Systems and methods for limb alignment

Abstract

To select and accurately position a component of an artificial joint without excessively complicating a technique, inundating medical workers, and / or burdening a doctor or a medical facility with a large cost of a complicated navigation system.SOLUTION: The present invention provides, in certain embodiments, a device for determining a tibial mechanical axis and a femoral mechanical axis. The present invention also provides surgical orientation devices, reference devices, and / or modules configured to track mechanical axes during movement to facilitate limb alignment. The present invention further provides surgical orientation devices, reference devices, and / or modules configured to determine gap measurements.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] Incorporation by reference of priority applications All applications for which a claim of foreign or domestic priority is specified in the Application Data Sheet as filed with this application, including U.S. Provisional Application No. 62 / 992,537, filed March 20, 2020, are hereby incorporated by reference in their entirety under 37 CFR 1.57.

[0002] This application relates to systems and methods for joint assessment and replacement, and in particular to systems and methods for knee and other limb joint assessment and replacement that utilize one or more inertial devices to measure limb alignment. [Background technology]

[0003] Joint replacement procedures, including knee replacement procedures, are commonly used to replace a patient's joint with one or more artificial joint components. Such procedures often use one or more systems of surgical tools and devices, including, but not limited to, cutting guides (e.g., cutting blocks) and surgical guides, to make surgical cuts along one or more portions of the patient's bone.

[0004] Current systems and methods may use expensive, complex, bulky, and / or large computer navigation systems that require one or more computers, even three-dimensional imaging, to track the spatial placement and / or movement of surgical instruments or landmarks within the human body. These systems are typically used to assist users in determining where instruments or landmarks are located in space and often require extensive training, significant expense, and large rooms.

[0005] When such complex and expensive systems are not used, simple methods, such as "eyeballing" the alignment of the rod with anatomical features, including the bones of the lower limb, are used. These simple methods are not sufficiently accurate to reliably align and place the prosthetic implant components and the bones to which they are attached. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent Application No. 12 / 509,388 [Patent Document 2] U.S. Patent Application No. 13 / 011815 [Patent Document 3] U.S. Patent Application No. 13 / 115065 [Patent Document 4] U.S. Patent Application No. 14 / 399046 [Patent Document 5] U.S. Patent Application No. 14 / 401,274 [Patent Document 6] U.S. Patent Application No. 10 / 864,085 [Patent Document 7] U.S. Patent Application No. 11 / 182,528 [Patent Document 8] U.S. Patent Application No. 12 / 557,051 [Patent Document 9] U.S. Patent Application No. 13 / 800620 [Patent Document 10] U.S. Patent Application No. 14 / 643864 [Patent Document 11] U.S. Patent Application No. 15 / 550,564 [Patent Document 12] U.S. Patent Application No. 15 / 920216 [Patent Document 13] U.S. Patent Application No. 15 / 920202 [Patent Document 14] International Application No. PCT / US2020 / 063785 Summary of the Invention [Problem to be solved by the invention]

[0007] Thus, there is a lack of devices, systems, and methods that can be used to assess joint characteristics, such as the relative alignment of the bones and soft tissue status of the joint, in relation to selecting and precisely positioning components of a prosthetic joint without overly complicating the procedure, overwhelming medical personnel, and / or incurring the significant costs of complex navigation systems to the physician or medical facility. [Means for solving the problem]

[0008] In some embodiments, a system for limb alignment is provided. The system can include a first orientation device configured to be coupled to the tibia, the first orientation device including at least one inertial sensor. The system can include a second orientation device configured to be coupled to the femur, the second orientation device including at least one inertial sensor. In some embodiments, the first or second orientation device includes a processor configured to receive inertial sensor data, the processor configured to calculate an angle between a femoral mechanical axis and a tibial mechanical axis.

[0009] In some embodiments, the system can include a tibial preparation system including a probe member. In some embodiments, the system can include a tibial preparation system including a midline reference probe assembly. In some embodiments, the system can include a tibial preparation system including a first device interface configured to couple to the first orienting device and a second device interface configured to couple to the second orienting device. In some embodiments, the system can include a femoral preparation system including a device interface configured to couple to the second orienting device. In some embodiments, the system can include a femoral preparation system including a cutting guide bracket configured to slide relative to the tibial preparation system. In some embodiments, the system can include a femoral preparation system including a swivel post configured to pivot relative to the tibial preparation system. In some embodiments, the system can include a femoral preparation system including an extension configured to be positioned relative to a threaded pin coupled to a portion of the distal femur. In some embodiments, the system can include a femoral preparation system including a connector configured to attach to a lateral portion of the femur. In some embodiments, the system can include a femoral preparation system including a connector including a device interface configured to couple to the second orienting device. In some embodiments, the processor is configured to determine the femur mechanical axis and the tibia mechanical axis based at least in part on the placement of the anatomical landmarks. In some embodiments, the processor is configured to determine the femur mechanical axis and the tibia mechanical axis based at least in part on the translation of the femur. In some embodiments, the processor is configured to determine the varus / valgus angles of the femur mechanical axis and the tibia mechanical axis.In some embodiments, the processor is configured to determine flexion / extension angles of the femoral mechanical axis and the tibial mechanical axis. In some embodiments, the processor is configured to determine a gap measurement.

[0010] In some embodiments, a method for determining limb alignment is provided. The method can include coupling a first orienting device configured with the tibia, the first orienting device comprising at least one inertial sensor. The method can include coupling a second orienting device configured with the femur, the second orienting device comprising at least one inertial sensor. The method can include calculating a femur mechanical axis and a tibia mechanical axis. The method can include measuring changes in the femur mechanical axis and the tibia mechanical axis.

[0011] In some embodiments, the method can include performing the resection and positioning the implant. In some embodiments, measuring the change in the femoral mechanical axis and the tibial mechanical axis further includes positioning the leg in extension. In some embodiments, the method can include calibrating the first and second orienting devices by mounting the first and second orienting devices on a tibial preparation system. In some embodiments, the method can include applying a force and measuring a gap distance.

[0012] In some embodiments, a system for limb alignment is provided. The system can include a first sensor configured to be coupled to the tibia, the first sensor including at least one inertial sensor. The system can include a second sensor configured to be coupled to the femur, the second sensor including at least one inertial sensor. The system can include a processor configured to receive output from one or more of the first and second sensors, the processor configured to calculate the position and / or orientation of the femoral mechanical axis and the tibial mechanical axis during movement.

[0013] In some embodiments, the system can include a surgical orientation device comprising a processor. In some embodiments, the surgical orientation device comprises a display. In some embodiments, the processor is configured to determine a varus / valgus angle. In some embodiments, the processor is configured to determine a varus angle at different flexion angles. In some embodiments, the processor is configured to determine an axial rotation. In some embodiments, the processor is configured to determine a flexion angle. In some embodiments, the processor is configured to determine an extension angle. In some embodiments, the processor is configured to provide a recommendation for a trial implant. In some embodiments, the processor is configured to determine a clearance between a tibial plateau and a femoral plateau. In some embodiments, the processor is configured to determine an angle between the tibial plateau and the femoral plateau.

[0014] In some embodiments, a method for determining limb alignment is provided. The method can include coupling a first reference sensor to a first bone of the limb, the first reference sensor including at least one inertial sensor. The method can include coupling a second reference sensor to a second bone of the limb, a joint formed between the first bone and the second bone, the second reference sensor including at least one inertial sensor. The method can include moving the limb to position the first bone relative to the second bone at a plurality of positions that vary in flexion, axial rotation, and / or varus / valgus. The method can include outputting a value indicative of limb alignment at one or more of the positions or based on one or more of the positions.

[0015] In some embodiments, the limb is a leg, the first bone is a tibia, and the second bone is a femur. In some embodiments, the method can include positioning a trial implant or implants on a resected surface of the tibia. In some embodiments, the method can include calibrating the first and second reference sensors. In some embodiments, outputting a value includes outputting a varus / valgus angle. In some embodiments, outputting a value includes outputting a varus angle at different flexion angles. In some embodiments, outputting a value includes outputting an axial rotation. In some embodiments, outputting a value includes outputting a flexion angle. In some embodiments, outputting a value includes outputting a gap measurement between the tibial plateau and the femoral plateau. In some embodiments, outputting a value includes outputting an angle between the tibial plateau and the femoral plateau.

[0016] In some embodiments, a system for limb alignment is provided. The system can include a first orienting device configured to be coupled to the tibia, the first orienting device comprising at least one inertial sensor. The system can include a second orienting device configured to be coupled to the femur, the second orienting device comprising at least one inertial sensor. In some embodiments, the first orienting device and the second orienting device are configured to calculate a relative orientation between the femur mechanical axis and the tibia mechanical axis when the leg is in extension.

[0017] In some embodiments, the first and second orienting devices are configured to calculate the relative orientation between the femur mechanical axis and the tibia mechanical axis when the leg is in extension before resection. In some embodiments, the first and second orienting devices are configured to calculate the relative orientation between the femur mechanical axis and the tibia mechanical axis when the leg is in extension after resection. In some embodiments, the first and second orienting devices are configured to calculate the relative orientation between the femur mechanical axis and the tibia mechanical axis when the leg is in extension and the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate the relative orientation between the femur mechanical axis and the tibia mechanical axis when the leg is in extension and a force is applied. In some embodiments, the cutting block is positioned relative to the femur mechanical axis. In some embodiments, the cutting block is positioned relative to the tibia mechanical axis. In some embodiments, the second orienting device is configured to be coupled to the femur at a fixed, known point. In some embodiments, the second orienting device is configured to be coupled with the femur when the leg moves from flexion to extension. In some embodiments, the femur mechanical axis and the tibia mechanical axis are two vectors in a three-dimensional coordinate system. In some embodiments, the first orienting device and the second orienting device are configured to determine an angulation at the joint. In some embodiments, the first orienting device and the second orienting device are configured to determine a mechanical axis of the leg. In some embodiments, the first orienting device and the second orienting device are configured to determine an angle in a sagittal plane. In some embodiments, the first orienting device and the second orienting device are configured to determine an angle in a coronal plane. In some embodiments, the first orienting device is configured to calculate the tibia mechanical axis. In some embodiments, the first orienting device is configured to determine at least two points on the tibia mechanical axis.In some embodiments, the second orienting device is configured to calculate the femoral mechanical axis. In some embodiments, the second orienting device is configured to determine at least two points on the femoral mechanical axis. In some embodiments, the first orienting device and the second orienting device are configured to couple to the tibia for calibration. In some embodiments, the system can include a device interface configured to couple to a lateral portion of the femur. In some embodiments, the first orienting device and the second orienting device are configured to determine the varus / valgus angles of the femoral mechanical axis and the tibial mechanical axis. In some embodiments, the first orienting device and the second orienting device are configured to determine the flexion / extension angles of the femoral mechanical axis and the tibial mechanical axis. In some embodiments, the first orienting device and the second orienting device are configured to determine a gap measurement.

[0018] In some embodiments, a system for limb alignment is provided. The system can include a first orienting device configured to be coupled to the tibia, the first orienting device including at least one inertial sensor. The system can include a second orienting device configured to be coupled to the femur, the second orienting device including at least one inertial sensor. In some embodiments, the first orienting device and the second orienting device are configured to calculate a change in position, orientation, or translation between the femur mechanical axis and the tibia mechanical axis.

[0019] In some embodiments, the first and second orienting devices perform cut verification. In some embodiments, the first and second orienting devices are configured to calculate an angle relative to a coronal plane when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate an angle relative to a sagittal plane when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate a varus / valgus angle when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate a flexion / extension angle when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate soft tissue balancing when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate a gap measurement when the implant is positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to verify the angle measurements against pre-operative measurements. In some embodiments, the first and second orienting devices are configured to verify the angle measurements against pre-operative measurements from an imaging technique. In some embodiments, the first and second orienting devices are configured to verify correction of the deformation when the implant is positioned between the tibia and the femur.

[0020] In some embodiments, a system for limb alignment is provided. The system can include a first orienting device configured to be coupled to the tibia, the first orienting device including at least one inertial sensor. The system can include a second orienting device configured to be coupled to the femur, the second orienting device including at least one inertial sensor. In some embodiments, the first orienting device and the second orienting device are configured to calculate a rotation of the tibia mechanical axis about the femur mechanical axis.

[0021] In some embodiments, the first and second orienting devices are configured to calculate the rotation of the tibia mechanical axis about the femoral mechanical axis in the sagittal plane. In some embodiments, the first and second orienting devices are configured to calculate the rotation of the tibia mechanical axis about the femoral mechanical axis in the coronal plane. In some embodiments, the first and second orienting devices are configured to calculate the rotation of the tibia mechanical axis as a varus / valgus angle between the tibia mechanical axis and the femoral mechanical axis. In some embodiments, the first and second orienting devices are configured to calculate the rotation of the tibia mechanical axis about the femoral mechanical axis after resection. In some embodiments, the first and second orienting devices are configured to calculate the rotation of the tibia mechanical axis about the femoral mechanical axis with the implant positioned between the tibia and the femur. In some embodiments, the first and second orienting devices are configured to calculate a rotation of the tibia mechanical axis about the femur mechanical axis for comparison with a preoperatively determined angle. In some embodiments, the first and second orienting devices are configured to calculate a rotation of the tibia mechanical axis about the femur mechanical axis for measuring clearance. In some embodiments, the first and second orienting devices are configured to calculate a rotation of the tibia mechanical axis about the femur mechanical axis for measuring soft tissue balancing. In some embodiments, the second orienting device is configured to be coupled to the tibia for calibration.

[0022] In some embodiments, a method for determining limb alignment is provided. The method can include coupling a first orienting device to the tibia, the first orienting device comprising at least one inertial sensor. The method can include coupling a second orienting device to the femur, the second orienting device comprising at least one inertial sensor. The method can include calculating a tibia mechanical axis. The method can include calculating a femur mechanical axis. The method can include moving the tibia into extension to calculate rotation of the tibia mechanical axis about the femur mechanical axis.

[0023] In some embodiments, the method may include calculating the tibia mechanical axis before calculating the femur mechanical axis. In some embodiments, the method may include calibrating the first orienting device and the second orienting device before moving the tibia into extension. In some embodiments, the method may include calculating the rotation of the tibia mechanical axis about the femur mechanical axis when a varus force is applied. In some embodiments, the method may include calculating the rotation of the tibia mechanical axis about the femur mechanical axis when a valgus force is applied. In some embodiments, the method may include calculating the rotation of the tibia mechanical axis about the femur mechanical axis during soft tissue release. In some embodiments, the method may include calculating the rotation of the tibia mechanical axis about the femur mechanical axis with the implant positioned between the tibia and the femur. In some embodiments, the method may include calculating the rotation of the tibia mechanical axis about the femur mechanical axis with respect to one or more planes.

[0024] In some embodiments, a femoral preparation system is provided. The femoral preparation system can include a connector configured to be positioned externally on the femur. The connector can include a coupler. The connector can include at least one opening configured to receive a fixation device. The femoral preparation system can include an orienting device configured to be removably coupled to the connector, wherein a first orienting device includes at least one inertial sensor.

[0025] In some embodiments, the femoral preparation system can include a device interface configured to couple with the coupler and the orienting device. In some embodiments, the femoral preparation system can include a cutting guide bracket configured to couple with a tibial preparation system coupled to the tibia. In some embodiments, the femoral preparation system can include a swivel post configured to position the extension relative to a fixation device positioned approximately at the center of the intercondylar notch. In some embodiments, the femoral preparation system can include a mounting bracket configured to couple with the extension and the coupler of the connector. In some embodiments, the at least one opening includes a pair of angled openings and an offset opening.

[0026] These and other features, aspects, and advantages are described below with reference to the drawings, which are intended to illustrate, but not limit, the present invention, in which like reference characters indicate corresponding features consistently throughout like embodiments. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 illustrates an exemplary limb including a tibia and a femur. [Figure 2] FIG. 1 shows the mechanical axes of the tibia and femur. [Figure 3] 1 illustrates a portion of a system for aligning the femoral mechanical axis. [Figure 4] 1 illustrates a portion of a system for aligning the tibial mechanical axis. [Figure 5] 1 illustrates a femoral preparation system coupled to a distal femur and a tibial preparation system coupled to a proximal tibia. [Figure 6] FIG. 10 is an assembly diagram for aligning the femoral mechanical axis. [Figure 7] FIG. 10 is an assembly diagram for aligning the femoral mechanical axis. [Figure 8] FIG. 1 is an assembly diagram for calibration. [Figure 9] FIG. 1 is an assembly diagram for calibration. [Figures 10A-10B] FIG. 1 illustrates the use of modules. [Figure 11] FIG. 1 is a diagram illustrating gap evaluation. [Figure 12] FIG. 1 illustrates one embodiment of a system. [Figure 13] FIG. 1 illustrates one embodiment of a system. [Figure 14] FIG. 1 illustrates one embodiment of a system. [Figure 15] FIG. 1 illustrates one embodiment of a system. [Figure 16] FIG. 1 illustrates one embodiment of a system. [Figure 17] FIG. 1 illustrates one embodiment of a system. [Figure 18] FIG. 1 illustrates one embodiment of a system. DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 illustrates the femur and tibia, with the distal portion of the femur and the proximal portion of the tibia forming a knee joint. An anatomical coordinate system is included on FIG. 1 to provide the reader with the proper orientation of the instrument and to help them more fully understand the structure of the instrument. The anatomical coordinate system indicates general directions—anterior, posterior, medial, and lateral—as well as superior and inferior. Other related terms include proximal, distal, varus, and valgus. For a given bone, the terms proximal and distal may refer to directions toward or away from the center of the body, respectively. For a given joint, varus may refer to a joint angle where the distal portion is closer to the midline of the body (e.g., genu varus). For a given joint, valgus may refer to a joint angle where the distal portion is farther from the midline of the body (e.g., genu valgus). These terms relate to the orientation of knee bones, such as the femur and tibia, and are used in the descriptions of the various instruments consistent with their known medical uses. Additionally, the terms varus / valgus and posterior / anterior are used herein to describe directional movements. Forces can be applied to bones to move them in an anatomical direction or orientation. Varus / valgus are broad terms used herein and include, without limitation, rotational movements in the medial and / or lateral directions (e.g., right and left within the page) relative to the knee joint shown in FIG. 1. Varus / valgus include movements or forces to temporarily create a varus / valgus condition. Clinically, these forces or movements reveal information about the static and kinematic properties of the joint. Posterior / anterior are broad terms used herein and include, without limitation, rotational movements in the posterior and / or anterior directions (e.g., into and out of the page) relative to the knee joint shown in FIG. 1.

