System and method for surgical registration

Abstract

To provide an alignment method for increasing accuracy while reducing an alignment time.SOLUTION: A system for surgical registration. The system can include at least one computing device in communication with the surgical navigation system and the surgical device. A) receive external bone registration data corresponding to locations on an external surface of the femur, b) calculate a first registration transform based on the external bone registration data, and c) transform a first bone removal plan of the surgical plan to the surgical coordinate system based on the first registration transform; D) receiving internal bone canal registration data corresponding to at least one of the location or orientation data from the internal canal of the femur, e) calculating a second registration transform based on both the external and internal bone canal bone registration data, and f) transforming a second bone removal plan of the surgical plan to the surgical coordinate system based on the second registration transform.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 814,057, filed March 5, 2019, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to surgical systems for orthopaedic joint replacement surgery, and more particularly to methods of surgical registration. [Background technology]

[0003] Robotic systems are often used in applications requiring a high degree of precision and / or accuracy, such as surgical procedures or other complex tasks. Such systems can include various types of robots, such as autonomous, teleoperated, and interactive.

[0004] Interactive robotic systems may be preferred for some types of surgery, such as joint replacement surgery, because they enable surgeons to maintain direct, hands-on control of the surgical procedure while still achieving a high degree of precision and / or accuracy. For example, in knee replacement surgery, a surgeon can use an interactive, haptically guided robotic arm in a passive manner to sculpt bone to accept a joint implant, such as a knee implant. To sculpt the bone, the surgeon grasps and manually manipulates the robotic arm to move a cutting tool (e.g., a rotating burr) coupled to the robotic arm to cut a pocket inside the bone. As long as the surgeon keeps the tip of the burr within a predefined virtual cutting boundary or within a haptic boundary defined, for example, by a haptic object, the robotic arm moves freely with low friction and inertia, allowing the surgeon to perceive the robotic arm as essentially weightless and to move it accordingly. However, if the surgeon attempts to move the tip of the bur to cut outside the virtual cutting boundary, the robotic arm provides tactile feedback (e.g., a forcible resistance force) that prevents or inhibits the surgeon from moving the tip of the bur beyond the virtual cutting boundary. As a result, the robotic arm enables highly accurate and repeatable bone cutting. When the surgeon manually implants a knee implant (e.g., a patellofemoral component) during corresponding bone cutting, the implant will generally be precisely aligned due to the configuration of and interface between the cut bone and the knee implant.

[0005] The interactive robotic system described above can also be used in hip replacement surgery, which may require the use of multiple surgical tools with different functions (e.g., reaming, impaction), different configurations (e.g., straight, offset), and different weights. A system designed to accommodate a variety of tools is described in application Ser. No. 12 / 894,071, filed Sep. 29, 2010, entitled "SURGICAL SYSTEM FOR POSITIONING PROSTHETIC COMPONENT AND / OR FOR CONSTRAINING MOVEMENT OF SURGICAL TOOL," which is incorporated herein by reference in its entirety.

[0006] In hip replacement surgery, as well as other robotic-assisted or fully autonomous surgical procedures, the patient's bones, including the pelvis and femur, are intraoperatively registered with corresponding virtual or computerized bone models to correlate the pose (i.e., position and rotational orientation) of the actual physical bones with the virtual bone models. The patient's bones (physical space) are also tracked in relation to a surgical robot, haptic device, or surgical tool (e.g., a rotary burr), which may include at least one degree of freedom. As a result, a virtual cutting or haptic boundary, controlled and defined on the virtual bone model via a computer, can be applied to the patient's bones (physical space) such that the haptic device is constrained in its physical motion (e.g., burring) as it operates relative to the patient's bones (physical space).

[0007] Intraoperative registration of the pelvis and femur can be challenging. Thus, while certain systems and methods exist in the art for registering a patient's pelvis and femur, there is a need in the art for registration methods that increase accuracy while decreasing registration time.

[0008] Aspects of the present disclosure may include a system for aligning a surgical device with a patient's femur. The femur may include an exterior surface and an internal canal. The patient's femur and the surgical device may be located within a surgical coordinate system. The system may include at least one computing device in communication with a surgical navigation system and the surgical device. The surgical navigation system is capable of tracking the surgical device. The at least one computing device stores a surgical plan in a virtual coordinate system. The at least one computing device is configured for the following steps: The at least one computing device may receive external bone alignment data corresponding to locations on the exterior surface of the femur; the at least one computing device may calculate a first alignment transform based on the external bone alignment data; and the at least one computing device may transform a first bone removal plan of the surgical plan to the surgical coordinate system based on the first alignment transform. The at least one computing device may receive internal bone canal alignment data corresponding to at least one of location or orientation data from the internal canal of the femur. The at least one computing device may calculate a second alignment transform based on both the external bone alignment data and the internal bone canal alignment data. The at least one computing device can transform the second bone removal plan of the surgical plan to the surgical coordinate system based on the second registration transformation.

