting the point after replacing the joint. In some embodiments, a comparison between the first position and the second position indicates a change in leg length or joint offset.

[0008] In some embodiments, the method may include coupling a measurement device and a probe to a patient. In some embodiments, the point is a structure. In some embodiments, the point is a burr. In some embodiments, the point is an anatomical landmark. In some embodiments, the method may include determining a cup angle relative to a vertical plane. In some embodiments, the method may include positioning the medical prosthesis at a predetermined angle relative to a vertical plane. In some embodiments, the method may include manually repositioning the femur after replacing the joint. In some embodiments, the method may include establishing a horizontal plane with the measurement device, the vertical plane and the horizontal plane defining a coordinate reference system.

[0009] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include establishing a vertical plane with a measurement device. The method can include projecting a pattern of light onto the patient's leg. The method can include recording the incidence of the light on the patient's leg. The method can include replacing the joint by inserting a cup, the angle of the cup being measured relative to the vertical plane. The method can include projecting the pattern of light onto the patient's leg after replacing the joint. The method can include repositioning the leg to align the recording of the incidence of the light with the pattern of light.

[0010] In some embodiments, the method can include recording a position of the probe when contacting the point prior to dislocation. In some embodiments, the method can include recording a position of the probe when contacting the point after instrumentation. In some embodiments, the method can include determining a change in leg length. In some embodiments, the method can include determining a change in leg length in a vertical plane. In some embodiments, the method can include determining a change in joint offset. In some embodiments, the method can include determining a change in joint offset in a plane perpendicular to the vertical plane. In some embodiments, the method can include establishing a horizontal plane with a measuring device, the vertical plane and the horizontal plane defining a coordinate reference system. In some embodiments, the method can include recording a point in the coordinate reference system. In some embodiments, the method can include recording a point pre-operatively in the coordinate reference system. In some embodiments, the method can include recording a point post-operatively in the coordinate reference system.

[0011] In some embodiments, a surgical system is provided for assisting a surgeon in obtaining a correct orientation of an acetabular prosthetic socket in a patient's acetabulum. In some embodiments, the instrument can include a support device. The instrument can include a first electronic orienting device having a coupler, the coupler for releasably coupling the first electronic orienting device to the support device. In some embodiments, the first electronic orienting device includes at least one inertial sensor. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to establish a reference plane based on a direction of gravity.

[0012] In some embodiments, the system may include a probe assembly including a base portion and an elongated member, the elongated member configured to pivot and translate relative to the base portion, the probe assembly including a second electronic orienting device, the second electronic orienting device including at least one inertial sensor. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to record a point when the probe contacts the point. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to record a point when the probe contacts the point pre-operatively and post-operatively. In some embodiments, the at least one inertial sensor of the first electronic orienting device or the at least one inertial sensor of the second electronic orienting device includes an accelerometer. In some embodiments, the reference plane includes a vertical plane. In some embodiments, the first electronic orienting device includes a display configured to provide an indication of a change in an angular position of the second electronic orienting device relative to the reference plane. In some embodiments, the system may further include an optical component configured to project a pattern of light.

[0013] In some embodiments, a hip joint navigation system is provided. The system can include a jig assembly. The system can include a first inertial navigation device configured to be rigidly coupled to the jig assembly. The system can include an optical component configured to project a pattern of light, and incidence of the pattern of light can be recorded to assist a user in realigning the femur to a pre-operative position. The system can include a second inertial navigation device configured to determine an orientation of the probe as the probe is moved to touch the point.

[0014] In some embodiments, the light pattern is a crosshair. In some embodiments, the light pattern is two lines. In some embodiments, the light pattern is three points.

[0015] There is a need for improved systems and methods for providing proper alignment of hip components with a patient's anatomy during a hip replacement procedure. This may involve the use of an anterior pelvic plane. This may involve the use of a table plane. This may involve the use of an adjusted plane. This may involve providing a user with additional information related to the anatomy including pelvic tilt and rotation.

[0016] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include coupling a measuring device and a probe to a patient. The method can include positioning the probe to contact a first point. The method can include recording a position of the probe when the probe is contacting the first point. The method can include positioning the probe to contact a second point. The method can include recording a position of the probe when the probe is contacting the second point. The method can include positioning the probe to contact a third point. The method can include recording a position of the probe when the probe is contacting the third point. In some embodiments, the first point, the second point, and the third point define a plane, and the plane can be rotated by a direction of gravity to define an adjusted plane.

[0017] The method can include coupling the measuring device with a second measuring device, the second measuring device including a digital display and providing an indication of a change in position of the probe. In some embodiments, the first point is the ipsilateral ASIS. In some embodiments, the second point is the contralateral ASIS. The method can include positioning the probe horizontally to measure a direction of gravity. The method can include determining a cup angle relative to a reference plane. The method can include positioning the medical prosthesis at a predetermined angle relative to the adjusted plane. In some embodiments, the first point and the second point define an inter-ASIS line. In some embodiments, the first point, the second point, and the third point define an anterior pelvic plane. In some embodiments, the third point is an anterior surface of the pubic symphysis.

[0018] In some embodiments, a surgical system is provided for assisting a surgeon in obtaining a correct orientation of an acetabular prosthetic socket in a patient's acetabulum. The instrument can include a support device. The instrument can include a first electronic orienting device having a coupler for releasably coupling the first electronic orienting device to the support device, the first electronic orienting device including at least one inertial sensor. The instrument can include a probe assembly including a base portion and an elongated member, the elongated member configured to pivot and translate relative to the base portion, the elongated member having a length sufficient to allow a tip thereof to contact an anatomy disposed about the pelvis at a plurality of discrete spaced apart locations, the probe assembly including a second electronic orienting device, the second electronic orienting device including at least one inertial sensor. In some embodiments, the first electronic orientation device and the second electronic orientation device are adapted to establish a reference plane based on a direction of gravity and based on a position of the at least one inertial sensor when the tip is in contact with the multiple spaced apart locations.

[0019] In some embodiments, at least one inertial sensor of the first electronic orienting device or at least one inertial sensor of the second electronic orienting device includes an accelerometer. In some embodiments, the reference plane includes an ASIS line. In some embodiments, the first electronic orienting device includes a display configured to provide an indication of a change in an angular position of the second electronic orienting device relative to the reference plane.

[0020] In some embodiments, a hip joint navigation system is provided. The system may include a jig assembly. The system may include a first inertial navigation device configured to be rigidly coupled to the jig assembly. The system may include a landmark acquisition probe configured to be movably coupled to the jig assembly, the landmark acquisition probe configured to move with multiple degrees of freedom relative to the jig assembly. The system may include a second inertial navigation device configured to determine an orientation of the landmark acquisition probe when the landmark acquisition probe is moved to touch an anatomical landmark. In some embodiments, the first inertial navigation device, the second inertial navigation device, or the first inertial navigation device and the second inertial navigation device are configured to adjust for tilt by rotating an anterior pelvic plane about an inter-ASIS line to determine a reference plane.

[0021] In some embodiments, the second inertial device includes a mounting device configured to removably connect the second inertial device to the landmark acquisition probe. In some embodiments, the second inertial device includes a camera. In some embodiments, the first inertial navigation device includes a display.

[0022] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include establishing a vertical plane with a measuring device. The method can include positioning a probe to contact a point. The method can include recording a position of the probe when the probe is contacting the point before replacing the joint. The method can include recording a second position of the probe when the probe is contacting the point after replacing the joint. In some embodiments, a comparison between the first position and the second position indicates a change in leg length or joint offset.

[0023] The method may include coupling a measuring device and a probe to a patient. In some embodiments, the point is a structure. In some embodiments, the point is a burr. In some embodiments, the point is an anatomical landmark. The method may include determining a cup angle relative to a vertical plane. The method may include positioning the medical prosthesis at a predetermined angle relative to the vertical plane. The method may include manually repositioning the femur after replacing the joint. The method of claim 1 further includes establishing a horizontal plane with the measuring device, the vertical plane and the horizontal plane defining a coordinate reference system.

[0024] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include establishing a vertical plane with a measuring device. The method can include projecting a pattern of light onto the patient's leg. The method can include recording the incidence of the light onto the patient's leg. The method can include replacing the joint by inserting a cup, and one or more angles of the cup are measured relative to the vertical plane. The method can include projecting a pattern of light onto the patient's leg after replacing the joint. The method can include repositioning the leg to align the recording of the incidence of the light with the pattern of light. The method can include recording a position of a probe when contacting the point before the dislocation. The method can include recording a position of a probe when contacting the point after instrumentation. The method can include determining a change in leg length. The method can include determining a change in leg length in the vertical plane. The method can include determining a change in joint offset. The method can include determining a change in joint offset in a plane perpendicular to the vertical plane. The method may include establishing a horizontal plane with a measuring device, the vertical and horizontal planes defining a coordinate reference system. The method may include recording points in the coordinate reference system. The method may include recording points pre-operatively in the coordinate reference system. The method may include recording points post-operatively in the coordinate reference system.

[0025] In some embodiments, a surgical system is provided for assisting a surgeon in obtaining a correct orientation of an acetabular prosthetic socket in a patient's acetabulum. The surgical system can include a support device. The surgical system can include a first electronic orienting device having a coupler, the coupler for releasably coupling the first electronic orienting device to the support device. In some embodiments, the first electronic orienting device includes at least one inertial sensor. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to establish a reference plane based on a direction of gravity.

[0026] The surgical system can include a probe assembly including a base portion and an elongated member, the elongated member configured to pivot and translate relative to the base portion. In some embodiments, the probe assembly includes a second electronic orienting device. In some embodiments, the second electronic orienting device includes at least one inertial sensor. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to record a point when the probe contacts the point. In some embodiments, the first electronic orienting device and the second electronic orienting device are adapted to record a point when the probe contacts the point pre-operatively and post-operatively. In some embodiments, the at least one inertial sensor of the first electronic orienting device or the at least one inertial sensor of the second electronic orienting device includes an accelerometer. In some embodiments, the reference plane includes a vertical plane. In some embodiments, the first electronic orienting device includes a display configured to provide an indication of a change in an angular position of the second electronic orienting device relative to the reference plane. The surgical system can further include an optical component configured to project a pattern of light.

[0027] In some embodiments, a hip joint navigation system is provided. The hip joint navigation system can include a jig assembly. The hip joint navigation system can include a first inertial navigation device configured to be rigidly coupled to the jig assembly. The hip joint navigation system can include an optical component configured to project a pattern of light. In some embodiments, the incidence of the pattern of light can be recorded to assist a user in realigning the femur to a pre-operative position. The hip joint navigation system can include a second inertial navigation device configured to determine an orientation of the probe as the probe is moved to touch the point.

[0028] In some embodiments, the light pattern is a crosshair. In some embodiments, the light pattern is two lines. In some embodiments, the light pattern is three points. In some embodiments, the optical component is configured to couple the jig assembly with one or more magnets. The hip navigation system can include a targeting probe for recording or displaying the light pattern, the targeting probe including an anatomical contact portion and a target portion. In some embodiments, the anatomical contact portion and the target portion are separate components. In some embodiments, the anatomical contact portion includes an incise drape.

[0029] In some embodiments, a hip joint navigation system is provided. The hip joint navigation system can include an impactor. The hip joint navigation system can include a coupler, the coupler configured to be rigidly coupled to and decoupled from the impactor. The hip joint navigation system can include an inertial navigation device configured to be rigidly coupled to the coupler. In some embodiments, the inertial navigation device is configured to determine an orientation of the impactor as the impactor is moved.

[0030] The hip navigation system can include a universal impactor adapter including a coupler. In some embodiments, the universal impactor adapter is configured to be removably coupled to the impactor. In some embodiments, the universal impactor adapter includes a clamp. In some embodiments, the universal impactor adapter includes a magnet.

[0031] In some embodiments, a method of positioning a medical prosthesis is provided. The method can include coupling a measuring device and a probe to a patient. The method can include positioning the probe to contact a first point. The method can include recording a position of the probe when the probe is contacting the first point. The method can include positioning the probe to contact a second point. The method can include recording a position of the probe when the probe is contacting the second point. The method can include positioning the probe to contact a third point. The method can include recording a position of the probe when the probe is contacting the third point. In some embodiments, the first point, the second point, and the third point define a plane, and the plane can be rotated by a direction of gravity to define an adjusted plane.

[0032] The method can include coupling the measuring device with a second measuring device, the second measuring device including a digital display and providing an indication of a change in position of the probe. In some embodiments, the first point is the ipsilateral ASIS. In some embodiments, the second point is the contralateral ASIS. The method can include positioning the probe horizontally to measure a direction of gravity. The method can include determining a cup angle relative to a reference plane. The method can include positioning the medical prosthesis at a predetermined angle relative to the adjusted plane. In some embodiments, the first point and the second point define an inter-ASIS line. In some embodiments, the first point, the second point, and the third point define an anterior pelvic plane. In some embodiments, the third point is an anterior surface of the pubic symphysis.

[0033] In some embodiments, a surgical system is provided for assisting a surgeon in obtaining a correct orientation of an acetabular prosthetic socket in a patient's acetabulum. The surgical system can include a support device. The surgical system can include a first electronic orienting device having a coupler for releasably coupling the first electronic orienting device to the support device. In some embodiments, the first electronic orienting device includes at least one inertial sensor. The surgical system can include a probe assembly including a base portion and an elongated member, the elongated member configured to pivot and translate relative to the base portion. In some embodiments, the elongated member has a length sufficient to allow a tip thereof to contact an anatomy disposed about the pelvis at a plurality of discrete spaced apart locations. In some embodiments, the probe assembly includes a second electronic orienting device. In some embodiments, the second electronic orienting device includes at least one inertial sensor. In some embodiments, the first electronic orientation device and the second electronic orientation device are adapted to establish a reference plane based on a direction of gravity and based on a position of the at least one inertial sensor when the tip is in contact with the multiple spaced apart locations.

[0034] In some embodiments, at least one inertial sensor of the first electronic orienting device or at least one inertial sensor of the second electronic orienting device includes an accelerometer. In some embodiments, the reference plane includes an ASIS line. In some embodiments, the first electronic orienting device includes a display configured to provide an indication of a change in an angular position of the second electronic orienting device relative to the reference plane.

[0035] In some embodiments, a hip joint navigation system is provided. The hip joint navigation system can include a jig assembly. The hip joint navigation system can include a first inertial navigation device configured to be rigidly coupled to the jig assembly. The hip joint navigation system can include a landmark acquisition probe configured to be movably coupled to the jig assembly. In some embodiments, the landmark acquisition probe is configured to move with multiple degrees of freedom relative to the jig assembly. The hip joint navigation system can include a second inertial navigation device configured to determine an orientation of the landmark acquisition probe when the landmark acquisition probe is moved to touch an anatomical landmark. In some embodiments, the first inertial navigation device, the second inertial navigation device, or the first inertial navigation device and the second inertial navigation device are configured to adjust for tilt by rotating an anterior pelvic plane about an inter-ASIS line to determine a reference plane.

[0036] In some embodiments, the second inertial device includes a mount device configured to removably connect the second inertial device to the landmark acquisition probe. In some embodiments, the second inertial device includes a camera. In some embodiments, the first inertial navigation device includes a display. In some embodiments, the second inertial navigation is configured to couple to the impactor. The hip joint navigation system can include a universal impactor adapter including a coupler, and the second inertial navigation is configured to couple the impactor with the adapter. In some embodiments, the universal impactor adapter includes a clamp. In some embodiments, the universal impactor adapter includes one or more magnets. The hip joint navigation system can include an optical component. In some embodiments, the optical component is configured to couple to the jig assembly with one or more magnets.

[0037] These and other features, aspects, and advantages are described below with reference to the drawings, which are intended to illustrate, but not to limit, the invention, in which like reference characters indicate corresponding features consistently throughout like embodiments. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a perspective view of a hip navigation system applied to a patient. [Diagram 2] FIG. 2 illustrates an exploded view of an embodiment of a fixed base of the system of FIG. 1. [Figure 3A] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3B] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3C] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3D]2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3E] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3F] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 3G] 2A-2D are various views of an embodiment of a first assembly of the system of FIG. 1. [Figure 4A] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 4B] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 4C] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 4D] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 4E] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 4F] 2A-2D are various views of an embodiment of a second assembly of the system of FIG. 1. [Figure 5A] 2A-2C are various views of an embodiment of an orientation sensing device of the system of FIG. 1. [Figure 5B] 2A-2C are various views of an embodiment of an orientation sensing device of the system of FIG. 1. [Figure 5C] 2A-2C are various views of an embodiment of an orientation sensing device of the system of FIG. 1. [Figure 6A] 1 illustrates an embodiment of an optical component. [Figure 6B] 1 illustrates an embodiment of an optical component. [Figure 6C] 1 illustrates an embodiment of an optical component. [Figure 7] FIG. 1 illustrates a hip navigation system. [Figure 8A] FIG. 8 illustrates an embodiment of a fixed base of the system of FIG. [Figure 8B] FIG. 8 illustrates an embodiment of a fixed base of the system of FIG. [Figure 9] FIG. 8 illustrates an embodiment of a first assembly of the system of FIG. 7. [Figure 10A] FIG. 8 illustrates an embodiment of a second assembly of the system of FIG. 7. [Figure 10B] FIG. 8 illustrates an embodiment of a second assembly of the system of FIG. 7. [Figure 10C] FIG. 8 illustrates an embodiment of a second assembly of the system of FIG. 7. [Figure 10D] FIG. 8 illustrates an embodiment of a second assembly of the system of FIG. 7. [Figure 11] 1A-1C are diagrams illustrating configurations for patient positioning in a posterior approach. [Figure 12A] FIG. 1 illustrates the configuration and manner of connection of the components of the system. [Figure 12B] FIG. 1 illustrates a configuration of a system with a calibration fixture. [Figure 12C] FIG. 1 illustrates an embodiment of a component described herein. [Figure 13A] FIG. 8 illustrates the fixation base and fixation pin of the system of FIG. 7 coupled to a pelvis. [Figure 13B] FIG. 8 illustrates the fixation base and fixation pin of the system of FIG. 7 coupled to a pelvis. [Figure 13C] FIG. 8 illustrates the fixation base and fixation pin of the system of FIG. 7 coupled to a pelvis. [Figure 14A] FIG. 8 illustrates the assembly of the system of FIG. [Figure 14B] FIG. 8 illustrates the assembly of the system of FIG. [Figure 14C] FIG. 8 illustrates the assembly of the system of FIG. [Figure 15A] 8 illustrates adjustment of the system of FIG. 7 including the optical component of FIG. 6A. [Figure 15B] A diagram illustrating the adjustment of the system of FIG. 7 including the optical component of FIG. 6A. [Figure 15C] A diagram illustrating the adjustment of the system of FIG. 7 including the optical component of FIG. 6A. [Figure 16] A diagram illustrating an embodiment of table alignment. [Figure 17A] A diagram illustrating an embodiment of point alignment before cup installation. [Figure 17B] A diagram illustrating an embodiment of point alignment before cup installation. [Figure 18A] A diagram illustrating an embodiment of an impactor including the orientation sensing device of FIGS. 5A - 5C. A diagram illustrating a hip joint prosthesis installation system. [Figure 18B] A diagram illustrating an embodiment of a universal impactor adapter. [Figure 18C] A diagram illustrating an embodiment of a universal impactor adapter. [Figure 18D] A diagram illustrating an embodiment of a universal impactor adapter. [Figure 19A] A diagram illustrating an embodiment of point alignment after cup installation. [Figure 19B] A diagram illustrating an embodiment of point alignment after cup installation. [Figure 19C] A diagram illustrating an embodiment of point alignment after cup installation. [Figure 20A] A diagram illustrating an embodiment of a target probe. [Figure 20B] A diagram illustrating an embodiment of a target probe. [Figure 20C] A diagram illustrating an embodiment of a target probe. [Figure 20D] A diagram illustrating an embodiment of a target probe. [Figure 20E] A diagram illustrating an embodiment of a target probe. [Figure 20F]FIG. 1 illustrates an embodiment of a target probe. [Figure 20G] FIG. 1 illustrates an embodiment of a target probe. [Figure 20H] FIG. 1 illustrates an embodiment of a target probe. [Figure 20I] FIG. 1 illustrates an embodiment of a target probe. [Figure 21] Here is an example of an x-ray that may be taken prior to surgery. [Figure 22] FIG. 2 illustrates the positioning of the patient prior to connection of the system of FIG. 1 in an anterior approach. [Figure 23] FIG. 2 illustrates a configuration of the system of FIG. 1 coupled to a pelvis. [Figure 24] FIG. 1 illustrates the anatomy of the anterior portion of the hip joint, including the pelvis and proximal femur. [Figure 25A] 1A-1D illustrate method steps for identifying the anterior pelvic plane. [Figure 25B] 1A-1D illustrate method steps for identifying the anterior pelvic plane. [Figure 25C] 1A-1D illustrate method steps for identifying the anterior pelvic plane. [Figure 25D] 1A-1D illustrate method steps for identifying the anterior pelvic plane. [Figure 26A] 1 illustrates method steps for identifying a table or other horizontally oriented flat surface. [Figure 26B] 1 illustrates method steps for identifying a table or other horizontally oriented flat surface. [Figure 26C] 1 illustrates method steps for identifying a table or other horizontally oriented flat surface. [Figure 26D] 1 illustrates method steps for identifying a table or other horizontally oriented flat surface. [Figure 27A] FIG. 1 illustrates method steps for calculating an adjusted plane. [Figure 27B] FIG. 1 illustrates method steps for calculating an adjusted plane. [Figure 27C] FIG. 1 illustrates method steps for calculating an adjusted plane. [Figure 27D] FIG. 1 illustrates method steps for calculating an adjusted plane. [Figure 28A] FIG. 1 illustrates a lateral view of the pelvis and its anterior pelvic plane and adjusted planes. [Figure 28B] FIG. 1 illustrates a lateral view of the pelvis and its anterior pelvic plane and adjusted planes. [Figure 28A-1] FIG. [Figure 28B-1] FIG. [Figure 28C] 1 is a top view of these planes. [Figure 29] FIG. 2 illustrates a screen display of the surgical orientation device of the system of FIG. 1. [Figure 30A] FIG. 1 illustrates the neutral position of the pelvis. [Figure 30B] FIG. 2 is a diagram illustrating two tilt positions of the pelvis. [Figure 30C] FIG. 2 is a diagram illustrating two tilt positions of the pelvis. [Figure 31A] FIG. 1 illustrates the neutral position of the pelvis. [Figure 31B] FIG. 2 illustrates two rotational positions of the pelvis. [Figure 31C] FIG. 2 illustrates two rotational positions of the pelvis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Discussed below are various systems and methods that may be used to improve patient outcomes by increasing the likelihood of proper placement of a medical prosthesis. These systems may focus on inertial navigation techniques to establish a reference plane. These systems may focus on inertial navigation techniques to measure leg length and / or joint offset.

[0040] A. Systems for anterior and posterior approaches 1. Hip Navigation System FIGURE 1 illustrates a hip navigation system 600 adapted to navigate a hip procedure with reference to anatomical landmarks. The system 600 is shown mounted on the pelvis in FIGURE 1, which is shown as a box for simplicity. The system 600 may be mounted on the pelvis for a posterior approach, as described herein. The system 600 may be mounted on the pelvis for an anterior approach, as described herein.

[0041] The system 600 can include a fixed base 602, a first assembly 604, and a second assembly 606. The first assembly 604 is rigidly connected to the hip joint or pelvis in the illustrated configuration such that movement of the pelvis causes corresponding movement of sensors in the first assembly 604 as discussed herein. Sensing this movement allows the system 600 to eliminate patient movement as a source of error in navigation. The second assembly 606 provides a full range controlled motion sensor that can coordinate with sensors in the first assembly 604 to track movement. Additional details of the systems, devices, sensors and methods can be found in U.S. patent application Ser. No. 10 / 864,085, filed Jun. 9, 2004; U.S. patent application Ser. No. 11 / 182,528, filed Jul. 15, 2009, which is related to U.S. Patent Application Publication No. 2010 / 0076505; U.S. patent application Ser. No. 12 / 557,051, filed Sep. 10, 2009, which is related to U.S. Patent Application Publication No. 2010 / 0076505; U.S. patent application Ser. No. 12 / 509,388, filed Jul. 24, 2009; U.S. patent application Ser. No. 13 / 011,815, filed Jan. 21, 2011; U.S. patent application Ser. No. 13 / 011,815, filed May 24, 2011; No. 13 / 115,065, issued as U.S. Patent Application No. 8,118,815; U.S. Patent Application No. 14 / 399,046, filed November 5, 2014; U.S. Patent Application No. 14 / 401,274, filed November 14, 2014; U.S. Patent Application No. 13 / 800,620, filed March 13, 2013; U.S. Patent Application No. 14 / 643,864, filed March 10, 2015; and U.S. Patent Application No. 15 / 550,564, filed August 11, 2017, all of which are incorporated herein by reference in their entireties for all purposes.The sensors in the assemblies 604, 606 preferably transfer data between themselves and, in some cases, wirelessly to external devices and monitors using Bluetooth, wifi, or other standard wireless telemetry protocols. The system 600 can include one or more fixation pins 610, 612. The system 600 can also include a surgical orientation device 172 and an orientation sensing device 204, as described herein.

[0042] The system 600 may include a fixed base 602, shown in FIG. 2. FIG. 2 shows an exploded view of the fixed base 602. The fixed base 602 may include a platform 620 and a support 622. The platform 620 may interact with the support 622 and function as a clamp. In the illustrated embodiment, the fixed base 602 may include one or more fixation devices 624, such as screws, etc. The fixation devices 624 may pass through the support 622 and engage corresponding holes in the platform 620.

[0043] The platform 620 and the support 622 form one or more channels therebetween. The number of channels can correspond to the number of fixation pins. As the fixation device 624 rotates, each fixation pin 610, 612 is held between the platform 620 and the support 622. The fixation base 602 can include a divot 630. The divot 630 can be associated with a parked configuration or a home position, as described herein.