[0029] Before replacing the femoral and tibial structures of the knee joint with prosthetic components, surgical cuts, commonly referred to as resections, are typically made using a saw or one or more other cutting tools along one or more portions of both the proximal tibia and distal femur. These cuts are made to prepare the tibia and femur for the prosthetic components. After the cuts are made, the prosthetic components may be attached and / or fixed to the tibia and femur.

[0030] The desired orientations and / or locations of these cuts, as well as the desired orientations and / or locations of the prosthetic components, may be determined preoperatively, for example, based on one or more mechanical axes through an individual patient's leg. After the desired placement of these cuts has been determined preoperatively, the surgeon can precisely align the cutting tools using the systems and methods described herein. Although the systems and methods are described in the context of knee replacement surgery, the systems and / or their components and methods may be similarly used in other types of medical procedures, including, but not limited to, shoulder and hip replacement surgery.

[0031] The systems and methods described herein may also be used for limb alignment and / or joint gap measurement. Figure 2 illustrates a mechanical axis passing through the femur. The systems and methods described herein can determine an axis 10 extending from the center of rotation of the femur in the hip socket to the center of the distal portion of the femur. The femoral resection 15 can be a plane perpendicular to the femoral mechanical axis 10. Figure 2 illustrates a mechanical axis passing through the tibia. The systems and methods described herein can determine an axis 20 extending from an anatomical proximal point on the tibia to a point midway between the malleoli on the patient's ankle. The tibial plateau 25 can be a plane perpendicular to the tibial mechanical axis 20. The systems and methods described herein can determine the angle between the plateaus 15, 25. The plateaus 15, 25 can be estimates of the post-resection plane of the tibia and / or femur. The plateaus 15, 25 may be planes established through some anatomical reference placement.

[0032] The systems and methods described herein can determine overall limb alignment. For knee surgery, the systems and methods can determine the overall alignment between the femur and tibia, for example, between the axes 10, 20, which can be determined by the systems and methods disclosed herein. The systems and methods described herein can be used in total knee arthroplasty. The systems and methods described herein can be used in unicompartmental knee arthroplasty. The systems and methods described herein can fulfill an unmet clinical need for limb alignment for knees and other joints.

[0033] In some embodiments, the systems and methods provide dynamic limb alignment angles. In some embodiments, the systems and methods provide dynamic limb alignment angles through a range of motion. In some embodiments, the systems and methods provide dynamic limb alignment angles in flexion / extension. In some embodiments, the systems and methods provide dynamic limb alignment angles when a user applies varus / valgus forces. In some embodiments, the systems and methods provide dynamic limb alignment angles before and after a tibial resection. In some embodiments, the systems and methods provide dynamic limb alignment angles before and after a femoral resection. In some embodiments, the systems and methods provide dynamic limb alignment angles before and after any resection. In some embodiments, the systems and methods provide static limb alignment angles.

[0034] In some methods, the method can include one or more steps of a surgical workflow. The method can include an incision to provide approximation to the joint. The method can include an initial assessment. The method can include estimating, directing, performing, or otherwise including a proximal tibial resection. The method can include a spacer block assessment for gap balancing. In some methods, the spacer block assessment can occur only after resections have been made on both the tibia and femur. The method can include estimating, directing, performing, or otherwise including a distal femoral resection. The method can include positioning a trial implant or implant. The method can include cementing the implant. The method can include closing the incision. One or more of these method steps can be facilitated by use of the systems and methods described herein.

[0035] In some methods, the method can include one or more steps involving limb alignment measurement. The method can include aligning the femoral mechanical axis. The method can include aligning the tibial mechanical axis. The method can include measuring limb alignment at initial evaluation. The method can include measuring limb alignment during femoral cut. The method can include measuring limb alignment during spacer block evaluation. The method can include measuring limb alignment during trial implant or implant positioning. The method can include the limb alignment measurement being saved in the patient record before closing the incision and / or completing the procedure, while closing the incision and / or completing the procedure, or after closing the incision and / or completing the procedure, the patient record being accessible for later review and use.

[0036] The systems and methods can provide many advantages. The systems and methods can provide reproducible tibial plateau varus / valgus assessment, instruction, or other forms of navigation for cut verification. The systems and methods can provide reproducible tibial plateau posterior slope assessment, instruction, or other forms of navigation. The systems and methods can provide low-destructive fixation methods for the instruments or jigs described herein. The systems and methods can be easily integrated into current surgical workflows. The systems and methods can provide reproducible measurement of the deep resection of the tibial plateau from the bottom of the articular bearing surface. The systems and methods can provide tibial plateau cut navigation.

[0037] The systems and methods can provide many advantages. The systems and methods can provide measurement of overall limb alignment of the tibial and femoral mechanical axes. The systems and methods can include instrumentation for minimal resection. The systems and methods can minimize soft tissue disruption with or by the instrumentation.

[0038] The systems and methods can provide many advantages. The systems and methods can facilitate control of tibial rotation. The systems and methods can provide an easy, reproducible measurement of the impact of tibial component rotation on limb alignment. In some methods, tibial rotation includes dynamic behavior of the tibia. In some methods, tibial rotation includes static, unloaded rotation in extension. In some methods, the impact of tibial component rotation in flexion and extension is measured and displayed. In some methods, dynamic rotation is measured and displayed. The systems and methods can provide an easy, reproducible measurement of the impact of tibial component rotation on limb alignment, i.e., the space between the femoral condyles and the tibial plateau, during varus / valgus forces. The systems and methods can facilitate gap balancing. The systems and methods can facilitate assessment, measurement, and adjustment of ligament tension. The systems and methods can provide meaningful physiological assessments, e.g., measurements for determining overall limb alignment.

[0039] In some embodiments, the systems and methods can include femoral mechanical axis alignment. Figure 3 illustrates a system positioned for femoral mechanical axis alignment. In some embodiments, the systems and methods can include tibial mechanical axis alignment. Figure 4 illustrates a system for tibial mechanical axis alignment. Figure 5 illustrates a femoral preparation system 100 and a tibial preparation system 200. The femoral preparation system 100 includes a fixture configured to be coupled to the femur. The tibial preparation system 200 includes a fixture configured to be coupled to the tibia. Figure 6 illustrates a system positioned for femoral mechanical axis alignment when the leg is in extension. Figure 7 illustrates a system positioned for femoral mechanical axis alignment when the leg is in flexion. Figures 8 and 9 illustrate systems positioned for calibration.

[0040] The systems and methods can include a femoral preparation system 100. In some methods, the femoral preparation system 100 can be utilized in procedures leading up to a resection, including a resection. In some methods, the femoral preparation system 100 can be utilized for evaluation and measurement before and / or after a resection. In some methods, the femoral preparation system 100 can be utilized in procedures leading up to a resection that does not include a resection. In some methods, the femoral preparation system 100 can be utilized for evaluation and measurement without performing a resection. The systems and methods can include a tibia preparation system 200. In some methods, the tibia preparation system 200 can be utilized in procedures leading up to a resection, including a resection. In some methods, the tibia preparation system 200 can be utilized for evaluation and measurement before and / or after a resection. In some methods, the tibia preparation system 200 can be utilized in procedures leading up to a resection that does not include a resection. In some methods, the tibia preparation system 200 can be utilized for evaluation and measurement without performing a resection. The systems and methods can include a surgical orientation device 300. The systems and methods can include a reference sensor 400.

[0041] In the femoral axis alignment shown in FIG. 3 , the femoral preparation system 100 can be coupled to the femur. A reference sensor 400 can be coupled to the femoral preparation system 100. The tibial preparation system 200 can be coupled to the tibia. A surgical orientation device 300 can be coupled to the tibial preparation system 200. The femoral preparation system 100 can determine a distal point on the femur corresponding to the location of the distal portion of the femoral mechanical axis and / or can be attached to the distal point on the femur. In some methods, a pin is inserted into the center of the knee joint on the femur. In some methods, the knee is placed in a flexed position. In some embodiments, the femoral preparation system 100 can be positioned at the intersection of the Whiteside line and the epicondylar axis. In some methods, the femoral anatomy is probed to determine the location corresponding to the distal point of the femoral mechanical axis. The femoral preparation system 200 can determine a proximal point disposed on the femoral mechanical axis. In some methods, an outrigger jig (not shown) is coupled to the pins placed in the center of the knee. The outrigger jig is utilized to guide the placement of the pins 102, 104 on the sides of the knee. The pins 102, 104 are coupled to a jig portion for mounting a reference sensor 400 for femoral axis alignment. The reference sensor 400 is mounted on the lateral side of the joint to allow the limb to be extended. In some methods, the femur is moved within a range of motion to determine the proximal point of the femoral mechanical axis. In some methods, the surgical orienting device 300 and the reference sensor 400 can determine the mechanical axis of the femur. In some methods, the reference sensor 400 is used to track the movement of the femur as well as the cutting block. In some methods, the surgical orienting device 300 is not attached to the femur during or after axis alignment. In some methods, the surgical orienting device 300 can be attached in situ to assist in the placement of the cutting block. The mechanical axis of the femur can be a line intersecting the distal and proximal points, hi some embodiments, the mechanical axis of the femur can be a line intersecting the distal point where the femoral preparation system 100 is attached.In some embodiments, the mechanical axis of the femur can be the line that intersects the proximal point established by the reference sensor 400 during femoral movement.

[0042] In the tibial axis alignment shown in FIG. 4 , the tibial preparation system 200 may be coupled to the tibia. The surgical orienting device 300 may be coupled to the tibial preparation system 200. The reference sensor 400 may be coupled to the tibial preparation system 200. In some embodiments, the femoral preparation system 100 is removed, or at least a portion of the femoral preparation system 100 is removed. The tibial preparation system 200 can determine the proximal point of the tibial mechanical axis. In some methods, the tibial anatomy is probed, thereby determining the proximal point of the tibial mechanical axis. The tibial preparation system 200 can determine the distal point of the tibial mechanical axis. In some methods, the tibial anatomy is probed as input to determining the distal point of the tibial mechanical axis. In some methods, two portions of the tibial anatomy are probed, thereby allowing the surgical orienting device 300 to determine the distal point corresponding to the tibial mechanical axis. The surgical orientation device 300 and the reference sensor 400 can determine the mechanical axis of the tibia, which can include a distal point and a proximal point of the tibia.

[0043] FIG. 5 illustrates additional features of the femoral preparation system 100 and the tibial preparation system 200. The femoral preparation system 100 can be used to calculate the femoral mechanical axis through the femur. In some embodiments, the femoral preparation system 100 can be used to modify the natural femur with a distal femoral resection, allowing a prosthetic component to be securely attached to the distal end of the femur. The femoral preparation system 100 can support a cutting block or guide to facilitate one or more resections. As described herein, the femoral preparation system 100 can be designed for total knee arthroplasty or unicondylar knee arthroplasty. In some embodiments, the femoral preparation system 100 is used to evaluate femoral characteristics, such as the orientation of the femoral mechanical axis relative to the tibia or contralateral femur, in a controlled manner to assess whether the joint should be modified by adjusting the orientation of the femur or another bone. Thus, the femoral preparation system 100 may be used for characterization without resection or other steps for preparation of the femoral joint component.

[0044] The femoral preparation system 100 can include a femoral jig assembly 102. The femoral jig assembly 102 can include a reference sensor device interface 104 that can be used to couple a reference sensor 400 to the femoral jig assembly 102. In some embodiments, the femoral jig assembly 102 can include a surgical orientation device interface 106 that can be used to couple a surgical orientation device 300 to the femoral jig assembly 102.

[0045] The surgical orienting device interface 106 may advantageously allow the surgical orienting device 300 to be quickly coupled and uncoupled with the femoral jig assembly 102 during a surgical procedure, allowing the surgical orienting device 300 to be used modularly with a variety of orthopedic fasteners during one or more stages of the procedure.

[0046] The reference sensor device interface 104 may advantageously allow the reference sensor 400 to be quickly coupled and uncoupled from the femoral jig assembly 102 during a surgical procedure, allowing the reference sensor 400 to be used modularly with a variety of orthopedic fixation devices during one or more stages of the procedure.

[0047] In some techniques for identifying the distal point of the femoral mechanical axis, the distal portion of the femur is exposed using any conventional surgical technique. The tibia and femur are then placed in approximately 90 degrees of flexion, as shown in Figure 3. Other degrees of flexion of the leg are also possible.

[0048] Then, eyelets for receiving portions of the fixation pins 108 of the femoral jig assembly 102 can be drilled using any conventional surgical technique in the appropriate anatomical location. In some methods, the femoral jig assembly 102 can be coupled to a distal portion of the femur. In some methods, the anatomical location can be along a Whiteside's line. In some methods, the anatomical location can be along the epicondylar axis. In some methods, the anatomical location can be the intersection of a Whiteside's line and the epicondylar axis. The method can include coupling one or more components of the femoral jig assembly 102 to the femur using one or more fixation pins 108.

[0049] In some methods, the femoral jig assembly 102 can be offset from the distal portion of the femur. In some methods, the anatomical location can be offset from Whiteside's line. In some methods, the anatomical location can be offset from the epicondylar axis. In some methods, the anatomical location can be offset from the intersection of Whiteside's line and the epicondylar axis. In some methods, this offset is input to determine a point along the femoral mechanical axis. In some methods, the anatomical location can be any suitable anatomical landmark or combination of landmarks within, adjacent to, or offset from the distal portion of the femur. After the femoral jig assembly 102 is attached to the femur, the method can include noting the distance indication provided by the fiducial markings to establish the offset and the placement of the fixation pin 108 relative to the fiducial markings. In this method, the distal point corresponding to the femoral mechanical axis can be approximated by using a portion of the femoral jig assembly 102 to identify the center of the femur.

[0050] The method may further include extending the leg after the surgical orienting device 300 and / or reference sensor 400 are coupled to the femoral jig assembly 102. The surgical orienting device 300 and / or reference sensor 400 may be used to determine the relative coordinates of a central pivot point on the femur. By determining the coordinates of the pivot point of the femoral head, the surgical orienting device 300 and / or reference sensor 400 can calculate the placement and / or orientation of a mechanical axis passing through the femur.

[0051] The leg may be moved (e.g., rocked) to determine the coordinates of the pivot point of the femoral head, and therefore the pivot point of the mechanical axis. Figures 6 and 7 show the femur in various positions for alignment of the femoral mechanical axis. The femur may be moved in any manner to determine the proximal point. In some methods, the reference sensor 400 can determine the mechanical axis of the femur. For example, the leg may be moved in multiple different directions and / or planes with the surgical orienting device 300 and / or reference sensor 400 coupled to the femoral jig assembly 102. Readings such as femoral angular velocity and acceleration (“surgical orienting device 300 and / or reference sensor 400 data”) may be taken by the surgical orienting device 300 and / or reference sensor 400 until the placement and / or orientation of the leg and femur mechanical axis (“femoral mechanical axis”) is determined. In one embodiment, when one or more multi-axis (e.g., three-axis) accelerometers and gyroscopes are used, the data from the surgical orientation device 300 and / or reference sensor 400 for each movement of the femur can be numerically integrated with respect to time to obtain a trajectory of position and velocity points.

[0052] The acceleration and angular velocity sensed by the surgical orienting device 300 and / or the reference sensor 400 during leg movement can be processed while the leg is moved about its pivot point. The surgical orienting device 300 and / or the reference sensor 400 can provide an output vector representing the center of rotation about the inertial sensor axes of the surgical orienting device 300 and / or the reference sensor 400. The leg can be moved about its pivot point while the inertial data is processed by the microprocessor. An algorithm implemented on the microprocessor can process the inertial data in real time and determine whether the leg is stationary or dynamically moving. Data from one or both states can be used by the algorithm to determine the pivot point.

[0053] The methods described herein for calculating the location and / or orientation of the femoral mechanical axis, and generally for calculating the location and / or orientation of any axis based on a pivot point, can provide accurate determination of pivot point locations and radii of curvature without the burdensome and sometimes impossible constraints of external measurements encountered in medical procedures. For example, the methods can enable calculation of pivot points in blind situations where the end joints are typically hidden or unobservable, such as in the case of the femoral head.