[0009] In a particular example, the first bone removal plan may be defined in virtual coordinate space and may include a first coordinate location for a first portion of bone removal from a virtual internal canal, which may represent the internal canal of the patient's femur.

[0010] In a particular example, the second bone removal plan may be defined in virtual coordinate space and may include a second coordinate location for a second portion of bone removal from a virtual internal canal, which may represent the internal canal of the patient's femur.

[0011] In certain examples, the first portion of bone removal from the first bone removal plan includes less bone removal from the virtual canal than the first and second bone removal plans combined. In certain examples, the first bone removal plan includes only a partial femoral canal preparation plan that may be less than the full canal preparation required for implantation of the femoral implant stem. In certain examples, the first portion of bone removal from the first bone removal plan and the second portion of bone removal from the second bone removal plan are collectively comparable in amount to the full canal preparation plan.

[0012] In certain instances, the second bone removal plan includes a robotic bone removal portion and a manual bone removal portion.

[0013] In certain instances, manual bone removal may be planned for broaching purposes.

[0014] In certain instances, the second coordinate location for the second portion of the bone removal includes the first coordinate location for the first portion of the bone removal.

[0015] In certain instances, the second coordinate location for the second portion of bone removal from the second bone removal plan encompasses the first coordinate location for the first portion of bone removal from the first bone removal plan.

[0016] In certain examples, a surgical navigation system can include a tracking device and at least one tool configured to be tracked during its movement by the tracking device.

[0017] In certain examples, the surgical plan may further include a position and orientation for femoral neck etching, wherein the at least one computing device is configured to receive femoral neck etching data corresponding to physical marks on the femoral neck, the marks being less than a complete resection of the femoral neck.

[0018] In certain examples, the at least one computing device is further configured to compare the first alignment transformation with the second alignment transformation, and to proceed with one of the first alignment transformation or the second alignment transformation based on the comparison.

[0019] Aspects of the present disclosure may include a computer-implemented method for aligning a surgical device with a patient's femur. The femur includes an exterior surface and an internal canal. The surgical device and the patient's femur are located within a surgical coordinate system. The computer-implemented method may include receiving external bone alignment data corresponding to locations on the exterior surface of the femur. The method may include calculating a first alignment transformation based on the external bone alignment data. The method may also include transforming a first bone removal plan of the surgical plan to the surgical coordinate system based on the first alignment transformation, the first bone removal plan including a partial femoral canal preparation plan that may be less than a full canal preparation plan required to accept a stem of a femoral implant. The method may include receiving internal bone canal alignment data corresponding to at least one of location or orientation data from the internal canal of the femur. The method may include calculating a second alignment transformation based on both the external bone alignment data and the internal bone canal alignment data. The method may then include transforming a second bone removal plan of the surgical plan to the surgical coordinate system based on the second registration transformation.

[0020] In certain examples, the method may further include determining a planned implant placement of the implant model relative to a femoral bone model, the femoral bone model representing a femur of the patient.

[0021] In certain examples, the method may further include determining a surgical plan for achieving the planned implant placement, where the surgical plan may include a first bone removal plan and a second bone removal plan.

[0022] In certain examples, the first bone removal plan may be planned in a virtual coordinate system relative to a femoral bone model representing the femur, the virtual coordinate system being different from the surgical coordinate system, and transforming the first bone removal plan to the surgical coordinate system based on the first registration transformation may include mapping the first bone removal plan in the surgical coordinate system to the femur in the same position and orientation that the first bone removal plan may be in relative to the femur bone model in the virtual coordinate system.

[0023] In certain examples, the second bone removal plan may be planned in a virtual coordinate system relative to a femoral bone model representing the femur, the virtual coordinate system being different from the surgical coordinate system, and transforming the second bone removal plan to the surgical coordinate system based on the second registration transformation may include mapping the second bone removal plan in the surgical coordinate system to the femur in the same position and orientation that the second bone removal plan may be in relative to the femur bone model in the virtual coordinate system.

[0024] In certain instances, the second bone removal plan includes removal of bone from the inner canal of the femur, and the second bone removal plan subsumes bone removal from the first bone removal plan. In certain instances, the second bone removal plan includes removal of additional bone beyond the bone in the first bone removal plan.

[0025] Aspects of the present disclosure may include a system for registering patient data of a first bone in a first coordinate system with a surgical plan associated with the first bone in a second coordinate system, the second coordinate system being different from the first coordinate system. The first bone may include a head portion and a shaft portion extending from the head portion. The system may include at least one computing device in communication with a surgical navigation system, the system may include a tracking device and at least one tool configured to be tracked during its movement by the tracking device. The at least one computing device stores the surgical plan in the second coordinate system. The surgical plan may include a virtual bone model representing the first bone, the first bone removal plan being associated with the virtual bone model, and the second bone removal plan being associated with the virtual bone model. The at least one computing device is configured to receive a first point cloud of data associated with the first bone, the first point cloud of data may include first data associated with the head portion of the first bone. The at least one computing device is configured to calculate a first registration transformation from the first point cloud of data. The at least one computing device is configured to transform a first bone removal plan of the surgical plan into the first coordinate system in position and orientation relative to the first bone using a first registration transformation, since the first bone removal plan exists in a second coordinate system relative to the virtual bone model. When the at least one device is configured to receive a second point cloud of data associated with the first bone, the second point cloud of data may include second data associated with an interior portion of a shaft portion of the first bone. The at least one computing device is configured to calculate the second registration transformation from both the first and second point clouds of data. And, the at least one computing device is configured to transform a second bone removal plan of the surgical plan into the first coordinate system in position and orientation relative to the first bone using the second registration transformation, since the second bone removal plan exists in the second coordinate system relative to the virtual bone model.