[0044] The fixed base 602 can include a first coupler 632. The first coupler 632 can be coupled to one or more components of the system 600. The first coupler 632 can include an elongated post 635. The first coupler 632 can include a slot 634. The slot 634 can be designed to interact with a detent of another component of the system 600, as described herein. The first coupler 632 can include a tapered surface 636. The tapered surface 636 can facilitate entry of the first coupler 632 among other components of the system 600. In some embodiments, the first coupler 632 can have a regular shape (e.g., a cylindrical shape). In some embodiments, the first coupler 632 can have an irregular shape (e.g., a triangular, teardrop, oval, rectangular). The irregular shape can facilitate alignment of other components of the system 600 with the platform 620 of the fixed base 602. In the illustrated embodiment, the other components of the system 600 can mate with the first coupler 632 in a single orientation.

[0045] The system 600 can include a first assembly 604 shown in FIGS. 3A-3G. The first assembly 604 can include a pelvic bracket 638. In the illustrated embodiment, the pelvic bracket 638 can be substantially vertical during use, as shown in FIG. 1. The first assembly 604 can be designed to couple with the fixed base 602. The first assembly 604 can include a locking lever 640 to couple the first assembly 604 with the fixed base 602. In some embodiments, a tapered surface 636 of the first coupler 632 causes the locking lever 640 to pivot. In some embodiments, a surgeon causes the locking lever 640 to pivot. The locking lever 640 can include a detent 642. The detent 642 is sized and shaped to be received within a slot 634. Engagement of the detent 642 and the slot 634 can rigidly couple the first assembly 604 with the fixed base 602.

[0046] The first assembly 604 can include an extension 644. The extension 644 can be coupled to the pelvic bracket 638. The extension 644 can include a second coupler 648. The second coupler 648 can be designed to couple with the second assembly 606. The second coupler 648 provides a stable manner for positioning the second assembly 606 relative to the first assembly 604.

[0047] The extension 644 can include a mount 646 designed to couple with the surgical orientation device 172. When engaged with the mount 646, the surgical orientation device 172 is rigidly coupled to the extension 644. The surgical orientation device 172 can be angled when coupled to the first assembly 604, as shown in FIG. 1. The surgical orientation device 172 can be angled at approximately 35° from the horizontal axis. Other angles from the horizontal axis are also contemplated (e.g., 5°, 10°, 15°, 20°, 25°, 30°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, or 85°, between 30° and 40°, between 25° and 45°). In some embodiments, the angle of the surgical orientation device 172 improves visibility. The angle is a compromise between tilting the surgical orientation device 172 up toward the surgeon and still allowing another surgeon or a surgical assistant on the other side of the patient to see the display. One reason for angling the surgical orientation device 172 is because in an anterior approach, the surgeon stands toward the patient's foot while impacting the acetabular implant and may have difficulty seeing on a horizontally oriented display.

[0048] The surgical orientation device 172 detects the orientation and rotation of the device 172 relative to a coordinate reference system. The surgical orientation device 172 preferably includes at least one sourceless sensor, such as an accelerometer, a gyroscope, or a combination of these and other sensors. In some embodiments, the surgical orientation device 172 includes a three-axis accelerometer for detecting orientation relative to gravity and multiple gyroscopes for detecting rotation. Other sensors can be used in various modifications. Examples of specific sensor combinations include the Analog Devices ADIS 16445 and Invensense MPU-6050 or MPU-9150, among others. In some approaches, the surgical orientation device 172 can be disposable, and thus the sensor is preferably a less expensive sensor. In some embodiments, the surgical orientation device 172 is disposable.

[0049] The surgical orientation device 172 includes one or more sensors that together form an inertial measurement unit (IMU). Among other things, the IMU can include a first sensor for determining acceleration and a second sensor for determining gyroscopic positioning. As discussed herein, the first sensor can be an accelerometer and the second sensor can be a gyro sensor. In some embodiments, the sensors can include a three-axis gyro sensor and a three-axis accelerometer sensor. The surgical orientation device 172 can include a transmitter for transmitting data to or receiving data from one or more sensors of the system 600, such as one or more sensors of the orientation sensing device 204. Information received from the orientation sensing device 204 can be fed to an input port, or alternatively, the electronic control unit can receive the information itself (e.g., wirelessly). Information from the orientation sensing device 204 may, for example, correspond to the position and / or orientation of the orientation sensing device 204 and may be used by the surgical orientation device 172 to determine the collective or overall position and / or orientation of the surgical orientation device 172.

[0050] The system 600 can include a second assembly 606 shown in FIGS. 4A-4F. The second assembly 606 can include a probe bracket 652. In the illustrated embodiment, the probe bracket 652 can be substantially angled relative to the pelvic bracket 638 during use, as shown in FIG. 1. The second assembly 606 can be designed to couple with the second coupler 648 of the first assembly 604. The second assembly 606 can include a lock lever 654. The lock lever 654 can be coupled to the probe bracket 652 by a pivot pin. The lock lever 654 can be pivoted relative to the probe bracket 652. In some embodiments, a tapered surface of the second coupler 648 causes the lock lever 654 to pivot. In some embodiments, the surgeon causes the lock lever 654 to pivot. The lock lever 654 can include a detent 656. The detent 656 is sized and shaped to be received within a slot of the second coupler 648. Engagement of the detent 656 and the slot can rigidly couple the second assembly 606 to the first assembly 604.

[0051] In the illustrated embodiment, the second assembly 606 includes a mount 658. The mount 658 can be coupled to the probe bracket 652 to allow for relative movement therebetween. The mount 658 can be received within an opening in the probe bracket 652. The mount 658 can allow for rotation about a longitudinal axis of the mount 658 relative to the probe bracket 652.

[0052] The second assembly 606 can include a dock 662. The dock 662 can be coupled to the mount 658 to allow for relative movement therebetween. The dock 662 can be coupled to the mount 658 by one or more pivot pins 660. The dock 662 can have two degrees of freedom with respect to the probe bracket 652 (e.g., rotational and pivotal movement). The dock 662 can include a sliding support with a through lumen 664. The through lumen 664 is sized to receive a probe 678. The probe 678 has a distal end 680 designed to touch a point or one or more locations as described herein. The distal end 680 can be straight, as shown in FIG. 4A. In other embodiments, the distal end 680 is beveled or curved.

[0053] A through lumen 664 of the dock 662 allows for slidable extension of the probe 678. The dock 662 is movable relative to the probe bracket 652 (e.g., via rotation of the mount 658 and pivoting of the pivot pin 660). The dock 662 can be rotated about the longitudinal axis of the mount 658 to different rotational positions relative to the attachment locations of the fixed pins 610, 612. This may require movement of the mount 658 in a rotational manner relative to the probe bracket 652. The dock 662 can be pivoted about the longitudinal axis of the pivot pin 660 to different positions relative to the attachment locations of the fixed pins 610, 612. This may require movement of the dock 662 in a pivotal manner relative to the mount 658.

[0054] The probe 678 may be coupled to the dock 662 such that the probe 678 is movable relative to the probe bracket 652 (e.g., via rotation of the mount 658 and pivoting of the pivot pin 660). This maneuverability allows the distal end 680 of the probe 678 to pivot or rotate to contact anatomical landmarks as discussed herein. The probe 678 may be slid relative to the dock 662 to different translational positions relative to the attachment locations of the fixation pins 610, 612. The slidability of the probe 678 within the dock 662 allows the distal end 680 to move to reach points or anatomical landmarks that are in the same plane of the probe 678 but closer to or further from the distal end 680.

[0055] The second assembly 606 allows the range of motion of the distal end 680 of the probe 678 to facilitate acquiring points that are spaced apart from the attachment locations of the fixed pins 610, 612. The second assembly 606 allows the range of motion of the distal end 680 of the probe 678 to facilitate acquiring multiple landmarks that are different distances from the attachment locations of the fixed pins 610, 612. In other words, the distal end 680 of the probe 678 can be extended away from the axis of the sliding support of the dock 662 or retracted to a position closer to the axis of the sliding support of the dock 662.

[0056] The dock 662 can include a third coupler 668. In some embodiments, the third coupler 668 is a universal coupler. In some embodiments, the third coupler 668 is the same as or substantially similar to the second coupler 648. This allows the orientation sensing device 204 to couple to either the second coupler 648 or the third coupler 668 as described herein. In some embodiments, the third coupler 668 can be substantially similar to the first coupler 632 as described herein. The third coupler 668 can be designed to couple with the orientation sensing device 204. FIGS. 5A-5C illustrate an embodiment of the orientation sensing device 204. The second assembly 606 can include an extension 670. The extension 670 can be coupled to the third coupler 668 of the dock 662. The engagement between the third coupler 668 and the extension 670 minimizes or prevents relative movement therebetween to avoid any mechanical relative movement during a navigation procedure. The extension 670 can include a mount 672 designed to couple with the orientation sensing device 204. In the illustrated embodiment, the mount 672 includes a lock and release lever, which can pivot relative to the extension 670. The orientation sensing device 204 can include features to mate with the lock and release lever. Other configurations are also contemplated. The orientation sensing device 204 is rigidly coupled to the extension 670 when engaged with the mount 672.

[0057] The orientation sensing device 204 may be angled when coupled to the second assembly 606, as shown in FIG. 1. The orientation sensing device 204 may be angled at approximately 35° from the horizontal axis. Other angles from the horizontal axis are also contemplated (e.g., 5°, 10°, 15°, 20°, 25°, 30°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, or 85°, between 30° and 40°, between 25° and 45°). In some embodiments, the angle of the orientation sensing device 204 improves visibility.

[0058] The orientation sensing device 204 detects the orientation and rotation of the probe 678 as described herein. The orientation sensing device 204 preferably includes at least one sourceless sensor, such as an accelerometer, a gyroscope, or a combination of these and other sensors. In some embodiments, the orientation sensing device 204 includes a three-axis accelerometer for detecting orientation relative to gravity and multiple gyroscopes for detecting rotation. Other sensors may be used in various modifications. In some embodiments, the orientation sensing device 204 is reusable.

[0059] 4A and 4C, the probe 678 may include markings 682. The markings 682 may indicate a length or extension of the probe 678 relative to the dock 662. The markings 682 may include a scale. In some embodiments, the markings 682 may be present over a range of about 8 inches, 10 inches, 12 inches, approximately 8-12 inches, etc. The markings 682 may be printed on the probe 678. In some embodiments, the markings 682 may be a separate component, such as a probe inlay 676. The probe inlay 676 may be received within a portion of the probe 678. In some embodiments, the probe inlay 676 is separated from a distal end 680 of the probe 678 by a predetermined distance.

[0060] 5A-5C, the orientation sensing device 204 can include a camera 184. The camera 184 can capture an image of the markings 682. In some embodiments, the dock 662 includes a window to allow the camera 184 to capture the image. The camera 184 can read the markings 682 and provide an accurate determination of the translational position of the probe 678 relative to the dock 662. In another embodiment, the camera data derived from the markings 682 can be used to confirm data from a sensor in the orientation sensing device 204.

[0061] 2.Optical components In some methods of use, system 600 includes optical component 174, shown in FIG. 6A. In some embodiments, optical component 174 is integrated into the surgical orientation device. In some embodiments, optical component 174 can be a separate component from surgical orientation device 172. Optical component 174 can be located below surgical orientation device 172, adjacent to a fixture that will be coupled with the patient, for example, closer to the patient's pelvis. Optical component 174 can be located beside, adjacent to, or above surgical orientation device 172. A display on surgical orientation device 172 can include instructions on how to use optical component 174.

[0062] In some embodiments, the optical component 174 can include a housing. The optical component 174 can include one or more light sources within the housing of the optical component 174. The optical component 174 can include one or more windows that allow light to project outwardly from the optical component 174. The optical component 174 can include one or more additional optical components, such as one or more lenses, one or more reflectors, one or more filters, one or more diffractors, and / or one or more diffusers. The optical component 174 can include one or more energy sources for providing energy to the light sources. The optical component 174 can include any feature of the surgical orientation device 172 and / or the orientation sensing device 204 described herein.

[0063] In some embodiments, the optical component 174 is coupled to the system 600. In some embodiments, the optical component 174 is coupled to the first assembly 604. In some embodiments, the optical component 174 may be rotated, pivoted, or otherwise moved relative to the first assembly 604. The system 600 may include additional features to facilitate positioning of the optical component 174 relative to the first assembly 604. The optical component 174 may include a bracket 176. The bracket 176 may facilitate a connection between the optical component 174 and another component of the system 600. In some embodiments, the bracket 176 may be a housing for a laser or other light source as described herein. The optical component 174 may include one or more features to enable independent adjustment of the optical component 174. The optical component 174 may include an adjustment mechanism 178. The adjustment mechanism 178 may rotate the optical component 174 relative to the first assembly 604. The adjustment mechanism 178 can rotate the optical component 174 relative to the second assembly 606. The adjustment mechanism 178 can rotate the optical component 174 relative to the fixed base 602. The adjustment mechanism 178 can rotate the optical component 174 relative to the pelvis. The adjustment mechanism 178 can be a knob. The adjustment mechanism 178 can be coupled to an axle and can rotate the optical component 174 about the axle. The adjustment mechanism 178 can be coupled to a bracket 176 and can rotate the bracket 176. The bracket 176 can include a sleeve or tubular portion designed to fit around the axle of the adjustment mechanism 178. In some embodiments, the optical component 174 is independently coupled to the patient's bone. The optical component 174 can be coupled to the pelvis. Other configurations of the optical component are also contemplated (see FIG. 12C).

[0064] 6B-6C illustrate another embodiment of the optical component 194. The optical component 194 can include one or more magnets 196. The one or more magnets 196 can be located on a surface of the optical component 194. The one or more magnets 196 can be disposed in or on the housing 200 of the optical component 194. In some embodiments, the optical component 194 can include one magnet, two magnets, three magnets, four magnets, etc. In some embodiments, the optical component 194 can include one or more magnets on a first surface 202 and one or more magnets on a second surface 204. The first surface 202 can be located opposite the second surface. In some embodiments, the optical component 194 can include one or more magnets on an opposite side of the optical component 194. In some embodiments, the one or more magnets 196 on either side of the optical component 194 can enable the optical component 194 to be coupled with any other component of the system disclosed herein on either side of the optical component 194.

[0065] In some embodiments, the optical component 194 is coupled to the system 600. In some embodiments, the optical component 194 is coupled to the first assembly 604. In some embodiments, the first assembly 604 can include one or more magnets 198. The one or more magnets 198 can be located on a surface of the first assembly 604. The one or more magnets 198 can be disposed in or on an outer flat surface of the first assembly 604. In some embodiments, the first assembly 604 can include one magnet, two magnets, three magnets, four magnets, etc. In some embodiments, the first assembly 604 includes one or more magnets 198 on a first surface and one or more magnets 198 on a second surface. In some embodiments, the first assembly 604 can include one or more magnets on both sides of the first assembly 604. In some embodiments, the optical component 194 can be coupled to either side of the first assembly 604. The one or more magnets 198 of the first assembly 604 can correspond in number, size, shape, and / or pattern to the one or more magnets 196 of the optical component 194. The one or more magnets 196 of the optical component 194 can be configured to attract and couple to the one or more magnets 198 of the first assembly 604. In some embodiments, the first assembly 604, or a portion thereof, includes a magnetic material. In some embodiments, the entire first assembly 604 is magnetic. In some embodiments, the one or more magnets 198 can be configured to attract a magnetic material disposed on or in a housing of the optical component 194. Thus, magnets can be positioned in or on the optical component 194, in or on the first assembly 604, or in or on both the component 194 and the assembly 604.

[0066] In some embodiments, the optical component 194 may be held in place relative to the first assembly 604 by one or more magnets 196, 198. In some embodiments, the optical component 194 may be removably coupled to and decoupled from the system 600. In some embodiments, the optical component 194 may allow for independent rotational adjustment of the optical component 194 relative to the system 600. In some embodiments, the optical component 194 may be connected to the system 600 in a single orientation. In some embodiments, the optical component 194 may be connected to the system 600 in one of a number of orientations. In some embodiments, the optical component 194 may be connected to the system 600 on either side of the first assembly 604. As described herein, the optical component 194 may include one or more magnets 196 on both sides of the optical component 194. The first assembly 604 may include one or more magnets 198 or magnetic surfaces on both sides of the first assembly 604.

[0067] In some embodiments, the optical component 194 and the first assembly 604 can include one or more mounting mechanisms 190, 192. The mounting mechanisms 190, 192 can include one or more recesses 190 and one or more protrusions 192. In some embodiments, the first assembly 604 can include one or more protrusions 192 and the optical component 194 can include one or more corresponding recesses 190. In some embodiments, the first assembly 604 can include two protrusions 192 and the optical component 194 can include two or more recesses 190. In the illustrated embodiment, the first assembly 604 includes two protrusions 192 and the optical component 194 includes three recesses 190. The two protrusions 192 can engage two of the recesses 190 in the first configuration and can engage two of the recesses in the second configuration. In an embodiment including three recesses 190 and two protrusions 192, one of the recesses 190 is engaged in both the first and second configurations. The first and second configurations can tilt the optical component 194 relative to the first assembly 604. Other configurations are contemplated (e.g., one protrusion, two protrusions, three protrusions, four protrusions, etc.) and (e.g., one recess, two recesses, three recesses, four recesses, five recesses, six recesses, etc.). In some embodiments, there are more recesses 190 than protrusions 192. The mounting mechanism 190, 192 can reduce or limit rotation between the optical component 194 and the first assembly 604. The mounting mechanism 190, 192 can facilitate alignment between the optical component 194 and the first assembly 604. The mounting mechanism 190, 192 can facilitate connection between the optical component 194 and the first assembly 604. The one or more magnets 196 of the optical component 194 may allow for quicker and easier installation into the system 600 .The one or more magnets 196 of the optical component 194 can enable a magnetic snap-on connection. In other embodiments, the polarity of the magnets 196 and / or magnets 198 can be configured such that only one or two relative positions of the optical component 194 and the assembly 604 result in an attractive force and magnetic locking therebetween. Other types of connections between the optical components and the systems described herein are also contemplated.

[0068] In some embodiments, the optical components 174, 194 can be positioned in any one of a number of discrete positions relative to the first assembly 604. For example, the system 600 can include a number of splines between the optical components 174, 194 and an adjacent structure. The splines can be sawtooth plates. The adjacent structure can be coupled to the first assembly 604. The splines can hold the position of the optical components 174, 194 relative to the first assembly 604. In some embodiments, the optical components 174, 194 can be oriented in an infinite number of positions relative to the first assembly 604. In some embodiments, the optical components 174, 194 can be oriented in a predetermined selected position along a series of movements. In some embodiments, the optical components 174, 194 can be oriented in one discrete position or orientation relative to the first assembly 604. In some embodiments, the optical components 174, 194 can be oriented in two discrete positions or orientations relative to the first assembly 604. In some embodiments, the optical components 174, 194 may be oriented in one discrete position or orientation on each side of the first assembly 604. In some embodiments, the optical components 174, 194 may be oriented in multiple discrete positions or orientations relative to the first assembly 604. The connection between the optical components 174, 194 and the first assembly 604 is sufficiently rigid to maintain the position of the optical components 174, 194 relative to the first assembly 604 once moved into the appropriate position.

[0069] As described herein, in some methods of use, the optical components 174, 194 may be attached to the patient's pelvis. In some embodiments, the optical components 174, 194 may be attached to any component of the system 600. In some embodiments, the optical components 174, 194 may be attached to the platform 602. In some embodiments, the optical components 174, 194 may be attached to the first assembly 604. In some embodiments, the optical components 174, 194 may be separately attached to the pelvis. In some methods of use, the optical components 174, 194 may be independently attached to the patient's pelvis. In some methods of use, the optical components 174, 194 may be spaced apart from the system 600. In some methods of use, the optical components 174, 194 may be fixed in a suitable position relative to the pelvis during a surgical procedure. In some methods of use, the optical components 174, 194 may project light from the same position during a surgical procedure. The rigidity of the system 600 can fix the position of the optical components 174, 194 once they are moved into the appropriate position. In some methods of use, the optical components 174, 194 can be positioned and / or moved until the optical components 174, 194 project light onto a selected portion of the anatomical structure. In some methods of use, the optical components 174, 194 can be positioned and / or moved until the optical components 174, 194 project light onto a target probe, as described herein. In some methods of use, the optical components 174, 194 can be positioned and / or moved until the optical components 174, 194 project light onto a sterile wrap, medical drape, bandage, tape, and / or other instrument. In some methods of use, the optical components 174, 194 can be positioned and / or moved until the optical components 174, 194 project light onto a device coupled to the anatomical structure.In some methods of use, the optical components 174, 194 can be positioned and / or moved until the optical components 174, 194 project light onto a device placed near the anatomy as described herein.

[0070] The optical components 174, 194 can emit a pattern of light. Examples of a pattern of light include one or more lines, one or more points, one or more planes, or one or more shapes. The optical components 174, 194 can be moved until the light is projected onto at least one anatomical region. In some methods of use, the light is projected onto at least one anatomical region having a small soft tissue. The soft tissue can be moved relative to the underlying bone. The surgeon can select a location for irradiating where the skin is near the underlying bone. In some methods of use, the optical components 174, 194 can project a pattern onto a portion of the anatomical structure. In some methods of use, the optical components 174, 194 can project a pattern onto a target that is coupled to the anatomical structure. The surgeon can complete any method steps described herein. The optical components 174, 194 can then project the same pattern onto the selected portion of the anatomical structure.

[0071] In some embodiments, the optical components 174, 194 can project light onto an anatomical surface. In some embodiments, the optical components 174, 194 can project light onto an anatomical feature or landmark. The light can illuminate a portion of the femur. The light can illuminate a portion of the knee joint. The light can illuminate a portion of the tibia. The light can illuminate a portion of the ankle. The light can illuminate a portion of the foot. The light can illuminate a portion of the foot constrained in a positioning boot. In some embodiments, the light can be projected onto a localized area that is flat or substantially flat. In some embodiments, the light can be projected onto a localized area that is curved or substantially curved. In some methods of use, the shape of the surface does not change the projection of the light, e.g., changes in angle, tilt, shape, etc. In some methods of use, the shape of the surface does not change the projection of the light. In some methods of use, the shape of the surface does not change the utility of the approach as described herein.

[0072] In this context, optical component is a broad term. The optical component 174, 194 can be any device designed to project light, including visible, ultraviolet, and infrared light. The optical component 174, 194 can include one or more lasers, which can be configured to project laser light. A laser can emit light with a very narrow spectrum, for example, light of a single color. The optical component 174, 194 can focus the light onto a single location, such as a point. The optical component 174, 194 can focus the light along a line. The optical component 174, 194 can project one or more points, one or more lines, one or more planes, one or more shapes, one or more colors, and / or one or more patterns. In some embodiments, the projection of light when incident on a surface can be seen as two intersecting lines, which pattern can be referred to herein as a crosshair.

[0073] The optical components 174, 194 may be positioned to project light toward a desired location. The optical components 174, 194 may provide a visual guide to recreate an original position of an anatomical feature relative to another anatomical feature, as described herein. In a manner in which the optical components 174, 194 are attached to the pelvis, the optical components 174, 194 may provide a visual guide to recreate an original position of a leg or portion of a leg relative to the hip joint. In some embodiments, the optical components 174, 194 may provide a visual guide to recreate an original position of a femur relative to the pelvis, as described herein. The optical components 174, 194 may provide alternative or additional orientation information to the surgeon regarding the position on the pelvis relative to the femur. In a manner in which the optical components 174, 194 are attached to the pelvis, the optical components 174, 194 may provide a visual guide to recreate an original position of a leg or portion of a leg relative to the hip joint. In some embodiments, the optical components 174, 194 can provide a visual guide to recreate the original orientation of the femur relative to the pelvis, as described herein. The optical components 174, 194 can provide alternative or additional orientation information to the surgeon regarding the orientation of the pelvis relative to the femur.

[0074] The optical components 174, 194 may be used to perform one or more methods or method steps. In some methods of use, the optical components 174, 194 may project a pattern of light pre-surgery. In some methods of use, the optical components 174, 194 may project a pattern of light prior to cup placement. In some methods of use, the optical components 174, 194 may project a pattern of light prior to joint replacement. In some methods of use, the optical components 174, 194 may project a pattern of light prior to joint dislocation. In some methods of use, the optical components 174, 194 may project a pattern of light that may be tracked. In some methods of use, the optical components 174, 194 may project a pattern of light after cup placement. In some methods of use, the optical components 174, 194 may project a pattern of light after instrumentation. In some methods of use, the optical components 174, 194 can project a pattern of light that can align with the markings as the femur is being moved. In some methods of use, the optical components 174, 194 can project a pattern of light onto the same surface before and after the cup is replaced. In some methods of use, the optical components 174, 194 can project a pattern of light onto the same surface intraoperatively. In some methods of use, the optical components 174, 194 can project a pattern of light onto the same surface intraoperatively more than once during a procedure.

[0075] 3. Alternative Hip Navigation Systems Figure 7 illustrates a hip joint navigation system 700. Figures 8A-8B illustrate an embodiment of a fixed base 702 of the system 700 of Figure 7. Figure 9 illustrates an embodiment of a first assembly 704 of the system 700 of Figure 7. Figures 10A-10D illustrate an embodiment of a second assembly 706 of the system 700 of Figure 7.

[0076] System 700 includes any of the features described herein with respect to system 600. Like elements are provided with like reference numerals. System 700 may include a fixed base 702, a first assembly 704, and a second assembly 706. System 700 may include a surgical orientation device 172 and an orientation sensing device 204. Orientation sensing device 204 may include a camera 184 as shown in FIG. 5A. System 700 may include an optical component 174 as shown in FIG. 6A and / or an optical component 194 as shown in FIGS. 6B-6C. Optical component 174 may include one or more of the following features: a bracket 176 and an adjustment mechanism 178 (see FIG. 6A). Optical component 194 may include one or more of the following features: one or more magnets 196 and one or more mounting mechanisms 190, 192 (see FIGS. 6B-6C).