[0054] FIG. 5 also illustrates a tibia preparation system 200. The tibia preparation system 200 can be used to calculate the tibial mechanical axis through the tibia. In some embodiments, the tibia preparation system 200 can be used to modify the natural tibia with a proximal tibial resection, allowing a prosthetic component to be securely attached to the proximal end of the tibia. The tibia preparation system 200 can support a cutting block or guide to facilitate one or more resections. As described herein, the tibia preparation system 200 can be designed for a total knee arthroplasty or a unicompartmental knee arthroplasty.

[0055] The tibial preparation system 200 may include a tibial jig assembly 202. The tibial jig assembly 202 may include a reference sensor device interface 204 that may be used to couple a reference sensor 400 to the tibial jig assembly 202. The tibial jig assembly 202 may include a surgical orienting device interface 206 that may be used to couple a surgical orienting device 300 to the tibial jig assembly 202.

[0056] The surgical orienting device interface 206 may advantageously allow the surgical orienting device 300 to be quickly coupled and uncoupled with the tibial jig assembly 202 during a surgical procedure, which allows the surgical orienting device 300 to be used in a modular manner, such as moving between the femoral jig assembly 102 and the tibial jig assembly 202.

[0057] The reference sensor device interface 204 may advantageously allow the reference sensor 400 to be quickly coupled and uncoupled from the tibial fixture assembly 202 during a surgical procedure. This allows the reference sensor 400 to be used in a modular manner, such as moving between the femoral fixture assembly 102 and the tibial fixture assembly 202.

[0058] The reference sensor 400 may preferably be coupled to the tibial fixture assembly 202 such that the reference sensor 400 follows the movement of the tibia and generally does not move independently with respect to the tibia during knee replacement surgery. The configuration of the reference sensor device interface 204 may allow the reference sensor 400 to be mounted at a low height below the other components of the tibial fixture assembly 202, such that the reference sensor 400 may be positioned between at least one moving component of the tibial fixture assembly 202 and the patient's tibia.

[0059] In some techniques for locating the proximal point of the tibia's mechanical axis, the proximal end portion of the tibia is exposed using any conventional surgical technique. The tibia and femur can then be placed in approximately 90 degrees of flexion, as shown in FIG. 5. Other degrees of leg flexion are also possible. An eyelet for receiving a portion of the fixation pin of the tibial jig assembly 202 can then be drilled in the appropriate anatomical location using any conventional surgical technique.

[0060] The tibia fixture assembly 202 can include a midline reference probe assembly 210. The midline reference probe assembly (not shown) can be positioned at an appropriate anatomical location on the proximal tibia. In some methods, the anatomical location can be a point immediately posterior to the insertion of the anterior cruciate ligament ("ACL"). In some methods, the anatomical location can be a location near the insertion of the anterior cruciate ligament ("ACL"). In some methods, the anatomical location can be a soft tissue point on the tibia, commonly referred to as the A / P point of the mechanical axis. This point is typically located along the tibial intercondylar eminence on the tibia and marks the location of the point along the mechanical axis of the tibia. In some methods, the anatomical location can be any suitable anatomical landmark. In some methods, the midline reference probe assembly 210 can rest on the anatomical location.

[0061] In some methods, the tibial fixture assembly 202 can be offset from the proximal end portion of the tibia. After the tibial fixture assembly 202 is coupled to the tibia and the midline reference probe assembly is positioned, the method can include noting the distance indication provided by the fiducial markings to establish the offset and the placement of the midline reference probe assembly relative to the fiducial markings. The offset can be input into the surgical orientation device 300. This offset can facilitate determining a proximal point on the tibia. In this method, the proximal point corresponding to the mechanical axis of the tibia can be approximated by using a portion of the tibial fixture assembly 202 to identify the center of the tibia.

[0062] In some methods, the tibial jig assembly 202 can include a probe assembly 212 including an elongated member 214 and a probe member 216. The probe member 216 can be configured to contact an anatomical landmark, such as the malleolus of the patient's ankle. The surgical orienting device 300 can be coupled to the probe assembly 212 such that movement of the probe assembly 212 causes corresponding movement of the surgical orienting device 300. The surgical orienting device 300 can thereby track the orientation of the probe assembly 212 as it contacts a distal point.

[0063] The method may further include acquiring landmarks to determine the location of the mechanical axis passing through the tibia. For example, the landmarks may be acquired by engaging the probe member 216 of the probe assembly 212 with the medial malleolus at a first reference position. For example, the landmarks may be acquired by engaging the probe member 216 of the probe assembly 212 with the lateral malleolus at a second reference position. Acquiring the malleolus may be accomplished by rocking one or more portions of the probe assembly 212 and / or the tibial jig assembly 202 so that the probe member 216 contacts the side of the ankle. The surgical orientation device 300 can then determine the location of the tibial mechanical axis. In some embodiments, the surgical orientation device 300 can locate sagittal and coronal planes passing through the tibial mechanical axis. In some embodiments, the surgical orientation device 300 can calculate the placement of the mechanical axis by assuming that the tibial mechanical axis extends from the point of contact between the proximal tibia and the midline probe assembly 210 through a point midway between the two malleolus points where the probe member 216 contacts.

[0064] For each landmark acquisition, the user can palpate the ankle. After the placement of the malleolus contacts the probe member 216, the user can press a user input on the surgical orienting device 300 to cause the surgical orienting device 300 to determine the orientation of the surgical orienting device 300 at the reference position. For example, the surgical orienting device 300 can register and / or calculate the current orientation of the surgical orienting device 300 based on data collected from a sensor inside the surgical orienting device 300 at the first and second reference positions. The orientation of the surgical orienting device 300 at the first and second reference positions can be used to identify the orientation of a coronal plane that passes through the tibia, including the mechanical axis of the tibia. The orientation of the surgical orienting device 300 at the first and second reference positions can be used to identify the placement and / or orientation of a sagittal plane that includes the mechanical axis of the tibia.

[0065] In some methods, the mechanical axis of the tibia is determined. The tibia and femur may be in flexion, as shown in FIG. 4 . A surgical orienting device 300 may be positioned on the tibial preparation system 200. A reference sensor 400 may be positioned on the tibial preparation system 200. During landmark registration, the surgical orienting device 300 determines the mechanical axis of the tibia in flexion. The reference sensor 400 can track the position of the tibia. The surgical orienting device 300 stores the tibial mechanical axis. In some embodiments, the surgical orienting device 300 determines a mechanical axis extending from the contact point of the midline probe assembly 210 and a point midway between the two malleolus points where the probe member 216 makes contact.

[0066] In some methods, the mechanical axis of the femur is determined. The tibia and femur may be in flexion, as shown in FIG. 3 . A surgical orienting device 300 may be positioned on the tibial preparation system 200. A reference sensor 400 may be positioned on the femoral preparation system 100. During landmark registration, the reference sensor 400 can determine the mechanical axis of the femur in flexion. The surgical orienting device 300 stores the femoral mechanical axis. In some embodiments, the surgical orienting device 300 determines a mechanical axis extending from the tangent point between the approximate center of the intercondylar notch and the center of rotation. In some methods, the mechanical axis of the tibia is determined before the mechanical axis of the femur. In other methods, the mechanical axis of the femur is determined before the mechanical axis of the tibia.

[0067] In some methods, the leg is brought into an extension position for limb alignment measurements. The leg is shown in an extension position in FIG. 6. Surgical orienting device 300 may be positioned on tibial preparation system 200. Reference sensor 400 may be positioned on femoral preparation system 100. In some methods, one of surgical orienting device 300 and reference sensor 400 is positioned on femoral preparation system 100, and the other of surgical orienting device 300 and reference sensor 400 is positioned on tibial preparation system 200.

[0068] The surgical orienting device 300 and the reference sensor 400 determined the mechanical axes of the tibia and femur before the leg was moved into extension. The surgical orienting device 300 stored the mechanical axes. The mechanical axes of the tibia and femur may be stored as vectors. In some embodiments, the surgical orienting device 300 and the reference sensor 400 are configured to sense changes in the orientation of the mechanical axis of the tibia relative to a fixed reference frame when the leg is in extension. In some embodiments, the surgical orienting device 300 and the reference sensor 400 are configured to sense changes in the orientation of the mechanical axes. In some embodiments, the surgical orienting device 300 and the reference sensor 400 sense changes in the orientation of the mechanical axes of the tibia and femur when the leg is in extension. In some embodiments, surgical orientation device 300 and reference sensor 400 sense changes in the orientation of the mechanical axes of the tibia and femur when the leg is in extension relative to the orientation of the mechanical axes of the tibia and femur when the leg is in flexion. The leg is shown in flexion in FIG. 7.

[0069] Changes in the orientation of the mechanical axes of the tibia and femur can determine the varus / valgus angle between the mechanical axes of the tibia and femur. Changes in the orientation of the mechanical axes of the tibia and femur can determine the flexion / contracture angle between the mechanical axes of the tibia and femur. Changes in the orientation of the mechanical axes of the tibia and femur can be measured in the coronal plane. Changes in the orientation of the mechanical axes of the tibia and femur can be measured in the sagittal plane.

[0070] The relative positioning of the surgical orienting device 300 and the reference sensor 400 can determine the angulation between the mechanical axes. Varus / valgus involves rotational movement in the medial and / or lateral directions. The surgical orienting device 300 and the reference sensor 400 can be used for limb alignment measurements. The surgical orienting device 300 and the reference sensor 400 can determine a mechanical axis extending from the center of rotation of the femur in the hip socket to a landmark on the distal portion of the femur. The femoral plateau can be a plane perpendicular to the femoral mechanical axis. The surgical orienting device 300 and the reference sensor 400 can determine a mechanical axis extending from a landmark on the proximal portion of the tibia to the midpoint between the malleoli on the patient's ankle. The tibial plateau can be a plane perpendicular to the tibial mechanical axis. The surgical orienting device 300 and the reference sensor 400 can determine the angle between the plateaus. The surgical orientation device 300 and reference sensor 400 can determine the varus / valgus angle between the plateaus. The surgical orientation device 300 and reference sensor 400 can determine the flexion / contracture angle between the plateaus. The surgical orientation device 300 and reference sensor 400 can determine angles relative to one or more planes. The surgical orientation device 300 and reference sensor 400 can determine angles relative to one or more anatomical planes. The surgical orientation device 300 and reference sensor 400 can determine angles based on positions in a three-dimensional coordinate system.

[0071] In some methods, the mechanical axes are determined prior to the resection. In some methods, the alignment of the tibial and femoral mechanical axes is determined prior to the resection. In some methods, the leg is moved into extension for limb alignment measurements prior to the resection. The change in orientation of the tibial and femoral mechanical axes between flexion and extension can be stored. The orientation of the tibial and femoral mechanical axes can be compared to preoperative measurements obtained from imaging techniques such as x-rays. The leg can be moved from extension to flexion for the resection. The leg in flexion is shown in FIG. 7. The surgeon can proceed with the resection. The femoral preparation system 100 can be coupled to the cutting guide. The tibial preparation system 200 can be coupled to the cutting guide. The surgical orientation device 300 can be coupled to the cutting guide. The reference sensor 400 can be coupled to the cutting guide. In some embodiments, the resection is performed for a total knee replacement. In some embodiments, the resection is performed for a partial knee replacement. Additional details of the cutting guide are disclosed in U.S. Patent Application Publication No. 2009 / 0029999, filed July 24, 2009; U.S. Patent Application Publication No. 2009 / 0029999, filed January 21, 2011; U.S. Patent Application Publication No. 2009 / 0029999, filed May 24, 2011; U.S. Patent Application Publication No. 2014 / 0029999, filed November 5, 2014; and U.S. Patent Application Publication No. 2014 / 0029999, filed November 14, 2014, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0072] In some methods, the alignment of the tibial and femoral mechanical axes is not determined prior to resection. The surgeon can proceed with resection after the mechanical axes are determined. The surgeon can proceed with resection after the mechanical axes are memorized by the surgical orientation device 300. The leg can remain in a flexed state. The leg can be positioned in a flexed state for mechanical axis alignment and resection.

[0073] In some methods, the alignment of the tibia and femur mechanical axes is determined after resection. In some methods, the alignment of the tibia and femur mechanical axes is determined before and after resection. In some methods, the alignment of the tibia and femur mechanical axes is determined only after resection. In some methods, the leg is moved into extension after resection for limb alignment measurement. The change in orientation of the tibia and femur mechanical axes in extension relative to the tibia and femur mechanical axes in flexion can be determined. The change in orientation of the tibia and femur mechanical axes can be compared to pre-operative measurements obtained from imaging techniques such as x-rays. The leg can be moved from extension to flexion for further resection.

[0074] 8 and 9 illustrate the calibration of the surgical orienting device 300 and the reference sensor 400. In some methods, the leg is in extension for calibration. In some methods, the leg is in flexion for calibration. In some methods, calibration is optional. In some methods, the surgical orienting device 300 and the reference sensor 400 are calibrated after determining the mechanical axes of the tibia and femur. In some methods, the surgical orienting device 300 and the reference sensor 400 are calibrated before limb alignment measurements. The surgical orienting device 300 may be positioned on the tibial preparation system 200 for calibration. The reference sensor device 400 may be positioned on the tibial preparation system 200 for calibration. The surgical orienting device 300 and the reference sensor 400 may be at a known orientation relative to each other when attached to the tibial preparation system 200. The surgical orienting device 300 and the reference sensor 400 may be zeroed. The surgical orienting device 300 and the reference sensor 400 can reduce errors caused by drift. The surgical orienting device 300 and the reference sensor 400 can be calibrated before the reference sensor 400 is positioned on the femoral preparation system 100 for limb alignment calculations. The reference sensor 400 can be returned to the femoral preparation system 100 after calibration. The femoral preparation system 100 and the tibial preparation system 200 can include a reference sensor device interface 104, 204 that can be used to couple the reference sensor 400 to the jig assembly 102, 202. Figures 7 and 8 illustrate one embodiment of the reference sensor device interface 104, 204.

[0075] 10A illustrates the alignment of module 500. Surgical orienting device 300 may be coupled to tibia jig assembly 202. Reference sensor 400 may be coupled to tibia jig assembly 202. In some embodiments, reference sensor 400 remains stationary with respect to the tibia. In some embodiments, module 500 is provided. Module 500 may include any of the features of surgical orienting device 300 and reference sensor 400 described herein. Module 500 may include any of the sensors described herein. In some embodiments, reference sensor 400 and module 500 have the same configuration. In some embodiments, reference sensor 400 and module 500 have different configurations. In some methods, both reference sensor 400 and module 500 are utilized. In some methods, reference sensor 400 is utilized but module 500 is not utilized. In some embodiments, reference sensor 400 may be utilized in place of module 500 in any manner. In some embodiments, the module 500 may be utilized in any manner in place of the reference sensor 400 .

[0076] The tibial jig assembly 202 may be partially or fully assembled for calibration of the module 500. The surgical orienting device 300 may be coupled to a movable portion of the tibial jig assembly 202. The reference sensor 400 may be coupled to a fixed or stationary portion of the tibial jig assembly 202. The surgical orienting device 300 and the reference sensor 400 may be coupled to the tibial jig assembly 202 in the same manner as these devices are coupled when positioning the tibial mechanical axis. The tibial jig assembly 202 may include a module interface 250 that may be used to couple the module 500 to the tibial jig assembly 202.

[0077] The module 500 may be coupled to the tibial jig assembly 202. In some embodiments, the module 500 couples to a moving portion of the tibial jig assembly 202. In some embodiments, the module 500 couples to the same moving portion of the tibial jig assembly 202 as the surgical orienting device 300. The angle between the surgical orienting device 300 and the module 500 may be fixed during calibration. The module 500 may be calibrated with respect to the surgical orienting device 300.

[0078] In some embodiments, the module 500 couples to a fixed portion of the tibial jig assembly 202. In some embodiments, the module 500 couples to the same fixed portion of the tibial jig assembly 202 as the reference sensor 400. The angle between the reference sensor 400 and the module 500 may be fixed during calibration. The module 500 may be calibrated with respect to the reference sensor 400.

[0079] In some methods, the leg is moved into extension as shown in FIG. 7A . The module 500 is aligned or calibrated relative to the reference sensor 400 and / or the surgical orienting device 300. In some methods, the module 500 is held stationary on the tibial jig assembly 202 during alignment. In some methods, the module 500 may be fixed relative to the tibia. In some methods, the module 500 is coupled to a moving portion of the tibial jig assembly 202 during alignment. The module 500 may be moved relative to the reference sensor 400 during alignment. In some methods, the leg is held stationary during alignment. In some methods, the tibia is held stationary during alignment. In some methods, the sensor of the module 500 is activated during alignment. In some methods, gyroscopic integration is initiated during alignment.