[0026] In certain examples, the first and second point clouds of data may be collected intraoperatively via a surgical device that may be tracked during its movement by a tracking device of a surgical navigation system.

[0027] In certain examples, the first bone removal plan includes a first plan for partial removal of bone from a virtual canal of the virtual bone model.

[0028] In a particular example, the second bone removal plan includes a second plan for full bone removal from a virtual canal of the virtual bone model, and the first and second bone removal plans are intended to prepare for implantation of a femoral implant stem.

[0029] Aspects of the present disclosure may include one or more tangible computer-readable storage media storing computer-executable instructions for executing a computer process on a computing system. The computer process may include the following steps: receiving multiple image scans of a patient's pelvis; generating a three-dimensional bone model of the patient's pelvis from the multiple image scans; identifying a scan axis associated with the multiple image scans, the scan axis defined along a long axis of a scanning table of an imaging device; identifying a bone axis associated with a three-dimensional bone model of the patient's pelvis; determining an angular offset between the scan axis and the bone axis; determining a virtual center of rotation of at least one virtual bone relative to the three-dimensional bone model of the patient's pelvis; using the angular offset and the virtual center of rotation as constraints in a registration transformation utilized in a surgical registration procedure.

[0030] Aspects of the present disclosure may include one or more tangible computer-readable storage media storing computer-executable instructions for executing a computer process on a computing system. The computer process may include the following steps: The computer process may include receiving a point cloud of data from at least one tool of a surgical navigation system, the at least one tool being tracked during its movement by a tracking device of the surgical navigation system; The at least one tool may be configured to store data points in the point cloud data; The point cloud of data may include first data and second data in a common coordinate system; The first data may include pairs of points located on or near a surgical table; The second data may include a plurality of points corresponding to a concave portion of a joint surface between a first bone, which may include a concave portion, and a second bone, which may include a convex portion; The computer process may include determining a vector between pairs of points of the first data; The computer process may include determining a center of rotation from the second data, the center of rotation being of the second bone relative to the first bone. The computer process may include utilizing a registration transformation to register the point cloud of data with a three-dimensional computer model of at least the first bone, the vector and center of rotation being constraints in the registration transformation.

[0031] Aspects of the present disclosure may include a computer-implemented method for surgical registration including the following steps. The method may include receiving a point cloud of data from at least one tool of a surgical navigation system, the at least one tool being tracked during its movement by a tracking device of the surgical navigation system. The at least one tool is configured to store data points in the point cloud data based on its position relative to the tracking device. The point cloud of data may include first and second data in a first coordinate system. The first data may include first and second coordinate points located on or near the surgical table. The second data may include one or more coordinate points corresponding to a center of rotation of a joint formed between a pair of bones. The method may include utilizing a registration transform to align the point cloud of data with a plurality of coordinate points associated with a three-dimensional computer model of or approximating the bone pair and joint. The plurality of coordinate points may include one or more coordinate points corresponding to a center of rotation of the joint. The plurality of coordinate points are located in a second coordinate system.

[0032] In a particular example, first and second coordinate points located on or near the surgical table are aligned parallel to the long axis of the surgical table.

[0033] In a particular example, the first data may include a third coordinate point located on or near the surgical table, and the third coordinate point may be located on an opposite side of the surgical table from the first and second coordinate points.

[0034] In certain instances, a three-dimensional computer model of, or approximating, the bone pair and joint can be generated from pre-operative image scans of the bone pair and joint.

[0035] In particular examples, the three-dimensional computer model of or approximating the bone pairs and joints may include a general bone model approximating the bone pairs and joints.

[0036] In certain instances, the three-dimensional computer model of or approximating the bone pairs and joints may include a statistical bone model approximating the bone pairs and joints.

[0037] Aspects of the present disclosure may include a surgical registration system including: a registration needle that may include a distal tip and a proximal light emitting diode (LED) optical marker, the proximal LED optical marker configured to be tracked by a tracking device of a surgical navigation system; a needle template that may include a template block having a plurality of through-holes extending therethrough, the plurality of through-holes being spaced apart from one another on the template block and each of the plurality of through-holes configured to guide the registration needle along a trajectory; and an optical localization tracker coupled to the needle template, the optical localization tracker configured to be tracked by the tracking device of the surgical navigation system.