[0077] 8A-8B, the fixation base 702 may include one or more of the following: a platform 720, a support 722, one or more fixation devices 724, a divot 730, and a first coupler 732 with a slot 734 and a tapered surface 736. The system 700 may include one or more fixation pins, such as fixation pin 710 and fixation pin 712 (see FIGS. 13A-13C).

[0078] Referring to FIG. 9, the first assembly 704 may include one or more of the following: a pelvic bracket 738, a locking lever 740, a detent 742 sized and shaped to be received within the slot 734 (see FIG. 3A for similar detent 642), an extension 744, a second coupler 748, and a mount 746 designed to couple with the surgical orientation device 172.

[0079] 10A-10B, the second assembly 706 can include one or more of the following: a probe bracket 752, a locking lever 754, a detent 756 (see FIG. 4A for similar detent 656), a mount 758 to allow rotation about a longitudinal axis of the mount 758 relative to the probe bracket 752, a dock 762 coupled to the mount 758, a through lumen 764 sized to receive a probe 778, a third coupler 768, an extension 770 (see FIG. 7), and a mount 772 (see FIG. 7). The orientation sensing device 204 can be coupled to either the second coupler 748 or the third coupler 768. With reference to FIGS. 10C-10D, the system 700 can include a probe 778. The probe 778 may include one or more of the following: a distal end 780 designed to touch a point, markings 782, and a probe inlay 776.

[0080] System 700 can include additional features from system 600 described herein. System 600 can include one or more of these additional features. Referring back to FIGS. 8A-8B , platform 720 can include an articulation joint 726. Articulation joint 726 can allow movement between platform 720 and first assembly 704. Articulation joint 726 can form a ball and socket joint with platform 720. Articulation joint 726 can include a head 728. Head 728 can interact with platform 720 to form a joint. In the illustrated embodiment, platform 720 includes a socket.

[0081] The articulation joint 726 can include a first coupler 732. The first coupler 732 can be coupled to one or more components of the system 700. In some embodiments, the first coupler 732 is a universal coupler. The first coupler 732 can include an elongated post 735. In some embodiments, the first coupler 732 can have a regular shape (e.g., cylindrical). In some embodiments, the first coupler 732 can have an irregular shape (e.g., triangular, teardrop, oval, rectangular). The irregular shape can facilitate alignment of other components of the system 700 with the platform 720 of the fixed base 702. In the illustrated embodiment, the other components of the system 700 can mate with the first coupler 732 in a single orientation. The articulation joint 726 can include a divot 730. The divot 730 can be associated with a parked configuration or home position as described herein.

[0082] The fixed base 702 can include a platform 720 and a support 722. The platform 720 can interact with the support 722 and function as a clamp. In the illustrated embodiment, the fixed base 702 can include one or more fixation devices 724. In the illustrated embodiment, the fixed base 702 includes two fixation devices 724. The fixation devices 724 can pass through the support 722 and engage corresponding holes in the platform 720. As the fixation devices 724 advance, the respective fixation pins 710, 712 are clamped between the platform 720 and the support 722. In some embodiments, the fixation devices 724 are screws, although other configurations are contemplated for clamping the platform 720 and the support 722.

[0083] The articulation joint 726 may be locked in position. The fixed base 702 may include a lock 727. The lock 727 may be advanced against the head 728 to reduce, limit, or prevent movement of the articulation joint 726. The lock 727 may include a fastener, such as a screw or the like. In some embodiments, the lock 727 may include a contact surface 729. The fastener may be rotated or translated to advance the contact surface 729 relative to the platform 720. The contact surface 729 may be moved away from the head 728 to allow the head 728 to articulate with the platform 720. The contact surface 729 may be moved towards the head 728 to apply a force or pressure to the head 728. The contact surface 729 may be moved towards the head 728 to press the head 728 against a surface of the platform 720. The force or pressure of the contact surface of the lock 727 against the head 728 may reduce movement of the head 728. Other configurations for reducing or preventing joint movement are also contemplated.

[0084] The articulation joint 726 is illustrated as a ball and socket joint. The articulation joint 726 can be any joint known in the art. The articulation joint 726 can include a shaft, a sleeve, a bearing, a bushing, and / or a swivel. The articulation joint 726 can be any joint or connection that allows movement about one or more planes or axes. Once moved into position, the articulation joint 726 can be sufficiently rigid to maintain the position of the first assembly 704 relative to the platform 720. Other configurations are contemplated.

[0085] In some methods of use, the fixed base 702 is attached to a pelvis as described herein. The position of the pelvis bracket 738 of the first assembly 704 may be adjusted via the articulation joint 726. The position of the extension 744 of the first assembly 604 may be adjusted via the articulation joint 726. The optical components 174, 194 may be coupled to the first assembly 604 as described herein. The position of the optical components 174, 194 may be adjusted via the articulation joint 726. In some embodiments, the position of the optical components 174, 194 is determined in part by the position of the articulation joint 726. The system 700 can have additional features for positioning the optical components 174, 194 as described herein. In other embodiments, the position of the optical components 174, 194 is determined entirely by the position of the articulation joint 726.

[0086] 10A-10D, the second assembly 706 or a portion thereof, such as, for example, the probe 778, may be easily removed when not in use. The distal end 780 of the probe 778 may be angled, bent, or curved to facilitate acquiring a point. The distal end 780 of the probe 778 may be bent or curved to reach a home position. The shape of the probe 778 may facilitate touching a point or structure in a posterior approach. In some embodiments, the probe 778 includes two or more components. In some embodiments, the distal end 680 is removable.

[0087] The second assembly 706 can include a dock 762. The dock 762 can be coupled to the mount 758 to allow for relative pivotal movement therebetween. For example, the dock 762 can be coupled to the mount 758 by one or more pivot pins 760. The dock 762 can have two degrees of freedom with respect to the probe bracket 752 (e.g., rotational and pivotal movement). The dock 762 can include a sliding support with a through lumen 764. The through lumen 764 is sized to receive a probe 778. The probe 778 has a distal end 780 designed to touch a point, as described herein. The distal end 780 can be beveled or curved. This maneuverability allows the distal end 780 of the probe 778 to pivot, rotate, or slide to touch a point, as discussed herein.

[0088] The through lumen 764 of the dock 762 allows for slidable extension of a probe 778. The probe 778 is able to slide relative to the dock 762 to different translational positions relative to the attachment locations of the fixed pins 710, 712. The slidability of the probe 778 within the dock 762 allows the distal end 780 to move to reach points that are offset from the plane of the probe 778 but closer to or further from the distal end 780.

[0089] The second assembly 706 can include a lock 766. The lock 766 can be advanced against the probe 778 to reduce, limit, or prevent movement of the probe 778. The lock 766 can include a fastener, such as a screw or the like. In some embodiments, the lock 766 includes a contact surface 767. In some embodiments, the contact surface 767 can be an end of a fastener. The fastener can be rotated or translated to advance the contact surface 767 relative to the dock 762. The contact surface 767 can be moved away from the probe 778 to allow the probe 778 to slide through the dock 762. The contact surface 767 can be moved towards the probe 778 to apply a force or pressure to the probe 778. The contact surface 767 can be moved towards the probe 778 to press the probe 778 against a surface of the dock 762. The force or pressure of the contact surface 767 of the lock 766 against the probe 778 can reduce movement of the probe 778. The lock 766 can limit or reduce the slidability of the probe 778 relative to the dock 762. In some methods of use, the probe 778 can still pivot (e.g., pivotal movement between the dock 762 and the mount 758). In some methods of use, the probe 778 can still rotate (e.g., rotational movement between the mount 758 and the probe bracket 752). The lock 766 can reduce the slidability when the points are aligned as described herein.

[0090] The system 700 may be utilized in a posterior approach as described herein.The system 700 may be utilized in an anterior approach as described herein.

[0091] B. Navigation for cup placement via posterior approach 1. Method for the posterior approach 1-10D illustrate hip navigation systems 600, 700 adapted to navigate a hip procedure from a posterior approach. Although the method is described with respect to system 700, any of the systems described herein or in the following publications may be utilized: U.S. Patent Application Publication No. 2016 / 0242934, filed March 10, 2015; U.S. Patent Application Publication No. 2014 / 0052149, filed March 13, 2013; and U.S. Patent Application Publication No. 2010 / 0137871, filed September 10, 2009, all of which are incorporated by reference in their entirety.

[0092] In some methods of cup placement in total hip replacement, the inclination and anteversion angles are relative to the anterior pelvic plane (defined as the plane generated by the two anterior superior iliac spines (ASIS) and the pubic symphysis). Although these anatomical features are visible / palpable while the patient is in the supine position, the majority of total hip replacements are accomplished via a posterolateral approach with the patient in some variation of the lateral position, in which most of these landmarks are not accessible or visible. Historically, navigation for posterior approach hip replacements was accomplished by aligning the anatomical features of the anterior pelvic plane with the patient first in the supine position, and once this plane is recorded by the navigation computer, the patient is moved to the lateral position and navigation is performed directly with respect to the aligned anterior pelvic plane to perform the hip surgery. This approach to hip navigation is suboptimal in terms of surgical workflow. The reason is that excessive patient movement from supine to lateral positions requires more surgeon and staff time, destroys sterility, and requires re-draping, which is one of the key reasons why hip navigation has not been adopted by most of the market.

[0093] Additionally, altered leg length is a common patient complaint resulting from hip replacement surgery and a common cause of malpractice lawsuits resulting from hip replacement. Because parts of the hip replacement procedure require precise measurement of the patient's leg length and joint offset, which are often difficult to visualize utilizing traditional instrumentation, an opportunity exists to improve surgeons' performance of these measurements using computer technology.

[0094] Most hip replacement procedures are currently performed from a posterior approach, in which the patient is positioned in a lateral decubitus position with the anterior pelvic plane oriented vertically, e.g., perpendicular to the plane of the table on which the patient is positioned. Most surgeons who perform hip replacements are very familiar with this approach and will immediately recognize the benefit of the enhanced certainty regarding the orientation of the relevant anatomy when the patient is in this position.

[0095] As discussed herein, the method of use can include using the probe 778 and the sensor 204 to estimate the horizontal plane of the surgical table on which the patient rests. As discussed herein, the method of use can include using the probe 778 and the sensor 204 to estimate the vertical plane utilizing a measurement of gravity. The system 700 can establish a coordinate reference system to guide cup placement without aligning landmarks. The system 700 can measure leg length and / or joint offset in the established coordinate reference system.

[0096] FIG. 11 illustrates an embodiment of patient positioning for a posterior hip approach. In a posterior hip approach, the patient may be placed in a lateral decubitus position. In some methods of use, the patient may be placed in a lateral decubitus position. When positioning the patient prior to surgery, the surgeon may align the anterior pelvic landmarks (both the ASIS landmarks and the pubic tubercle landmarks) in a vertical plane parallel to the long edge of the surgical table. In some methods of use, when positioning the patient prior to surgery, the surgeon may align the anterior pelvic landmarks (both the ASIS landmarks and the pubic tubercle landmarks) in a vertical plane perpendicular to the surface of the table. In some methods of use, when positioning the patient prior to surgery, the surgeon may align the anterior pelvic landmarks (both the ASIS landmarks and the pubic tubercle landmarks) in a vertical plane parallel to gravity. In some methods of use, when positioning the patient prior to surgery, the surgeon may align the anterior pelvic plane parallel to gravity. In some methods of use, when positioning the patient prior to surgery, the surgeon can align the anterior pelvic plane vertically. The surgeon can ensure that the pelvis is held securely by an appropriate positioning device, such as a pegboard or a vice-type patient positioner. The surgeon can verify that the patient is positioned in the proper position for the posterior approach. Correct patient positioning is important for accurate navigation. In some methods of use, the system 700 calculates the cup angle based on the assumption that the pelvis is correctly positioned during table alignment. In some methods of use, the system 700 calculates the cup angle based on the assumption that the anterior pelvic plane is vertical during a posterior procedure.

[0097] The surgical orientation device 172 and the orientation sensing device 204 may be turned on before the procedure begins. If the system may be used in a knee or hip procedure, a method may require the surgeon to select the module that corresponds to the hip joint. If the system may be used in a posterior or anterior approach, a method may require the surgeon to select the module that corresponds to the posterior approach. The surgical orientation device 172 may include a display screen. The surgical orientation device 172 may include a user interface, such as a button that may be pressed by a user. The display screen may confirm communication between the surgical orientation device 172 and the orientation sensing device 204.

[0098] The system 700 may be partially assembled for calibration. Although the system 600 is shown in FIG. 12A, the system 700 may be coupled in a similar manner. In some embodiments, the first assembly 604, 704 may be assembled. The pelvic bracket 638, 738 may be coupled to the extension 644, 744 if it is a separate component. The surgical orientation device 172 may be coupled to the mount 646, 746. In some techniques, the extension 670, 770 may be coupled to the second coupler 648, 748. The orientation sensing device 204 may be coupled to the mount 672, 772. The surgical orientation device 172 and the orientation sensing device 204 form a generally V-shaped configuration, similar to the orientation shown in FIG. 12A. The orientation sensing device 204 may be fixed in an appropriate position relative to the surgical orientation device 172.

[0099] In some methods of use, the probe 778 may be calibrated. The extension 770 may be decoupled from the second coupler 748. The second assembly 706 may be assembled as shown in FIG. 12B. The first assembly 704 may be coupled to the second assembly 706 as shown in FIG. 12B. In some methods of use, the system 700 may include a calibration fixture 790. The first assembly 704 and the second assembly 706 may be mounted in the calibration fixture 790. The calibration fixture may include multiple points for the probe 778 to contact.

[0100] In some methods of use, the probe 778 can contact a center hole in the base of the calibration fixture 790 to calibrate a center point. A user can press a button when the probe 778 is placed. In some methods of use, the probe 778 can contact a left hole in the base of the calibration fixture 790 to calibrate a left point. A user can press a button when the probe 778 is placed. In some methods of use, the probe 778 can contact a right hole in the base of the calibration fixture 790 to calibrate a right point. A user can press a button when the probe 778 is placed. The calibration fixture 790 can be utilized prior to a procedure. The calibration fixture 790 can be located away from the patient, for example, on a back table. Other calibration fixtures and jigs are contemplated.

[0101] The surgical orientation device 172 and the orientation sensing device 204 may be calibrated. The surgical orientation device 172 may be placed on a flat horizontal surface with the display oriented horizontally (facing up). The surgeon may hold the assembly 704, 706 steady until the surgical orientation device 172 indicates completion. The orientation sensing device 204 may be placed on a flat horizontal surface with the display oriented vertically (facing towards the user). The surgeon may hold the assembly 704, 706 steady until the surgical orientation device 172 indicates completion. The surgical orientation device 172 may be placed on a flat horizontal surface with the display oriented horizontally (to the left). The surgeon may hold the assembly 704, 706 steady until the surgical orientation device 172 indicates completion. The surgical orientation device 172 may be placed on a flat horizontal surface with the display again in a horizontal orientation (facing up). The surgeon can hold the assemblies 704, 706 steady until the surgical orientation device 172 indicates completion. Other orientations of the surgical orientation device 172 and orientation sensing device 204 are also contemplated for calibration.

[0102] The user can remove the required tools and prepare the tools for use. FIG. 12C illustrates an example of the components described herein. The optical components 174, 194 can be activated. In some embodiments, the optical components 174, 194 can include a movable cover or screen, such as a shutter. The user can close the shutter and insert a battery into the optical components 174, 194. In some embodiments, the optical components 174, 194 can be coupled to the first assembly 704 using one or more fasteners. In some embodiments, the fastener is an adjustment mechanism 178. In some embodiments, the fastener can be secured using a driver 792 (see FIG. 12C). In some embodiments, the optical components 174, 194 are attached to the first assembly 704 using a hex driver. In some embodiments, the optical components 174, 194 are attached to the first assembly 704 using a ball driver. In some embodiments, the optical components 174, 194 may be attached to the first assembly 704 using one or more magnets as described in connection with FIGS. 6B-6C. In some embodiments, the optical components 174, 194 may be attached to the first assembly 704 using one or more removable coupling devices, e.g., clips, straps, bayonet connections, etc., and / or using non-removable coupling devices, e.g., adhesives, integrally formed, monolithically formed, etc. The surgeon can ensure that the optical components 174, 194 are securely attached and do not rotate on the first assembly 704. In some embodiments, the bracket 176 facilitates coupling of the optical components and the first assembly 704. In some embodiments, the adjustment mechanism 178 facilitates coupling of the optical components and the first assembly 704. In some embodiments, the optical components 174, 194 are coupled to the fixed base 702.In some embodiments, the optical component is coupled to a fixed pin 710, 712. In some embodiments, the optical component is coupled to the second assembly 606, 706. In some embodiments, the optical component 174, 194 is directly coupled to the pelvis. In some embodiments, the optical component 174, 194 lasts as long as the battery is installed. The laser or other light emission is shown or hidden through the movement of a shutter. The optical component 174, 194 can include markings to indicate the direction of the emission. In some embodiments, the optical component 174, 194 can include an arrow to indicate the direction of the laser.

[0103] A user can interact with the surgical orientation device 172. If the system 700 can be used in either hip procedure, one method may require the surgeon to select a module corresponding to the right or left hip. In some methods of use, the user can input a target cup abduction angle. This is a radiographic abduction angle defined as the coronal plane projection of the angle between the acetabular axis and the longitudinal axis of the body. Abduction and adduction are also used to describe the limb's movement in the coronal plane. In some methods of use, the user can input a target cup anteversion angle. This is a radiographic anteversion angle defined as the angle between the acetabular axis and the coronal plane. The user can input a target angle, which can be stored by the surgical orientation device 172. In some methods of use, these target angles are utilized by the surgical orientation device 172 during cup placement.

[0104] The system 700 may be attached to the pelvis as shown in FIGS. 13A-13C. The user may position the system 700 so that it has a strong and stable mount for attachment of the instrumentation to the pelvis. In some methods of use, all measurements and references are based on an initial alignment process, and any movement of the first assembly 704 thereafter will result in errors in the resulting readings of cup position, leg length, and / or joint offset. In some methods, the fixation pins 710, 712 are placed in the ipsilateral iliac crest. With reference to FIG. 13A, for the first fixation pin 710, the surgeon may make a stab incision above the ipsilateral iliac crest just superior to the greater trochanter. The surgeon may insert the fixation pin 710. In some embodiments, the fixation pin 710 is a 4.0 mm threaded fixation pin. The fixation pin 710 may be inserted vertically using a wire driver. Referring to FIG. 13B, the surgeon can make a second stab incision and insert the second fixation pin 710 2 cm anteriorly parallel to the first pin 712 into the iliac crest. The surgeon can use the fixation base 702 as a guide to space the pins 710 and 712. Referring to FIG. 13C, the surgeon can slide the fixation base 702 over both pins to skin level. The surgeon can use a driver to tighten the two fixation devices 724 to fix the fixation base 702 to the fixation pins 710, 712. In some methods of use, the fixation pins 710, 712 are installed in a manner similar to the installation of pins for pelvic external fixation. In some methods of use, the fixation pins 710, 712 enter the iliac wing at its uppermost surface and travel between the medial and lateral bone tables of the iliac wing. In some methods of use, the fixation base 702 is attached prior to dislocating the hip joint to ensure proper patient positioning and navigation accuracy. The surgeon can take steps to avoid penetrating the medial wall of the iliac wing. The surgeon can verify that the fixation base 702 is securely attached to the bone. The surgeon is able to minimize divergence or bending of the fixation pins 710, 712.

[0105] The system 700 may be assembled as shown in FIGS. 14A-14C. With reference to FIG. 14A, the orientation sensing device 204 may be coupled to a probe 778. In some embodiments, the orientation sensing device 204 and / or the probe 778 may include indicia, such as an arrow, to facilitate alignment. With reference to FIG. 14B, the first assembly 704 may be secured to the fixed base 702 with the surgical orientation device 172 attached. The first assembly 704 may be secured by pressing a lock lever 740, as described herein. With reference to FIG. 14C, the second assembly 706 may be secured to the fixed base 702 with the orientation sensing device 204 attached. In some embodiments, the second assembly 706 and / or the fixed base 702 may include indicia, such as an arrow, to facilitate alignment. The second assembly 706 may be secured by pressing a lock lever 754, as described herein. The optical components 174, 194 may be secured to the first assembly 704. In some embodiments, the optical components 174, 194 and / or the first assembly 704 may include indicia, such as arrows or the like, to facilitate alignment.

[0106] The system 700 may be aligned as shown in FIG. 15A. The surgeon may place the leg on the surgical side in a neutral position. The surgeon may open the shutters on the optical components 174, 194. The surgeon may align the optical components 174, 194 so that the laser projects a pattern of light. One example of light incidence is shown as 180. In some embodiments, the light pattern includes two lines. In some embodiments, the light pattern includes two intersecting lines. In some embodiments, the light pattern includes two perpendicular lines. In some embodiments, the light pattern includes two parallel lines. In some embodiments, the light pattern includes three points. In some embodiments, the light pattern includes three points that form a triangle. In some embodiments, the light pattern includes three points that are not on the same line. In some embodiments, the light pattern is projected onto the leg. In some embodiments, the light pattern is projected onto the knee. In some embodiments, the light pattern is projected onto the distal foot. In some embodiments, the light pattern is projected onto the distal thigh. In some embodiments, the light pattern is projected onto a portion of the leg that includes the sterile wrap.

[0107] The system 700 may be adjusted as shown in FIGS. 15B-15C. To adjust the projection of the optical components 174, 194, the user can adjust the articulation joint 726. To adjust the projection of the optical components 174, 194, the user can adjust the adjustment mechanism 178 (see FIG. 6A). To adjust the projection of the optical components 174, 194, the user can adjust the repositioning of the fixed base 702. The surgeon can loosen the fixation device 724 and adjust the fixed base 702 as desired. The surgeon can adjust the articulation joint 726 and position the articulation joint 726 as desired. The surgeon can adjust the bracket 176 and / or the adjustment mechanism 178 to position the optical components as desired. The surgeon can reposition any component of the system 700 as desired.

[0108] Once the system 700 is in the desired position, the components of the system 700 may be immobilized. The surgeon may tighten the fixation device 724 to fix the fixation base 702. The fixation base 702 may be secured to the fixation pins 710, 712. In some methods of use, the fixation base 702 remains in this position for the procedure. The articulation joint 726 may be locked in place. The fixation base 702 may include a lock 727. The surgeon may advance the lock 727 against the head 728 to prevent the articulation joint 726 from moving. In some methods of use, the surgeon may use a driver to rotate the lock 727. The driver may be a 3.5 mm hex driver to advance the contact surface 729 against the head 728 of the articulation joint 726. In some methods of use, the articulation joint 726 remains in this position for the procedure. The surgeon can adjust the lock 727 to reduce or prevent movement of the articulation joint 726. The optical components 174, 194 can be secured to the first assembly 704 and / or the fixed base 702. In some embodiments, the adjustment mechanism 178 can be self-locking. The adjustment mechanism 178 can include a plurality of discrete locations. The adjustment mechanism 178 can lock when moved to one of the plurality of discrete locations. In some methods of use, the optical components 174, 194 can remain immobilized during the remainder of the procedure. In some methods of use, the first assembly 604 can remain immobilized during the remainder of the procedure.

[0109] Referring back to FIG. 15A, the method can include recording the incidence of the light 180. The surgeon can record the shape of the projection. The surgeon can record the incidence of the light from the optical component onto the surface. The incidence of the light can be the intersection of the light with an anatomical surface of the patient. The anatomical surface can be any surface of the patient. The anatomical surface can be any surface on the leg. The method can include marking the location of the light. The method can include marking two or more points along the line of light. The method can include drawing a line along the line of light. The method can include capturing an image of the incidence of the light. The method of use can include utilizing a camera to capture the incidence of the light. In some embodiments, the surgeon can track the pattern of the light. In some embodiments, the surgeon can make marks on the femur, such as bobby marks, pen marks, stitches, or other durable indications.

[0110] In some embodiments, the surgeon can mark the incidence of light 180. In some embodiments, the surgeon can mark two lines. In some embodiments, the surgeon can mark two intersecting lines. In some embodiments, the surgeon can mark two perpendicular lines. In some embodiments, the surgeon can mark two parallel lines. In some embodiments, the surgeon can mark a crosshair. In some embodiments, the surgeon can mark the incidence of light from a projected light pattern. In some embodiments, the surgeon can mark three points. In some embodiments, the surgeon can mark three points that are not on the same line. In some embodiments, the surgeon can mark three points that are localized on an area of ​​the leg. In some embodiments, the surgeon can mark three points that are projected on the femur. In some embodiments, the surgeon can mark three points, one or more of which are on the femur. In some embodiments, the surgeon may mark three points, with one or more points being on the femur, tibia, knee, ankle, or foot, or any combination thereof. In some embodiments, the surgeon may mark on the leg. In some embodiments, the surgeon may mark on the knee. In some embodiments, the surgeon may mark on the distal foot. In some embodiments, the surgeon may mark on the distal thigh. In some embodiments, the surgeon may trace a pattern with a marker. In some embodiments, the surgeon may trace a pattern directly onto the leg.

[0111] In some embodiments, the surgeon is able to trace a pattern on the sterile wrap. In some embodiments, a pattern of light is projected onto a portion of the leg that includes the sterile wrap. In some embodiments, the surgeon traces a pattern of light on the sterile wrap. In some embodiments, the surgeon marks two lines on the sterile wrap. In some embodiments, the surgeon marks three points on the sterile wrap.