[0080] As shown in FIG. 10B , the module 500 can be moved to the femur during limb alignment and gap measurement. In some methods, the module 500 is moved from its position on the tibial jig assembly 202 to its position on the femoral jig assembly 102. FIG. 7B illustrates the positions of the surgical orienting device 300, the reference sensor 400, and the module 500 during limb alignment and gap measurement. In some embodiments, the surgical orienting device 300 can be coupled to a movable portion of the tibial jig assembly 202. In some embodiments, the surgical orienting device 300 can be coupled to a fixed portion of the tibial jig assembly 202. In some embodiments, the reference sensor 400 can be coupled to a fixed portion of the tibial jig assembly 202. In some embodiments, the reference sensor 400 can be coupled to a fixed portion of the movable jig assembly 202. In some embodiments, the surgical orienting device 300 tracks the position of the tibia during limb alignment and gap measurement. In some embodiments, orienting device 300 received information during limb alignment and gap measurement from reference sensor 400. In some embodiments, orienting device 300 received information during limb alignment and gap measurement from module 500.

[0081] In some methods, the module 500 can be coupled to the femoral fixture assembly 102 during limb alignment and gap measurement. In some embodiments, the module 500 couples to a fixed portion of the femoral fixture assembly 102. In some embodiments, the module 500 couples to a movable portion of the femoral fixture assembly 102. In some methods, the module 500 tracks the position of the femur during limb alignment and gap measurement.

[0082] In some embodiments, the reference sensor 400 may be moved to the femur during limb alignment and gap measurement. In some methods, the reference sensor 400 is moved from a position on the tibial jig assembly 202 to a position on the femur jig assembly 102. The surgical orienting device 300 may be coupled to the tibial jig assembly 202. The module 500 may be coupled to the tibial jig assembly 202. In some embodiments, the surgical orienting device 300 tracks the position of the tibia during limb alignment and gap measurement. In some embodiments, the orienting device 300 receives information from the reference sensor 400 during limb alignment and gap measurement. In some embodiments, the orienting device 300 receives information from the module 500 during limb alignment and gap measurement.

[0083] In some methods, the reference sensor 400 can be coupled to the femoral fixture assembly 102 during limb alignment and gap measurement. In some embodiments, the reference sensor 400 is coupled to a fixed portion of the femoral fixture assembly 102. In some methods, the reference sensor 400 tracks the position of the femur during limb alignment and gap measurement.

[0084] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can track the position of the tibia and femur during limb alignment and gap measurement. In some embodiments, the surgical orienting device 300 tracks the tibia. In some embodiments, the reference sensor 400 tracks the femur. In some embodiments, the module 500 tracks the femur. Other configurations are contemplated. In some embodiments, the reference sensor 400 can track the position and orientation of the tibia. In some embodiments, the module 500 can track the position and orientation of the tibia. A user can obtain position and / or orientation signals from the reference sensor 400 and the module 500 in real time. A user can obtain limb alignment measurements in real time. In some embodiments, the tracking of the tibia and femur is limited in time. In some embodiments, the tracking of the tibia and femur is limited in terms of time before recalibration is required. Recalibration can include any of the steps described herein for aligning or calibrating the module 500.

[0085] In some methods, the surgical orienting device 300, the reference sensor 400, and / or the module 500 receive static measurements based on the position of the tibia and femur. In some methods, the surgical orienting device 300, the reference sensor 400, and / or the module 500 perform dynamic measurements based on the position of the tibia and femur within a range of motion. In some embodiments, a reaction force may be applied to the tibia and returned to a neutral position. Any degree of stress may be applied before the tibia is returned to a neutral position. The leg may be abducted. Load may be applied until the clinician feels resistance. Other ranges and degrees of movement are also possible. In some embodiments, the leg may be swung in one general looping motion from a home position back to the home position, the looping motion causing both abduction and lift of the leg. In some embodiments, the tibia and femur may be placed in approximately 90 degrees of flexion. In some embodiments, the tibia and femur may be placed in full extension. Other degrees of leg flexion are also possible. Other leg movements are contemplated.

[0086] 10B, the reference sensor 400 can track the tibia and the module 500 can track the femur. Other configurations are contemplated. In other embodiments, the reference sensor 400 can be coupled to the femur fixture assembly 102 during limb alignment and gap measurements. The module 500 can be coupled to the tibia fixture assembly 202. In some embodiments, one of the reference sensor 400 and the module 500 is coupled to the tibia and the other of the reference sensor 400 and the module 500 is coupled to the femur.

[0087] In other embodiments involving the surgical orienting device 300 and the reference sensor 400, the surgical orienting device 300 may be moved to a fixed portion of the tibial jig assembly 202, or the portion of the tibial jig assembly 202 to which the surgical orienting device 300 is attached may be fixed by activating a clamp or other locking device. The reference sensor 400 may be coupled to a fixed portion of the tibial jig assembly 202. The surgical orienting device 300 and the reference sensor 400 may be aligned with one another. The surgical orienting device 300 may be moved to a fixed portion of the femoral jig assembly 102 during limb alignment and gap measurement. In some embodiments, one of the surgical orienting device 300 and the reference sensor 400 is coupled to the tibia and the other of the surgical orienting device 300 and the reference sensor 400 is coupled to the femur during limb alignment and gap measurement. In some methods, only the surgical orienting device 300 and the reference sensor 400 are utilized in limb alignment and gap measurement.

[0088] In some methods, the surgeon can perform a laxity test to assess ligament gap balancing. Reference sensor 400 and module 500 can be in the same position for limb alignment and laxity testing, as shown in FIG. 10B. In some embodiments, module 300 can track the position and / or orientation of the tibia. In some embodiments, reference sensor 400 can track the position and / or orientation of the femur. In some embodiments, module 500 can track the position and / or orientation of the femur.

[0089] FIG. 11 illustrates a gap balancing assessment with at least two of the surgical orienting device 300, the reference sensor 400, and the module 500. During the gap assessment, one or more of the surgical orienting device 300, the reference sensor 400, and the module 500 are attached to the tibia. During the gap assessment, one or more of the surgical orienting device 300, the reference sensor 400, and the module 500 are attached to the femur. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing before the limb alignment measurement. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing after the limb alignment measurement. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing when the leg is in extension for the limb alignment measurement. In FIG. 11, the surgical orienting device 300, the reference sensor 400, and the module 500 are shown as icons. In some methods, the surgical orienting device 300 is positioned on the tibia. In some methods, the reference sensor 400 is positioned on the femur. In some methods, the reference sensor 400 may be positioned on the tibia and the module 500 may be positioned on the femur, or vice versa. In some methods, the reference sensor 400 and the surgical orienting device 300 are utilized. The reference sensor 400 may be positioned on the tibia and the surgical orienting device 300 may be positioned on the femur, or vice versa. In some methods, the module 500 and the surgical orienting device 300 are utilized. The module 500 may be positioned on the femur and the surgical orienting device 300 may be positioned on the tibia, or vice versa. In some methods, the tibia mechanical axis is calculated prior to the gap balancing assessment, and the femur mechanical axis is calculated prior to the gap balancing assessment. In some methods, resections are performed prior to the gap balancing measurements. In some methods, limb alignment measurements are performed before gap balancing measurements.

[0090] During the gap measurement, at least one of the surgical orienting device 300, the reference sensor 400, and the module 500 can track the position and / or orientation of the tibia. During the gap measurement, at least one of the surgical orienting device 300, the reference sensor 400, and the module 500 can track the position and / or orientation of the femur. During the gap measurement, the reference sensor 400 can track the position and / or orientation of the tibia, and the module 500 can track the position and / or orientation of the femur in the arrangement shown in FIG. 11 . In some methods, the gap balancing is performed using a trial implant or implants. In some methods, the gap balancing is performed using at least one implant positioned between the tibia and the femur. The leg can be positioned in extension. The angle between the reference sensor 400 and the module 500 can be determined with the condyles in contact. This angle can be registered as 0 degrees. The tibia and femur can be put through a range of motion. In some embodiments, a varus force is applied to the tibia, and the angle between the surgical orienting device 300, reference sensor 400, and / or module 500 on the tibia and the surgical orienting device 300, reference sensor 400, and / or module 500 on the femur can be determined. In some embodiments, a force is applied to the tibia, and the angle between the surgical orienting device 300, reference sensor 400, and / or module 500 on the tibia and the surgical orienting device 300, reference sensor 400, and / or module 500 on the femur can be determined. In some embodiments, a varus force is applied to the tibia, and the angle between the surgical orienting device 300 on the tibia and the reference sensor 400 on the femur can be determined. The intercondylar distance can be known. The intercondylar distance can be determined from an image, such as an x-ray image. The intercondylar distance can be measured intraoperatively. This distance can be an input to the surgical orienting device 300. In the illustrated example, the intercondylar distance is 55 mm. The varus force gap can be determined based on a geometric relationship based on the known applied varus force and the intercondylar distance.

[0091] During clearance assessment, the tibia and femur may be put through a range of motion as a valgus force is applied. In some embodiments, a valgus force is applied to the tibia, and the angle between the surgical orienting device 300, reference sensor 400, and / or module 500 on the tibia and the surgical orienting device 300, reference sensor 400, and / or module 500 on the femur may be determined. In some embodiments, a force is applied to the tibia. When the force is applied, the angle between the surgical orienting device 300, reference sensor 400, and / or module 500 on the tibia and the surgical orienting device 300, reference sensor 400, and / or module 500 on the femur may be determined. In some embodiments, a valgus force is applied to the tibia, and the angle between the surgical orienting device 300 on the tibia and the reference sensor 400 on the femur may be determined. The intercondylar distance may be known. Valgus force clearance may be determined based on geometric relationships in the same manner as varus force clearance.

[0092] The clearance can be calculated by applying a force and measuring the change in angle between the femoral mechanical axis and the tibial mechanical axis. This angle and the intercondylar distance can provide an estimate of the clearance. In some methods, the user applies a varus torque. In some methods, the user applies a valgus torque. In some methods, the user applies a varus torque, then a valgus torque. In some methods, the user applies a valgus torque, then a varus torque. In some methods, the user applies a varus and / or valgus force to the knee in extension. In some methods, the user applies a varus and / or valgus force to the knee in flexion. In some methods, the user applies a varus force in flexion and extension. In some methods, the user applies a valgus force in flexion and extension.

[0093] One or more of the surgical orienting device 300, the reference sensor 400, and the module 500 can calculate the gap distance. The gap distance is the product of the measured angle between the surgical orienting device 300, the reference sensor 400, and / or the module 500 on the tibia and the surgical orienting device 300, the reference sensor 400, and / or the module 500 on the femur. The gap distance is the product of the known intercondylar distance. In some embodiments, the dynamic gap height provides insight into medial / lateral ligament tension. The gap height can provide insight into soft tissue balancing. The gap measurement can be assessed before resection. The gap can be assessed after resection. The gap can be assessed before and after resection. The gap can be assessed using multiple implants or trial implants.

[0094] The surgical orientation device 300, reference sensor 400, and / or module 500 may be used to measure and record the placement of anatomical landmarks used in knee procedures. The surgical orientation device 300, reference sensor 400, and / or module 500 may be used to determine the placement of the proximal or distal points of the tibia's mechanical axis. The surgical orientation device 300, reference sensor 400, and / or module 500 may be used to determine the placement of the proximal or distal points of the femur's mechanical axis. The surgical orientation device 300, reference sensor 400, and / or module 500 may be used to perform limb balancing measurements. The surgical orientation device 300, reference sensor 400, and / or module 500 may be used to perform gap balancing measurements. These measurements can improve patient outcomes by quantifying limb alignment, improving implant selection, and / or improving implant placement.

[0095] The surgical orientation device 300, the reference sensor 400, and / or the module 500 can include one or more inertial sensors. The inertial sensors can track the orientation and / or position of the tibia and femur during limb alignment and gap measurements. The sensors in the surgical orientation device 300 and the reference sensor 400 can determine the mechanical axis of the femur and the mechanical axis of the tibia. These mechanical axes can guide a cutting block for the desired resection. These mechanical axes can also be utilized for limb balancing measurements. These mechanical axes can also be utilized for gap measurements.

[0096] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include at least one inertial sensor, such as an accelerometer, a gyroscope, or a combination of these and other sensors. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can utilize sensors other than optical trackers. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can measure acceleration. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can measure velocity. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can measure physical properties of the bone to which it is attached. In some embodiments, the surgical orienting device 300, the reference sensor 400, and the module 500 can include a three-axis accelerometer to detect orientation relative to gravity and multiple gyroscopes to detect rotation. Other sensors can also be used with various modifications.

[0097] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include one or more sensors that together form an inertial measurement unit (IMU). In some embodiments, the IMU can include a first sensor for determining acceleration and a second sensor for determining gyroscopic positioning. As described herein, the first sensor can be an accelerometer and the second sensor can be a gyroscopic sensor. In some embodiments, the sensors can include a three-axis gyroscopic sensor and a three-axis acceleration sensor.

[0098] The surgical orienting device 300, the reference sensor 400, and / or the sensors within the module 500 preferably transfer data between themselves and, possibly, to external devices such as computers, tablets, and / or smartphones, as well as to external displays. The surgical orienting device 300, the reference sensor 400, and the module 500 may be positioned within the surgical field. The external device may be positioned within or outside the surgical field. The surgical orienting device 300, the reference sensor 400, and the module 500 may transfer data wirelessly using Bluetooth®, Wi-Fi®, or other standard wireless telemetry protocols.

[0099] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include transmitters for transmitting and / or receiving data. In some embodiments, the surgical orienting device 300 can receive data from the reference sensor 400 and the module 500. The surgical orienting device 300, the reference sensor 400, and the module 500 can include transmitters for transmitting data or receiving data from an external output device. In some embodiments, the surgical orienting device 300 can transmit data to the reference sensor 400 and the module 500. In some embodiments, the reference sensor 400 and the module 500 can transmit data between them.

[0100] Information from reference sensor 400 and module 500 can correspond, for example, to the position and / or orientation of the tibia and femur during limb alignment and / or clearance measurement. Information from reference sensor 400 and module 500 can correspond, for example, to the position and / or orientation of the tibia and femur during clearance measurement. Information from reference sensor 400 can correspond, for example, to the position and / or orientation of the tibia mechanical axis during a range of motion. Information from reference sensor 400 can correspond, for example, to the position and / or orientation of the tibia mechanical axis while a force is applied. Information from module 500 can correspond, for example, to the position and / or orientation of the femur mechanical axis during a range of motion. Information from module 500 can correspond, for example, to the position and / or orientation of the femur mechanical axis while a force is applied.

[0101] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include an indicator. The indicator can be located on the front of the respective device. The indicator can be located on the exterior surface of the respective device. The indicator can be a light or LED that indicates that the respective device is on. The indicator can be a light or LED that indicates that the respective device is sensing movement. The indicator can be a separate component from the outer housing of the respective device or can be integrated on or within the outer housing of the respective device.

[0102] Surgical orienting device 300, reference sensor 400, and / or module 500 can include a display. In some embodiments, surgical orienting device 300 includes a display. The display can be sized so that a user can easily read numbers, lettering, and / or symbols on the display while performing a medical procedure. The display can be sized so that a user can receive instructions. The display can be sized so that a user can view measurement data.

[0103] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include a user input device. The user input device can be located on the front of the respective device. The user input device can be located on the exterior of the respective device. The user input device can include a touchscreen. The user input device can include one or more buttons. The user input device can include one or more switches. The user input device can include one or more scroll wheels. The user input device can be activated, for example, by a finger, a hand, and / or an instrument, to select one or more modes of operation of the respective device. The user input device can be a component separate from the outer housing of the respective device or can be integrated on or within the outer housing of the respective device. In some embodiments, the user input device is a component separate from the housing. For example, the user input device can include a remote input device coupled to the respective device via a wired or wireless connection. Each device can include means for receiving user input.

[0104] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can include one or more functional components configured to sense position, orientation, or movement. The surgical orienting device 300, the reference sensor 400, and the module 500 can include an electronic control unit in communication with one or more inertial sensors. The surgical orienting device 300, the reference sensor 400, and the module 500 can include a power source. The surgical orienting device 300, the reference sensor 400, and the module 500 can include internal memory.

[0105] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can communicate with an external memory. The surgical orienting device 300, the reference sensor 400, and the module 500 can communicate with an external output device described herein. In some embodiments, the external output device can include an external memory. The external memory can be a separate component from the external output device or can be integrated on or within the external output device. The external output device can enable a surgeon, medical personnel, and / or other user to operate the surgical orienting device 300, the reference sensor 400, and the module 500 with ease, efficiency, and accuracy.

[0106] In some embodiments, the electronic control unit of the surgical orienting device 300, the reference sensor 400, and / or the module 500 receives input from one or more sensors of the surgical orienting device 300, the reference sensor 400, and / or the module 500. The electronic control unit can control and / or transmit output to an external memory. The electronic control unit can control and / or transmit output to an external output device. The electronic control unit can be configured to receive and transmit electronic data. The electronic control unit can be configured to perform calculations based on the received electronic data. The electronic control unit can include a transmitter. The electronic control unit can transfer data wirelessly using Bluetooth®, Bluetooth Low Energy™, Wi-Fi®, or other standard wireless telemetry protocols. The electronic control unit can include a Bluetooth® radio. The electronic control unit can include a Bluetooth Low Energy™ radio. In some embodiments, the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include a wireless module. In some embodiments, surgical orienting device 300, reference sensor 400, and / or module 500 comprise at least one accelerometer, at least one gyroscope, and a wireless module.