[0038] Aspects of the present disclosure may include a system for registering patient data collected during surgery of a vertebra with a computer model of the vertebra within a coordinate system. The vertebra may include a cortical bone shell having an outer surface and an inner surface, and cancellous bone within the cortical bone shell. The vertebra may define a spinal canal bounded by the cortical bone shell. The system may include a surgical navigation system including a tracking device and at least one tool configured to be tracked during its movement by the tracking device, the at least one tool including an end effector having a cutting element at a distal end thereof and a load cell configured to sense a load on the cutting element. The system may also include at least one computing device in communication with the surgical navigation system, the at least one computing device storing the computer model of the vertebra within the coordinate system. The at least one computing device is configured to receive load data associated with a load experienced by a cutting element at a distal end of the end effector when the cutting element contacts the cortical bone shell and the cancellous bone. The at least one computing device is configured to identify, based on the load data, when the cutting element contacts the inner surface of the cortical bone shell. With the at least one computing device configured to receive a point cloud of data associated with the vertebrae, the point cloud of data may include coordinate locations on the inner surface of the cortical bone shell, the point cloud of data being collected via the cutting element at the distal end of the end effector. The at least one computing device is configured for at least one of performing and updating a transformation to align the point cloud of data associated with the vertebrae with a computer model of the vertebrae in a common coordinate system. [Brief explanation of the drawings]

[0039] [Figure 1A] FIG. 1 is a perspective view of the femur and pelvis. [Figure 1B] FIG. 1B is a perspective view of the hip joint formed by the femur and pelvis of FIG. 1A. [Figure 2A]FIG. 1 is an exploded perspective view of a femoral component and an acetabular component for a total hip replacement procedure. [Figure 2B] 2B is a perspective view showing the placement of the femoral component and acetabular component of FIG. 2A in relation to the femur and pelvis of FIG. 1, respectively. [Figure 3A] FIG. 1 is a perspective view of one embodiment of a surgical system. [Figure 3B] FIG. 3B is a perspective view of one embodiment of a robotic arm of the surgical system of FIG. 3A. [Figure 4] 1 illustrates one embodiment of a computer display used in a surgical procedure. [Figure 5] 1 illustrates one embodiment of steps in a hip replacement procedure. [Figure 6] 1 illustrates one embodiment of a pelvis alignment method shown on a display screen. [Figure 7] 1 illustrates one embodiment of a pelvis alignment method shown on a display screen. [Figure 8] 1 illustrates steps of a femoral alignment method. [Figure 9] FIG. 9A depicts a preoperative image of a proximal femur undergoing segmentation, FIG. 9B depicts the proximal femur with the canal partially resected, FIG. 9C depicts the proximal femur being internally probed along the femoral canal, and FIG. 9D depicts the proximal femur with the femoral canal completely resected. [Figure 10] 1 illustrates steps of a femoral alignment method. [Figure 11] FIG. 11A depicts a preoperative image of a proximal femur undergoing segmentation, FIG. 11B depicts the proximal femur with the femoral canal partially resected, FIG. 11C depicts the proximal femur with the femoral canal partially resected and the inner surface of the femur being probed by the burr of the end effector, and FIG. 11D depicts the proximal femur with the femoral canal completely resected. [Figure 12] 1 illustrates steps of a femoral alignment method. [Figure 13]Figure 13A depicts a preoperative image of a proximal femur undergoing segmentation, Figure 13B depicts the proximal femur with the femoral canal partially resected and with an alignment tool extending into the femoral canal, Figure 13C depicts the proximal femur with the femoral canal partially resected and with the alignment tool extending into the femoral canal and with the tool expanded to the internal bone surface, and Figure 13D depicts the proximal femur with the femoral canal completely resected. [Figure 13E] 1 depicts an exemplary flowchart for planning and performing a surgical procedure on the proximal femur. [Figure 13F] 1 depicts an exemplary flowchart for planning and performing a surgical procedure on the proximal femur. [Figure 14A] 1 illustrates a pre-operative step of a registration method that utilizes information from the patient's orientation on the imaging table. [Figure 14B] 1 illustrates an intraoperative step of a registration method that utilizes information from the patient's orientation on the imaging table. [Figure 14C] 1 illustrates the pre-operative and intra-operative steps of the registration method. [Figure 14D] 1 illustrates the pre-operative and intra-operative steps of the registration method. [Figure 15] FIG. 15A depicts an overhead view of the patient on the imaging table, FIG. 15B depicts an overhead view of the patient on the operating room table, and FIG. 15C depicts the angular offset between the vector determined in the operating room and the pelvic axis determined from the orientation of the patient on the imaging table. [Figure 15D] Draw an overhead view of the patient on the imaging table. [Figure 15E] Draw an overhead view of the patient on the operating room table. [Figure 15F] Draw an overhead view of the patient on the imaging table. [Figure 15G] Draw an overhead view of the patient on the operating room table. [Figure 16A] Needles of various lengths and diameters and needle templates are depicted. [Figure 16B] 1 depicts an anterior view of a femur with a first embodiment of a needle-based alignment system. [Figure 16C] 1 depicts an anterior view of a femur with a second embodiment of a needle-based alignment system. [Figure 17A] 1 depicts a needle-based alignment system used on the mid-distal portion of the femur. [Figure 17B] 1 depicts a needle-based alignment system used on the mid-distal portion of the femur. [Figure 17C] 1 depicts a needle-based alignment system used on the mid-distal portion of the tibia. [Figure 18] 1 depicts a lateral view of the ilium with a needle-based registration system utilized on the iliac crest. [Figure 19A] 1 depicts a side view of a needle-based alignment system utilized on the spine. [Figure 19B] 1 depicts an axial cross-sectional view of a needle-based alignment system utilized on the spine. [Figure 20A] 1 is an axial cross-sectional image of a vertebra with a bone anchor positioned within the pedicle. [Figure 20B] 1 is an axial cross-sectional image of a vertebra with a bur positioned in the cervical region of the pedicle. [Figure 20C] 1 is an axial cross-sectional image of a vertebra with a bur positioned in the cervical region of the pedicle. [Figure 20D] FIG. 10 is an axial cross-sectional image of a vertebra with a burr positioned through the cervical region of the pedicle to the far medial cortical wall. [Figure 21] 1 illustrates an exemplary computing system having one or more computing units that may implement the various systems and methods disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0040] This application incorporates by reference International Patent Application Publication No. PCT / US2017 / 049466, filed August 30, 2017, entitled "SYSTEMS AND METHODS FOR INTRA-OPERATIVE PELVIC REGISTRATION," U.S. Patent Application No. 12 / 894,071, filed September 29, 2010, entitled "SURGICAL SYSTEM FOR POSITIONING PROSTHETIC COMPONENT AND / OR FOR CONSTRAINING MOVEMENT OF SURGICAL TOOL," and U.S. Patent Application No. 13 / 234,190, filed September 16, 2011, entitled "SYSTEMS AND METHOD FOR MEASURING PARAMETERS IN JOINT REPLACEMENT SURGERY," and U.S. Patent Application No. 13 / 234,190, filed September 16, 2011, entitled "HAPTIC GUIDANCE SYSTEM AND METHOD FOR MEASURING PARAMETERS IN JOINT REPLACEMENT SURGERY." No. 11 / 357,197, filed February 21, 2006, entitled "TRANSMISSION WITH FIRST AND SECOND TRANSMISSION ELEMENTS," U.S. Patent Application No. 12 / 654,519, filed December 22, 2009, entitled "DEVICE THAT CAN BE ASSEMBLED BY COUPLING," U.S. Patent Application No. 12 / 644,964, filed December 22, 2009, entitled "DEVICE THAT CAN BE ASSEMBLED BY COUPLING," and U.S. Patent Application No. 11 / 750,807, filed May 18, 2007, entitled "SYSTEM AND METHOD FOR VERIFYING CALIBRATION OF A SURGICAL DEVICE."