[0112] In some embodiments, a target probe may be provided to record the incidence of light. FIGS. 20A-20I illustrate examples of target probes. FIGS. 20A-20B illustrate target probe 18a, and FIGS. 20C-20D illustrate target probe 18b. At least one target probe 18a, 18b, or other target or device, may include structures for contacting a patient's anatomy and for serving as a target for light emitted from optical components 174, 194. For example, in some embodiments, at least one target probe 18a, 18b may include an elongated member 106 with an anatomical contact portion 107 and a target portion 108. The anatomical contact portion 107 may include an end of the elongated member 106 or other structure configured to contact an anatomical feature or surface. In some embodiments, the anatomical contact portion 107 contacts the femur. In some embodiments, the anatomical contact portion 107 contacts the knee. In some embodiments, the anatomical contact portion 107 contacts the upper thigh. In some embodiments, the anatomical contact portion 107 may be held against an anatomical feature. In some embodiments, the anatomical contact portion 107 may be drilled into an anatomical feature. In some embodiments, the anatomical contact portion 107 may be coupled to an anatomical feature.

[0113] The anatomical contact portion 107 may be connected to or integrally formed with the target portion 108. The target portion 108 may include a surface that may be marked by the surgeon. The target portion 108 may include a surface on which the incidence of light may be recorded. The target portion 108 is configured to assist in recording the incidence of light. Aligning the incidence of light on the target portion 108 before and after cup placement may assist in aligning the underlying anatomy before and after cup placement.

[0114] In some embodiments, the target portion 108 may include one or more target shapes 110 in the form of markings, slits, or other structures. In some methods of use, the target shape 110 may be marked prior to placement of the targets 18a, 18b on the anatomical structure. In some methods of use, the target shape 110 may be marked by the surgeon after placement of the targets 18a, 18b on the anatomical structure. In some methods of use, the target shape 110 may be marked by the surgeon prior to cup placement. In some methods of use, the target shape 110 may be wide enough, for example when in the form of a slot, to allow a beam of laser light, such as a beam in the form of a plane or crosshair beam, to pass through the target shape 110. FIG. 20 illustrates an embodiment of a target probe 18b with a target shape 110 in the form of a single slot, and a target probe 18a with two slots in the form of a cross, for example formed as two perpendicular lines or slots. FIG. 20 may illustrate both sides of the same target probe. For example, one side of the target probe may have a crosshair target 110 and the other side of the target probe may have a single slot target 110 .

[0115] In some embodiments, the optical components 174, 194 are adjusted to align the incidence of light with the targets 18a, 18b. In some embodiments, the system 700 is adjusted to align the incidence of light with the targets 18a, 18b. For example, the articulation joint 726 can be adjusted. In some embodiments, the targets 18a, 18b are adjusted to align the incidence of light with the target portion 108 of the targets 18a, 18b. The target portion 108 can be adjustable such that the target portion 108 can be moved relative to the anatomical landmark when the anatomical contact portion 107 is held in place against the anatomical landmark. For example, the target portion 108 can include a screw or other element that can be adjusted to change the length of the target probe 18a, 18b. In one embodiment, a device is provided to allow the position of the target portion 108 on the elongated member 106 to be adjusted. The device allows the target portion 108 to be moved closer to or away from the contact portion 106. Such adjustments provide one technique for aligning the incidence of light with the targets 18a, 18b. The target probes 18a, 18b may further include one or more markings that indicate the current length of the target probes 18a, 18b and / or indicate the degree or amount of adjustment made to the target probes 18a, 18b. For example, the target portion 108 may include millimeter markings or other visual indicia that correspond to a longitudinal offset along the length of the target portion 108 to indicate a millimeter length adjustment.

[0116] 20E-20F illustrate an embodiment of the target probe 18c. In some embodiments, the target probe 18c is not rigidly attached to the leg. In some embodiments, the target probe 18c is held in place by the user. FIG. 20E illustrates the target probe 18c in place against the patient's anatomy, and FIG. 20F illustrates the target probe 18c being removed by the surgeon. In the illustrated embodiment, the leg is wrapped with an incise drape. The incise drape can be marked by the user. The user has marked the longitudinal axis of the bone and a home position for the target probe 18c. These markings on the drape can be performed when the surgeon marks the incidence of light on the target probe 18c. The target probe 18c can be oriented in the home position and the incidence of light can be marked. During the procedure, the user can align the markings with the marked longitudinal axis. The surgeon can adjust the anatomy until the incidence of light aligns with the markings on the target 18c. The target 18c can be any shape that allows for marking of the incidence of light. In the illustrated embodiment, the target 18c is generally L-shaped. In some embodiments, the target probe 18c is removable during surgery. The target probe 18c can be positioned on the leg. In some methods of use, one or more markings on the thigh 182 can assist in repositioning the target 18c. The markings can include one or more lines, points, shapes, symbols, etc. In the illustrated embodiment, the markings on the thigh 182 can include crosshairs or other patterns that are related to the incidence of the light 180. In some methods of use, the surgeon can position the target 18c before and after a cup exchange. In some methods of use, the surgeon can mark the incidence of light before a joint dislocation. In some methods of use, the surgeon can mark the incidence of light aligns with the markings. Thus, it is possible to reposition the femur after cup placement.

[0117] FIG. 20G illustrates an embodiment of a target probe 18d. The target probe 18d can include an anatomical contact portion 107 and a target portion 108. The anatomical contact portion 107 can include a strap, clip, bracket, zip tie, or other structure configured to wrap around an anatomical feature or surface. In some embodiments, the anatomical contact portion 107 contacts the thigh. In some embodiments, the anatomical contact portion 107 contacts the knee. In some embodiments, the anatomical contact portion 107 contacts the shin. In some embodiments, the target portion 108 can be moved relative to the anatomical contact portion 107. The target portion 108 can be rotated, pivoted, and / or translated to position the target portion 108 relative to the anatomical contact portion 107. In some embodiments, the target portion 108 is fixed relative to the anatomical contact portion 107. The target portion 108 can include one or more surfaces for marking the incidence of light.

[0118] 20H-20I illustrate an embodiment of a target probe 18e. The target probe 18e can include an anatomical contact portion 107 and a target portion 108. The anatomical contact portion 107 can include a bendable surface configured to conform to and directly contact or indirectly couple to the patient's anatomy. The contact portion 107 can generate a tri-fold shape or can be formed into a continuous curve. The contact portion 107 can include a portion for wrapping around an anatomical feature or surface of the patient. In some embodiments, the wrap is a separate component that is stretched or wrapped around the contact portion 107. The contact portion 107 can include or be wrapped by an incise drape 109, such as an iodine-impregnated incise drape (Ioban® manufactured by 3M®). The incise drape 109 can provide strong adhesion to the surface of the skin. In some embodiments, the incise drape 109 can provide antimicrobial properties for reduction of wound infections after surgery. The contact portion 107 can be glued or otherwise coupled to the incise drape 109 or to the leg prior to wrapping the drape 109. The contact portion 107 can be integrally formed with the incise drape 109. The target portion 108 can be integrally formed with the contact portion 107. The target portion 108 can be integrally formed with the incise drape 109. Other wraps or drapes are also contemplated. The contact portion 107 can be connected to the patient's anatomy through any means. In some embodiments, the contact portion 107 includes an adhesive. In some embodiments, the contact portion 107 is adjustable, such as through the use of an adjustable adhesive or putty. In some embodiments, the contact portion 107 includes a tape or other medical wrap. In some embodiments, the contact portion 107 includes one or more fixation pins.

[0119] In some embodiments, the incise drape 109 wraps around the patient's thigh. In some embodiments, the incise drape 109 wraps around the patient's knee. In some embodiments, the incise drape 109 wraps around the patient's shin. In some embodiments, the target portion 108 is fixed relative to the anatomical contact portion 107 and / or the incise drape 109. In some embodiments, the target portion 108 can be moved relative to the anatomical contact portion 107 and / or the incise drape 109. The target portion 108 can be rotated, pivoted, and / or translated to position the target portion 108 relative to the anatomical contact portion 107. The target portion 108 can include one or more surfaces for marking the incidence of light. The target probe 18e can be a vertical laser target. The target portion 108 can extend vertically from the patient's skin. The target portion 108 can extend horizontally from the patient's skin.

[0120] The target probe 18e may be formed of two pieces. The contact portion 107 and the target portion 108 may be separate components. The contact portion 107 and the incise drape 109 may be separate components. The target portion 108 and the incise drape 109 may be separate components. The contact portion 107 and / or the incise drape 109 may be rigidly attached to the patient's body. In some embodiments, the contact portion 107 and / or the incise drape 109 may be permanently fixed, or may be permanently fixed at least for the duration of the procedure. The contact portion 107 and / or the incise drape 109 may be attached to the thigh and form a self-supporting structure with the thigh. The target portion 108 may be removably attached to the contact portion 107. The target portion 108 and the contact portion 107 can be coupled via any mechanical connection, such as a snap fit, one or more hooks, pinch tabs or buttons, sliding pins, bayonets, and / or one or more magnets.

[0121] In some methods, the incise drape 109 is removed from the protective covering to expose the adhesive. In some methods, the surgeon can couple the contact portion 107 to the incise drape 109. In some methods, the incise drape 109 and the contact portion 107 are coupled and provided to the surgeon. The surgeon can position the contact portion 107 relative to the anatomy. The contact portion 107 can be positioned such that the contact portion 107 is aligned with the optical components 174, 184. The contact portion 107 can be positioned against a portion of the anatomy that has little or no soft tissue. The contact portion 107 can be positioned adjacent to a bone. In some embodiments, the contact portion 107 contacts the patient's skin. In some embodiments, the contact portion 107 is spaced from the patient's skin.

[0122] In some methods, the incise drape 109 may be coupled to the contact portion 107 prior to positioning the contact portion 107. In some methods, the incise drape 109 may be provided with an adhesive to couple the contact portion 107 to the patient. In some methods, the surgeon positions both the contact portion 107 and the incise drape 109 at the same time. In some methods, the incise drape 109 may be coupled to the contact portion 107 after positioning the contact portion 107 on the patient's leg. In some methods, the incise drape 109 may be coupled to the patient after positioning the contact portion 107. In some methods, the surgeon positions the contact portion and the incise drape 109 independently. The surgeon may cover the anatomical structure with the incise drape 109. In some methods, the surgeon may wrap the anatomical structure with the incise drape 109 to form one or more closed loops around the anatomical structure.

[0123] In some methods, the target portion 108 may be coupled to the contact portion 107 prior to positioning the contact portion 107. In some methods, the target portion 108 may be coupled to the contact portion 107 after positioning the contact portion 107. In some methods, the target portion 108 may be coupled to the contact portion 107 by a snap-fit ​​connection. In some methods, the incise drape 109 is positioned above the contact portion 107. In some methods, the target portion 108 may be coupled to the contact portion 107 even when the incise drape 109 is positioned above the contact portion 107. The target portion 108 may be coupled to the contact portion 107 to form a rigid connection. The target portion 108 may be coupled to the contact portion 107 to form a releasable connection. In some embodiments, the target portion 108, once coupled, cannot be removed from the contact portion 107.

[0124] The surgeon can activate the optical components 174, 194 to project light. The surgeon can align the optical components 174, 194 to project a pattern of light onto the target portion 108. One example of the incidence of light is shown as 180. In some embodiments, the pattern of light includes two lines. In some embodiments, the pattern of light includes two intersecting lines. The surgeon can adjust the optical components 174, 194 so that the incidence of the light 180 is located on the target portion 108. In some embodiments, the optical components 174, 194 emit light before or as the surgeon positions one or more of the contact portion 107, the target portion 108, and / or the incise drape 109. In some embodiments, the optical components 174, 194 emit light after the surgeon positions one or more of the contact portion 107, the target portion 108, and / or the incise drape 109. The surgeon can mark the incidence of light 180 onto the target portion 108. The target portion 108 can include a markable flat surface to facilitate marking the incidence of light 180. The surgeon can perform one or more of the methods or method steps described herein.

[0125] The surgeon can activate the optical components 174, 194 and project light again. The surgeon can move the patient's anatomy connected to the target probe 18e. In some methods, the target probe 18e is coupled to the thigh and the surgeon moves the thigh. In some methods, the target probe 18e is coupled to the upper leg (e.g., femur) and the surgeon moves the upper leg (e.g., femur). In some methods, the target probe 18e is coupled to the lower leg (e.g., tibia) and the surgeon moves the lower leg (e.g., tibia). In some methods, the target probe 18e is coupled to the foot and the surgeon moves the foot. The surgeon can realign the portion of the anatomy so that the incidence of the light 180 aligns with the mark on the target portion 108. The surgeon can manually realign the portion of the anatomy with the position of the anatomy when the incidence of the light 180 was recorded. A surgeon can realign a portion of the anatomy to measure joint offset. A surgeon can realign a portion of the anatomy to measure leg length change. A surgeon can realign a portion of the anatomy to compare measurements before and after joint replacement.

[0126] The surgeon can align the parked configuration or home position. In some techniques, the distal end 780 of the probe 778 can be engaged with a point on the fixed base 702, such as a divot 730. The probe 778 can be vertical in the home position. The orientation sensing device 204 can be vertical in the home position. The distal end of the probe 778 can be curved or bent to facilitate aligning the home position.

[0127] When aligning the home position, the user can hold the probe 778 close to the distal end 780 to maximize the accuracy of the measurement of the points. When interacting with the surgical orientation device 172, the user can support the back of the surgical orientation device 172 to avoid bending the fixation pins 710, 712 and / or the fixed base 702. The user can align the home position by pressing a button on the surgical orientation device 172. If the alignment is not acceptable, the user can hold the probe 778 stationary and press the button again.

[0128] FIG. 16 illustrates one embodiment of aligning the table. FIG. 16 is a top view with the patient in the lateral position for a posterior approach. The surgeon can verify that the sagittal plane of the pelvis is horizontal. During positioning of the patient, the anterior pelvic plane is positioned vertically. The anterior pelvic plane can be defined as the plane generated by the two anterior superior iliac spines (ASIS) and the anterior surface of the pubic symphysis.

[0129] The anterior pelvic plane may be oriented vertically when the patient is in the lateral decubitus position for a posterior approach. The top surface of the surgical table on which the patient is positioned is positioned horizontally. The patient may be positioned so that the anterior pelvic plane is perpendicular to the table. In some embodiments, the surgeon may visually verify that the anterior pelvic plane is perpendicular. In some embodiments, the surgeon may use a device to position the patient's body to align the anterior pelvic plane perpendicular to the plane of the top surface of the table.

[0130] If it is not already horizontal, the surgeon may position the surgical table horizontally. The table plane may be a horizontal or generally horizontal plane. In some techniques, the surgical table is horizontal and the table plane approximates the plane of the table. In some techniques, the table plane may be oriented relative to other surfaces in the operating room. In some techniques, the floor is horizontal and the table plane approximates the plane of the floor. In some techniques, the walls are vertical and the table plane approximates a plane perpendicular to the walls. In some techniques, the ceiling is horizontal and the table plane approximates the ceiling. Other surfaces may be used to approximate the horizontal plane.

[0131] During table alignment, the probe 778 is coupled to the orientation sensing device 204. In some methods of use, the probe 778 and the orientation sensing device 204 are constrained. As one example, the probe 778 may be coupled to other components of the first assembly 704 and / or the second assembly 706. In some methods of use, the system 700 is assembled such that the first assembly 704 and the second assembly 706 are coupled to the patient via the fixation pins 710, 712. There may be a mechanical constraint imparted by the configuration of the system 700.

[0132] FIG. 16 illustrates one position of the probe 778 for calculating the direction of gravity when the probe 778 is generally horizontal. The probe 778 is rotated and / or pivoted by the mount 758. The probe 778 may extend toward the patient's feet. The probe 778 may be aligned with the long axis of the body. The probe 778 may be held substantially parallel to the plane of the table. In some embodiments, the user may align the probe 778 with the horizontal direction. The user may visually inspect the probe 778 from one or more locations. For example, the user may inspect the probe 778 from a top view and a side view. In some embodiments, the user may align the probe 778 with a sagittal plane. The probe 778 may be parallel to the sagittal or parasagittal plane. The sagittal plane divides the body into right and left sides. As described herein, the orientation sensing device 204 may be positioned horizontally to measure gravity. As described herein, the probe 778 coupled to the orientation sensing device 204 may be positioned horizontally or substantially horizontally to measure gravity. Referring back to FIG. 11, a side view of the patient illustrates one dotted line parallel to the table. During table alignment, the probe 778 can be parallel to the table when viewed from the side.

[0133] The probe 778 may be held or immobilized in place. The probe 778 may be held stable during table alignment. The second assembly 706 may include a lock 766. The lock 766 may limit or reduce the slidability of the probe 778 relative to the dock 762. In some methods of use, the probe 778 may still pivot (e.g., pivotal movement between the dock 762 and the mount 758). In some methods of use, the probe 778 may still rotate (e.g., rotational movement between the mount 758 and the probe bracket 752). The lock 766 may reduce the slidability when the table is aligned. The lock 766 limits or reduces one degree of freedom during table alignment.

[0134] The position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The user may enter an input to align the table (e.g., press a button on the surgical orientation device 172). The user may interact with a user interface on the surgical orientation device 172 to signal the surgical orientation device 172 to capture data for the orientation sensing device 204. The surgical orientation device 172 may indicate that the data has been recorded. In some methods of use, the table alignment may be performed at any point during the procedure. The table alignment may be performed during pre-operative calibration. The table alignment may be performed during intra-operative calibration. The table coordinate reference system may be calculated in addition to or as an alternative to the table plane. The surgical orientation device 172 may store the table plane and / or the table coordinate reference system.

[0135] In some techniques, table alignment may be completed before dislocating the hip joint. The torque applied during dislocation may move the pelvis away from the correct initial alignment. In some techniques, the fixed base 702 may not be adjusted by the user after table alignment. For example, the user cannot adjust the fixed base 702 relative to the pins 710, 712. The fixed base 702 remains in place throughout the remainder of the procedure. In some techniques, the pelvic bracket 738 may not be adjusted by the user after table alignment. The pelvic bracket 738 remains in place throughout the remainder of the procedure. In some techniques, the angle of the pelvic bracket 738 relative to the fixed base 702 may not be changed after table alignment.

[0136] In some embodiments, information from one or more inertial sensors is used during table registration. As described herein, the orientation sensing device 204 and the surgical orientation device 172 can include one or more inertial sensors. In some embodiments, the position and / or orientation of the one or more inertial sensors can provide data associated with the table plane. The one or more inertial sensors can detect gravity and provide a vector with respect to a downward direction.

[0137] The table alignment can utilize a measurement of gravity. As described herein, the surgical orientation device 172 includes one or more inertial sensors. As described herein, the orientation sensing device 204 includes one or more inertial sensors. In some embodiments, inertial data from the one or more inertial sensors is used to calculate a vertical plane and / or a horizontal plane. In some embodiments, the position and / or orientation data of the one or more inertial sensors is used to calculate a table plane or table coordinate reference system. The surgical orientation device 172 and / or the orientation sensing device 204 can include an accelerometer, which can provide a measurement of the direction of gravity. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 includes a sensor for detecting the direction of gravity. The surgical orientation device 172 and / or the orientation sensing device 204 can be sensitive to the direction of gravity. The one or more inertial sensors can provide a vector aligned with the vertical direction, for example, for a downward direction. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 include a three-axis accelerometer to detect orientation relative to or of gravity.

[0138] In some embodiments, the surgical orientation device 172 includes an accelerometer. In some embodiments, the orientation sensing device 204 includes an accelerometer. The accelerometer at rest can measure acceleration due to the Earth's gravity. The accelerometer can measure acceleration from gravity straight down or vertically. In some embodiments, the accelerometer can detect the magnitude and direction of the force of gravity. The accelerometer can create a vertical vector. The accelerometer can create a horizontal vector by transforming the vertical vector (e.g., by rotating 90 degrees). The accelerometer can provide orientation and / or position data such that the table plane is perpendicular to the force of gravity.

[0139] In some embodiments, the orientation sensing device 204 measures gravity. In some embodiments, the surgical orientation device 172 measures gravity. The surgical orientation device 172 and / or the orientation sensing device 204 can provide an indication of up / down or vertical. The orientation sensing device 204 and / or the surgical orientation device 172 can create a vertical vector. The surgical orientation device 172 and / or the orientation sensing device 204 can create a horizontal vector by translating the vertical vector of gravity (e.g., by rotating 90 degrees). In some embodiments, the surgical orientation device 172 remains stationary when measuring gravity. In some embodiments, the surgical orientation device 172 is coupled or attached to the patient's pelvis when measuring gravity. In some methods of use, the surgical orientation device 172 is coupled to the patient via fixation pins 710, 712 when measuring gravity. In some methods of use, the surgical orientation device 172 is constrained when measuring gravity. As one example, the surgical orienting device 172 may be coupled with other components of the first assembly 704 and / or the second assembly 706. In some methods of use, the orientation sensing device 204 is constrained when measuring gravity. As one example, the orientation sensing device 204 may be coupled with other components of the first assembly 704 and / or the second assembly 706. In some embodiments, the orientation sensing device 204 and the surgical orienting device 172 both determine the direction of gravity. In some embodiments, inertial data from two or more sensors are used to measure gravity.

[0140] The surgical orientation device 172 and / or the orientation sensing device 204 can provide a reference value for zero gravity. As referred to herein, zero gravity generally represents an orientation in which the axis of the sensor is perpendicular to the force of gravity, thereby experiencing no angular offset, e.g., tilt, pitch, roll, or yaw, relative to the gravity vector. The surgical orientation device 172 can store zero gravity for calculations related to the table plane. In some methods, zero gravity is aligned once and utilized throughout the procedure. Table alignment can include recording a measurement of zero gravity.

[0141] In some methods of use, the orientation sensing device 204 may be positioned in a manner other than horizontal to measure the direction of gravity. In some methods of use, the orientation sensing device 204 may measure gravity when in the home position. In some methods of use, the orientation sensing device 204 may be positioned vertically or substantially vertically to measure gravity. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with a point or anatomical landmark. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with a point prior to cup placement. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with the tracker 784. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with a point on the femur. The point on the femur may be a mark such as Fm as described herein. The point on the femur may be an anatomical landmark. In some methods of use, the orientation sensing device 204 is capable of measuring the force of gravity at any angular orientation, hi some methods of use, the orientation sensing device 204 determines the vertical vector of gravity when held in any position.

[0142] The table coordinate reference system may include two perpendicular planes. The two perpendicular planes may include a vertical plane and a horizontal plane. The table alignment generates two planes, a plane that includes a vector for the force of gravity and a plane perpendicular to said plane. The table plane is considered to be a horizontal plane. In some methods of use, a vector for the downward direction may be used by the system to verify that the table plane is a horizontal plane. The horizontal plane may be recorded and stored by the surgical orientation device 172 and / or the orientation sensing device 204.

[0143] In some methods of use, the vector in the downward direction can be used by the system to establish a vertical plane. In some methods of use, the vector in the downward direction can be used by the system to establish true vertical and true horizontal. The vertical plane can approximate the anterior pelvic plane. For example, abduction and anteversion angles can be calculated relative to the vertical plane. The vertical plane can provide an estimate of the orientation of the anterior pelvic plane. The vertical plane can be recorded and stored by the surgical orientation device 172 and / or the orientation sensing device 204. The system 700 can calculate the cup angle based on the vertical plane based on the assumption that the patient's pelvis is correctly positioned so that the anterior pelvic plane is vertical. In some methods of use, the abduction and anteversion angles for cup placement in a total hip replacement can be relative to the vertical plane determined during table alignment.

[0144] The orientation of the vertical plane can be a baseline for placement of the cup portion of the hip prosthesis. The surgical orientation device 172 can display information about the vertical plane. In some methods of use, the abduction and anteversion angles of the cup placement in a total hip replacement can be relative to the vertical plane. In some embodiments, the vertical plane is determined by the surgical orientation device 172 and / or the orientation sensing device 204. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 can provide orientation and / or position data associated with a table coordinate reference system. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 can provide orientation and / or position data associated with the vertical plane. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 can provide orientation and / or position data associated with a horizontal plane.

[0145] In some embodiments, the table plane is determined completely independent of any anatomical landmarks. The table plane provides a reference plane that is not affected by pelvic tilt. The table plane provides a reference plane that is not affected by errors in landmark alignment due to soft tissue. The table plane also appears in a large console navigation that may be familiar to the surgeon. In some methods of use, the horizontal plane is calculated based on aligning the probe 778. In some methods of use, the vertical plane is calculated based on a measurement of gravity. In some methods of use, the target cup angle is relative to the anterior pelvic plane. In some methods of use, the navigated cup angle is relative to a vertical plane that approximates the anterior pelvic plane. Pre-operative and / or post-operative images, such as x-rays, are captured in a reference plane similar to the anterior pelvic plane. Table registration can provide a reference plane that approximates the reference plane of the imaging technique. Table registration can provide a reference plane that approximates the anterior pelvic plane.

[0146] 17A-17B, in some methods of use, the surgeon may align a point. In some methods of use, the surgeon may align only one point. In some methods of use, the surgeon aligns a single point on the femur. In some methods of use, the surgeon aligns a single anatomical landmark during the procedure. The point may be located on the femur of the joint being operated on. For some procedures on the patient's left hip, the point is on the left femur. For some procedures on the patient's right hip, the point is on the right femur. In some methods of use, the surgeon may make a standard incision. In some methods of use, the surgeon may identify a point along the femoral head line on the proximal femur. In some methods of use, the point is located on the greater trochanter.

[0147] The surgeon can position the distal end 780 of the probe 778 to a point. In some methods of use, the distal end 780 of the probe 778 is placed on a point on the greater trochanter. In some methods of use, the tip of the distal end 780 is contacted with a portion of the greater trochanter or anywhere on the proximal femur. In some methods of use, the tip of the distal end 780 is contacted with any point on the patient's anatomy.