[0107] In certain embodiments, the electronic control unit of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be configured to convert electronic data from a machine-readable format to a human-readable format for presentation on an external output device or a display of the surgical orienting device 300, the reference sensor 400, and / or the module 500.

[0108] The electronic control units of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can communicate with an internal memory to retrieve and / or store data. The electronic control units of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can communicate with an external memory to retrieve and / or store data. The electronic control units can communicate with the internal memory and / or the external memory to retrieve program instructions for the software and / or hardware. The internal and external memories can include random access memory (“RAM”), such as static RAM, for temporary storage of information and / or read-only memory (“ROM”), such as flash memory, for more permanent storage of information. The external memory may be integrated into a cloud database. An external output device can retrieve data from the cloud database. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can interact with the external memory via cloud integration. The external memory may be a server.

[0109] The electronic control unit of surgical orienting device 300, reference sensor 400, and / or module 500 may be configured to receive real-time data from one or more sensors. The electronic control unit may be configured to use the sensor data to determine, estimate, and / or calculate the mechanical axis of the tibia. The electronic control unit may be configured to use the sensor data to determine, estimate, and / or calculate the mechanical axis of the femur. The electronic control unit may be configured to use the sensor data to determine, estimate, and / or calculate alignment between the mechanical axis of the tibia and the mechanical axis of the femur. The electronic control unit 20 may be configured to use the sensor data to determine, estimate, and / or calculate limb alignment. The electronic control unit 20 may be configured to use the sensor data to determine, estimate, and / or calculate gap distance under varus / valgus forces.

[0110] In some embodiments, the one or more sensors of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may comprise at least one orientation sensor configured to provide real-time data related to the movement, orientation, and / or position of the patient's corresponding anatomical structures to the electronic control unit. In some embodiments, the one or more sensors may include at least one gyro sensor, accelerometer, tilt sensor, magnetometer, and / or other similar device or devices. The one or more sensors may be configured to measure the alignment of the leg's mechanical axis. In some embodiments, the one or more sensors may be configured to provide measurements relative to a reference point, line, plane, and / or zero gravity. Zero gravity, as referred to herein, generally refers to an orientation in which the sensor's axis is perpendicular to the force of gravity, thereby resulting in no angular offset, e.g., tilt, pitch, roll, or yaw, relative to the gravity vector. In some embodiments, the one or more sensors may be configured to provide measurements for use in dead reckoning or inertial navigation systems.

[0111] In some embodiments, the surgical orienting device 300, the reference sensor 400, and / or the module 500 can collect data relative to a coordinate system. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned with a global coordinate system. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be synchronized with the global coordinate system. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned with a coordinate system that includes the mechanical axis of the tibia. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned with a coordinate system that includes the mechanical axis of the femur. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned with a coordinate system that includes an origin. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned to a coordinate system related to upright lateral film or x-ray images. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned to a coordinate system related to anterior / posterior x-rays. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be aligned to a coordinate system determined during calibration or alignment.

[0112] In some methods, the surgical orienting device 300 and / or the reference sensor 400 can determine the orientation of the tibia during limb alignment measurements. In some methods, the module 500 can determine the orientation of the femur during limb alignment measurements. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can determine the orientation of the femur relative to the tibia. In some methods, the surgical orienting device 300 and / or the reference sensor 400 can determine the orientation of the tibia mechanical axis. In some methods, the surgical orienting device 300 and / or the reference sensor 400 can determine the orientation of the femur mechanical axis. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can track these mechanical axes through a range of motion. The systems and methods can determine various measurements related to limb alignment, including femoral and tibial alignment. The systems and methods can determine various measurements related to gap, including gap measurements under applied force.

[0113] The systems and methods can determine global varus / valgus limb alignment angles. The systems and methods can determine global varus / valgus limb alignment angles while the leg is in flexion. The systems and methods can determine global varus / valgus limb alignment angles while the leg is in extension. The systems and methods can determine global varus / valgus limb alignment angles through a range of motion. Varus / valgus relates to angulation within the shaft of the bone or at the joint. Valgus relates to the distal portion of the joint being more lateral, and varus relates to the distal portion of the joint being more medial.

[0114] In normal knee alignment, the mechanical axes of the tibia and femur are roughly aligned. Misalignment creates an angle between the mechanical axes of the tibia and femur. In varus, the compressive force on the medial condyle is greater than the compressive force on the lateral condyle. In valgus, the compressive force on the lateral condyle is greater than the compressive force on the medial condyle.

[0115] The surgical orientation device 300, reference sensor 400, and / or module 500 can determine the overall varus / valgus limb alignment angle by determining the relationship between the tibial and femoral mechanical axes. In some methods, this is a static determination when the knee is in flexion. In some methods, this is a static determination when the knee is in extension. In some methods, this is a dynamic determination as the knee goes through a range of motion, for example, from flexion to extension or from extension to flexion.

[0116] The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall varus / valgus limb alignment angle. In some methods, this angle can be determined before any resection. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall varus / valgus limb alignment angle postoperatively. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall varus / valgus limb alignment angle during a trial reduction. One or more trial implants can be positioned between the tibia and the femur. The knee can be positioned or put through a range of motion. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall varus / valgus limb alignment angle for each of the trial implants. A trial implant that achieves the target varus / valgus limb alignment can be selected. An implant corresponding to the trial implant can be implanted.

[0117] The system and method can measure range of motion by measuring the overall change from maximum extension to maximum flexion. The system and method can determine the overall anterior / posterior (flexion / extension) limb alignment angle. The system and method can determine the overall knee flexion angle while the leg is in flexion. The system and method can determine the overall knee extension angle while the leg is in extension. The system and method can determine the overall anterior / posterior (flexion / extension) limb alignment angle through the range of motion. Knee flexion is bending the knee joint to bring the foot toward the posterior thigh. Knee extension is straightening the knee joint. Flexion and extension relate to the joint movement of the knee. The normal range of motion of the knee is approximately 0° extension and approximately 140° flexion. Some patients may have reduced flexion / extension.

[0118] The surgical orienting device 300, reference sensor 400, and / or module 500 can determine limb alignment statically in flexion. The surgical orienting device 300, reference sensor 400, and / or module 500 can determine limb alignment statically in extension. The surgical orienting device 300, reference sensor 400, and / or module 500 can dynamically determine limb alignment as the knee goes through a range of motion. The surgical orienting device 300, reference sensor 400, and / or module 500 can determine knee extension and knee flexion angles by determining the relationship between the tibia and femur mechanical axes.

[0119] The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall knee extension and flexion angles before any resection. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the knee extension and flexion angles after any resection. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall knee extension and flexion angles during a trial reduction. One or more trial implants can be positioned between the tibia and the femur. The knee can be positioned or put through a range of motion. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the overall knee extension and flexion angles for each of the trial implants. A trial implant that achieves the target knee extension and flexion angles can be selected. For example, the trial implant can improve the patient's range of motion toward a normal range of motion. For example, the trial implant can enable full extension. For example, the trial implant may allow for full flexion, and an implant corresponding to the trial implant may be implanted.

[0120] The system and method can calculate the clearance space. The system and method can calculate the clearance space while the leg is in flexion. The system and method can calculate the clearance space while the leg is in extension. The system and method can calculate the clearance space throughout the range of motion. The clearance space is related to the distance between the medial and lateral femoral condyles and the tibial plateau. In some methods, the clearance space can be calculated as the gap opening from a single femoral condyle to the tibial plateau, assuming contact between the tibial plateau and the femoral condyles of the other compartment. When an implant or trial implant is positioned within the clearance space, the clearance distance can be related to the distance between the medial and lateral femoral condyles and the implant or trial implant.

[0121] In a healthy knee, there is a layer of cartilage separating the end of the tibia from the end of the femur. Due to variations in wear between the medial and lateral femoral condyles relative to the tibial condyles in an arthritic knee, the gap between the tibial and femoral plateaus can narrow symmetrically or asymmetrically.

[0122] The surgical orienting device 300, reference sensor 400, and / or module 500 can calculate the clearance space by determining the relationship between the tibia and femur. In some methods, the clearance space is calculated, at least in part, by distance measurements. In some methods, the clearance space is calculated, at least in part, by inertial measurements. In some methods, this is a static determination when the knee is in flexion. In some methods, this is a static determination when the knee is in extension. In some methods, this is a dynamic determination as the knee goes through a range of motion, for example, from flexion to extension or from extension to flexion.

[0123] The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the gap space before any resection. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the gap space after any resection. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the gap space during a trial reduction. One or more trial implants can be positioned between the tibia and the femur. The knee can be positioned or put through a range of motion. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the gap space of each of the trial implants. A trial implant that achieves the target gap space can be selected. An implant corresponding to the trial implant can be implanted.

[0124] The systems and methods can estimate limb alignment angles based on navigated tibial resection angles. The systems and methods can estimate limb alignment angles based on navigated cut tibial resection angles. The systems and methods can estimate limb alignment angles while the leg is in flexion. The systems and methods can estimate limb alignment angles while the leg is in extension. The systems and methods can estimate limb alignment angles through a range of motion. In some embodiments, the estimated limb alignment angle is varus / valgus. In some embodiments, the estimated limb alignment angle is flexion / extension.

[0125] The navigated tibial resection angle may be a target angle determined preoperatively. The navigated tibial resection angle may be a target angle determined based on preoperative imaging. The navigated tibial resection angle may be a target angle navigated by adjusting the tibial preparation system 200. The cut tibial resection angle may be determined based on the anatomical structure of the tibia after resection. The cut tibial resection angle may be determined intraoperatively. The cut tibial resection angle may be determined after the resection is performed for cut verification. In some embodiments, the navigated tibial resection angle and the cut tibial resection angle are the same angle.

[0126] The navigated femoral resection angle may be a target angle determined preoperatively. The navigated femoral resection angle may be a target angle determined based on preoperative imaging. The navigated femoral resection angle may be a target angle navigated by adjusting the femoral preparation system 100. The cut femoral resection angle may be determined based on the anatomical structure of the femur after resection. The cut femoral resection angle may be determined intraoperatively. The cut femoral resection angle may be determined after the resection has been performed for cut verification. In some embodiments, the navigated femoral resection angle and the cut femoral resection angle are the same angle.

[0127] The surgical orientation device 300, reference sensor 400, and / or module 500 can determine a limb alignment angle based on the navigated tibial resection angle by determining the relationship between the tibial and femoral mechanical axes. In some methods, this is a static determination when the knee is in flexion. In some methods, this is a static determination when the knee is in extension. In some methods, this is a dynamic determination as the knee goes through a range of motion, for example, from flexion to extension or from extension to flexion.

[0128] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can estimate the limb alignment angle preoperatively. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can estimate the limb alignment angle postoperatively. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can estimate the limb alignment angle during a trial reduction. One or more trial implants can be positioned between the tibia and the femur. The knee can be positioned or put through a range of motion. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can estimate the limb alignment angle for each of the trial implants. A trial implant that achieves the target limb alignment can be selected. An implant corresponding to the trial implant can be implanted.

[0129] The systems and methods can perform range of motion calculations. The systems and methods can calculate range of motion while the leg is in flexion. The systems and methods can calculate range of motion while the leg is in extension. The systems and methods can calculate range of motion throughout the leg range of motion. In some embodiments, the calculated range of motion is inversion / valgus. In some embodiments, the calculated range of motion is flexion / extension. In some embodiments, the calculated range of motion is axial rotation.

[0130] The surgical orientation device 300, reference sensor 400, and / or module 500 can calculate the range of motion by determining the relationship between the tibia and femur mechanical axes. In some methods, this is a static determination when the knee is in flexion. In some methods, this is a static determination when the knee is in extension. In some methods, this is a dynamic determination as the knee goes through a range of motion, for example, from flexion to extension or from extension to flexion.

[0131] The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the range of motion preoperatively. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the range of motion postoperatively. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the range of motion during a trial reduction. One or more trial implants can be positioned between the tibia and the femur. The knee can be positioned or put through a range of motion. The surgical orientation device 300, the reference sensor 400, and / or the module 500 can determine the range of motion for each of the trial implants. A trial implant that achieves the target range of motion can be selected. An implant corresponding to the trial implant can be implanted.

[0132] The surgical orientation device 300, reference sensor 400, and / or module 500 may be utilized to determine static limb alignment angles. The surgical orientation device 300, reference sensor 400, and / or module 500 may be utilized to determine dynamic limb alignment angles. Static measurements include measurements of the leg while the leg is in a stationary position. Dynamic measurements include measurements while the femur is moving, while the tibia is moving, or while both the tibia and femur are moving.

[0133] The surgical orientation device 300, the reference sensor 400, and / or the module 500 may be utilized in a unicompartmental knee replacement procedure. The surgical orientation device 300, the reference sensor 400, and / or the module 500 may be utilized in a total knee replacement procedure.

[0134] The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be utilized for intraoperative measurements. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be utilized for preoperative measurements. The surgical orienting device 300, the reference sensor 400, and / or the module 500 can be utilized for postoperative measurements.

[0135] One or more of the surgical orientation device 300, the reference sensor 400, and / or the module 500 can provide a visual representation to the user. In some embodiments, the surgical orientation device 500 can include a display. The visual representation can include angles, distances, or any other measurements. The visual representation can include limb alignment angles, including varus / valgus, medial / lateral, anterior / posterior, and / or flexion / extension. The visual representation can include a graphic representation of the tibia, femur, and / or leg.

[0136] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be reusable. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be sterilized. In some embodiments, the surgical orienting device 300, the reference sensor 400, and the module 500 may be resterilizable. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be sterilized in an autoclave. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be disposable. In some embodiments, the surgical orienting device 300, the reference sensor 400, and the module 500 may be discarded after a single use.

[0137] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include one or more inertial sensors. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include an accelerometer. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include a gyroscope. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include a wireless module. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include at least one inertial sensor and a wireless module. In some embodiments, each of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can include at least one inertial sensor and a wireless module.

[0138] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be configured to communicate with an external device. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be configured to communicate with the cloud. The surgical orienting device 300, the reference sensor 400, and / or the module 500 are configured to communicate among themselves. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can receive signals related to position and / or orientation. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 can transmit signals related to position and / or orientation.

[0139] One or more of surgical orienting device 300, reference sensor 400, and / or module 500 can have any of the features of the surgical orienting devices and reference devices described in U.S. Patent Application Publication No. 2009 / 0229994, which is incorporated herein by reference. One or more of surgical orienting device 300, reference sensor 400, and / or module 500 can include any navigation unit including one or more of an accelerometer, a gyroscope, a display, a touchscreen, a button, and a wireless module.

[0140] In some embodiments, the inertial sensor communicates with a central processor. In some embodiments, the reference sensor 400 communicates with a central processor of the surgical orienting device 300. In some embodiments, the reference sensor 400 communicates with a central processor of an external device, such as an external memory or the cloud. In some embodiments, the module 500 communicates with the central processor of the surgical orienting device 300. In some embodiments, the module 500 communicates with a central processor of an external device, such as an external memory or the cloud. In some embodiments, the surgical orienting device 300 communicates with a central processor of an external device, such as an external memory or the cloud. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 communicate with the surgical orienting device 300. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 communicate with an external device, such as a computer, tablet, or smartphone. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 comprise any device that includes a wireless module.

[0141] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be coupled to one or more of the tibia and the femur. The surgical orienting device 300 and / or the reference sensor 400 may be attached directly to the tibia during tibia preparation. The surgical orienting device 300 and / or the reference sensor 400 may be attached directly to the femur during femur preparation. The surgical orienting device 300 and / or the reference sensor 400 may be attached directly to the femur and / or tibia in an open wound.

[0142] The femur preparation system 100 and / or the tibia preparation system 200 can include a pin jig configured to be coupled to the respective bone. The femur preparation system 100 and / or the tibia preparation system 200 can include a reference sensor device interface 104, 204 that can be used to couple a reference sensor 400 to the jig assembly 102, 202. The femur preparation system 100 and / or the tibia preparation system 200 can include a surgical orienting device interface 106, 206 that can be used to couple the reference sensor 400 to the jig assembly 102, 202. The surgical orienting device 300 and / or the reference sensor 400 can be percutaneously attached to the assembly 102, 202 with the interface 104, 106, 204, 206.

[0143] The module 500 may be coupled to one or more of the tibia and femur. The module 500 may be attached directly to the tibia during limb alignment and gap measurement. The module 500 may be attached directly to the femur during limb alignment and gap measurement. The module 500 may be coupled to the femur jig assembly 102. The module 500 may be coupled to the tibia jig assembly 202. The module 500 may be coupled to the femur jig assembly 102 during calibration. The module 500 may be coupled to the tibia jig assembly 202 during calibration. The module 500 may be coupled to any interface of the assemblies 102, 202. The module 500 may be percutaneously coupled to the assembly 202.

[0144] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be coupled to the femur. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be coupled to the tibia. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be coupled to the patient's skin. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may be coupled to the patient's soft tissue.

[0145] One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may include an adhesive configured to adhere to the patient's skin. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may comprise a wrap or strap configured to encircle a portion of the patient's anatomy. One or more of the surgical orienting device 300, the reference sensor 400, and / or the module 500 may comprise an inertial sensor embedded in fabric.