[0041] I. Overview The hip joint is the joint between the femur and pelvis and functions primarily to support the body's weight in static (e.g., standing) and dynamic (e.g., walking) postures. FIG. 1A shows the working bones of the hip joint 10, including the left pelvis or ilium 12 and the proximal end of the left femur 14. While the right pelvis and proximal end of the right femur are not shown in FIG. 1A, the description herein is applicable to both right and left femurs and pelvises without limitation. Continuing, the proximal end of the femur 14 includes a femoral head 16 disposed on a femoral neck 18. The femoral neck 18 connects the femoral head 16 to a femoral shaft 20. As shown in FIG. 1B, the femoral head 16 fits into a concave socket in the pelvis 12, called the acetabulum 22, thereby forming the hip joint 10. Both the acetabulum 22 and the femoral head 16 are covered by articular cartilage, which absorbs shock and facilitates articulation of the joint 10 .

[0042] Over time, the hip joint 10 may deteriorate (e.g., due to osteoarthritis), resulting in pain and decreased function. This may result in the need for a hip replacement procedure, such as a total hip arthroplasty or hip resurfacing. During a total hip replacement, a surgeon replaces a portion of the patient's hip joint 10 with an artificial component. In a total hip replacement, the surgeon removes the femoral head 16 and neck 18 and replaces the natural bone with a prosthetic femoral component 26 having a head 26 a, a neck 26 b, and a stem 26 c (shown in FIG. 2A ). As shown in FIG. 2B , the stem 26 c of the femoral component 26 is anchored within a cavity created by the surgeon in the intramedullary canal of the femur 14. Alternatively, if the disease is confined to the surface of the femoral head 16, the surgeon may opt for a less invasive approach in which the femoral head is resurfaced (e.g., using a cylindrical reamer) and mated with a prosthetic femoral head cup (not shown). Similarly, if the natural acetabulum 22 of the pelvis 12 is worn or diseased, the surgeon resurfaces the acetabulum 22 using a reamer and replaces the natural surface with a prosthetic acetabular component 28 having a hemispherical cup 28a (shown in FIG. 2A ), which may include a liner 28b. To install the acetabular component 28, the surgeon connects the cup 28a to the distal end of an impactor tool and impacts the cup 28a into the reamed acetabulum 22 by repeatedly striking the proximal end of the impactor tool with a mallet. If the acetabular component 28 includes a liner 28b, the surgeon snaps the liner 28b into the cup 28a after implanting the cup 28a. Depending on where the surgeon positions the patient for the procedure, the surgeon can use a straight or offset reamer to ream the acetabulum 22, or a straight or offset impactor to implant the acetabular cup 28a.For example, a surgeon using a postero-lateral approach may prefer straight reaming and impaction, while a surgeon using an anterior-lateral approach may prefer offset reaming and impaction.