[0148] In some methods of use, after the point is found and / or contacted, the clinician can make a mark on the femur. In some methods of use, the surgeon can make the mark using a bobby mark, a pen mark, a stitch, or other durable indication. In some methods of use, the surgeon can connect the tracker 784. The tracker 784 can be a fastener, such as a screw, a bolt, a pin, a plate, or other durable structure. In some methods of use, the surgeon can insert a 20 mm screw into the femur. In some embodiments, the tracker 784 can be fixed to the femur. The tracker 784 can be rotated to be fixed into the femur. The tracker 784 can be advanced into the femur with a driver. The surgeon should ensure that the tracker 784 is sufficiently lateral so as not to interfere with the stem. The point can be located on the tracker 784. In some methods of use, the surgeon can create a divot or burr into the bone or other portion of the patient's anatomy. In some embodiments, the divot or burr is in the femur. The point can be located on the divot or burr. In some methods of use, the surgeon can modify the femur to provide a reliable indication of the point being aligned.

[0149] The probe 778 may be immobilized to align the point. In some embodiments, the surgeon may hold the tip of the probe 778 at the point. In some embodiments, the surgeon may hold the tip of the probe 778 in a divot or burr. In some embodiments, the surgeon may hold the tip of the probe 778 in a hole in the tracker 784. In some embodiments, the surgeon may hold the tip of the probe 778 at an anatomical landmark. In some embodiments, the surgeon may hold the tip of the probe 778 at a marked point Fm.

[0150] As described herein, the second assembly 706 can include a lock 766. The lock can limit or reduce the slidability of the probe 778 relative to the dock 762. In some methods of use, the probe 778 can still pivot (e.g., pivotal movement between the dock 762 and the mount 758). In some methods of use, the probe 778 can still rotate (e.g., rotational movement between the mount 758 and the probe bracket 752). The lock 766 can reduce the slidability when the points are aligned. In some embodiments, the lock 766 is advanced before the points are aligned. In some methods of use, the lock 766 limits or reduces one degree of freedom during point alignment.

[0151] Once the tip of the distal end 780 is in contact with the desired point, the system 700 processes the data from one or more sensors in the orientation sensing device 204 and stores the orientation. During alignment, the position of the orientation sensing device 204 may be recorded by the surgical orientation device 172. During alignment, the orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. During alignment, the extension of the orientation sensing device 204 may be recorded by the surgical orientation device 172.

[0152] The distance associated with the extension of the probe 778 may be used with the position and / or orientation data from the orientation sensing device 204. Additionally, in some embodiments, the probe 778 is provided with markings 782 that indicate the position of the tip of the probe 778, for example, relative to the dock 762 or some other relevant fixed feature of the patient or the system 700. The markings 782 may be read by the clinician or by the camera 184. In some embodiments, the camera 184 records the markings 782 that indicate the extension of the probe 778. The distance that the probe 778 is extended to contact the point, as captured by the camera 184, may be recorded by the orientation device 172. In some methods, the orientation sensing device 204 or the surgical orientation device 172 may convert the image of the camera 184 into an extension measurement of the probe 778. When registering the anatomical point, the camera 184 captures an image of the markings 782. The camera 184 can read the markings 782 and provide an accurate determination of the translational position of the probe 778 relative to the dock 762. The camera 184 can be directly above the markings 782. In some methods, the camera 184 can read the binary code of the markings 782. The surgical orientation device 172 can use the length measurements from the camera 184 and the data from the orientation sensing device 204 to determine the location of the distal end 780 of the probe 778.

[0153] In some embodiments, the surgeon will enter an input (e.g., press a button) to collect data from the orientation sensing device 204. In some methods, the surgeon will enter an input (e.g., press a button) to collect data from the camera 184. In some embodiments, the surgeon will enter an input (e.g., press a button) to collect data from the orientation sensing device 204 and the camera 184 simultaneously. In some methods, the orientation sensing device 204 and / or the camera 184 will simply send data if the orientation sensing device 204 is steady or not moving. In some embodiments, the surgeon can press a button on the surgical orientation device 172 to align a point. The surgeon can enter an input to align a point. Other ways of entering an input include interacting with a touch screen, using a verbal command, touching an icon, holding the probe 778 steady for a predetermined period of time, and / or reaching the end of a countdown clock, etc. The surgical orientation device 172 can indicate that a point has been recorded.

[0154] In some methods, the surgeon marks the light incidence before aligning the points. In some methods, the surgeon marks the light incidence after aligning the points. In some methods, the surgeon marks the light incidence at the same time as aligning the points. In some methods, the surgeon marks the light incidence but does not align the points. In some methods, the surgeon aligns the points but does not mark the light incidence. In some methods, the surgeon marks the light incidence independent of aligning the points. In some methods, the surgeon marks the light incidence and aligns the points after the legs are immobilized. In some methods, the surgeon marks the light incidence and aligns the points when the legs are in the same orientation.

[0155] The surgical orientation device 172 can record a point in a table coordinate reference system. The table coordinate reference system can form a coordinate system. The table coordinate reference system can include a vertical plane and a horizontal plane. In some methods of use, the registered point is located at the origin of the table coordinate reference system. In some methods of use, the center of rotation of the femur is located at the origin of the table coordinate reference system. The user can record a point in the table coordinate reference system before cup placement. The user can record the same point in the table coordinate reference system after cup placement. The system 700 can compare measurements of the same point before and after cup placement. The comparison can relate to leg length. The comparison can relate to joint offset. In some embodiments, a change in the registered point along the vertical plane indicates a change in leg length. In some embodiments, a change in the registered point along the horizontal plane indicates a change in joint offset.

[0156] In some techniques, table alignment is completed before dislocating the hip. In some techniques, the points are aligned before dislocating the hip. In some techniques, the light incidence is marked before dislocating the hip. Once alignment is complete, the surgeon can proceed to dislocate the hip, resect the femoral head, and prepare the acetabulum according to the implant manufacturer's technique. Torque applied during dislocation can move the pelvis away from the correct initial alignment.

[0157] In some techniques, the fixed base 702 cannot be adjusted by the user after table alignment, home alignment, recording light incidence, and / or point alignment. For example, the user cannot adjust the fixed base 702 relative to the pins 710, 712. The fixed base 702 remains in place for the remainder of the procedure. In some techniques, the pelvic bracket 738 cannot be adjusted or removed. The pelvic bracket 738 remains in place for the remainder of the procedure. In some techniques, the angle of the pelvic bracket 738 relative to the fixed base 702 cannot be changed. In some techniques, the probe 778 cannot be replaced with a different probe. The same probe 778 is used for the remainder of the procedure.

[0158] In some methods of use, the surgical orientation device 172 may provide options to the user as to how to proceed. In some methods of use, the surgeon may set an anteversion cup angle and / or an abduction cup angle. In some methods of use, the surgical orientation device 172 may store a target cup angle. In some methods of use, the surgeon may input an anteversion cup angle and / or an abduction cup angle into the surgical orientation device 172. In some methods of use, the surgeon sets a target angle for the cup. In some methods of use, the surgical orientation device 172 may allow the surgeon to check the target angle after the surgeon sets the target angle for the cup.

[0159] In some methods of use, the surgical orientation device 172 can provide options related to leg length and joint offset. In some methods of use, the surgical orientation device 172 can measure leg length from a pre-operative state. In some methods of use, the surgical orientation device 172 can measure offset from a pre-operative state. In some methods of use, the surgical orientation device 172 can measure leg length before cup placement. In some methods of use, the surgical orientation device 172 can measure joint offset before cup placement. In some methods of use, the surgical orientation device 172 can measure a change in the registered point. In some methods of use, the surgical orientation device 172 can measure a change in the registered point in a table coordinate reference system. In some methods of use, the surgical orientation device 172 can measure a change in the registered point in a table coordinate reference system that includes a vertical plane. In some methods of use, the surgical orientation device 172 can measure a change in the registered point in a table coordinate reference system that includes a horizontal plane. In some methods of use, the surgical orientation device 172 is capable of measuring changes in a registered point in a table coordinate reference system that includes vertical and horizontal planes.

[0160] In some methods of use, the surgical orientation device 172 may provide an option related to a home position. In some methods of use, the surgeon may position the probe 778 in the home position during the procedure. In some methods of use, the surgeon may position the probe 778 in the home position and verify that one or more components of the system 700 remain fixed. In some methods of use, the surgical orientation device 172 may repeat the alignment of the points. In some methods of use, the surgical orientation device 172 may repeat the acquisition of the points to be used. The surgical orientation device 172 may repeat the acquisition of the points before the joint is dislocated. The surgical orientation device 172 may repeat the acquisition of the points after the insertion of the medical prosthesis. In some methods of use, the surgical orientation device 172 may indicate the end of the procedure. In some methods of use, the surgeon may end the procedure and select the other hip joint for a bilateral procedure.

[0161] Once the alignment is complete, the user can proceed to dislocate the hip joint, resect the femoral head, and prepare the acetabulum. The user can prepare the impactor and shell. The user can remove the second assembly 706 from the first assembly 704. The user can remove the orientation sensing device 204 from the probe 778. The user can dock the orientation sensing device 204 to the first assembly 704. The surgical orientation device 172 and the orientation sensing device 204 form a generally V-shaped configuration, similar to the orientation shown in FIG. 12. The user can set the cup angle. In some methods of use, the surgeon can hold the hip joint stable until the surgical orientation device 172 provides an indication to proceed.

[0162] The user may remove the orientation sensing device 204 from the first assembly 704. The orientation sensing device 204 and the surgical orientation device 172 may be used at this point to guide the placement of the cup in a predetermined orientation. The surgeon may remove the extension 770 from the third coupler 768. The surgeon may couple the extension 770 to the impactor. In some embodiments, if the orientation sensing device 204 is moved too quickly, an error message will appear on the surgical orientation device 172. In some embodiments, if the orientation sensing device 204 is moved too quickly, the orientation sensing device 204 may be coupled to the first assembly 704 as shown in FIG. 12.

[0163] FIG. 18A illustrates an embodiment of an impactor 300A. In some methods of use, an orientation sensing device 204 may be coupled to the impactor 300A. The orientation sensing device 204 may determine a cup angle relative to a reference plane as the impactor 300A is moved. The impactor 300A may include a shell 312A. Movement of the shell 312A is cushioned by a plurality of spring members 340, 344 configured to absorb at least some of the shock of an impact on the impactor 300A. The shell 312A may include a fourth coupler 342 (see FIGS. 18B-18D). The fourth coupler 342 allows the orientation sensing device 204 to couple to the shell 312A. The orientation sensing device 204 may be removably coupled to the fourth coupler 342. An orientation sensing device 204 may be coupled to the impactor 300A to navigate the cup angle, as described herein.

[0164] In some embodiments, the fourth coupler 342 can be a universal coupler. This allows the fourth coupler 342 to couple to any other device or subsystem as described herein. In some embodiments, the fourth coupler 342 is identical to or substantially similar to the first coupler 632, the second coupler 648, and / or the third coupler 668. The fourth coupler 342 can couple to one or more components of the system 600, such as, for example, the orientation sensing device 204. The fourth coupler 342 can include an elongated post. The fourth coupler 342 can include a slot. The slot can be designed to lock with the orientation sensing device 204 or a component thereof, such as, for example, the extension 670. The extension 670 can include a detent. The detent can be sized and shaped to be received within the slot of the fourth coupler 342. The detent and slot engagement can rigidly couple the orientation sensing device 204 with the fourth coupler 342. The engagement between the fourth coupler 342 and the extension 670 of the orientation sensing device 204 minimizes or prevents relative movement therebetween, avoiding any relative mechanical movement during a navigation procedure.

[0165] The fourth coupler 342 can include a tapered surface. The tapered surface can facilitate entry of the fourth coupler 342 into the extension 670. In some embodiments, the fourth coupler 342 can have a regular shape (e.g., cylindrical). In some embodiments, the orientation sensing device 204 can mate with the fourth coupler 342 in multiple orientations. In some embodiments, the fourth coupler 342 can have an irregular shape (e.g., triangular, teardrop, oval, rectangular). The irregular shape can facilitate alignment of the orientation sensing device 204 to the fourth coupler. In some embodiments, the orientation sensing device 204 can mate with the fourth coupler 342 in a single orientation.

[0166] The orientation sensing device 204 may be releasably coupled to the extension 670. The extension 670 may include a mount 672 that is designed to couple with the orientation sensing device 204. In the illustrated embodiment, the mount 672 includes a lock and release lever that may pivot relative to the extension 670. The orientation sensing device 204 may include features for mating with the lock and release lever. Other configurations are also contemplated. The orientation sensing device 204 is rigidly coupled to the extension 670 when engaged by the mount 672.

[0167] In some embodiments, an impactor 300A is provided that includes a shell 312A with a fourth coupler 342. The impactor 300A may be provided by a manufacturer of other components of the system described herein. The impactor 300A can include a fourth coupler 342, allowing the impactor 300A to interface with the orientation sensing device 204. In some embodiments, an impactor is provided that does not include a fourth coupler 342. FIGS. 18B-18D illustrate an embodiment of a universal impactor adapter. The universal impactor adapter can allow any impactor to be used with the system described herein. The universal impactor adapter can allow the orientation sensing device 204 to couple with any impactor. In some embodiments, the universal impactor adapter can be an attachment that provides a fourth coupler 342 to allow the orientation sensing device 204 to be mounted thereon. The orientation sensing device 204 can be mounted on a large array of impactors, not just impactor 300A. A universal impactor adapter can be coupled to any impactor and provide the fourth coupler 342. The universal impactor adapter can provide a means for rigidly coupling the fourth coupler 342 to the impactor. The universal impactor adapter can provide a means for rigidly coupling the orientation sensing device 204 to the impactor.

[0168] FIG. 18B is an embodiment of a universal impactor adapter 350. FIG. 18C-D are an embodiment of a universal impactor adapter 352. The universal impactor adapter 350, 352 can be designed to couple to multiple impactors. The universal impactor adapter 350, 352 can be designed to couple to impactors having a particular range of shaft or coupling portion sizes. The universal impactor adapter 350, 352 can be designed to couple to impactors having different shapes or configurations. The universal impactor adapter 350, 352 can include a fourth coupler 342. The universal impactor adapter 350, 352 can include any coupler designed to couple to the orientation sensing device 204. The universal impactor adapter 350, 352 can be coupled to the impactor shaft by any manner of connection. The universal impactor adapter 350 can be connected to the impactor shaft by one or more magnets 354. The one or more magnets 354 of the universal impactor adapter 350 may be configured to attract and couple to one or more magnets (not shown) of an impactor. The impactor is configured to be inserted into the recess 358. The recess 358 is an arcuate channel for receiving the shaft of an impactor within a predetermined range of impactor shaft sizes. Although four magnets 354 are shown in FIG. 18B, other configurations are contemplated (e.g., one magnet, two magnets, three magnets, four magnets, five magnets, six magnets, etc.). The four magnets may be angled downward toward the recess 358. This orientation will concentrate the magnetic force into the recess 358, enhancing the attractive force of the adapter 350 to the shaft of the impactor that is fitted into the recess 358. The four magnets may be angled downward relative to the fourth coupler 342. Although two magnets are shown on one side of the universal impactor adapter 350, two additional magnets 354 have a mirror image configuration on the other side of the device in the embodiment shown. The magnets are oriented towards a recess 358 and, in one embodiment, are aligned with the corresponding magnets on the impactor. The one or more magnets 354 of the universal impactor adapter 350 may be configured to attract and couple to the one or more magnets of the impactor. In some embodiments, the one or more magnets 354 may be configured to attract a magnetic material disposed on or in the shaft of the impactor. In some embodiments, the impactor or a portion thereof includes a magnetic material. In some embodiments, the entire impactor is magnetic. The one or more magnets 354 of the universal impactor adapter 350 may enable the universal impactor adapter 350 and the fourth coupler 342 to form a self-supporting structure with the impactor when assembled. The fourth coupler 342 may be rigidly coupled such that any movement of the impactor corrects for movement of the fourth coupler and the reference sensor device 204 coupled thereto. The one or more magnets 354 of the universal impactor adapter 350 may reduce or prevent undesired movement between the impactor and the orientation sensing device 204.

[0169] The universal impactor adapter 352 can be connected to the shaft of the impactor by one or more clamps 356. Figure 18C illustrates the clamp 356 when tightened and Figure 18D illustrates the clamp 356 when loosened. The clamps are an example of a mechanical connection between the universal impactor adapter 352 and any impactor. The clamps 356 can include a rounded inner surface to connect to the rounded outer surface of the impactor.

[0170] The clamp 356 of the universal impactor adapter 352 can enable the universal impactor adapter 352 and the fourth coupler 342 to form a self-supporting structure with the impactor. The clamp 356 of the universal impactor adapter 352 can reduce or prevent undesired movement between the impactor and the orientation sensing device 204. The clamp 356 can apply the necessary force to rigidly couple to the exterior surface of the impactor. Other configurations of the universal impactor adapter are also contemplated.

[0171] The impactor 300A, or any impactor with a universal impactor adapter 350, 352, can be modified to suit any of a number of hip prostheses. For example, multiple tip components 348 can be provided in a kit, where each tip component is attachable to and detachable from the distal end of the impactor shaft. Two types of tip adapters are shown in FIG. 12C. In some embodiments, the tip adapter 348 can be offset. Multiple tip adapters are optional.

[0172] The acetabular shell may be threaded onto the tip component 348. A user may select the appropriate shell adapter for the desired impactor. Also, the impactor 300A, or any impactor with a universal impactor adapter 350, 352, is configured to be modified to fit any of a number of hip prostheses. In some methods of use, a surgeon may threadably attach the acetabular shell onto the tip component 348. In some methods of use, a surgeon may snap the tip component 348 onto the end of the impactor shaft. In some embodiments, the tip component 348 may be rotated to multiple angles relative to the impactor to align the threaded holes of the shell as desired. In some embodiments, if none of the available tip components 348 fit onto the selected shell, the impactor 300A may not be navigated. In some embodiments, if none of the available tip components 348 fit onto the selected shell, another impactor is selected based on the selected shell. The impactor may include a universal impactor adapter 350, 352 to allow for coupling with the orientation sensing device 204. In some embodiments, before impacting, the surgeon may verify that the shell is fully seated on the shoulder of the impactor. In some embodiments, before impacting, the surgeon may verify that the threads do not protrude beyond the outer surface of the shell. Another embodiment of an impactor is shown in FIG. 12C. Impactor 300B may have any of the features of impactor 300A described herein. Impactor 300B is an offset shell impactor. Impactor 300A is a straight shell impactor. Multiple impactors are optional.

[0173] In some methods of use, the impactor is not navigated as described herein. In some embodiments, the cup angle can be checked after insertion by aligning the hip joint center. In some methods of use, the surgeon can align three points on the outer edge of the cup. These three points define the hip joint center. In some embodiments, the point equidistant from all three points is the hip joint center. Additionally, these three points define the plane of the cup. The cup angle is defined as the angle of an axis perpendicular to this plane. Note that the impactor is perpendicular to this axis. Additional information regarding point alignment and hip joint center identification may be found in U.S. Patent Application No. 14 / 639,758, filed March 5, 2015; U.S. Patent Application No. 14 / 639,784, filed March 5, 2015; U.S. Patent Application No. 13 / 800,620, filed March 13, 2013; and U.S. Patent Application No. 14 / 643,864, filed March 10, 2015, the disclosures of which are incorporated by reference in their entireties. In some methods of use, there is no alignment of the hip joint center. In some methods of use, only a single point is aligned. In some methods of use, points are aligned before and after cup placement with respect to leg length and / or joint offset. In some methods of use, no points are aligned at all. In some methods of use, the surgeon does not use point alignment to calculate leg length and / or joint offset.

[0174] The acetabular shell may be inserted into the acetabulum and positioned at a desired angle. As described herein, the surgeon may memorize the target angle with the surgical orientation device 172. The surgical orientation device 172 may guide the surgeon in placing the cup relative to the target angle. As described herein, the target abduction and anteversion angles may be the cup angles hammered into the surgical orientation device 172 by the surgeon. The target abduction and anteversion angles may be inputs into the system 700.

[0175] In some methods of use, when the orientation sensing device 204 is attached to the impactor 300A, or any other impactor with a universal impactor adapter 350, 352, the surgical orientation device 172 can display the radiographic tilt and anteversion angle of the impactor. In some methods of use, when the orientation sensing device 204 is attached to the impactor, the surgical orientation device 172 can display the radiographic tilt and anteversion angle of the impactor relative to the anterior pelvic plane. In some methods of use, when the orientation sensing device 204 is attached to the impactor, the surgical orientation device 172 can display the radiographic tilt and anteversion angle of the impactor relative to a vertical plane. In some methods of use, when the orientation sensing device 204 is attached to the impactor, the surgical orientation device 172 can display the radiographic tilt and anteversion angle of the impactor relative to a plane that approximates the anterior pelvic plane. The angles of the impactor can be calculated in real time.

[0176] The surgical orientation device 172 can graphically display as the orientation sensing device 204 navigates to the target abduction and anteversion angles. The surgical orientation device 172 can include indicia, such as a target or bull's eye, to indicate the pre-determined abduction and anteversion angles. The surgical orientation device 172 can include indicia, such as a dot or crosshairs, to indicate movement of the impactor. Aligning the indicia with the center of the target or bull's eye can indicate that the impactor is aligned with the predetermined cup angle. In some methods of use, the surgeon aligns the crosshairs with the center of the bull's eye. In some methods of use, the surgeon aligns a bubble level. In some methods of use, the surgeon aligns two indicia. In some methods of use, the surgeon substantially aligns the moving indicia with the fixed indicia. In some methods of use, the surgeon moves the indicia on the user interface of the surgical orientation device 172 by moving the impactor. In some methods of use, the surgeon moves indicia on the user interface of the surgical orientation device 172 by moving the orientation sensing device 204. Aligning visual indicators displayed on the surgical orientation device 172 can guide the user to position the impactor at the desired cup angle. The indicia can move in real time.

[0177] The surgical orientation device 172 is capable of graphically displaying the abduction and anteversion angles as the orientation sensing device 204 is moved. In some methods of use, the indicia align when the impactor is positioned at the target anteversion angle. In some methods of use, the indicia align when the impactor is positioned at the target abduction angle. In some methods of use, the surgeon hammers the target anteversion angle and / or target abduction angle into the surgical orientation device 172.

[0178] In some methods of use, the surgical orientation device 172 displays the target angles. The target abduction and anteversion angles may be displayed statically. The surgical orientation device 172 may include readouts of the abduction and anteversion angles. The readouts of the abduction and anteversion angles may change as the impactor is moved. The readouts of the abduction and anteversion angles may be real-time. In some methods of use, the surgeon may compare the readouts and the target angles and position the cup at the target angles. In some methods of use, the surgical orientation device 172 provides a graphical display to assist the surgeon in aligning the cup with the target angles. In some methods of use, the surgical orientation device 172 provides a user interface to assist the surgeon in aligning the cup with the target angles. In some methods of use, the surgical orientation device 172 provides visual feedback when the impactor is aligned with one or more target angles. As described herein, the displayed angles may be calculated according to their radiographic definitions. In some methods of use, the surgical orientation device 172 is capable of dynamically providing an angular readout.

[0179] The user can type in an input when the desired cup angle is reached. The user can have a predefined set amount of time to align the impactor with the desired cup angle. In some methods of use, the surgeon must align the impactor to the desired target angle within a predefined period of time. In some methods of use, the surgeon must align the impactor to the desired target angle within 30 seconds, within 25 seconds, within 20 seconds, in less than one minute, in less than 30 seconds, etc. The user can align the impactor to the desired cup angle. In some methods, the cup angle can be displayed statically after the impactor is positioned relative to the desired cup angle. The cup angle can be checked after impacting by repeating one or more of the ongoing steps.

[0180] In some methods of use, the surgical orientation device 172 proceeds to the next step if a timer expires (e.g., a 30 second timer, a 25 second timer, a 20 second timer, a 1 minute timer, etc.). In some methods of use, the surgical orientation device 172 proceeds to the next step if a button on the surgical orientation device 172 is pressed. In some methods of use, the surgical orientation device 172 proceeds to the next step if the orientation sensing device 204 detects a crash strong enough to disrupt navigation. In some methods of use, the surgical orientation device 172 statically displays the abduction cup angle and / or anteversion cup angle. In some methods of use, the surgical orientation device 172 statically displays the abduction cup angle and / or anteversion cup angle after a crash. In some methods of use, the surgical orientation device 172 displays the abduction cup angle and / or anteversion cup angle after a timer expires. In some methods of use, the surgical orientation device 172 displays the abduction cup angle and / or anteversion cup angle after a user types an input, such as by pressing a button. In some methods of use, the surgical orientation device 172 displays the abduction cup angle and / or anteversion cup angle after navigation is terminated.

[0181] The surgical orientation device 172 can provide the cup angle relative to any reference plane, including those described herein. The surgical orientation device 172 can provide the cup angle relative to a vertical plane. The surgical orientation device 172 can provide the cup angle relative to a plane that approximates the anterior pelvic plane. The surgical orientation device 172 can provide the cup angle relative to a plane acquired during table alignment. The surgical orientation device 172 can provide the cup angle relative to a plane that includes a vector relative to gravity.