[0146] The tibial implant is selected and placed after the tibial resection is complete. The femoral implant is selected and placed after the femoral resection is complete. The tibial implant can be rotated in any direction on the resected tibial surface. The tibial implant can be selected from multiple implants with different gap heights. The tibial implant can be selected from multiple implants with different varus angles. The tibial implant can be selected from multiple implants with different valgus angles. The tibial implant can be selected from multiple implants with different ranges of motion. The tibial implant can be selected from multiple implants with different flexion. The tibial implant can be selected from multiple implants with different extension.

[0147] More accurate and / or quantifiable alignment methods are likely to improve implant performance and patient satisfaction. Systems and methods, in some embodiments, provide such more accurate and / or quantifiable alignment methods for improving implant performance and patient satisfaction. Systems and methods provide methods for quantifying alignment of the mechanical axes of the tibia and femur. Systems and methods provide methods for quantifying limb alignment angles. Systems and methods provide methods for quantifying gap height.

[0148] The systems and methods can provide trial implant or implant recommendations. The systems and methods can provide estimated gap distances. The systems and methods provide a means to quantify varus force as a function of angle measurements. The angle can determine gap, which is a function of applied angle and intercondylar distance. The systems and methods provide a means to quantify valgus force as a function of angle measurements. The systems and methods provide a means to quantify global knee extension angle. The systems and methods provide a means to quantify global knee flexion angle. The systems and methods provide a means to quantify axial rotation. The systems and methods provide a means to quantify range of motion.

[0149] In some embodiments, the systems and methods provide a method for selecting one or more of the tibial and femoral implants through limb alignment and / or clearance measurements based on the mechanical axes of the femur and tibia. For some patients, the femur contacts the tibia at two points, one on the medial side and one on the lateral side. As the knee flexes through the range of motion, the placement of these contact points on the tibia can change. There can be medial and lateral contact points throughout the range of motion. The tibial and femoral implants can be selected based on contact geometry. As an example, the tibial and femoral implants can be selected to alter clearance. The tibial and femoral implants can be selected to increase or decrease the overall flexion angle.

[0150] In some methods, one of the reference sensor 400 and the module 500 is securely attached to each of the femur and the tibia. In some methods, the reference sensor 400 attached to the tibia can be approximately aligned with the tibia mechanical axis. In some methods, the module 500 attached to the femur can be approximately aligned with the femur mechanical axis. The reference sensor 400 and the module 500 are preferably attached in a manner that allows the patella to function normally and replicate normal knee kinematics. In some embodiments, medialized attachment to both the tibia and the femur is preferred to accommodate typical surgical exposures. The surgical orienting device 300 can also be within the surgical field. In some methods, the surgical orienting device 300 is coupled to the tibial jig assembly 202.

[0151] In several methods, the orientation of the tibia and femur mechanical axes is calculated. The mechanical axes may be calculated relative to the surgical orientation device 300, the reference sensor 400, and / or the module 500. The mechanical axes may be calculated relative to a reference frame that includes gravity. The mechanical axes may be calculated relative to a global coordinate system. The mechanical axes may be calculated relative to an external reference coordinate system. The mechanical axes may be calculated with an offset based on the configuration of one or more of the tibia jig assembly 202 or the femur jig assembly 102. The offset may be applied to the calculated mechanical axes to improve accuracy.

[0152] To establish the characteristics of the knee, the surgeon can place the knee in full extension. The surgeon can also place the knee in full flexion. The surgeon can move the leg through a short range of motion. The surgeon can pivot about the femoral head in all directions. The surgeon can rotate about the long axis of the leg. The surgeon can apply a varus torque to the knee. The surgeon can apply a valgus torque to the knee. The surgeon can perform one or more of these actions sequentially. The surgeon can perform one or more of these actions simultaneously. These actions can be performed prior to resection to establish the characteristics of the knee. These actions can be performed after resection to determine the characteristics of the knee with a trial implant or implant. These actions can be performed post-operatively to establish the characteristics of the knee.

[0153] In some methods, the reference sensor 400 and the module 500 may be stationary relative to one another during calibration. The reference sensor 400 and the module 500 may be attached to the tibial jig assembly 202. The reference sensor 400 and the module 500 may be in a fixed relationship relative to one another. While stationary, the reference sensor 400 and the module 500 may perform a transfer alignment to calculate the relative misalignment between the reference sensor 400 and the module 500. In some embodiments, the orientation of the module 500 may be established within the frame of reference of the reference sensor 400. In some embodiments, the orientation of the reference sensor 400 and the module 500 may be established in the frame of reference of the surgical orienting device 300.

[0154] The knee is then put through a range of motion during limb alignment and / or gap balancing. The relative rotation between the tibia and femur is measured by comparing the angular changes recorded by the respective reference sensors 400 and modules 500 throughout the range of motion. The inertial measurements may be transmitted to the surgical orienting device 300. These rotations may result in three directions corresponding to flexion / extension, axial rotation, and varus / valgus directions. The processor of the surgical orienting device 300 may provide a user-readable output related to one or more of these rotations. The user-readable output may be a flexion angle. The user-readable output may be an extension angle. The user-readable output may be a varus angle. The user-readable output may be a valgus angle. The user-readable output may be an axial rotation of the tibia relative to the femur. The user-readable output may be an axial rotation measurement. The user-readable output may be a graphical display. The user-readable output may be a graph. The user-readable output may be the varus / valgus angle at different degrees of flexion. The surgical orienting device 300 may display a numerical value. The surgical orienting device 300 may display a numerical value for the varus / valgus angle at various flexion angles, such as 90 degrees or 120 degrees. The surgical orienting device 300 may display a numerical value for the rotation angle at various flexion angles, such as 90 degrees or 120 degrees.

[0155] During trial reduction, the surgeon repeats the transfer alignment. In some methods, the surgeon places the surgical orienting device 300 on the tibia and the reference sensor 400 on the femur. The leg is put through a range of motion. The surgical orienting device 300 then displays limb alignment and / or gap balancing measurements related to the trial implant. In some embodiments, the surgical orienting device 300 can compare the inertial sensor output to targets. These targets may be based on published averages for healthy knees. These targets may be based on kinematic measurements taken from the patient prior to resection. These targets may be based on kinematic measurements taken from the contralateral knee.

[0156] In some embodiments, the surgical orienting device 300 can provide recommendations related to the trial implant. In some embodiments, the surgical orienting device 300 can provide recommendations for changing the varus / valgus angle of the trial implant. In some embodiments, the surgical orienting device 300 can provide recommendations for changing the gap height. In some embodiments, the surgical orienting device 300 can provide recommendations for rotating the trial implant. In some embodiments, the surgical orienting device 300 can provide recommendations based on the inertial sensor measurements of the reference sensor 400 and the module 500.

[0157] In some methods, the surgeon applies alternating varus and valgus torque to the knee to gauge the allowable opening in each compartment. This varus or valgus angle can be displayed on the surgical orienting device 300. This measurement can supplement traditional visual estimation of knee laxity in the varus / valgus direction. This angle provides a means to quantitatively compare medial and lateral laxity. In some embodiments, the surgeon can use inertial data from the reference sensor 400 and / or module 500 to balance medial / lateral laxity. In some embodiments, the surgeon can use inertial data from the reference sensor 400 and / or module 500 to release the soft tissue around the knee. In some embodiments, the surgeon can use inertial data from the reference sensor 400 and / or module 500 to quantify knee joint laxity. In some embodiments, the surgeon can use inertial data from the reference sensor 400 and / or module 500 to quantify the varus / valgus angle at a specific flexion angle. In some embodiments, the surgeon can utilize inertial data from the reference sensor 400 and / or module 500 to quantify the varus / valgus angles through the range of motion.

[0158] The surgeon can adjust or replace the trial implant. This process can be repeated until the trial implant is satisfactory. The surgeon can position the implant based on the trial implant. In some embodiments, the trial implant or range of motion of the implant is stored by the surgical orientation device 300. In some embodiments, the trial implant or range of motion of the implant is transmitted by the surgical orientation device 300 for post-operative comparison.

[0159] 12-18 illustrate a femoral preparation system 600 and a tibial preparation system 700. The femoral preparation system 600 may include any of the components of the femoral preparation system 100 described herein. The tibial preparation system 700 may include any of the components of the tibial preparation system 200 described herein. The femoral preparation system 600 and the tibial preparation system 700 may include a fixture that allows placement of the femoral preparation system 600 relative to the tibial preparation system 700.

[0160] The femur preparation system 600 can be used to position the reference sensor 400 relative to the femur. The reference sensor 400 can be positioned lateral to the distal end of the femur. The reference sensor 400 can be positioned so that the leg is in extension. The reference sensor 400 can be positioned at a known distance from an anatomical landmark. The reference sensor 400 can be positioned at a known angle from an anatomical landmark. The reference sensor 400 can communicate inertial sensor data related to position and orientation to the surgical orienting device 300.

[0161] The femoral preparation system 600 is configured to be securely mounted on the side of the femur. The femoral preparation system 600 may also include one or more cutting guides for modifying the natural femur with a distal femoral resection to allow for secure attachment of a prosthetic component to the distal end of the femur as described herein.

[0162] The femoral preparation system 600 can include a cutting guide rod 602. The cutting guide rod 602 can be coupled to the tibial preparation system 700. The cutting guide rod 602 can include a threaded post 604. The threaded post 604 can engage a threaded bore in the tibial preparation system 700. The threaded bore can engage a midline reference probe assembly, as described herein, before the femoral preparation system 600 is mounted thereon. The cutting guide rod 602 can be removable. The cutting guide rod 602 can be rotated to disengage the femoral preparation system 600 from the tibial preparation system 700. The cutting guide rod 602 can be rotated to couple the femoral preparation system 600 to the tibial preparation system 700. The cutting guide rod 602 can include a flange 606. The cutting guide rod 602 can include a cap 608.

[0163] The femoral preparation system 600 can include a cutting guide bracket 610. The cutting guide bracket 610 can include a slot 612. The slot 612 can allow for adjustment of the cutting guide bracket 610 relative to the tibial preparation system 700. The slot 612 can allow for adjustment of the cutting guide bracket 610 relative to the patient's anatomy. The cutting guide bracket 610 can slide relative to the cutting guide rod 602. The cutting guide rod 602 can be positioned within the slot 612. The flange 606 can be below the cutting guide bracket 610. The cap 608 can be above the cutting guide bracket 610. The cutting guide bracket 610 can slide relative to the cutting guide rod 602. The cutting guide bracket 610 can rotate relative to the cutting guide rod 602. The cutting guide bracket 610 can position the femoral preparation system 600 to the left of the tibial preparation system 700, as shown. The cutting guide bracket 610 can position the femoral preparation system 600 to the right of the tibial preparation system 700. The cutting guide bracket 610 can be a universal bracket that allows for positioning on the left or right side of the tibial preparation system 700. The cutting guide bracket 602 can include a step 614. The step 614 can position the cutting guide bracket 602 proximally to the tibial preparation system 700. The step 614 can prevent interference between the cutting guide bracket 610 and other components of the system. The cutting guide bracket 602 can include an opening 616.

[0164] The femoral preparation system 600 can include a swivel post 620. The swivel post 620 can include a flange 622. The swivel post 620 can include a cap 624. The opening can allow rotation of the swivel post 620 relative to the cutting guide bracket 602. The opening 616 can allow rotation of the swivel post 620 relative to the patient's anatomy. The swivel post 620 can rotate relative to the cutting guide bracket 610. The swivel post 620 can be positioned within the opening 616 in the cutting guide bracket 602. The flange 622 can be above the cutting guide bracket 602. The cap 624 can be below the cutting guide bracket 602.

[0165] The femoral preparation system 600 can include an extension 630. The extension 630 can be coupled to a swivel post 620. The extension 630 and the swivel post 620 can be formed separately. The extension 630 and the swivel post 620 can be formed integrally. The extension can include an opening 632. The opening 632 can slide into engagement with a threaded pin 634. The opening 632 can receive the threaded pin 634. The threaded pin 634 can be an intramedullary pin. The length of the extension 630 can be an input to the surgical orientation device 300. The length of the extension 630 can be selected based on the patient's anatomy. The extension 630 can have a fixed length regardless of the patient's anatomy. The extension 630 can include a groove 636. The groove 636 can be a keyed groove. The groove 636 can be a dovetail groove. The extension 630 can be angled towards the patient.

[0166] The femoral preparation system 600 can include a mounting bracket 640. In some embodiments, the mounting bracket 640 can be an L-shaped bracket. The mounting bracket 640 can include a first portion 642. The first portion 642 can be a tapered protrusion. The first portion 642 can slide relative to the groove 636 of the extension 630. The first portion 642 and the groove 636 can interlock. The first portion 642 and the groove 636 can have one degree of freedom. The first portion 642 can include a scale. The first portion 642 can include markings to indicate a length relative to the extension 630. The first portion 642 can include markings to indicate a length relative to the pin 634. Distance indicia on the first portion 642 can be recorded as an input to the surgical orienting device 300. The mounting bracket 640 can include a second portion 644. The first portion 642 and the second portion 644 can be perpendicular. The second portion 644 may include a hub 646 .

[0167] The femoral preparation system 600 can include a push button 650. The push button 650 can slide relative to the hub 646 of the mounting bracket 640. The femoral preparation system 600 can include a spring 652. The spring 652 can bias the push button 650.

[0168] The femoral preparation system 600 can include a connector 660. The connector 660 can include a coupler 662. The connector 660 can include one or more openings 664. The connector 660 can include two openings 664. The openings 664 can receive a threaded pin 666. The femoral preparation system 600 can include one or more threaded pins 666. The femoral preparation system 600 can include two threaded pins 666. The two openings 664 can define a trajectory for the threaded pin 666. The coupler 662 can engage a reference sensor interface 680 shown in FIG. 18 . The reference sensor interface 680 can be attached directly to the connector 662 after portions of the femoral preparation system 600 are removed.

[0169] The push button 650 can engage with the coupler 662. The push button 650 can be biased into engagement with the coupler 662. When pressed, the push button 650 can decouple portions of the femoral preparation system 600. When pressed, the push button 650 can allow the mounting bracket 640 to disengage from the connector 660. The push button 650 can be released to disengage the coupler 662. The push button 650 can be released to allow the reference sensor interface 680 to be attached to the connector 662.

[0170] The tibial preparation system 700 can include an orthopedic assembly used to prepare the tibia for a prosthetic component. The tibial preparation system 700 can include components for adjusting the posterior / anterior tilt of the surgical orientation device 300. The tibial preparation system 700 can include components for adjusting the posterior / anterior tilt of the cutting block. The tibial preparation system 700 can include, or can include, components for adjusting the varus / valgus tilt of the surgical orientation device 300. The tibial preparation system 700 can include, or can include, components for adjusting the varus / valgus tilt of the tilt of the cutting block.

[0171] The tibial preparation system 700 may include a landmark acquisition assembly 710. The landmark acquisition assembly 710 may include a structure configured to contact and / or acquire information about anatomical landmarks on the human body. The landmark acquisition assembly 710 may include an elongated member 712. The landmark acquisition assembly 710 may include a probe member 714 disposed on at least one end of the elongated member 712. The probe member 714 may be configured to contact an anatomical landmark, such as, for example, the malleolus of the patient's ankle. The elongated member 712 may further include a series of markings indicating distance and / or length. The markings may be used, for example, to measure the AP offset of the probe member 714.

[0172] The tibia preparation system 700 can include a midline reference probe assembly. The tibia preparation system 700 can include a threaded bore that can engage the midline reference probe assembly before the femoral preparation system 600 is mounted thereon. The midline reference probe assembly can be positioned in an appropriate anatomical location on the proximal tibia. The midline reference probe assembly can be located at a point just posterior to the insertion of the anterior cruciate ligament (ACL) or another suitable anatomical landmark. For example, the tip of the midline reference probe assembly can rest over the insertion point of the anterior cruciate ligament in the knee and / or a soft spot on the top of the tibia, commonly referred to as the A / P point of the mechanical axis. This point is typically located along the tibial intercondylar eminence on the tibia, marking the placement of the point along the mechanical axis of the leg. Distance markings on the upper surface of the midline reference probe assembly can be noted, and the corresponding A / P offset location can be input to the surgical orientation device 300. The A / P point can correspond to a point on the mechanical axis. The surgical orientation device 300 can calculate a second point on the mechanical axis. The surgical orientation device 300 can determine a mechanical axis vector.

[0173] The tibia preparation system 700 can include a reference sensor interface 780. The tibia preparation system 700 can include a surgical orienting device interface 770. The reference sensor 400 can be coupled to the reference sensor interface 780. The surgical orienting device 300 can be coupled to the surgical orienting device interface 770. During tibia alignment, the tibia preparation system 700 is assembled with the reference sensor 400 coupled to the reference sensor interface 780 and the surgical orienting device 300 coupled to the surgical orienting device interface 770. The surgical orienting device 300 can be attached to a movable portion of the tibia preparation system 700. The reference sensor 400 can be attached to a fixed portion of the tibia preparation system 700. The reference sensor 400 can track the position of the tibia during landmark acquisition.