[0043] II. Illustrative Robotic Systems The surgical systems described herein can be utilized to perform not only hip replacements, but other surgical procedures as well. As shown in Figure 3A, one embodiment of a surgical system 5 for surgical use in accordance with the present disclosure includes a computer-assisted navigation system 7, a tracking device 8, a computer 15, a display device 9 (or multiple displays 9), and a robotic arm 30.

[0044] The robotic arm 30 can be used interactively by a surgeon to perform surgical procedures on a patient, such as a hip replacement procedure. As shown in FIG. 3B, the robotic arm 30 includes a base 32, an articulated arm 34, a force system (not shown), and a controller (not shown). A surgical tool 58 (e.g., a rotary burring device as seen in FIG. 3A, an end effector 40 having a motion member as seen in FIG. 3B) is coupled to one end of the articulated arm 34, and a surgeon manipulates the surgical tool 58 by grasping and manually moving the articulated arm 34 and / or the surgical tool.

[0045] The force system and controller are configured to provide control or guidance to the surgeon during manipulation of the surgical tool. The force system is configured to provide at least some force to the surgical tool via the articulated arm 34, and the controller is programmed to generate control signals for controlling the force system. In one embodiment, the force system includes an actuator and a back-drivable transmission that provides haptic (or force) feedback to restrict or prohibit the surgeon from manually moving the surgical tool beyond a predefined virtual boundary defined by a haptic object, as described, for example, in U.S. patent application Ser. No. 11 / 357,197, filed February 21, 2006 (U.S. Patent Application Publication No. 2006 / 0142657), and / or U.S. patent application Ser. No. 12 / 654,519, filed December 22, 2009, each of which is incorporated herein by reference in its entirety. In a specific embodiment, the surgical system is the RIO™ Robotic Arm Interactive Orthopedic System manufactured by MAKO Surgical Corp. of Fort Lauderdale, Fla. The force system and controller may be housed within the robotic arm 30 or may be part of an autonomous or handheld unit. In general, the surgical registration method can be performed by the robotic arm of a surgical robot operating autonomously or guided by a surgeon under haptic control. Similarly, the surgical registration method can also be performed via a handheld unit operating within a zone of acceptable motion.

[0046] The tracking device 8 is configured to track the relative locations of the surgical tool 58 (coupled to the robotic arm 30) and the patient's anatomy. The surgical tool 58 may be tracked directly by the tracking device 8. Alternatively, the pose of the surgical tool may be determined by tracking the location of the base 32 of the robotic arm 30 and calculating the pose of the surgical tool 58 based on joint encoder data from the joints of the robotic arm 30 and the known geometric relationship between the surgical tool and the robotic arm 30. Specifically, the tracking device 8 (e.g., optical, mechanical, electromagnetic, or other known tracking system) tracks (or enables the determination of) the pose (i.e., position and orientation) of the surgical tool and the patient's anatomy such that the navigation system 7 knows the relative relationship between the tool and the anatomy.

[0047] In operation, a user (e.g., a surgeon) manually moves the robotic arm 30 to manipulate a surgical tool 58 (e.g., a rotary burring device, an end effector 40 having a moving member) to perform a surgical task on a patient, such as cutting bone or placing an implant. As the surgeon manipulates the tool 58, the tracking device 8 tracks the location of the surgical tool, and the robotic arm 30 provides haptic (or force) feedback to limit the surgeon's ability to move the tool 58 beyond a predefined virtual boundary registered (or mapped) to the patient's anatomy, resulting in highly accurate and repeatable bone cutting and / or implant placement. The robotic arm 30 operates in a passive manner and provides haptic feedback when the surgeon attempts to move the surgical tool 58 beyond the virtual boundary. The haptic feedback is generated by one or more actuators (e.g., motors) within the robotic arm 30 and transmitted to the surgeon via a flexible transmission, such as a cable-driven transmission. When the robotic arm 30 is not providing haptic feedback, the robotic arm 30 is free to move by the surgeon and preferably includes a virtual brake that can be activated by the surgeon as appropriate. During the surgical procedure, the navigation system 7 displays images related to the surgical procedure on one or both of the displays 9.

[0048] To assist in tracking the various units of equipment within the system, the robotic arm 30 may include equipment markers 48 for tracking the global or gross position of the robotic arm 30, tool end markers 54 for tracking the distal end of the articulating arm 34, and a freehand navigation probe 56 for use in the alignment process. Each of these markers 48, 54, 56 (in addition to others, such as navigation markers positioned within the patient's bones) can be tracked by a tracking device 8 having, for example, an optical camera.