[0182] In some embodiments, the surgeon can check the cup angle after impact as it will change during impact. In some embodiments, the cup angle is typically displayed after the first mallet strike until the beginning of impaction. In some methods of use, the surgeon will typically hit the impactor several times during cup placement. In some methods of use, these strikes can change the orientation of the cup. In some embodiments, the surgical orientation device 172 will only display the cup angle from before impaction. In some methods of use, the surgeon will repeat the cup navigation procedure by coupling the orientation sensing device 204 to the first assembly 704 such that the orientation sensing device 204 is in a fixed orientation relative to the surgical orientation device 172. In some methods of use, the configuration can be similar to the configuration shown in FIG. 12A. In some methods of use, the surgeon can interact with the orientation sensing device 204 and / or the surgical orientation device 172 using one or more of the method steps described herein. The surgeon will then move the orientation sensing device 204 to the impactor. The system 700 will now display the current cup angle. In some embodiments, the surgeon can check the cup angle after impact to improve accuracy. In some embodiments, the surgeon can verify the position of the orientation sensing device 204 and the surgical orientation device 172 after impacting before checking the angle. In some embodiments, the surgeon can visually confirm the cup angle before proceeding.

[0183] After positioning the cup, the user can attach the second system 706 to the first system 704, similar to the configuration shown in FIG. 7. In some methods of use, the user can measure for leg length and / or joint offset. At the surgeon's discretion, the system 700 can be used to navigate the condition, location, and / or orientation of the femur prior to a hip replacement. At the surgeon's discretion, the system 700 can be used to navigate the condition, location, and / or orientation of the femur after a hip replacement.

[0184] 19A-19B, the surgeon may manually reposition the femur. In some embodiments, the surgeon may manually reposition the femur to an orientation where the points were recorded. In some embodiments, the surgeon may manually reposition the femur to an orientation prior to cup placement. In some embodiments, the surgeon may manually reposition the femur to an orientation prior to joint replacement. In some methods, the surgeon opens a shutter on the optical components 174, 194. The method may include projecting light from the optical components 174, 194. In some methods of use, the incidence of the light may not be aligned with the markings. In some methods of use, the femur has moved from an orientation where the points were aligned. In some methods of use, the femur has moved from a previously recorded orientation. In some methods, the surgeon positions the leg such that the optical components 174, 194 project light onto the leg. In some embodiments, the optical components 174, 194 project onto the femur. In some embodiments, the optical components 174, 194 project onto the sterile wrap. In some embodiments, the optical components 174, 194 project light onto the distal thigh.

[0185] 19A-19B, the method may include aligning the incidence of light with a previous marking or recording of the incidence of light. In some embodiments, the surgeon may manually position the femur by moving the femur. The femur may be moved in an anterior-posterior direction. The femur may be moved in a varus-valgus direction. The femur may be rotated about the head of the femur. In some embodiments, the surgeon may manually position the femur after the joint has been replaced, for example after a cup has been placed into the joint. In some embodiments, the surgeon may realign the femur so that it is in the same position before and after cup placement. In some embodiments, the surgeon may realign the femur so that it is in the same position before and after the joint replacement. In some embodiments, the surgeon may position the femur so that it is in the same position when the surgeon tracked the incidence of light. In some embodiments, the surgeon may position the femur so that it is in the same position when the surgeon recorded the points. The surgeon can lengthen and / or rotate the femur to position it.

[0186] In some embodiments, the surgeon positions the leg such that the incidence of light from the optical components 174, 194 aligns with the tracked pattern. In some embodiments, the surgeon positions the femur relative to the pelvis. In some embodiments, the surgeon positions the femur such that the incidence of light from the optical components 174, 194 aligns with one or more marks. In some embodiments, the surgeon positions the femur such that the incidence of light aligns with two lines. In some embodiments, the surgeon positions the femur such that the incidence of light aligns with the marked crosshairs. In some embodiments, the surgeon positions the femur such that the incidence of light aligns with three marked points. In some embodiments, the surgeon positions the femur such that the incidence of light aligns with the markings on the sterile wrap. In some embodiments, the surgeon positions the femur such that the incidence of light aligns with the markings on the target probes 18a, 18b. In some embodiments, the surgeon positions the femur such that the incidence of light passes through one or more slots in the target probes 18a, 18b. In some embodiments, the surgeon discontinues use of the optical component if the crosshair pattern becomes blurred.

[0187] Referring to Fig. 19C, in some methods of use, the surgeon can align the points after positioning the femur. In Fig. 19C, the incidence of light 180 is aligned with the markings. Although a crosshair pattern is shown in Fig. 19C, the incidence of light 180 and the markings can be any pattern. By aligning the incidence of light 180 and the markings, the femur is in the same position before and after cup placement.

[0188] In some methods of use, the surgeon may align the point after cup placement. In some methods of use, the surgeon may align the same point during surgery. In some embodiments, the surgeon may align the point after the cup is placed at one or more desired target angles. In some embodiments, the surgeon may align the point after a joint replacement. The surgeon may position the distal end 780 of the probe 778 at the point. In some methods of use, the distal end 780 of the probe 778 is placed on a portion of the greater trochanter or anywhere on the proximal femur. In some methods of use, the distal end 780 of the probe 778 is placed on a mark on the femur. In some methods of use, the distal end 780 of the probe 778 is placed on a tracker 784. In some methods of use, the distal end 780 of the probe 778 is placed on a divot or burr on the femur.

[0189] The probe 778 may be immobilized to align the point. In some embodiments, the surgeon may hold the tip of the probe 778 on the point. The second assembly 706 may include a lock 766. The lock 766 may limit or reduce the slidability of the probe 778 relative to the dock 762. The lock 766 limits or reduces one degree of freedom during point alignment.

[0190] Once the tip of the distal end 780 is in contact with the desired point, the system 700 processes data from one or more sensors in the orientation sensing device 204 and stores the orientation. During alignment, the position of the orientation sensing device 204 may be recorded by the surgical orientation device 172. During alignment, the orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. During alignment, the extension of the orientation sensing device 204 may be recorded by the surgical orientation device 172. In some embodiments, the surgical orientation device 172 may align the point. In some embodiments, the surgeon may press a button on the surgical orientation device 172 to align the point.

[0191] In some methods, the surgeon aligns the markings with the light projection before aligning the points. In some methods, the surgeon aligns the markings with the light projection at the same time as aligning the points. In some methods, the surgeon aligns the markings with the light projection but does not align the points. In some methods, the surgeon aligns the points but does not align the markings with the light projection. In some methods, the surgeon aligns the markings with the light projection independent of aligning the points. In some methods, the surgeon aligns the markings with the light projection and aligns the points after the leg is fixed. In some methods, the surgeon aligns the markings with the light projection, fixes the femur, and then aligns the points after the femur is fixed.

[0192] If points are acquired in the procedure prior to separating the natural joint, the same points can be acquired after the prosthetic joint is placed to verify that the joint replacement has not changed either the leg length, the leg offset from the patient's torso, or both. After the joint replacement, the distal end 780 of the probe 778 can be brought into contact with the same points acquired earlier in the procedure. The orientation of the orientation sensing device 204 and the extension of the probe 778 can be input into the surgical orientation device 172. These data allow the surgical orientation device 172 to output the amount of change in leg length and leg offset.

[0193] The system 700 can measure the orientation of the femur relative to the pelvis during a baseline measurement of a point. The system 700 can measure the orientation of the femur relative to the pelvis during a measurement of one or more intraoperative points. The system 700 can store the two-dimensional coordinates of the point in a table coordinate reference system. In some methods of use, the surgeon can correct the change in orientation by performing a rotation about the center of rotation of the femur. In some methods of use, the surgeon can correct the change in orientation by aligning the incidence of light from the optical components 174, 194 with a marking on the femur. In some methods of use, the surgeon manually realigns the femur to take a measurement of another point. In some methods of use, the method can require obtaining a single point on the femur. The single point can be a mark. The single point can be a tracker 784 or other fixture, such as a screw or pin. The single point can be an anatomical landmark. The single point can be a burr or divot in the femur. The points may be located by the probe 778 intraoperatively each time leg length and / or joint offset is to be measured.

[0194] Prior to navigation systems such as system 700, surgeons do not make measurements intraoperatively. Rather, surgeons typically look at cup placement during the procedure and determine if the current cup placement looks like the previous cup placement. The surgeon will visually review the cup placement during surgery and past experience when viewing the post-op images. The surgeon will determine if the current cup placement tends to correlate to the correct abduction and anteversion angles post-op. The surgeon will look at the cup placement and, based on their experience viewing the post-op images, will determine that the placement looks like 40 degrees by 15 degrees. The surgeon's confidence in the procedure will be based on their correlation of the cup placement and the post-op images.

[0195] With respect to the system 700, the user is provided with an output to assist the user in navigating the proper cup placement. The output can be the abduction and anteversion angles displayed on the surgical orientation device 172. The user can navigate to the desired abduction and anteversion angles by moving components of the system 700, such as the impactor 300A or any impactor with a universal impactor adapter 350, 352. When the user places the cup at the desired abduction and anteversion angles, the user will want to see the same or similar angles on the post-operative image. If the abduction and anteversion angles produced by the system 700 match the post-operative image, the user's confidence in navigating the system 700 is increased. The vertical plane determined from gravity as described herein can match the plane used in the post-operative image. In some embodiments, the vertical plane can be similar to the reference plane of the imaging technique. In some methods of use, the vertical plane provides some patients with abduction and anteversion angles that closely match the post-operative images.

[0196] In some methods of use, as described herein, the method may include one or more of the following steps: The method may include recording a position of the probe 787 when the probe touches the point after replacing the hip joint. The method may include comparing the position of the probe when the probe touches the point to a position recorded before replacing the hip joint. In some embodiments, the surgical orientation device 172 compares measurements of two or more points. In some embodiments, the surgical orientation device 172 compares measurements of points before and after the cup is replaced. In some embodiments, the surgical orientation device 172 may provide a visual output of leg length change. In some embodiments, the surgical orientation device 172 may provide a visual output of joint offset change. In some embodiments, the surgical orientation device 172 may provide a visual output of the direction of leg length change (e.g., becoming longer or becoming shorter). In some embodiments, the surgical orientation device 172 may provide a visual output of the direction of joint offset change (e.g., lateral).

[0197] In some methods of use, as described herein, the method may include one or more of the following steps: The method may include verifying leg length after replacing the hip joint. The method may include verifying joint offset after installing the hip joint. When measuring changes in leg length and / or lateral joint offset, the apparent change is sensitive to changes in the orientation of the femur relative to the pelvis. In some methods, the change is particularly sensitive to the abduction angle. The change is moderately sensitive to rotation about the mechanical axis of the femur. The optical components 174, 194 may be used to verify the orientation of the femur relative to the pelvis before and after replacing the hip joint. In some methods, verifying the leg length and / or joint offset may include acquiring a single point on the femur. The method of use may include manually realigning the femur about the center of rotation (COR) of the hip joint.

[0198] In some methods of use, as described herein, the method may include one or more of the following steps: The method may include projecting light after replacing the hip joint. The method may include comparing a position of the light before and after replacing the hip joint. The method may include comparing the incidence of light after replacing the hip joint with one or more marks made before replacing the hip joint. The method may include comparing the incidence of light after replacing the hip joint with two or more marks made before replacing the hip joint. The method may include comparing the incidence of light after replacing the hip joint with a line made before replacing the hip joint.

[0199] In some methods of use, as described herein, the method may include one or more of the following steps: The method may include verifying the position of the leg relative to the pelvis after replacing the hip joint. The method may include verifying the position of the femur relative to the pelvis after replacing the hip joint. The optical components 174, 194 may be useful to measure the orientation of the leg relative to the pelvis during a pre-operative baseline and after surgery. The surgeon may correct for changes in orientation by repositioning the leg based on the incidence of the light. These marks may guide the surgeon in recreating the orientation of the leg relative to the pelvis whenever a leg length measurement or joint offset measurement is required. The optical components 174, 194 may be used with the posterior approach described herein.

[0200] In some embodiments, the surgeon can verify the home position after measuring leg length and / or joint offset. The second assembly 706 can be coupled to the first assembly 704. The first assembly 704 can be coupled to the fixed base 702. In some techniques, the distal end 780 of the probe 778 can be engaged with a point on the fixed base 702, such as a divot 730. The user can type an input to record the home position. In some methods of use, the home position remains fixed relative to the pelvis throughout the procedure. In some embodiments, the surgical orientation device 172 can indicate a change in the home point. The displayed number may not be zero due to mechanical play and noise of the orientation sensing device 204. In some methods of use, if the displayed number is greater than 3 mm, the surgeon can verify that all reference sensor attachments and jig connections are correct and fixed before repeating. In some methods of use, if the displayed number is greater than 3 mm, the surgeon may repeat the alignment of the points or the alignment of the femur. In some methods of use, repeating the alignment may result in the loss of all previous alignment. In some methods of use, the surgeon may determine if the fixed base 702 has moved. In some methods of use, the surgeon may end the procedure. In some methods of use, ending the procedure may result in the loss of previous alignment. In some methods of use, ending the procedure may result in the information being stored. In some methods of use, the leg length is stored. In some methods of use, the joint offset is stored. In some methods of use, the target angle is stored. In some methods of use, the fixed base 702 and fixation pins 710, 712 are removed prior to closure. In some embodiments, the surgical orientation device 172 is discarded. In some embodiments, the orientation sensing device 204 is reusable. In this embodiment, the optical components 174, 194 are reusable.

[0201] The table plane may be an improvement over the landmark-based reference plane for some patients. In some embodiments, the landmark-based reference plane may differ from the vertical reference plane calculated here due to patient-specific factors. For example, pelvic tilt may orient the landmark-based reference plane at a certain angle from the vertical reference plane. For example, a high body mass index of a patient may affect the ability to contact anatomical landmarks. For example, the anatomical features of the reference points may not be visible and / or palpable while the patient is in the lateral position in a posterior approach. For example, the ipsilateral ASIS, contralateral ASIS, and / or pubic symphysis may not be visible and / or palpable. Patient-specific factors may result in a difference between the navigated cup angle from the landmark-based reference plane and the angle measured post-operatively. In some methods of use, the landmark-based reference plane may not provide some patients with abduction and anteversion angles that match the post-operative view.

[0202] The systems and methods described herein are capable of improving hip prosthesis placement using navigation. These hip prosthesis procedures typically guide the hip prosthesis to an orientation in the acetabulum that minimizes the likelihood of dislocation due to impingement of the femoral neck against the cup or against the bone surrounding the acetabulum, or due to other reasons related to suboptimal orientation of the prosthesis. Various techniques utilize population averages of proper placement, while others are amenable to patient-specific refinement.

[0203] C. Navigation using one or more reference planes via a forward approach 1. Anterior approach method 1-5C illustrate a hip navigation system 600 adapted to navigate a hip procedure from an anterior approach. FIGS. 7-10D illustrate a hip navigation system 700 adapted to navigate a hip procedure from an anterior approach. Although the method is described with reference to the system 600, any of the systems described herein or in the following publications may be utilized: U.S. Patent Application Publication No. 2016 / 0242934, filed March 10, 2015; U.S. Patent Application Publication No. 2014 / 0052149, filed March 13, 2013; and U.S. Patent Application Publication No. 2010 / 0137871, filed September 10, 2009, all of which are incorporated by reference in their entirety. An anterior approach to hip replacement can advantageously be less invasive than a posterior approach. Among other things, an anterior approach can allow for smaller incisions, less soft tissue dissection, and shorter patient recovery times.

[0204] In some embodiments, the navigation system 600 is configured to locate relevant anatomical features to aid in proper placement of the hip prosthesis. In some methods, pre-operative imaging techniques are used. In some methods of use, the surgeon may use a standing or supine anteroposterior (AP) pelvic x-ray. FIG. 21 shows a standing AP radiograph taken with the patient standing with feet shoulder-width apart in neutral rotation. The x-ray tube-to-film distance should be 120 cm, with the crosshairs centered on the midpoint between the upper edge of the pubic symphysis and a line drawn connecting the anterior superior iliac spine (ASIS). The coccyx should be centered in line with the pubic symphysis, and the iliac wings, obturator foramen, and radiographic teardrop should be symmetrical in appearance. For proper pelvic tilt or abduction, a 1-3 cm gap should be seen between the tip of the coccyx and the upper edge of the pubic symphysis. This positioning can be important for measuring the patient-specific Rim Teardrop (RT) angle.

[0205] To obtain a patient-specific Rim Teardrop (RT) angle from an AP pelvic x-ray, the surgeon can complete one or more of the following steps: The surgeon can draw a line on the x-ray connecting the bottom of the teardrops. The surgeon can draw a line from the lateral most point on the rim (R) of the acetabulum on the operative side through the bottom of the teardrop (T) to the horizontal inter-teardrop line. If osteophytes are present on the rim (R), the surgeon can draw a line through the lateral most osteophyte. The surgeon can measure the angle between the inter-teardrop line and the RT line just drawn. This patient-specific RT abduction angle can be an input for the system 600, 600A.

[0206] FIG. 22 illustrates patient positioning for an anterior hip approach. In an anterior hip approach, the patient should be placed in a supine position. When positioning the patient prior to surgery, the surgeon should take care to align the patient's spine and femur in a horizontal plane parallel to the long edge of the operating table. The surgeon can verify that the patient is positioned in the appropriate position (e.g., supine).

[0207] 23 illustrates a system 600 adapted to navigate a hip procedure with reference to anatomical landmarks from an anterior approach. The system 600 includes an orientation sensing device 204 (not shown in FIG. 23). The system 600 can be adapted for either a posterior or an anterior approach. In the anterior approach, the patient is in a supine position.

[0208] The surgical orientation device 172 and the orientation sensing device 204 may be switched on before the procedure begins. If the system may be used in a knee or hip procedure, a method may require the surgeon to select the module that corresponds to the hip joint. If the system may be used in a posterior or anterior approach, a method may require the surgeon to select the module that corresponds to the anterior approach. The surgical orientation device 172 may include a display screen. The surgical orientation device 172 may include a user interface, such as a button that may be pressed by a user. The display screen may confirm communication between the surgical orientation device 172 and the orientation sensing device 204.

[0209] The system 600 may be partially assembled for calibration as shown in FIG. 12A. In some embodiments, the first assembly 604 may be assembled. The pelvic bracket 638, if a separate component, may be coupled to the extension 644. The surgical orientation device 172 may be coupled to the mount 646. In some techniques, the extension 670 may be coupled to the second coupler 648. The orientation sensing device 204 may be coupled to the mount 672. The surgical orientation device 172 and the orientation sensing device 204 form a generally V-shaped configuration, similar to the orientation shown in FIG. 12A. The orientation sensing device 204 may be secured in an appropriate position relative to the surgical orientation device 172.

[0210] The surgical orientation device 172 and the orientation sensing device 204 may be calibrated. The surgical orientation device 172 may be placed on a flat horizontal surface with the display oriented horizontally (facing up). The surgeon may hold the assembly 604, 606 steady until the surgical orientation device 172 indicates completion. The orientation sensing device 204 may be placed on a flat horizontal surface with the display oriented vertically (facing towards the user). The surgeon may hold the assembly 604, 606 steady until the surgical orientation device 172 indicates completion. The surgical orientation device 172 may be placed on a flat horizontal surface with the display oriented horizontally (to the left). The surgeon may hold the assembly 604, 606 steady until the surgical orientation device 172 indicates completion. The surgical orientation device 172 may be placed on a flat horizontal surface with the display again in a horizontal orientation (facing up). The surgeon can hold the assemblies 604, 606 steady until the surgical orientation device 172 indicates completion. Other orientations of the surgical orientation device 172 and orientation sensing device 204 are also contemplated for calibration.

[0211] The user can remove the required tools and prepare the tools for use. FIG. 18A illustrates an impactor 300A. As described herein, the impactor 300A can include a fourth coupler 342 to couple the impactor 300A to the orientation sensing device 204. In some methods, any impactor can be used with the systems and methods described herein. A universal impactor adapter 350, 352 can provide a fourth coupler 342 to couple the impactor to the orientation sensing device 204. In some methods of use, the orientation sensing device 204 can be coupled to the impactor 300A. In some methods of use, the orientation sensing device 204 can be coupled to any impactor via the universal impactor adapter 350, 352. The orientation sensing device 204 can determine the cup angle relative to a reference plane as the impactor is moved. As described herein, the impactor 300A can include a shell 312A. Movement of the shell 312A is cushioned by a plurality of spring members 340, 344 configured to absorb at least some of the shock of an impact on the impactor 300A. The shell 312A can include a fourth coupler 342, which allows the orientation sensing device 204 to couple to the shell 312A. The impactor 300A can be configured to be modified to suit any of a number of hip joint prostheses. For example, a number of tip components 348 can be provided in a kit, where each tip component is attachable to and detachable from the distal end of the shaft of the impactor 300A. An acetabular shell can be threadably attached onto the tip component 348. A user can select an appropriate shell adapter for a desired impactor.

[0212] Any impactor may be utilized as described herein. The surgeon may utilize a universal impactor adapter 350, 352. The universal impactor adapter 350, 352 may include a fourth coupler 342, which allows the orientation sensing device 204 to couple to the impactor. The universal impactor adapter 350, 352 may form any rigid connection to the impactor. Although a magnet and clamp are described herein, any mechanical connection between the universal impactor adapter 350, 352 and the impactor is contemplated. The impactor may be adapted for any of a number of hip joint prostheses. For example, a number of tip components 348 may be provided in a kit, where each tip component is attachable to and detachable from the distal end of the shaft of the impactor. The impactor may be adapted for a particular hip joint prosthesis. The tip of the impactor may be designed to interface with a single acetabular shell. The acetabular shell may be threadably mounted onto the impactor. Universal impactor adapters 350, 352 may allow any impactor to be used with the orientation sensing device 204 as described herein.

[0213] The user can interact with the surgical orientation device 172. If the system can be used in either hip procedure, one method may require the surgeon to select the module corresponding to the right hip or the left hip. In some methods of use, the user can input a target cup abduction angle. This is the radiographic abduction angle defined as the coronal plane projection of the angle between the acetabular axis and the longitudinal axis of the body. Abduction and adduction are also used to describe the movement of the limb in the coronal plane. In some methods of use, the user can input a target cup anteversion angle. This is the radiographic anteversion angle defined as the angle between the acetabular axis and the coronal plane.

[0214] The probe 678 may be calibrated. The extension 670 may be decoupled from the second coupler 648. The second assembly 606 may be assembled as shown in FIG. 12B. The first assembly 604 may be coupled to the second assembly 606 as shown in FIG. 12B. In some methods of use, the system 600 may include a calibration fixture 690. The first assembly 604 and the second assembly 606 may be mounted in the calibration fixture 690. The calibration fixture may include multiple points for the probe 678 to contact.

[0215] The probe 678 can contact a center hole in the base of the calibration fixture 690 to calibrate the center point. The user can press a button when the probe 678 is in place. The probe 678 can contact a left hole in the base of the calibration fixture 690 to calibrate the left point. The user can press a button when the probe 678 is in place. The probe 678 can contact a right hole in the base of the calibration fixture 690 to calibrate the right point. The user can press a button when the probe 678 is in place. The calibration fixture 690 can be utilized prior to a procedure. The calibration fixture 690 can be located away from the patient, for example, on a back table. Other calibration fixtures and jigs are contemplated.

[0216] The system 600 may be attached to the pelvis as shown in FIG. 23. The user may position the system 600 so that it has a strong and stable mount for attachment of the instrumentation to the pelvis. In some methods of use, all measurements and references are based on an initial alignment process, and any movement of the first assembly 604 thereafter will result in an error in the resulting reading of the cup position. In some methods, the fixation pins 610, 612 are placed in the ipsilateral iliac crest in a parallel manner. The fixation pins 610, 612 are placed in a manner similar to the placement of pins for pelvic external fixation. The fixation pins 610, 612 enter the iliac wing at its uppermost surface and travel between the medial and lateral bone tables of the iliac wing.

[0217] To prevent subsequent femoral exposure and broaching failure with an anterior approach, in some methods of use, the most anterior fixation pin should be placed 2-4 cm posterior to the ASIS. It is also helpful to evaluate the patient's pre-operative x-rays to assess the relative angle that will allow passage of the fixation pin 610, 612 into the bone. The optimal location for the fixation pin 610, 612 will be entered at an approximately 45 degree angle from the anterior pelvic plane, allowing the pin to enter into the thicker supracelabial bone along the anterior column. In some methods of use, fixation pins 610, 612 that are passed at an angle greater than 45 degrees run the risk of exiting the cortical bone where the ilium becomes thinner more posteriorly.

[0218] The fixation pins 610, 612 are designed with a sharp tip to allow for firm placement while starting through the thicker outer cortical bone. This reduces the risk of pin slippage and malplacement. It is also important that the user feels for any significant resistance when threading the fixation pins 610, 612 to the appropriate depth to avoid perforating the cortical bone. If there is concern about the pin location, the user can aim for the more outer iliac wall. In some methods of use, the fixation pins 610, 612 can be stabilized if they are placed at least half their length into the bone. This will provide a stable build with the mount. The fixation base 602 is designed to allow for parallel placement with the anterior pelvic plane if the pins are placed at 45 degrees.

[0219] The fixation pins 610, 612 may be inserted into the bone. In some techniques, one or more of the fixation pins 610, 612 are positioned as described herein. In some techniques, one or more of the fixation pins 610, 612 are positioned above the iliac crest. In some techniques, one of the fixation pins 610, 612 is positioned above the iliac crest 2-4 cm posterior to the ASIS. In some techniques, the other fixation pin 610, 612 is positioned 2 cm posterior to the first fixation pin. The fixation base 602 may be slid over the fixation pins 610, 612 to skin level. The fixation device 624 of the fixation base 602 may be tightened to secure the fixation base 602 to the fixation pins 610, 612. In some methods of use, the fixation base 602 must be attached before dislocating the hip joint.

[0220] The system 600 may be assembled as shown in FIG. 1. The orientation sensing device 204 may be coupled to a probe 678. In some embodiments, the orientation sensing device 204 and / or the probe 678 may include indicia, such as an arrow, to facilitate alignment. The first assembly 604 may be secured to the fixed base 602 with the surgical orientation device 172 attached. The first assembly 604 may be secured by pressing the lock lever 640, as described herein. The second assembly 606 may be secured to the fixed base 602 with the orientation sensing device 204 attached. In some embodiments, the second assembly 606 and / or the fixed base 602 include indicia, such as an arrow, to facilitate alignment.