[0174] The method for tibial alignment can include acquiring landmarks to determine the location of a mechanical axis passing through the tibia. For example, landmarks can be acquired by first engaging the probe member 714 of the landmark acquisition assembly 710 with the medial malleolus and then the lateral malleolus (or vice versa). Acquisition of the other malleolus can similarly be achieved by rocking one or more portions of the landmark acquisition assembly 710 so that the probe member 714 contacts the other side of the leg. The surgical orienting device 300 can then determine the location of the mechanical axis, for example, by identifying sagittal and coronal planes that pass through the mechanical axis. In some embodiments, the surgical orienting device 300 can calculate the location of the mechanical axis by assuming that the mechanical axis extends from the contact point of the proximal tibia with the midline reference probe assembly through a point midway between the two malleolus points that contact the probe members of the landmark acquisition assembly 710 on either side of the leg, or any other suitable point.

[0175] In some embodiments, a user can activate surgical orienting device 300 at each landmark acquisition, such as by pressing one of the user inputs on surgical orienting device 300. Once activated, surgical orienting device 300 can register (e.g., record) the orientation of surgical orienting device 300 as a reference position (e.g., a first reference position). For example, surgical orienting device 300 can register and / or calculate the current orientation of surgical orienting device 300 based on data collected from a sensor inside surgical orienting device 300. The orientation of surgical orienting device 300 at the first reference position can be used to identify and register the orientation of a coronal plane containing the mechanical axis of the leg, and also to determine a first reference point for identifying the placement and / or orientation of a sagittal plane containing this same mechanical axis.

[0176] The user can then swing the probe member of the landmark acquisition assembly 710 onto the other (e.g., medial) side of the leg, thereby positioning the reference probe 714 adjacent to the other malleolus. For each landmark acquisition, the user can palpate the ankle. After the location of the other (e.g., medial) malleolus is identified, the user can press one of the user inputs on the surgical orienting device 300 to cause the surgical orienting device 300 to determine its orientation at the second reference position. For example, the surgical orienting device 300 can register and / or calculate its current orientation based on data collected from a sensor inside the surgical orienting device 300.

[0177] The orientation of the surgical orientation device 300 at the second reference position may again be used to identify the orientation of a coronal plane through the tibia containing the mechanical axis of the leg, and / or may be used to place a second reference point for identifying the placement and / or orientation of a sagittal plane containing the same mechanical axis.

[0178] When using surgical orienting device 300 to determine the first and second reference positions, the output of sensors within surgical orienting device 300 can be monitored to minimize errors in the readings. For example, to arrive at an accurate estimate of a given anatomical landmark, a transient phase can be eliminated in the output of the sensors.

[0179] After information regarding both the first and second reference positions is obtained and aligned with the surgical orienting device 300, the surgical orienting device 300 can determine (e.g., calculate) the location of a desired plane between the lateral and medial malleolus. The desired plane can correspond to a sagittal plane that includes the mechanical axis. The desired plane can vary depending on factors such as the patient's particular anatomy and the surgeon's training and experience. For example, the desired plane can be located midway between the lateral and medial malleolus, or 55% from the lateral malleolus toward the medial malleolus, or some other predetermined location.

[0180] A user can use one or more user inputs to direct surgical orientation device 300 to calculate the placement and / or orientation of the sagittal plane. After surgical orientation device 300 calculates where the sagittal plane is, surgical orientation device 300 can provide placement feedback to the user, for example, in the form of one or more visual signals on a display, indicating that the placement of the sagittal plane has been calculated.

[0181] The method for femoral alignment can include obtaining landmarks to determine the placement of a mechanical axis passing through the femur. The femoral preparation system 600 can include an orthopedic assembly for femoral preparation. The femoral preparation system 600 is configured to be securely mounted on the side of the femur. In some embodiments, the femoral preparation system 600 can include a cutting guide rod 602, a cutting guide bracket 610, a swivel post 620, an extension 630, a mounting bracket 640, a push button 650, and a connector 660.

[0182] The femoral preparation system 600 can be attached to the tibial preparation system 700. The cutting guide rod 602 can engage with the tibial preparation system 700. The femoral preparation system 600 can be adjustable. The femoral preparation system 600 can be inserted into and secured to the tibial preparation system 700. The cutting guide bracket 610 can slide relative to the cutting guide rod 602. The swivel post 620 can pivot relative to the cutting guide bracket 610. The extension 630 can be positioned relative to the anatomy.

[0183] The femoral preparation system 600 can be aligned to the patient's anatomy. In preparing a distal femoral resection, the method can include identifying a distal point that intersects with the mechanical axis of the femur. The method can include positioning a threaded pin 634. The threaded pin 634 can be positioned relative to the distal point of the femoral mechanical axis. The threaded pin 634 can be a midline pin. The threaded pin 634 can be approximately centered in the intercondylar notch. The threaded pin 634 positions the femoral preparation system 600 in an approximately centered position on the distal portion of the femur. The method can include positioning an extension 630. The extension 630 can pivot via a swivel post 620. The extension 630 can include an opening 632. In some methods, the threaded pin 634 is inserted first, and the extension 630 is positioned relative to the threaded pin 634. Alternatively, the opening 632 may act as a drill guide for inserting the threaded pin 634. In some methods, the mounting bracket 640 is decoupled from the extension 630 upon positioning of the extension 630.

[0184] In some methods, the mounting bracket 640 is coupled to the connector 660. The push button 650 can be biased. The push button 650 can couple the mounting bracket 640 and the connector 660 to form a unitary structure. In some methods, the mounting bracket 640, push button 650, and connector 660 can be pre-assembled.

[0185] In several ways, the mounting bracket 640 can be positioned relative to the extension 630. The mounting bracket 640 and extension 630 can form a tongue-and-groove connection. The method can include sliding the assembled mounting bracket 640 and connector 660 relative to the extension 630. The method can include reducing the mounting bracket 640 and connector 660 until the connector 660 is flush with the bone. During this movement of the mounting bracket 630 and connector 660, the extension 630 remains fixed to the femur via the threaded pin 634. The positioning of the mounting bracket 640 relative to the extension 630 can be an input to the system. The distance the mounting bracket 640 slides relative to the extension 630 can be an input to the system.

[0186] The connector 660 can include one or more openings 664. In some methods, the one or more openings 664 can act as drill guides for inserting threaded pins 666. The threaded pins 666 are inserted through the openings 664 in the connector 660. The openings 664 can be angled. The openings 664 can be offset. The openings 664 can be angled and offset drill guide holes. The connector 660 can be secured to the femur via the one or more pins 666.

[0187] The mounting bracket 640 can be detached from the connector 660. The push button 650 can be pushed towards the connector 660. The push button 650 can disengage the connector 660. The mounting bracket 640 can slide relative to the connector 660 to disengage from the connector 660. The mounting bracket 640 can slide relative to the extension 630 to disengage from the extension 630. The extension 630 can be removed.

[0188] The cutting guide rod 602, cutting guide bracket 610, swivel post 620, and extension 630 can be removed. The connector 660 remains fixed to the femur. The connector 660 can be coupled to the reference sensor 400. The connector 660 can be coupled to the reference sensor interface 680. The reference sensor 400 can be coupled to the reference sensor interface 680. In some methods, the cutting block is attached to the threaded pin 634 for resection. In some methods, the threaded pin 634 can be removed.

[0189] The reference sensor device 400 and / or the orienting device 300 can be used to determine the relative coordinates of the central pivot point on the femur. By determining the coordinates of the pivot point of the femoral head, the reference sensor device 400 and / or the surgical orienting device 300 can calculate the placement and / or orientation of the mechanical axis passing through the femur.

[0190] The leg may be moved (e.g., rocked) to determine the coordinate of the femoral head pivot point (i.e., the pivot point of the mechanical axis). For example, with the reference sensor device 400 attached, the leg may be moved in multiple different directions and / or planes. Readings such as femoral angular velocity and acceleration may be obtained by the reference sensor device 400 until the position and / or orientation of the leg and femoral mechanical axis (the "femoral mechanical axis") is known. In one embodiment, when one or more multi-axis (e.g., two-axis) accelerometers and gyroscopes are used, the reference sensor data for each movement of the femur may be numerically integrated with respect to time to obtain a trajectory of position and velocity points (one point for each IMU data point). The IMU data may be integrated without imposing a planar trajectory restriction on the femoral movement.

[0191] The acceleration and angular velocity sensed by the reference sensor device 400 during leg movement may be processed while the leg is moved about its pivot point. The reference sensor device 400 may provide an output vector representing the center of rotation about the inertial sensor axes of the reference sensor device 400.

[0192] In some embodiments, prior to determining the location and / or orientation of the center of rotation of the mechanical axes, error compensation techniques may be used to remove biases in the surgical orienting device 300 and the reference sensor 400. For example, the error compensation techniques may include assessing 1) static bias, 2) gyroscope bias, and 3) accelerometer bias in the surgical reference sensor 400 and the surgical orienting device 300.

[0193] During alignment, the surgical orientation device 300 and reference sensor 400 determine the mechanical axes of the tibia and femur in flexion. The surgical orientation device 300 stores the mechanical axes. In some methods, the leg is moved into extension after both mechanical axes are acquired. The surgical orientation device 300 and reference sensor 400 are configured to sense changes in orientation. The change in orientation when the leg is in flexion and when the leg is in extension can determine the angulation of the mechanical axis. The change in mechanical axis can determine the varus / valgus angle. The change in mechanical axis can determine the flexion / extension angle. The change in mechanical axis can be measured in the coronal plane. The change in mechanical axis is measured in the sagittal plane. In some methods, leg alignment measurements are performed before resection. The leg is placed in extension. The change in the tibial mechanical axis relative to the femoral mechanical axis is calculated. Limb alignment at the hip, knee, and ankle is calculated. The relative positioning of the mechanical axes can be memorized by a surgical orientation device prior to resection.

[0194] The surgical orientation device 300 and / or reference sensor 400 can provide guidance to the surgeon on how to position the cutting block on the bone to achieve a cut plane perpendicular to the bone's load-bearing axis. The surgical orientation device 300 and / or reference sensor 400 can provide guidance to the surgeon on how to position the cutting block on the bone to offset the cut plane by a few degrees from its perpendicular plane, if necessary. The surgical orientation device 300 and / or reference sensor 400 can provide guidance regarding the varus / valgus angle relative to the cut plane. The surgical orientation device 300 and / or reference sensor 400 can provide guidance regarding the flexion / extension angle relative to the cut plane.

[0195] In some methods, the cutting guide is fixed to the bone to be cut, and the reference sensor 400 and / or surgical orienting device 300 may be coupled to the cutting guide. The tibial preparation system 700 may include a cutting guide. In some methods, one device is attached to a fixed portion of the tibial preparation system 700 to serve as a reference for bone orientation, and another device is attached to an articulating arm of the tibial preparation system 700 to provide the surgeon with a means to locate and set the desired cutting plane. The articulating arm of the tibial preparation system 700 may be limited to moving only in two dimensions, e.g., pitch and yaw (but not rotation). These two axes form a plane that can be adjusted to guide the placement of a cutting block that guides the saw to cut the bone in that plane.

[0196] After the mechanical axis is identified, the tibial cutting block may be utilized. The cutting block may be positioned so that it is spaced away from the anterior surface of the tibia. The surgical orienting device 300 and the tibial preparation system 700 may be used to adjust the cutting block to obtain the desired orientation for resection of the top of the tibia. For example, the posterior slope assembly and varus / valgus assembly of the tibial preparation system 700 may each be independently adjusted to change the angle of the cutting block and, subsequently, the angle of the intended resection. During this adjustment, the surgical orienting device 300 may provide one or more readings on the display indicating whether the surgical orienting device 300 and the cutting block are aligned with the sagittal and / or coronal planes that contain the tibial mechanical axis.

[0197] After the mechanical axis is identified, a femoral cutting block may be utilized. The cutting block may be positioned so that the cutting block is spaced apart from the distal surface of the femur. The reference sensor 400 and femoral preparation system 600 may be used to adjust the cutting block to obtain the desired orientation for resection of the femur. After the reference sensor device 400 and / or the surgical orientation device 300 calculate the mechanical axis pivot point and locate the mechanical axis as described above, the user may begin adjusting and orienting the femoral cutting block relative to the mechanical axis alignment. For example, the surgical orientation device 300 may display the varus / valgus and flexion / extension angle adjustments required for the cutting block to reach neutral alignment with the mechanical axis passing through the femoral head.

[0198] After the cutting block is in place, it may be attached to the surface with a plurality of pins. After the cutting block is attached to the tibia, the proximal portion of the tibia may be resected. After the cutting block is attached to the femur, the distal portion of the femur may be resected.

[0199] Advantageously, the mechanical axis may be verified after resection. In some methods, the leg is placed in extension after resection. The implant may be positioned within the knee joint. Limb alignment may verify implant placement. Limb alignment may verify varus / valgus angles in extension. Alignment may verify flexion / extension angles in extension. In some methods, a change in the tibia mechanical axis is determined after resection. In some methods, a change in the femur mechanical axis is determined after resection. In some embodiments, placement of the reference sensor device 400 on the femur allows the leg to be moved into extension. In extension, the relative positioning of the mechanical axes is determined.

[0200] In some embodiments, the reference sensor device 400 can track the relative position of the femur, allowing the procedure to proceed without immobilizing the operative leg. For example, at least one of the reference sensor device 400 and the surgical orienting device 300 can communicate with the other, such that any relative movement of one of these devices can be tracked by the other, and the resulting overall orientation of the reference sensor device 400 and / or the surgical orienting device 300 can be displayed on the display of the surgical orienting device 300. In some embodiments, the reference sensor device 400 can track movement of the femur. In some embodiments, the surgical orienting device 300 can track movement of the tibia.

[0201] The surgical orientation device 300 and reference sensor 400 can record any point or axis. They can memorize these points and axes during the procedure. The surgical orientation device 300 can reference these memorized mechanical axes after resection. The surgical orientation device 300 and reference sensor 400 can be used to measure and record the placement of anatomical landmarks. The mechanical axis of the leg, as defined herein, generally refers to a line extending from the center of rotation of the proximal head of the femur (e.g., the center of the femoral head), ideally through the approximate center of the knee, to the center, or midpoint, of the ankle. The mechanical axis of the femur is the same axis extending from the center of rotation of the proximal head of the femur through the center of the distal end of the femur (the center of the distal end of the femur is commonly described as the center of the intercondylar notch). Generally, a patient's ideal mechanical axis allows load to pass from the center of the hip joint, through the center of the knee joint, and to the center of the ankle.

[0202] The surgical orientation device 300, in conjunction with the reference sensor 400, can be used to identify the spatial orientation of a mechanical axis. In some methods, the surgical orientation device 300 and the reference sensor 400 can be used to identify one, two, or more planes that intersect the mechanical axis. In some methods, the surgical orientation device 300 and the reference sensor 400 can be used to identify a coronal plane. In some methods, the surgical orientation device 300 and the reference sensor 400 can be used to identify a sagittal plane. The surgical orientation device 300 and the reference sensor 400 can be used to verify the alignment of one or more orthopedic fasteners or one or more cutting planes prior to resection. The surgical orientation device 300 and the reference sensor 400 can be used to verify the alignment of one or more orthopedic fasteners or one or more cutting planes after resection. The surgical orientation device 300 and the reference sensor 400 can be used to determine the alignment of a mechanical axis prior to resection. The surgical orientation device 300 and the reference sensor 400 can be used to determine the alignment of the mechanical axes after resection.The surgical orientation device 300 and the reference sensor 400 can be used to determine the gap measurements after resection.

[0203] The surgical orienting device 300 may be mounted on the tibial preparation system 700 during tibial alignment. The surgical orienting device 300 can remain mounted on the tibial preparation system 700 during femoral alignment. The surgical orienting device 300 can remain mounted on the tibial preparation system 700 when the leg is extended for limb alignment and / or gap measurement. The surgical orienting device 300 can remain mounted on the tibial preparation system 700 to determine one or more angles between the mechanical axes. The surgical orienting device 300 can remain mounted on the tibial preparation system 700 during and after resection. The surgical orienting device 300 can remain attached to the tibial preparation system 700 during limb alignment measurement after resection.

[0204] In some methods, the reference sensor 400 can be mounted on the tibial preparation system 700 during tibia alignment. The reference sensor 400 can be moved with the femoral preparation system 600 during femoral alignment. The reference sensor 400 can remain mounted on the femoral preparation system 600 during limb alignment and / or gap balancing measurements. The reference sensor 400 can remain mounted on the femoral preparation system 600 when the leg is extended. The reference sensor 400 can remain mounted on the femoral preparation system 600 to determine one or more angles between the mechanical axes. The reference sensor 400 can remain mounted on the femoral preparation system 600 during and after resection. In some methods, the reference sensor 400 can be returned to the tibial preparation system 700 during and after resection. In some methods, the reference sensor 400 can be returned to the tibial preparation system 700 for calibration. The reference sensor 400 may be returned to the femoral preparation system 600 during post-resection limb alignment measurements.

[0205] Limb alignment measurements can include angulation at the tibial mechanical axis and femoral mechanical axis when the leg is in extension. Limb alignment measurements can be useful in partial knee replacements. Limb alignment measurements can be useful in total knee replacements. Limb alignment measurements can improve the service life of any implant. Limb alignment measurements can determine the mechanical axes passing through a patient's hip, knee, and ankle. Limb alignment measurements can determine the varus / valgus angle between the mechanical axes of the tibia and femur. Limb alignment measurements can determine the angle in the coronal plane. Limb alignment measurements can determine the flexion / extension angle between the mechanical axes of the tibia and femur. Limb alignment measurements can determine the angle in the sagittal plane.