[0049] The computer 15 may include a display and input devices (e.g., keyboard, mouse) and is configured to communicate with the navigation system 7, tracking device 8, various display devices 9, and robotic arm 30 within the system. Additionally, the computer 15 may receive information related to a particular surgical procedure and perform various functions related to the performance of the surgical procedure. For example, the computer 15 may include the software needed to perform functions related to image analysis, surgical planning, alignment, navigation, image guidance, and haptic guidance. A more detailed analysis of an exemplary computing system having one or more computing units that may implement the various systems and methods described herein is described below with reference to FIG. 14 .

[0050] FIG. 3B illustrates an end effector 40 that is particularly suited for use in robotic-assisted hip replacement surgery. The end effector 40 is configured to be attached to one end of a robotic arm 30. The end effector 40 includes a mounting portion 50, a housing, a coupling device, and a release member. The end effector 40 is configured to individually and interchangeably support and precisely position multiple motion members relative to the robotic arm 30. As seen in FIG. 3B, the end effector 40 is coupled to a motion member 100. The end effector 40 and related tools, systems, and methods are described in U.S. patent application Ser. No. 12 / 894,071, filed Sep. 29, 2010, which is incorporated herein by reference in its entirety.

[0051] A mounting portion (or mount) 50 preferably couples the end effector 40 to the robotic arm 30. Specifically, the mounting portion 50 extends from the housing and is configured to couple the end effector 40 to a corresponding mounting portion 35 of the robotic arm 30 using, for example, mechanical fasteners, such that the mounting portions are fixed relative to one another. The mounting portion 50 can be attached to the housing or can be integrally formed with the housing and is configured to accurately and repeatably position the end effector 40 relative to the robotic arm 30. In one embodiment, the mounting portion 50 is a semi-kinematic mount as described in U.S. patent application Ser. No. 12 / 644,964, filed December 22, 2009, which is incorporated herein by reference in its entirety.

[0052] 3B is one example of a variety of tools that may be tracked and used by surgical robotic arm 30. Other tools known in the art (e.g., drills, burrs) may also be attached to the robotic arm for a given surgical procedure.

[0053] III. Preoperative planning of surgical procedures Prior to the surgical procedure, a preoperative CT (Computed Tomography) scan of the patient's pelvis 12 and femur 14 is generated by a medical imaging device. While this description will focus on CT scans, other imaging modes (e.g., MRI) can be utilized as well. Additionally or alternatively, X-ray images and / or three-dimensional models 512, 514 derived from CT scans can be used for surgical planning, which can be useful for surgeons accustomed to planning implant placement using actual X-ray images rather than CT-based models. Additionally, generic or statistical models of bone could also be used. These models could be morphed to the patient's bones during the registration process. Additionally or alternatively, patient-specific bone models could also be generated using a combination of two-dimensional X-ray images, with or without patient data collected during registration (e.g., 2D to 3D model).

[0054] The CT scan can be performed by the surgeon or at an independent imaging facility. Additionally or alternatively, intraoperative imaging methods can be used to generate a patient model of the bone. For example, various bone surfaces of a subject can be probed with a tracked probe to generate a surface profile of the subject's surface. The surface profile can be used as the patient bone model. Thus, the present disclosure is applicable to all methods of generating a patient bone model or portion thereof.

[0055] As shown in FIG. 4 , the CT scan or data from the CT scan is segmented to obtain a three-dimensional model 512 of the pelvis 12 and a three-dimensional model 514 of the femur 14. The three-dimensional models 512, 514 are used by the surgeon to construct a surgical plan. The surgeon generates the surgical plan by specifying the desired pose (i.e., position and orientation) of the acetabular component and the femoral component relative to the models 512, 514 of the patient's anatomy. For example, a planned pose 500 of the acetabular cup can be specified and displayed on a computer display, such as a display device 9. During the surgical procedure, the motion of the patient's anatomy and surgical tools in physical space is tracked by a tracking device 8, and these tracked objects are registered to corresponding models in a navigation system 7 (image space). As a result, objects in physical space are associated with corresponding models in image space. Thus, the surgical system 5 knows the actual position of the surgical tools in relation to the patient's anatomy and the planned pose 500, and this information is displayed graphically on the display device 9 during the surgical procedure.

[0056] In certain embodiments, the models 512, 514 may be of the full bone surfaces 12, 14, respectively. In certain embodiments, the models 512, 514 may be trimmed three-dimensional models that provide only important regions of interest, such as the acetabulum 22 and femoral head 16. That is, the trimmed three-dimensional models represent only a portion of the full bone models 512, 514. In certain embodiments, the models 512, 514 may be a combination of multiple models. For example, the model 512 may be a combination of individual three-dimensional models of the surgical pelvis, the non-surgical pelvis, and the spine.