[0221] The surgical orientation device 172 may be aligned with the sagittal plane. The system 600 may be installed such that the probe 678 can reach all required landmarks that define the anterior pelvic plane. The fixed base 602 may be adjusted. In some methods of use, the fixed base 602 may be slid along the fixation pins 610, 612. In some methods of use, the angle or tilt of the fixed base 602 may be adjusted. After adjustment, the screws on the fixed base 602 may be tightened to secure the fixed base 602 to the fixation pins 610, 612 for the remainder of the procedure.

[0222] The surgeon can align the parked configuration or home position. In some techniques, the distal end 680 of the probe 678 can be engaged with a point on the fixed base 602, such as a divot 630. The probe 678 can be vertical in the home position. The orientation sensing device 204 can be vertical in the home position. The distal end of the probe 678 can be curved or bent to facilitate locating an anatomical landmark or point.

[0223] When aligning a point, the user can hold the probe 678 close to the distal end 680 to maximize the accuracy of the measurement of the point. When interacting with the surgical orientation device 172, the user can support the back of the surgical orientation device 172 to avoid bending the fixation pins 610, 612 and / or the fixed base 602. The user can align the point by pressing a button on the surgical orientation device 172. If the alignment is not acceptable, the user can hold the probe 678 stationary and press the button again.

[0224] The surgeon may position the distal end 680 of the probe 678 at various anatomical landmarks or points. FIG. 24 illustrates the anatomy of the hip joint. As illustrated by FIG. 24, two landmarks are circled. The landmarks include the two anterior superior iliac spines (ASIS), which are bony processes of the ilium. The anterior superior iliac spines may be visualized and / or palpated by the user during surgery. The anterior superior iliac spine is the anterior end of the iliac crest of the pelvis. The inter-ASIS line extends between these landmarks. The inter-ASIS line extends between the ipsilateral ASIS and the contralateral ASIS. In other methods of use, other landmarks are used. Other landmarks that may be used include locations above the ilium, ischium, and pubis, the anterior insertion point of the transverse acetabular ligament onto the ischium, the midpoint of the inferior aspect of the acetabular notch, the anterior superior iliac spine, the anterior inferior iliac spine, the convergence point of the acetabulum and the anterior inferior iliac spine, and other landmarks known in the art.

[0225] The system 600 has one or more processors that receive data and determine the relative positions and / or orientations of the anatomical landmarks when the probe 678 is in contact with the anatomical landmarks. The data may be generated by inertial sensors, as discussed elsewhere herein, or by other types of sensors of the system 600. Preferably, the sensors are small enough to be mounted on or in a handheld housing or embedded in an instrument, such as the surgical orientation device 172 and the orientation sensing device 204. The system 600 also preferably has a memory device to at least temporarily store the positions of these points. The system 600 also preferably has the capability to at least temporarily store the associated position and / or orientation data when the probe 678 is in contact with the anatomical landmarks. In some methods of use, the system 600 records the position and / or orientation of the probe 678 when the probe 678 is in contact with the respective anatomical landmark or point. In some methods of use, the system 600 stores the recorded position and / or orientation of the probe 678 during the length of the procedure. In some methods of use, the system 600 stores the recorded position and / or orientation of the probe 678 until the system is powered off.

[0226] 25A-D illustrate method steps for calculating the anterior pelvic plane. The anterior pelvic plane may be defined as the plane generated by the two anterior superior iliac spines (ASIS) and the anterior surface of the pubic symphysis. Three points provide sufficient information to calculate the plane. The system 600 can generate the anterior pelvic plane by aligning point 1, point 2, and point 3. These anatomical features are visible and / or palpable while the patient is in the supine position. In some methods, the probe 678 aligns the anterior pelvic plane by direct contact of anatomical landmarks while the patient is in the supine position. The system 600 can then provide user navigation data of the orientation of the hip joint instrument (e.g., impactor 300A, or any impactor with universal impactor adapter 350, 352) relative to the anterior pelvic plane. In some embodiments, the system 600 can provide user navigation data in real time. In the anterior approach, the patient is positioned supine with the anterior pelvic plane oriented substantially horizontally, eg, substantially parallel to the plane of a table on which the patient is positioned.

[0227] FIG. 25A illustrates the approximate location of three points on the anterior pelvic plane. The surgeon may align point 1, point 2, and point 3. The illustrated embodiment shows point 1 on the left hip, point 2 on the right hip, and point 3 on the right hip. Other configurations are contemplated. For some procedures on the patient's left hip, point 1 is on the left hip and point 2 is on the right hip. For some procedures on the patient's right hip, point 1 is on the right hip and point 2 is on the left hip. Other methods are contemplated. In some methods, point 1 is the ipsilateral ASIS. In some methods, the distal end 680 of the probe 678 is placed on the ipsilateral ASIS landmark. The probe 678 may be immobilized and the position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The surgeon may enter an input to align point 1 (e.g., pressing a button on the surgical orienting device 172). Other manners of entering an input include interacting with a touch screen, using a verbal command, touching an icon, holding the probe 678 steady for a predetermined period of time, and / or reaching the end of a countdown clock, etc. The surgical orienting device 172 may indicate that point 1 has been recorded. Additionally, the distance that the probe 678 is extended to contact the ipsilateral ASIS, as captured by the camera 184, may be recorded by the orienting device 172. The process for recording the ipsilateral ASIS may be repeated for one or more additional points.

[0228] In some methods, point 2 is the contralateral ASIS. In some methods, the distal end 680 of the probe 678 is placed at the contralateral ASIS landmark. The probe 678 may be immobilized and the position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The surgeon may enter an input (e.g., press a button on the surgical orientation device 172) to align point 2. The surgical orientation device 172 may indicate that point 2 has been recorded. Additionally, the distance the probe 678 is extended to contact the contralateral ASIS, as captured by the camera 184, may be recorded by the orienting device 172. The process for recording the contralateral ASIS may be repeated for one or more additional points.

[0229] In some methods, point 3 is the anterior surface of the pubic symphysis. In some methods, the distal end 680 of the probe 678 is placed at a pubic landmark. In some methods, any of the pubic tubercles may be used as point 3. In some embodiments, the contralateral pubic tubercle is used as point 3. The probe 678 may be immobilized and the position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The surgeon may enter an input (e.g., press a button on the surgical orientation device 172) to align point 3. The surgical orientation device 172 may indicate that point 3 has been recorded. Additionally, the distance the probe 678 is extended to contact the pubic symphysis, as captured by the camera 184, may be recorded by the orienting device 172. The process for recording the pubic symphysis may be repeated for one or more additional points.

[0230] Distances related to the extension of the probe 678 may be used along with position and / or orientation data from the orientation sensing device 204. In some methods, the orientation sensing device 204 converts the image of the camera 184 into an extension measurement of the probe 678. In some embodiments, the surgical orientation device 172 converts the image of the camera 184 into an extension measurement of the probe 678. When aligning the anatomical points, the camera 184 captures an image of the markings 682. The camera 184 can read the markings 682 to provide an accurate determination of the translational position of the probe 678 relative to the dock 662. The camera 184 can be directly above the markings 682. In some methods, the camera 184 can read the binary code of the markings 682.

[0231] The surgical orientation device 172 can use the length measurements from the camera 184 and the data from the orientation sensing device 204 to determine the location of the distal end 680 of the probe 678. In some embodiments, the surgeon will enter an input (e.g., press a button) to collect data from the orientation sensing device 204. In some embodiments, the surgeon will enter an input (e.g., press a button) to collect data from the camera 184. In some methods, the surgeon will enter an input (e.g., press a button) to simultaneously collect data from the orientation sensing device 204 and the camera 184. In some methods, the orientation sensing device 204 and / or the camera 184 will only send data if the orientation sensing device 204 is stable or not moving.

[0232] Once the aforementioned points of the pelvis have been navigated and data recorded into the surgical orientation device 172, the anterior pelvic plane can be calculated from the data indicative of the navigated points. The system 600 is capable of calculating the anterior pelvic plane from three points recorded by the system 600. The three points are shown in FIG. 12A. FIG. 25B illustrates the inter-ASIS line. The inter-ASIS line connects point 1 and point 2. The inter-ASIS line provides a straight line between the ipsilateral ASIS and the contralateral ASIS. FIG. 25C illustrates the generally horizontal orientation of the anterior pelvic plane. The anterior pelvic plane can be considered to be a horizontal plane that pivots about the inter-ASIS axis depending on the location of point 3. FIG. 25D illustrates the anterior pelvic plane (APP) determined by point 3. The anterior pelvic plane includes the anterior surfaces of the ipsilateral ASIS, the contralateral ASIS, and the pubic symphysis.

[0233] As described herein, the system 600 can determine a reference plane. The plane can be uniquely determined by any of the following: three non-collinear points, a line and a non-collinear point, two separate but intersecting lines, or two parallel lines. In some methods of use, the anterior pelvic plane is calculated based on three non-collinear points. In some methods of use, the anterior pelvic plane is calculated based on the anterior surfaces of the ipsilateral ASIS, the contralateral ASIS, and the pubic symphysis. In some methods of use, the orientation of the anterior pelvic plane can be a baseline for placement of the cup portion of the hip joint prosthesis. The surgical orientation device 172 can display information about the anterior pelvic plane. In some methods of use, the abduction and anteversion angles for cup placement in a total hip replacement can be with respect to the anterior pelvic plane. The anterior pelvic plane is cited in the literature as a useful anatomical plane to guide cup placement. In some embodiments, the anterior pelvic plane is determined by the surgical orientation device 172 and / or the orientation sensing device 204. In some embodiments, a coordinate reference system is established by the anterior pelvic plane. The anterior pelvic plane coordinate reference system is a three-dimensional coordinate reference system. The anterior pelvic plane coordinate reference system is a coordinate reference system that contains the anterior pelvic plane. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 are capable of providing orientation and / or position data related to the anterior pelvic plane coordinate reference system. In some embodiments, the surgical orientation device 172 is capable of displaying orientation and / or position data with respect to the anterior pelvic plane coordinate reference system.

[0234] 26A-D illustrate method steps for calculating the table plane. Any method for establishing the table plane described herein or incorporated by reference may be utilized. The table plane can be a horizontal or generally horizontal plane. In some techniques, the surgical table is horizontal and the table plane approximates the plane of the table. In some techniques, the table plane may be oriented relative to other surfaces in the operating room. In some techniques, the floor is horizontal and the table plane approximates the plane of the floor. In some techniques, the walls are vertical and the table plane approximates a plane perpendicular to the walls. In some techniques, the ceiling is horizontal and the table plane approximates the ceiling. Other surfaces may be used to approximate the horizontal plane. Table alignment estimates the coronal or frontal plane. The coronal plane is the plane that divides the body into anterior and posterior sections. The coronal plane is the horizontal reference plane when the patient is in the supine position for an anterior approach. The orientation sensing device 204 can align the surgical table or perform table alignment for an anterior approach. The upper surface of the surgical table on which the patient is positioned is positioned horizontally. The patient can be positioned so that the coronal plane of the pelvis is horizontal, e.g., parallel to the table and / or also horizontal. The user can visually verify that the coronal plane is horizontal or can use the device to position the patient's body so that the coronal plane is aligned with the plane of the upper surface of the table. In some embodiments, a reference plane based on the plane of the upper surface of the table can be input into the system 600.

[0235] The table plane provides clinical value. In some techniques, the table plane can provide a secondary reference plane to the anterior pelvic plane. In some embodiments, the table plane is determined completely independent of any anatomical landmarks. The table plane provides a check against gross errors from anatomical alignment. The table plane provides a reference plane that is not affected by pelvic tilt. The table plane provides a reference plane that is not affected by alignment errors due to soft tissue. The table plane appears in the large console navigation. The table plane is calculated based on properly aligning the probe 678. In some methods of use, the alignment of the probe 678 can be done entirely by eye. The table plane provides a horizontal plane that can be useful for comparing navigated cup angles with pre- and / or post-operative images. Pre- and / or post-operative images, such as x-rays, are captured in a horizontal reference plane. The table plane can provide a horizontal reference plane that approximates the horizontal reference plane of the imaging technique.

[0236] During table alignment, the probe 678 is coupled to the orientation sensing device 204. In some methods of use, the probe 678 and the orientation sensing device 204 are constrained. As one example, the probe 678 may be coupled to other components of the first assembly 604 and / or the second assembly 606. In some methods of use, the system 600 is assembled such that the first assembly 604 and the second assembly 606 are coupled to the patient via the fixation pins 610, 612. There may be a mechanical constraint imparted by the pivoting configuration of the system 600.

[0237] FIG. 26A illustrates the position of the probe 678 during table alignment. The probe 678 is rotated and / or pivoted by the mount 658 so that the probe 678 points in a direction parallel to the patient's sagittal plane. The probe 678 may extend toward the patient's feet. The probe 678 may be aligned with the long axis of the body. The probe 678 may be held substantially parallel to the plane of the table. Referring back to FIG. 22, a side view of the patient illustrates one line parallel to the table. During table alignment, the probe 678 may be parallel to the table when viewed from the side. In some embodiments, the user may align the probe 678 with the horizontal direction. The user may visually inspect the probe 678 from one or more locations. For example, the user may inspect the probe 678 from a top view and a side view. In some embodiments, the user may align the probe 678 with the sagittal plane. The probe 678 may be parallel to the sagittal or parasagittal plane. The sagittal plane divides the body into a right side and a left side.

[0238] 26B illustrates the table plane (TP) in a method of use. The probe 678 may be immobilized and the position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The user may enter an input to align the table (e.g., press a button on the surgical orientation device 172). The user may interact with a user interface on the surgical orientation device 172 to send a signal to the surgical orientation device 172 to capture the position and / or orientation of the orientation sensing device 204. The surgical orientation device 172 may indicate that the table plane has been recorded.

[0239] In some embodiments, information from one or more inertial sensors is used during table registration. As described herein, the orientation sensing device 204 and the surgical orientation device 172 can include one or more inertial sensors. In some embodiments, the position and / or orientation of the one or more inertial sensors can provide data associated with the table plane. The one or more inertial sensors can detect gravity and provide a vector with respect to a downward direction. The table plane is considered to be a horizontal plane. In some methods of use, the vector with respect to the downward direction can be used by the system to verify that the table plane is a horizontal plane. In some embodiments, only the direction of the projection of the probe 678 onto the horizontal plane is used. In some embodiments, the table plane is determined by the surgical orientation device 172. In some embodiments, a coordinate reference system is established by the table plane. The table coordinate reference system is a three-dimensional coordinate reference system. The table coordinate reference system can be determined by the orientation sensing device 204 and the surgical orientation device 172. The table coordinate reference system can be determined in different manners for anterior and posterior approaches. For example, different sensors of the orientation sensing device 204 and the surgical orientation device 172 may be utilized to determine the table coordinate reference system for the anterior and posterior approaches.

[0240] The table plane provides an estimate of the coronal plane orientation. The table plane can be recorded and stored in the system 600. The system 600 can calculate the cup angle based on the table plane, based on the assumption that the patient's pelvis is correctly positioned during table plane alignment. In some methods of use, the abduction and anteversion angles for cup placement in a total hip replacement can be relative to the plane determined during table alignment.

[0241] In some techniques, table alignment may be completed before dislocating the hip joint. The torque applied during dislocation may move the pelvis away from the correct initial alignment. In some techniques, the fixed base 602 may not be adjusted by the user after table alignment. For example, the user cannot adjust the fixed base 602 relative to the pins 610, 612. The fixed base 602 remains in place throughout the remainder of the procedure. In some techniques, the pelvic bracket 638 may not be adjusted by the user after table alignment. The pelvic bracket 638 remains in place throughout the remainder of the procedure. In some techniques, the angle of the pelvic bracket 638 relative to the fixed base 602 may not be changed after table alignment. In some techniques, the probe 678 may not be replaced with a different probe after table alignment. The same probe 678 is used throughout the remainder of the procedure.

[0242] 26C and 26D illustrate another result of table alignment. In some methods of use, the probe 678 can be oriented at a myriad of angles from the horizontal during table alignment. For example, when viewed from the side as in FIG. 22, the probe 678 can be seen to be aligned with the coronal plane. However, the top view shown in FIG. 26C shows the probe to be angled with respect to the sagittal plane. The user may introduce other errors based in part on the user's viewpoint when the probe 678 is positioned. FIG. 26D shows the resulting table plane (TP). FIGS. 13B and 26D show two different planes that are calculated during table alignment. In both methods of use, the probe 678 is positioned parallel to the surgical table. However, the two planes are angled based on the positioning of the probe 678. In some methods of use, the possibility of misalignment may exist due to improper positioning of the probe 678.

[0243] 27A-27D illustrate method steps for calculating the ADJUSTED plane. FIG. 27A illustrates the inter-ASIS line. The inter-ASIS line connects point 1 and point 2 discussed above in connection with FIG. 25A. The inter-ASIS line provides a straight line between the ipsilateral ASIS and the contralateral ASIS. Point 1 and point 2 may be recorded by the system 600 as described herein. Point 1 and point 2 may be recorded as part of the method for calculating the anterior pelvic plane. Point 1 and point 2 may be recorded independently from the method for calculating the anterior pelvic plane. The adjusted plane may be calculated in addition to or as an alternative to the anterior pelvic plane. In some methods, point 1 and point 2 are used to calculate the anterior pelvic plane and the adjusted plane. The system 200 may store point 1 and point 2 with respect to the anterior pelvic plane and the adjusted plane. In some methods, point 1 and point 2 are aligned only once with respect to the anterior pelvic plane and the adjusted plane.

[0244] The system 600 can generate an adjusted plane by aligning point 1 and point 2. These anatomical features can be seen and / or palpated while the patient is in a supine position. The system 600 can then provide the user navigational data of the orientation of the hip joint instrument (e.g., impactor 300A or any impactor with universal impactor adapter 350, 352) relative to the adjusted plane. In some methods of use, the navigational data is provided in real time. In the anterior approach, the patient is positioned supine and the adjusted plane is oriented substantially horizontally, for example, relative to the plane of a table on which the patient is positioned.

[0245] FIG. 27A illustrates the approximate location of two points on the adjusted plane. The surgeon can align point 1 and point 2 as described herein. In some methods, point 1 is the ipsilateral ASIS. In some methods, the distal end 680 of the probe 678 is positioned at the ipsilateral ASIS landmark. While the probe 678 is in contact with the landmark, the position and / or orientation of the orientation sensing device 204 can be transmitted to the surgical orientation device 172. While the probe 678 is in contact with the landmark, the distance the probe 678 is extended, as measured by the camera 184, can be transmitted to the surgical orientation device 172. The user can type an input (e.g., press a button on the surgical orientation device 172) to record point 1. The surgical orientation device 172 can provide an indication that point 1 has been recorded, such as a visual or audio cue.

[0246] In some methods, point 2 is the contralateral ASIS. In some methods, the distal end 680 of the probe 678 is placed at the contralateral ASIS landmark. In some methods, the distal end 680 of the probe 678 is positioned at the contralateral ASIS landmark. While the probe 678 is in contact with the landmark, the position and / or orientation of the orientation sensing device 204 may be transmitted to the surgical orientation device 172. While the probe 678 is in contact with the landmark, the distance the probe 678 is extended, as measured by the camera 184, may be transmitted to the surgical orientation device 172. The user may type an input (e.g., press a button on the surgical orientation device 172) to record point 2. The surgical orientation device 172 may provide an indication that point 2 has been recorded, such as a visual or audio cue.

[0247] The adjusted plane is found by rotation of the anterior pelvic plane around the inter-ASIS line, which will be perpendicular to the force of gravity. The adjusted plane utilizes a measurement of gravity. As described herein, the surgical orientation device 172 includes one or more inertial sensors. As described herein, the orientation sensing device 204 includes one or more inertial sensors. In some embodiments, inertial data from the one or more inertial sensors is used to calculate the adjusted plane. In some embodiments, the position and / or orientation data of the one or more inertial sensors is used to calculate the adjusted plane. The surgical orientation device 172 and / or the orientation sensing device 204 can include an accelerometer, which can provide a measurement of the direction of gravity. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 includes a sensor for detecting the direction of gravity. The surgical orientation device 172 and / or the orientation sensing device 204 can be sensitive to the direction of gravity. The one or more inertial sensors can provide a vector aligned with the vertical direction, for example, with respect to a downward direction. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 include a three-axis accelerometer to detect orientation relative to or of gravity.

[0248] In some embodiments, the surgical orientation device 172 includes an accelerometer. In some embodiments, the orientation sensing device 204 includes an accelerometer. The accelerometer at rest can measure acceleration due to the Earth's gravity. The accelerometer can measure acceleration from gravity straight down or vertically. In some embodiments, the accelerometer can detect the magnitude and direction of the force of gravity. The accelerometer can create a vertical vector. The accelerometer can create a horizontal vector by transforming the vertical vector (e.g., by rotating 90 degrees). The accelerometer can provide orientation and / or position data such that the adjusted plane is perpendicular to the force of gravity.

[0249] The surgical orientation device 172 and / or the orientation sensing device 204 can provide a reference value for zero gravity. As referred to herein, zero gravity generally refers to an orientation in which the axis of the sensor is perpendicular to the force of gravity, thereby experiencing no angular offset, e.g., tilt, pitch, roll, or yaw, relative to the gravity vector.

[0250] In some methods of use, the gravity measurement may be taken at any point during the procedure. The gravity measurement may be taken during pre-operative calibration. The gravity measurement may be taken during table alignment. In some methods, the probe 678 is placed in a horizontal orientation. The placement of the probe 678 may provide verification that there is no significant error in the gravity measurement. FIG. 27B illustrates one position of the probe 678 for calculating the direction of gravity when the probe 678 is generally horizontal. The probe 678 is rotated and / or pivoted by the mount 658 so that the probe 678 points in a direction parallel to the sagittal plane of the patient. The probe 678 may extend toward the patient's feet. The probe 678 may be aligned with the long axis of the body. The probe 678 may be held substantially parallel to the plane of the table. In some embodiments, the user may align the probe 678 horizontally. The user may visually inspect the probe 678 from one or more locations. For example, the user can inspect the probe 678 from a top view and a side view. In some embodiments, the user can align the probe 678 with a sagittal plane. The probe 678 can be parallel to the sagittal plane or the parasagittal plane. The sagittal plane divides the body into right and left sides. As described herein, the orientation sensing device 204 can be positioned horizontally to measure gravity. As described herein, the probe 678 coupled to the orientation sensing device 204 can be positioned horizontally or substantially horizontally to measure gravity.

[0251] The probe 678 may be held or immobilized in place. The position and / or orientation of the orientation sensing device 204 may be recorded by the surgical orientation device 172. The user may enter an input (e.g., press a button on the surgical orientation device 172) when the probe 678 is positioned horizontally. The user may interact with a user interface on the surgical orientation device 172 to signal the surgical orientation device 172 to capture data of the orientation sensing device 204 when the probe 678 is positioned horizontally. The surgical orientation device 172 may indicate that the data has been recorded. The adjusted plane may be calculated in addition to or as an alternative to the table plane. The system 200 may store a gravity zero for calculations related to the anterior pelvic plane. In some methods, the gravity zero is aligned and utilized only once throughout the procedure.

[0252] In some methods of use, the orientation sensing device 204 may be positioned in a manner other than horizontal to measure the direction of gravity. In some methods of use, the orientation sensing device 204 may measure gravity when in a home position. In some methods of use, the orientation sensing device 204 may be positioned vertically or substantially vertically to measure gravity. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with a point or anatomical landmark. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with point 1. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with point 2. In some methods of use, the orientation sensing device 204 may measure gravity when in contact with a point on the femur. The point on the femur may be a mark such as Fm described herein. The point on the femur may be a structure. The point on the femur may be an anatomical landmark. In some methods of use, the orientation sensing device 204 is capable of measuring the force of gravity at any angular orientation, hi some methods of use, the orientation sensing device 204 determines the vertical vector of gravity when placed in any position.

[0253] In some embodiments, the surgical orientation device 172 measures gravity. The surgical orientation device 172 can provide an indication of up / down or vertical. The surgical orientation device 172 can create a horizontal vector by transforming the vertical vector of gravity (e.g., by rotating 90 degrees). In some embodiments, the surgical orientation device 172 remains stationary when measuring gravity. In some embodiments, the surgical orientation device 172 is coupled or attached to the patient's pelvis when measuring gravity. In some methods of use, the surgical orientation device 172 is coupled to the patient via fixation pins 610, 612 when measuring gravity. In some methods of use, the surgical orientation device 172 is constrained when measuring gravity. As one example, the surgical orientation device 172 can be coupled to other components of the first assembly 604 and / or the second assembly 606. In some embodiments, the orientation sensing device 204 and the surgical orientation device 172 both determine the direction of gravity. In some embodiments, inertial data from two or more sensors is used to measure gravity.

[0254] FIG. 27C illustrates the horizontal direction of the adjusted plane. The adjusted plane may be considered to be a horizontal plane that pivots around the inter-ASIS line in response to a measurement of gravity. FIG. 27D illustrates the adjusted plane. Once the aforementioned points of the pelvis are navigated and data is recorded into the surgical orientation device 172, the adjusted plane may be calculated from the data indicating the navigated points and the gravity measurement. The adjusted plane includes the ipsilateral ASIS and the contralateral ASIS. The adjusted plane includes the inter-ASIS line. The system 600 can combine the horizontal vector with point 1 and point 2 to calculate the adjusted plane. In some embodiments, the adjusted plane may be considered to be a horizontal plane determined by the direction of gravity. In some embodiments, the adjusted plane may be considered to be a horizontal plane that contains the inter-ASIS line.