[0206] Limb alignment measurements can provide amputation verification. The surgeon can perform the resection. The resection can be a neutral resection. The resection can be at an angle relative to the coronal plane. The resection can be at an angle relative to the sagittal plane. In a total knee replacement, the resection can include a proximal-distal resection. In a total knee replacement, the resection can include a medial and lateral compartment resection. In a partial knee replacement, the resection does not include a proximal-distal resection. In a partial knee replacement, the resection can include one compartment. The implant can change the overall alignment of the mechanical axis of the leg. The implant can change the varus / valgus angle. The implant can change the flexion / extension angle. The implant can change the gap. Limb alignment measurements can determine the relative orientation of the mechanical axis after implant placement. Limb alignment measurements can determine whether the implant provides correction in the coronal plane. Limb alignment measurements can determine whether the implant provides correction in the sagittal plane. Limb alignment measurements can determine if the measured angles correlate with the preoperative angles determined from imaging techniques. These measurements can provide information on whether soft tissue release is necessary. These measurements can determine lift-off for the implant.

[0207] Limb alignment measurements can determine how the mechanical axis of the tibia rotates about the mechanical axis of the femur. Limb alignment measurements can be performed after the mechanical axis is acquired. Limb alignment measurements can be performed after the mechanical axis is stored. Limb alignment measurements can be performed after the surgical orientation device 300 and reference sensor 400 are calibrated. Limb alignment measurements can be performed before resection. Limb alignment measurements can be performed after resection. Limb alignment measurements can be performed with the leg in extension. Limb alignment measurements can be performed after the implant is positioned. Limb alignment measurements can be performed at any time during the surgical procedure.

[0208] In some methods, a force is applied to the knee. The surgical orienting device 300 can perform a gap balancing assessment in conjunction with the reference sensor 400. During the gap assessment, the reference sensor 400 is attached to the femur. During the gap assessment, the surgical orienting device 300 is attached to the tibia. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing before the limb alignment measurement. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing after the limb alignment measurement. In some methods, the surgical orienting device 300 and the reference sensor 400 perform gap balancing when the leg is in extension. In some methods, the gap balancing is performed with at least one implant positioned between the tibia and the femur. The angle between the surgical orienting device 300 and the reference sensor 400 can be determined with the condyles in contact. This angle can be registered as 0 degrees. The tibia and femur may be put through a range of motion. In some embodiments, a varus force is applied to the tibia. In some embodiments, a valgus force is applied to the tibia. The angle between the surgical orienting device 300 on the tibia and the reference sensor 400 on the femur may be determined. In some methods, the user applies a varus torque. In some methods, the user applies a valgus torque.

[0209] The intercondylar distance can be known. The intercondylar distance can be determined from an image, such as an x-ray image. The intercondylar distance can be measured intraoperatively. This distance can be input to the surgical orientation device 300. In the illustrated example, the intercondylar distance is 55 mm. The clearance due to varus force can be determined based on a geometric relationship based on a known applied varus force and the intercondylar distance. The clearance due to valgus force can be determined based on a geometric relationship in the same manner as the clearance due to varus force. The clearance can be calculated by applying a force and measuring the change in angle between the femoral mechanical axis and the tibial mechanical axis. This angle and the intercondylar distance can provide an estimate of the clearance.

[0210] One or more of the surgical orientation device 300 and the reference sensor 400 can calculate the gap distance. The gap distance is the product of the measured angles between the tibia and femur. The gap distance is the product of the known intercondylar distances. In some embodiments, the dynamic gap height provides insight into medial / lateral ligament tension. The gap height can provide insight into soft tissue balancing. The gap measurement can determine whether further soft tissue release is needed. The gap measurement can be determined before resection. The gap measurement can be determined after resection. The gap can be assessed before and after resection. The gap can be assessed using multiple implants or trial implants.

[0211] The surgical orienting device 300 can include a display. The surgical orienting device 300 is positioned within the surgical field during limb alignment measurements. The surgical orienting device 300 is positioned within the surgical field during gap measurements. The display can be sized to allow a user to easily read numbers, lettering, and / or symbols displayed on the display screen while performing the procedure. The display can facilitate positioning of the cutting guide during resection. The display can provide information for verifying the position of the mechanical axis after resection. The display can provide information regarding limb alignment. The display can provide information regarding gap balancing.

[0212] The surgical orienting device 300 can store measured or calculated data. The surgical orienting device 300 can store data input by a user. The surgical orienting device 300 can store distance measurements corresponding to the mounting bracket 640 relative to the extension 630. The surgical orienting device 300 can store the length and / or angle of the extension 630. The surgical orienting device 300 can store the orientation of the femoral preparation system 600. The surgical orienting device 300 can further include at least one user input device. The at least one user input device may include a plurality of buttons disposed adjacent to the display. The buttons may be activated, for example, by a finger, hand, and / or instrument, to input data. The data may include distance measurements related to anatomical landmarks. The surgical orienting device 300 includes a user interface that a clinician can interact with during a procedure.

[0213] The surgical orienting device 300 and the reference sensor 400 can acquire and store data related to position and orientation. The surgical orienting device 300 includes an electrical system. The electrical system can comprise one or more features including one or more sensors, an electronic control unit in communication with the one or more sensors, one or more visual alignment indicators, a power supply, a display, memory, one or more user input devices, one or more processors, program logic, other board configurations representing data and instructions, controller circuitry, processor circuitry, processors, general-purpose single-chip or multi-chip microprocessors, digital signal processors, embedded microprocessors, microcontrollers, other output devices, and / or one or more input / output ("I / O") ports. In certain embodiments, the electronic control unit can be configured to convert electronic data from a machine-readable format to a human-readable format for presentation on the display of the surgical orienting device 300. The electronic control unit can communicate with internal and / or external memory to retrieve and / or store data and / or program instructions for the software and / or hardware. The internal and external memory may include random access memory ("RAM"), such as static RAM, for temporary storage of information and / or read-only memory ("ROM"), such as flash memory, for more permanent storage of information. Generally, the sensors may be configured to provide continuous real-time data to one or more processors. The electronic control unit may be configured to receive the real-time data from the sensors and use the sensor data to determine, estimate, and / or calculate the orientation or position of the surgical orienting device 300 and / or the orientation or position of the reference sensor 400.

[0214] In some embodiments, in addition to or instead of the surgical orienting device 300, the system can include an external display. The electronics can include one or more handheld devices, such as a computer, a desktop computer, a laptop computer, or a tablet computer such as an iPad®. In some embodiments, the display is positioned within the surgical field. In some embodiments, the display is positioned outside the surgical field. In some embodiments, the reference sensor device 400 can include a display. In some embodiments, in addition to or instead of the surgical orienting device 300, the electronics can include at least one user input device. The user input device can be activated, for example, by a finger, a hand, and / or an instrument. The electronics can include software and / or hardware for the systems described herein. The electronics can include external memory for the systems described herein. The surgical orienting device 300 and / or the reference sensor device 400 can be connected to the Internet. The surgical orienting device 300 and / or the reference sensor device 400 can transmit or receive information from the Internet. The surgical orienting device 300 and / or the reference sensor device 400 can be connected to the cloud. The surgical orienting device 300 and / or the reference sensor device 400 can transmit or receive information from the cloud.

[0215] In some arrangements, one or more sensors of the surgical orienting device 300 and / or the reference sensor device 400 may include at least one orientation sensor configured to provide real-time data related to the movement, orientation, and / or position of the surgical orienting device 300 and / or the reference sensor device 400 to the electronic control unit. For example, the sensor module may include at least one gyro sensor, accelerometer, tilt sensor, magnetometer, and / or other similar device or devices configured to measure and / or facilitate orientation determination of the surgical orienting device 300 and / or the reference sensor device 400. In some embodiments, the sensors may be configured to provide measurements relative to a reference point, line, plane, and / or zero gravity. Zero gravity, as referred to herein, generally refers to an orientation in which the axis of the sensor is perpendicular to the force of gravity, thereby resulting in no angular offset, e.g., tilt, pitch, roll, or yaw, relative to the gravity vector. In other embodiments, the sensors may be configured to provide measurements for use in dead reckoning or inertial navigation systems.

[0216] In various embodiments, the sensor includes one or more accelerometers that measure static acceleration of the surgical orienting device 300 and / or reference sensor device 400 due to gravity. For example, the accelerometers may be used as tilt sensors to detect rotation of the surgical orienting device 300 and / or reference sensor device 400 about one or more axes. The one or more accelerometers may include a two-axis accelerometer (capable of measuring rotation about two axes of rotation) or a three-axis accelerometer (capable of measuring rotation about three axes of rotation). Changes in orientation about the accelerometer's axis may be determined relative to zero gravity and / or relative to a reference plane aligned during the tibial or femoral preparation procedure described herein.

[0217] In certain embodiments, a multi-axis accelerometer (such as the ADXL203CE MEMS accelerometer available from Analog Devices, Inc. or the LIS331DLH accelerometer available from ST Microelectronics) detects changes in orientation about two axes of rotation. For example, the multi-axis accelerometer can detect changes in the angular position of the surgical orienting device 300 and / or reference sensor device 400 from the horizontal plane (e.g., anterior / posterior rotation) and changes in the angular position of the surgical orienting device 300 and / or reference sensor device 400 from the vertical plane (e.g., roll rotation). The changes in the angular position of the surgical orienting device 300 and / or reference sensor device 400 from the horizontal and vertical planes (as measured by the sensors) can also be used to determine changes in the medial / lateral orientation of the surgical orienting device 300 and / or reference sensor device 400 (e.g., varus / valgus rotation).

[0218] In some arrangements, the sensors comprise at least one single-axis or multi-axis gyroscope sensor and at least one single-axis or multi-axis acceleration sensor. For example, the sensors may include a three-axis gyroscope sensor (or three gyroscope sensors) and a three-axis acceleration sensor (or three acceleration sensors) to provide position and orientation measurements for all six degrees of freedom of the surgical orienting device 300 and / or reference sensor device 400. In some embodiments, the sensors provide an inertial navigation or dead reckoning system that continuously calculates the position, orientation, and velocity of the surgical orienting device 300 and / or reference sensor device 400 without the need for an external reference.

[0219] Reference sensor 400 can include any of the features of surgical orienting device 300. Surgical orienting device 300 and / or reference sensor 400, in one embodiment, include one or more sensors that together may form an inertial measurement unit (IMU). In particular, the IMU includes a first sensor for determining acceleration and a second sensor for determining gyroscopic positioning. As described herein, the first sensor can be an accelerometer and the second sensor can be a gyroscope sensor. Reference sensor 400 also includes a transmitter for transmitting data from the sensor to the electrical system of surgical orienting device 300. Information received from reference sensor 400 can be provided to an input port, or alternatively, the electronic control unit of surgical orienting device 300 itself can receive the information wirelessly. Information from the reference sensor 400 may, for example, correspond to the position and / or orientation of the reference sensor 400 and may be used by the surgical orientation device 300 to determine the overall, relative, or global position and / or orientation of the surgical orientation device 300 and / or the reference sensor device 400.

[0220] The surgical orientation device 300 and / or the reference sensor device 400 may be used to measure and record the placement of anatomical landmarks, such as the placement of the mechanical axes of the leg, tibia, and femur. Additional details of the systems, devices, sensors, and methods are set forth in U.S. Patent No. 6,239,499, filed June 9, 2004; U.S. Patent No. 6,239,499, filed July 15, 2009; U.S. Patent No. 6,239,499, filed September 10, 2009; U.S. Patent No. 6,239,499, filed July 24, 2009; U.S. Patent No. 6,239,499, filed January 21, 2011; U.S. Patent No. 6,239,499, filed May 24, 2011; U.S. Patent No. 6,239,499, filed November 5, 2014; U.S. Patent No. 6,239,499, filed November 14, 2014; U.S. Patent No. 6,239,499, filed March 13, 2013; U.S. Patent No. 6,239,499, filed March 10, 2015; U.S. Patent No. 6,239,499, filed August 11, 2017; U.S. Patent No. 6,239,499, filed March 13, 2018; U.S. Patent No. 6,239,499, filed March 13, 2018; and U.S. Patent No. 6,239,499, filed December 8, 2020, all of which are incorporated herein by reference in their entirety for all purposes.

[0221] While 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 the present 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 many variations of the invention have been shown and described in detail, other modifications, which are within the scope of the present 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 these embodiments may be made and fall within the scope of the present application. For example, the present application contemplates that a connection hub, alone or in combination with any of the other modules, may comprise another aspect. Or, any one or combination of these modules may be directly connected to an umbrella hub or overhead support to form other separate aspects. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another to form varying forms 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 instead be determined solely by a fair reading of the following claims.

[0222] Likewise, this method of disclosure should not be interpreted as reflecting an intention that any claim require more features than are expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in combinations of fewer than all features of a single foregoing disclosed embodiment. Accordingly, 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]

[0223] 10 axes 15 Excision, plateau 20 axes 20 Tibial mechanical axis, electronic control unit 25 Tibial Plateau 100 Femur Preparation System 102 femoral jig assembly, pin 104 Reference Sensor Device Interface, pin 106 Surgical Orientation Device Interface 108 Fixing pin 200 Tibia Preparation System 202 Tibia Jig Assembly 204 Reference Sensor Device Interface 206 Surgical Orientation Device Interface 210 Midline Reference Probe Assembly 212 Probe Assembly 214 Slender Members 216 Probe component 250 Module Interface 300 Surgical Orientation Device 400 Reference Sensor, Reference Sensor Device 500 Modules 600 Femur Preparation System 602 Cutting guide rod 604 threaded post 606 flange 608 Cap 610 Cutting guide bracket 612 Slots 614 steps 616 Opening 620 Swivel Post 622 flange 624 Cap 630 Extension part 632 Opening 634 Threaded Pin 636 Groove 640 Mounting Bracket 642 First Part 644 Second Part 646 Hub 650 push button 652 Spring 660 Connector 662 Connectors, Couplers 664 Opening 666 threaded pin 680 Reference Sensor Interface 700 Tibia Preparation System 710 Landmark Acquisition Assembly 712 Slender members 714 Probe components 770 Surgical Orientation Device Interface 780 Reference Sensor Interface

Claims

1. A system for limb alignment, A first orientation device configured to be connected to the tibia in order to establish the characteristics of the knee joint, comprising at least one inertial sensor, A second orientation device configured to be connected to the femur in order to establish the characteristics of the knee joint, the second orientation device comprising at least one inertial sensor, Equipped with, The system comprises one or more processors configured to receive inertial sensor data, the one or more processors configured to determine the femoral mechanical axis and the tibial mechanical axis, and the one or more processors configured to calculate the angle between the femoral mechanical axis and the tibial mechanical axis when an inversion torque is applied to the knee and / or an eversion torque is applied to the knee.

2. The system according to claim 1, wherein the processor is configured to calculate the angle formed by the femoral mechanical axis and the tibial mechanical axis when the knee is in a fully extended state.

3. The system according to claim 1, wherein the processor is configured to calculate the angle formed by the femoral mechanical axis and the tibial mechanical axis when the knee is in a fully flexed state.

4. The system according to claim 1, wherein the processor is configured to calculate the angle between the femoral mechanical axis and the tibial mechanical axis when the varus torque is applied to the knee and when the valgus torque is continuously applied to the knee.

5. The system according to claim 1, wherein the processor is configured to determine the tibial mechanical axis at least in part based on the arrangement of anatomical landmarks.

6. The system according to claim 1, wherein the processor is configured to determine the femoral mechanical axis at least in part based on the movement of the femur.

7. The system according to claim 1, wherein the processor is configured to determine the gap distance as the product of the intercondylar distances.

8. The system according to claim 1, wherein the processor is configured to determine the gap distance as the product of the angles.

9. The system according to claim 1, wherein the processor is configured to determine the gap height to provide insight into medial / lateral ligament tension.

10. The system according to claim 1, wherein the processor is configured to determine gap height to provide insights regarding soft tissue balancing.

11. The system according to claim 1, wherein the processor is configured to evaluate the gap before and after excision.

12. The system according to claim 1, wherein the processor is configured to evaluate gaps using a plurality of implants or trial implants.

13. The system according to claim 1, wherein the first orientation device and / or the second orientation device are configured to provide a visual representation to the user.

14. The system according to claim 1, wherein the first orientation device and / or the second orientation device are configured to transfer data between the first orientation device and the second orientation device.

15. The system according to claim 1, wherein the first orientation device and / or the second orientation device are configured to transfer data with an external device such as a computer, tablet, and / or smartphone.

16. The system according to claim 1, wherein the first orientation device and the second orientation device are configured to be coupled with a tibial preparation system for calibration.

17. The system according to claim 1, wherein the first orientation device and the second orientation device are configured to calculate the varus / valgus angle when the implant is positioned between the tibia and the femur.

18. The system according to claim 1, wherein the first orientation device and the second orientation device are configured to calculate the flexion / extension angle when the implant is positioned between the tibia and the femur.

19. The system according to claim 1, wherein the first orientation device and the second orientation device are configured to calculate soft tissue balancing when the implant is positioned between the tibia and the femur.

20. The system according to claim 1, wherein the processor is configured to calculate the gap opening from a single femoral condyle to the tibial plateau.

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