[0255] As described herein, three anatomical landmarks are aligned with respect to the anterior pelvic plane. The ipsilateral ASIS, the contralateral ASIS, and the pubic symphysis, as aligned by the probe 678, define the anterior pelvic plane. As described herein, two anatomical landmarks are aligned with respect to the adjusted plane. The two landmarks define the inter-ASIS line.

[0256] In some embodiments, the surgical orientation device 172 can provide a corrected coordinate reference system by transforming, for example, by rotating the anterior pelvic plane about the inter-ASIS line based on the direction of gravity. In some embodiments, the surgical orientation device 172 can rotate the anterior pelvic plane about the inter-ASIS line to provide a corrected coordinate reference system that is aligned with the horizontal. The measurement of gravity allows the surgical orientation device 172 to rotate the anterior pelvic plane. The measurement of gravity allows the surgical orientation device 172 to establish an adjusted plane. The measurement of gravity allows the surgical orientation device 172 to calculate the angle that the anterior pelvic plane must rotate to be aligned with the horizontal. In some embodiments, the orientation sensing device 204 can rotate the anterior pelvic plane about the inter-ASIS line based on the direction of gravity. The surgical orientation device 172 and / or the orientation sensing device 204 can include hardware or software to enable the transformation of the anterior pelvic plane, for example, the rotation of the anterior pelvic plane, based on the direction of gravity. One or more inertial sensors of the orientation sensing device 204 and / or the surgical orientation device 172 can provide data to determine how to translate (e.g., rotate) a plane containing the inter-ASIS axis so that it is perpendicular to the force of gravity. In some methods of use, a vector relating to a downward direction can be used by the orientation sensing device 204 and / or the surgical orientation device 172 to determine a horizontal plane containing the inter-ASIS axis. In some methods of use, inertial data related to gravity can be used by the system 600 to determine the number of degrees to rotate the anterior pelvic plane about the inter-ASIS axis so that it is horizontal.

[0257] The orientation of the adjusted plane can be a baseline for placement of the cup portion of the hip prosthesis. The surgical orientation device 172 can display information about the adjusted plane. In some methods of use, the abduction and anteversion angles for cup placement in a total hip replacement can be relative to the adjusted plane. In some embodiments, the adjusted plane is determined by the surgical orientation device 172 and / or the orientation sensing device 204. In some embodiments, a coordinate reference system is established by the adjusted plane. The adjusted plane coordinate reference system is a three-dimensional coordinate reference system. The adjusted plane coordinate reference system is a coordinate reference system that contains the adjusted plane. In some embodiments, the surgical orientation device 172 and / or the orientation sensing device 204 can provide orientation and / or position data associated with the adjusted plane coordinate reference system. In some embodiments, the surgical orientation device 172 can display orientation and / or position data with respect to the adjusted plane coordinate reference system.

[0258] Once alignment is complete, the user can proceed to dislocate the hip joint, resect the femoral head, and prepare the acetabulum. The user can prepare the impactor and shell. The user can remove the second assembly 606 from the first assembly 604. The user can remove the orientation sensing device 204 from the probe 678. The user can dock the orientation sensing device 204 to the first assembly 604. The surgical orientation device 172 and the orientation sensing device 204 form a generally V-shaped configuration, similar to the orientation shown in FIG. 12A.

[0259] The user can set the cup angle. The user can remove the orientation sensing device 204 from the first assembly 604. The orientation sensing device 204 and the surgical orientation device 172 can be used at this point to guide the placement of the cup in a predetermined orientation. The surgeon can remove the extension 670 from the third coupler 668. The surgeon can couple the extension 670 to the impactor 300A (shown in FIG. 18A). The surgeon can couple the extension 670 to any of the universal impactor adapters 350, 352 described herein. The universal impactor adapters 350, 352 can be utilized to attach the fourth coupler 342 to any impactor. The fourth coupler 342 can allow the orientation sensing device 204 to couple to the impactor. The impactor may be configured to be modified to suit any of a number of hip joint prostheses, or the impactor may be designed to suit a particular hip joint prosthesis.

[0260] The acetabular shell may be inserted into the acetabulum and positioned at the desired angle. The surgical orientation device 172 may guide the surgeon in setting the appropriate cup angle. The surgical orientation device 172 may graphically display as the orientation sensing device 204 is navigated to the desired abduction and anteversion angles. The desired abduction and anteversion angles may be the pre-operative cup angles struck by the surgeon during calibration. The surgical orientation device 172 may graphically display the abduction and anteversion angles as the orientation sensing device 204 is being moved. The user may align the impactor to the desired cup angle. Aligning the visual indicators of the surgical orientation device 172 may guide the user to position the impactor to the desired cup angle. The abduction and anteversion angles may be statically displaced. The cup angle may be checked after impaction by repeating the procedural steps.

[0261] The surgical orientation device can provide the cup angle relative to any reference plane, including those described herein. The adjusted plane can provide several advantages over table alignment. The adjusted plane can increase the accuracy of table alignment. For example, the adjusted plane provides horizontal verification of the probe 678 via a measurement of gravity. For example, the adjusted plane improves the placement of the horizontal plane by including anatomical landmarks or points. For example, the adjusted plane can include one or more anatomical locations. For example, the adjusted plane can include an anatomical line. For example, the adjusted plane can include the inter-ASIS line as described above. From a side view, the adjusted plane can appear as if it is the same as the table plane. However, the adjusted plane includes the inter-ASIS line, while the table plane may not always include this line. Table alignment can introduce some error in orienting the horizontal plane. There can be greater accuracy in the adjusted plane because it orients the plane based on anatomical landmarks and measurements of gravity.

[0262] The surgical orientation device 172 may include indicia, such as a target or bull's eye, to indicate the pre-determined abduction and anteversion angles. The surgical orientation device 172 may include indicia, such as a dot or crosshairs, to indicate the movement of the impactor. Aligning the indicia with the center of the target or bull's eye may indicate that the impactor is aligned with the predetermined cup angle. The indicia may move in real time. The surgical orientation device 172 may include readouts of the abduction and anteversion angles. The angles may be calculated in real time. The angles may change as the impactor is moved. The user may have a set amount of time to align the impactor with the desired cup angle. The user may type an input once the desired cup angle is reached. In some methods, the cup angle may be displayed statically after the impactor is positioned for the desired cup angle. The surgical orientation device 172 may dynamically provide information about the pelvis or other information.

[0263] After positioning the cup, the user can attach the second system 606 to the first system 604, similar to the configuration shown in FIG. 1. The user can verify the home position. In some techniques, the distal end of the probe 678 can be engaged with a point, such as a divot, on the fixed base 602. The probe 678 can be oriented vertically in the home position. The orientation sensing device 204 can be oriented vertically in the home position. The user can repeat the alignment if the home position shifts. The user can end the procedure. The user can remove the system 600 before closure.

[0264] In some methods of use, the user can make measurements regarding leg length and joint offset. At the surgeon's discretion, the system 600 can be used to navigate the condition, location, and / or orientation of the femur prior to hip replacement. In some embodiments, a mark Fm as shown in FIG. 24 can be made on the proximal femur. In some embodiments, a structure such as a pin or the like is attached to the femur. In some embodiments, a burr or detent is made in the femur. The orientation sensing device 204 can then be initialized or set to zero, for example, by placing it back in a home position. The distal end 680 of the probe 678 can then be brought into contact with the femoral mark Fm. The surgical orientation device 172 can be signaled to record the orientation of the orientation sensing device 204. The distance from the point of attachment of the fixation pins 610, 612 to the marked location on the femur can then be recorded in the surgical orientation device 172. The position can be based on capturing the markings 682, the probe 678, or the probe inlay 676 by the camera 184 in combination with inertial data from the orientation sensing device 204.

[0265] If a femoral landmark Fm is acquired in the procedure prior to separating the natural joint, the same landmark can be acquired after the prosthesis is placed to verify that the joint replacement has not changed either the leg length, the leg offset from the patient's torso, or both. The distal end 680 of the probe 678 can then be brought into contact with the same landmark (e.g., Fm) acquired earlier in the procedure. The orientation of the orientation sensing device 204 and the extension of the probe 678 can be input into the surgical orientation device 172. These data enable the surgical orientation device 172 to output the amount of change in leg length and leg offset.

[0266] In some methods of use, the system 600 includes the optical component 174 shown in FIG. 6A and / or the optical component 194 shown in FIGS. 6B-6C. In some embodiments, the optical components 174, 194 are separate components. In some embodiments, the optical components 174, 194 are coupled to the first assembly 604. In some embodiments, the optical component 174 can be rotated relative to the first assembly 604, for example, by the knob 176. The optical components 174, 194 can include one or more lasers, and the one or more lasers can be configured to project laser light. The optical components 174, 194 can provide a visual guide to replicate the original position of the femur relative to the pelvis. The laser light can be used to project a point, a plane, and / or a crosshair onto one or more targets, including, but not limited to, an anatomical feature or landmark. The surgeon can mark one or more points along the line of projection of the optical components 174, 194. The surgeon may complete any of the steps described herein. Afterwards, the surgeon may verify that the point or points are along the line of projection of the optical components 174, 194. When measuring changes in leg length and lateral joint offset, the change in appearance is sensitive to changes in the orientation of the femur relative to the pelvis. The user may reposition the femur before measuring the change so that the orientation of the femur relative to the pelvis is the same as when the pre-operative baseline measurement was taken.

[0267] Another method is to measure the orientation of the femur relative to the pelvis during a pre-op baseline and post-op, then correct for the change in orientation by performing a virtual rotation about the femur's center of rotation post-op. The method may require obtaining three points on the femur. The three points on the femur can be marks or anatomical landmarks. The three points can be on the femoral plate. The three points on the femur or femoral plate can be aligned and resolved for femoral orientation by the probe 678 pre-op and then post-op each time leg length is to be measured.

[0268] 2. Comparison of the adjusted plane and the anterior pelvic plane FIG. 28A illustrates a side view of the anterior pelvic plane. The anterior pelvic plane includes the inter-ASIS line, as described herein. FIG. 28B illustrates a comparison between the anterior pelvic plane and the adjusted plane. FIGS. 28A-1 and 28B-1 illustrate another side view of the system with the ASIS aligned. FIG. 28B illustrates a side view of the anterior pelvic plane and the adjusted plane. FIG. 28C illustrates a top view of the anterior pelvic plane and the adjusted plane. As described herein, the anterior pelvic plane and the adjusted plane both contain the inter-ASIS line. The anterior pelvic plane also contains point 3 to define the plane. The adjusted plane utilizes the direction of gravity to define the plane. In some embodiments, the anterior pelvic plane and the adjusted plane are coaxial about the inter-ASIS line, as shown in FIG. 28B and 28B-1. The adjusted plane is a rotation of the anterior pelvic plane about the inter-ASIS line. The adjusted plane and the anterior pelvic plane can form angle alpha, as shown in Figures 28B and 28B-1. Angle alpha can be a measurement of pelvic tilt. Angle alpha can measure the difference from the anterior pelvic plane to horizontal. Angle alpha can adjust the anterior pelvic plane so that the cup angle more closely matches what is shown on the post-operative x-ray. In some embodiments, the adjusted plane adjusts for tilt. In some embodiments, the adjusted plane adjusts for pubic tilt relative to the inter-ASIS line.

[0269] The adjusted plane has clinical value. Pre-op and post-op x-rays produce two-dimensional images on a horizontal plane. An image receptor is positioned horizontally with the patient in a supine position. The image receptor captures the residual beam as it exits the patient's body. The patient's anatomy is projected on the horizontal plane of the image receptor. For pelvic x-rays, the routine projection is anterior-posterior projection. The navigated angle can be correlated to the post-op x-ray view via the adjusted plane. The adjusted plane can provide a horizontal reference plane that approximates the horizontal reference plane of the imaging technique. There is a clinical benefit in providing the user with a navigated cup angle during the procedure that will reflect what is measured on the post-op x-ray. The navigated cup angle based on the adjusted plane can be provided in addition to or instead of one based on the anterior pelvic plane. The navigated cup angle based on the adjusted plane can be provided in addition to or instead of one based on the table plane.

[0270] The adjustment from the anterior pelvic plane to the adjusted plane can provide the user with a cup angle that correlates to a clinically expected cup angle. The adjustment from the anterior pelvic plane to the adjusted plane can provide the user with a cup angle that correlates to what the user expects to see during surgery (e.g., comparison between the cup image and the output of the system 600). The adjustment from the anterior pelvic plane to the adjusted plane can provide the user with a cup angle that correlates to what the user expects to see on a post-op image (e.g., comparison between the output of the system 600 and the post-op image). The user, such as a surgeon, correlates the output of the system 600 to a number that correlates to clinical experience (e.g., calibrated to what the user expects to see in the post-op image). The post-op image can be a supine film six weeks after surgery. The post-op image is taken from a horizontal cross-section of the patient's body. The adjusted plane can be more similar to the plane of the post-op image.

[0271] Prior to navigation systems such as system 600, surgeons do not make measurements intraoperatively. Rather, surgeons typically look at cup placement during the procedure and determine if the current cup placement looks like a previous cup placement. The surgeon will visually review the cup placement during surgery and past experience in viewing the post-op images. The user will determine if the current cup placement tends to correlate to the correct abduction and anteversion angles post-op. The surgeon will look at the cup placement and, based on their experience viewing the post-op images, will determine that the placement looks like 40 degrees by 15 degrees. The surgeon's confidence in the procedure will be based on their correlation of the cup placement and the post-op images.

[0272] With respect to the system 600, the user is provided with an output to assist the user in navigating proper cup placement. The output can be the abduction and anteversion angles displayed on the surgical orientation device 172. The user can navigate to the desired abduction and anteversion angles by moving components of the system 600, such as the impactor. When the user places the cup at the desired abduction and anteversion angles, the user will want to see the same or similar angles on the post-operative image. If the abduction and anteversion angles produced by the system 600 match the post-operative image, the user's confidence in navigating the system 600 is increased.

[0273] The adjusted plane may be an improvement over landmark-only reference planes such as the anterior pelvic plane for some patients. In some embodiments, the anterior pelvic plane may differ from the horizontal reference plane of the imaging technique due to patient-specific factors. For example, pelvic tilt may orient the anterior pelvic plane at a certain angle from the horizontal reference plane of the imaging technique. For example, a high body mass index of a patient may affect the ability to contact anatomical landmarks. For example, the anatomical features of the reference points may not be visible and / or palpable while the patient is in the supine position. For example, the ipsilateral ASIS, contralateral ASIS, and / or pubic symphysis may not be visible and / or palpable. Patient-specific factors may result in a difference between the navigated cup angle from the anterior pelvic plane and the angle measured after surgery. In some methods of use, the anterior pelvic plane may not provide some patients with abduction and anteversion angles that match the post-operative image.

[0274] The adjusted plane can be an improvement over the table plane-only coordinate reference system for the procedure. In some embodiments, the table plane can be different from the horizontal reference plane of the imaging technique. The user can introduce error into the table plane by improper placement of the probe 678. In some methods of use, for some patients, the table plane cannot provide abduction and anteversion angles that match the post-operative image.

[0275] In some methods of use, two or more reference planes may be provided, such as, for example, any combination of the adjusted plane, the table plane, the horizontal plane, and the anterior pelvic plane. Any of the foregoing combinations of reference planes provide redundancy to ensure that the angle information provided to the user is accurate and reliable, such that the procedure being performed will be better contained within the acetabular cup "safe zone."

[0276] The systems and methods described herein can combine preoperative imaging and landmark referencing to improve hip prosthesis placement using navigation. These hip prosthesis procedures typically guide the hip prosthesis to an orientation in the acetabulum that minimizes the chance of dislocation due to impingement of the femoral neck against the cup or against the bone surrounding the acetabulum, or due to other reasons related to suboptimal orientation of the prosthesis. Various techniques utilize population averages of proper placement, while others are amenable to patient-specific refinement.

[0277] 3. Pelvis Tracking FIG. 29 shows a screen display for a hip joint method generated by one embodiment of the interactive user interface of the surgical orientation device 172. When the orientation sensing device 204 is attached to the impactor 300A or any other impactor coupled to the universal impactor adapter 350, 352, the surgical orientation device 172 can display the abduction and anteversion angles on the impactor radiograph relative to a reference plane. The reference plane can be any plane including the anterior pelvic plane, the anterior pelvic plane, the table plane, an adjusted plane, etc. The surgical orientation device 172 can display the abduction and anteversion angles for two or more planes. In the illustrated embodiment, the surgical orientation device 172 can display the abduction and anteversion angles on the radiograph relative to the anterior pelvic plane. The surgical orientation device 172 displays the "pelvis" angle relative to the anterior pelvic plane. The anterior pelvic plane is based on input from anatomical landmarks. In the illustrated embodiment, the surgical orientation device 172 can display the abduction and anteversion angles on the radiograph relative to the adjusted plane. The surgical orientation device 172 displays the "adjusted" angles relative to the adjusted plane. The adjusted plane is the reference plane in which the anterior pelvic plane is rotated about the inter-ASIS axis until its superior-inferior axis is parallel to the flat table. This effectively adjusts for pelvic tilt. The "adjusted" angles can be correlated to post-operative x-rays using a horizontal plane.

[0278] The surgical orientation device 172 can display additional information for the user. For example, the surgical orientation device 172 can display information related to the position and orientation of the pelvis. As described herein, the surgical orientation device 172 can be coupled to the pelvis such that the surgical orientation device 172 can measure changes in the pelvis. The surgical orientation device 172 can include one or more inertial sensors that can track the position of the pelvis during the procedure. The surgical orientation device 172 can display changes in the positioning of the pelvis in real time. The surgical orientation device 172 can provide an indication, for example, by a visual or audio cue, if the position of the pelvis has changed beyond a threshold.

[0279] The surgical orientation device 172 can track the tilt of the pelvis. The tilt of the pelvis can be dynamically displayed on the surgical orientation device 172. FIGS. 30A-30C illustrate the tilt of the pelvis. At the start of the procedure, the pelvis can be ideally positioned. However, the pelvis can shift throughout the rigors of the procedure. The surgical orientation device 172 can provide information about where the pelvis is relative to the rest of the body. The surgical orientation device 172 can indicate the tilt of the pelvis from a neutral position. The surgical orientation device 172 can indicate posterior or anterior tilt. The surgical orientation device 172 can track the pelvis throughout the entire surgical procedure.

[0280] The surgical orientation device 172 can track the pelvis rotation. The pelvis rotation can be dynamically displayed on the surgical orientation device 172. FIGS. 31A-31C illustrate the rotation of the pelvis. The surgical orientation device 172 can indicate the pelvis rotation. The surgical orientation device 172 can include one or more sensors to provide an output. The surgical orientation device 172 can track the pelvis as it moves during the procedure. The surgical orientation device 172 can graphically indicate when the pelvis is in neutral rotation. For example, neutral rotation can be recorded by the surgical orientation device 172 at the beginning of the procedure when the pelvis is ideally seated.

[0281] 29, the screen display of the surgical orientation device 172 can indicate pelvic tilt. In the illustrated embodiment, the pelvic tilt is shown as an angle measurement. The screen display of the surgical orientation device 172 can indicate pelvic rotation. In the illustrated embodiment, the pelvic tilt is shown as an angle measurement.

[0282] The surgical orientation device 172 can include indicia, such as a target or bull's eye, to indicate when the pelvic tilt and pelvic rotation are neutral. In the illustrated embodiment, the pelvic tilt can be along the Y-axis or vertical axis of the bull's eye. In the illustrated embodiment, the pelvic rotation can be along the X-axis or horizontal axis of the bull's eye. The surgical orientation device 172 can include indicia, such as a dot, to indicate the degree of pelvic tilt and rotation. The indicia can move in real time. As the degree of pelvic tilt increases, the indicia can move farther away from the origin or center of the bull's eye. As the degree of pelvic tilt decreases, the indicia can move closer to the origin or center of the bull's eye. As the degree of pelvic rotation increases, the indicia can move farther away from the origin or center of the bull's eye. As the degree of pelvic rotation decreases, the indicia can move closer to the origin or center of the bull's eye. The indicia can assist the user in understanding the alignment of the pelvis. The indicia can assist the user in positioning the pelvis. For example, the user can reposition the pelvis to a neutral position, e.g., a position having a neutral tilt and / or neutral rotation, during surgery.

[0283] Referring back to FIG. 28C, the adjusted plane may be provided by transforming, for example, by rotating the anterior pelvic plane to correct for pelvic tilt. The adjusted plane may rotate the anterior pelvic plane about the inter-ASIS line to correct for anterior or posterior tilt. The transformation between the anterior pelvic plane and the adjusted plane takes into account the patient's pelvic tilt. The transformation between the anterior pelvic plane and the adjusted plane takes into account the pelvic tilt due to the location of the pubic symphysis. The adjusted plane rotates the location corresponding to the pubic symphysis in the anterior pelvic plane from the location where the pubic symphysis was probed to a horizontal location.

[0284] 31A-31C, pelvic rotation corresponds to the relative location of the ipsilateral and contralateral ASIS. Regardless of pelvic rotation, the inter-ASIS line connects the ipsilateral and contralateral ASIS. The adjusted plane and the anterior pelvic plane both contain the inter-ASIS line.

[0285] Although these inventions have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that this application extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the invention, as well as obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications that are within the scope of the invention will be readily apparent to those skilled in the art based on this disclosure. It is also contemplated that various combinations or subcombinations of specific features and aspects of the embodiments can be made and still fall within the scope of the present application. For example, the present application contemplates a connection hub, either alone or in combination with any of the other modules, and can include separate aspects. Or, any one or combination of the modules can be directly connected to an umbrella hub or overhead support to form another separate aspect. Thus, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another to form various modes of the disclosed embodiments. Accordingly, it is intended that the scope of the invention disclosed herein should not be limited by the particular disclosed embodiments described above, but should be determined solely by a fair reading of the claims that follow.

[0286] Likewise, this method of disclosure should not be interpreted as reflecting an intention that any claim requires more features than are expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of less than all features of any single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment. [Explanation of symbols]

[0287] 18a Target Probe 18b Target Probe 18c Target Probe 18d Target Probe 18e Target Probe 106 Long and thin members 107 Anatomical contacts 108 Target Part 109 Insize Drape 110 Target Shape 172 Surgical Orientation Device 174 Optical Components 176 Bracket 178 Adjustment mechanism 180 light 182 Thigh 184 Cameras 190 Attachment Mechanism 192 Attachment Mechanism 194 Optical Components 196 Magnet 198 Magnet 202 First Surface 204 Second Surface, Orientation Sensing Device 300A Impactor 300B Impactor 312A Shell 340 Spring member 342 The Fourth Coupler 344 Spring member 348 Tip Components 350 Universal Impactor Adapter 352 Universal Impactor Adapter 354 Magnet 356 Clamp 358 Recess 600 Hip Navigation System 602 Fixed base 604 First Assembly 606 Second Assembly 610 Fixing pin 612 Fixing pin 620 Platform 622 Support 624 Fixed Device 630 Divot 632 First Coupler 634 Slots 635 Long and thin post 636 Tapered Surface 638 Pelvic Bracket 640 Lock lever 642 Detent 644 Extension 646 Mount 648 Second Coupler 652 Probe bracket 654 Lock lever 656 Detent 658 Mount 660 Pivot pin 662 Dock 664 through lumen 668 The third coupler 670 Extension 672 Mount 676 Probe Inlay 678 Probe 680 Distal end 682 Marking 700 System 702 Fixed base 704 First Assembly 706 Second Assembly 710 Fixing pin 712 Fixing pin 720 Platform 722 Support 724 Fixed Device 726 Articulation 727 Rock 728 Head 729 Contact surface 730 Divot 732 First Coupler 734 Slots 735 Long and thin post 736 Tapered Surface 738 Bracket 740 Lock lever 742 Detent 744 Extension 746 Mount 748 Second Coupler 752 Probe bracket 754 Lock lever 756 Detent 758 Mount 760 Pivot pin 762 Dock 764 through lumen 766 Rock 768 The Third Coupler 770 Extension 772 Mount 776 Probe Inlay 778 Probe 780 Distal end 782 Marking 784 Tracker 790 Calibration Fixture 792 Driver Fm mark

Claims

1. 1. A surgical system for assisting a surgeon in obtaining a correct orientation of an acetabular prosthetic socket in a patient's acetabulum, the surgical system comprising: Support devices and a first electronic orienting device, the first electronic orienting device including at least one inertial sensor, the first electronic orienting device configured to be releasably coupled to the support device; and a second electronic orienting device including at least one inertial sensor, the second electronic orienting device configured to be releasably coupled to the support device; and a probe configured to be releasably coupled to the second electronic directing device; Including, the first electronic orientation device, the second electronic orientation device, or the first electronic orientation device and the second electronic orientation device are adapted to record a position of the probe when the probe is in contact with one of a first point, a second point, and a third point, the first point, the second point, and the third point defining a plane; A surgical system, wherein the first electronic orienting device, the second electronic orienting device, or the first electronic orienting device and the second electronic orienting device are configured to estimate the adjusted reference plane by utilizing a measurement of the direction of gravity to calculate the angle that the plane must be rotated to be aligned with the adjusted reference plane.

2. The surgical system of claim 1 , wherein the probe includes an elongated member, the elongated member configured to pivot and translate relative to a probe bracket.

3. 10. The surgical system of claim 1, wherein the first electronic orienting device and the second electronic orienting device are adapted to record a point when the probe is in contact with the point pre-operatively and post-operatively.

4. The surgical system of claim 1 , wherein the at least one inertial sensor of the first electronic orienting device or the at least one inertial sensor of the second electronic orienting device includes an accelerometer.

5. The surgical system of claim 1 , wherein the adjusted reference plane comprises a vertical plane.

6. 10. The surgical system of claim 1, wherein the first electronic orienting device includes a display configured to provide an indication of a change in an angular position of the second electronic orienting device relative to the adjusted reference plane.

7. The surgical system of claim 1 , further comprising an optical component configured to project the pattern of light.

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