[0057] IV. Intraoperative Procedures A. FIG. 5 illustrates one embodiment of the intraoperative steps for performing a total hip replacement. In this embodiment, steps S1-S7, S9, S11, and S12 can be performed with or without robotic assistance. In other embodiments, S1-S2 may not be required, S3-S5 could be performed before S1-S2, and S7 could be performed at any time before S8. Steps S8 and S10 are preferably performed using a robotic arm 30. For example, step S8 (reaming) could be performed using the robotic arm 30 of FIG. 3 having an end effector 40 coupled to a motion member 100, and step S10 (impactation) could be performed using a robotic arm 30 having an end effector 40 coupled to another motion member.

[0058] B. Tracking and Aligning the Femur In step S1 of the surgical procedure, a tracking array is attached to the femur 14 to enable the tracker 8 to track the motion of the femur 14. In step S2, the femur 14 is aligned to correlate the pose of the femur 14 (physical space) with the 3D model 514 of the femur 14 in the navigation system 7 (image space). Additionally, femur checkpoints can be attached. In step S3, the femur is prepared for surgery.

[0059] The following description provides an exemplary method for preparing and aligning a femur in a surgical procedure on a patient's hip joint. In a particular example, the method for preparing and aligning the femur will be described with reference to Figures 8-13. Additionally, specific steps in the preoperative planning of the femoral implant and femoral preparation will also be described.

[0060] Please refer first to FIGS. 8 and 9A-9D. In a particular example, the registration method 800 may include picking points on both the exterior surface of the proximal portion of the femur and the interior bone surface, such as along the medullary cavity prepared for implantation of the stem of the femoral implant component. As a result, the registration transformation may include interior and exterior bone information to increase the accuracy of the transformation. As observed in FIG. 8, the registration method 800 may include segmenting or modeling the lateral and medial bone surfaces of the femur at 802. A single medical image 900 of a proximal femur 902 is shown in FIG. 9A, where both the lateral bone surface 904 and the medial bone surface 906 have been identified for segmentation. Although only a single medical image 900 is shown, the registration method 800 may include segmenting multiple medical images encompassing the full bone. Thus, the medial and lateral bone surfaces of each of the multiple medical images may be segmented.

[0061] Additionally, the registration method 800 may include identifying a point cloud at 802 of Figure 8 on the proximal femur. As can be seen in Figure 9A, a series of points 908 and their respective locations are identified and stored within the point cloud. As can be seen in the figure, the series of points 908 are located on the femoral neck, femoral head, and greater trochanter.

[0062] Step 802 of alignment method 800 occurs prior to the surgical procedure, while steps 804-808 occur intraoperatively. Alignment method 800 may include, at 804 in FIG. 8, resecting the proximal femur with a bar end effector within a smaller haptic volume than planned to clear the bone cavity for point pickup. As seen in FIG. 9B, the proximal femur 902 has been resected within a volume 910 that is smaller than volume 912 for subsequent resection for implant stem placement.

[0063] Referring again to FIG. 8 , the registration method 800 may include, at 806, a step in which a surgeon picks, logs, or captures points on the internal bone surface along the medullary canal. As seen in FIG. 9C , a tracked probe 914 with a sharp tip may be used to capture points on the internal bone surface along the medullary canal of the proximal femur 902. The probe tip may extend through the undercut volume 910 and into the stem volume 912 to a point 916 for capture. The registration method 800 may also include, at 806, performing an optimization method, such as an Iterative Closest Point (ICP) transform, with the combined new and existing point cloud data, and the registration transform may be updated.

[0064] At step 808 of the alignment method 800, preparation of the femur (i.e., using the bar end effector) to the planned volume for subsequent implantation of the femoral component stem can be completed. As can be seen in FIG. 9D, a full volume 912 has been resected for implantation of the femoral component stem.

[0065] Another femur registration method 1000 is shown in FIGS. 10 and 11A-11D. As can be seen in FIG. 10, the registration method 1000 may include, in step 1002, segmenting the lateral and medial bone surfaces of the femur. In addition, step 1002 also includes picking up a point cloud at the proximal femur for bone registration. FIG. 11A shows a medical image 1100 of a proximal femur 1102, where both the lateral bone surface 1104 and the medial bone surface 1106 have been identified for segmentation. The medical image 1100 also includes a set of points 1108 stored in the point cloud. As can be seen in the figure, the set of points 1108 are located on the femoral neck, femoral head, and greater trochanter.

[0066] Step 1002 of alignment method 1000 occurs prior to the surgical procedure, while steps 1004-1008 occur intraoperatively. Step 1004 of FIG. 10 involves resecting the proximal femur with an end-effector burr within a volume smaller than that ultimately planned for implantation of the femoral implant component stem. This relatively small volume clears the interior femoral cavity for point pickup. As seen in FIG. 11B, the end-effector burr 1114 resects a volume 1110 within the interior portion of the proximal end of the femur 1102. Generally, the burr 1114 can resect in a distal or downward trajectory through the femoral neck and greater trochanter. In certain instances, the femoral head may remain unresected at this point in the procedure. The ablated volume 1110 is within the limits of the relatively large final preparation volume 1112 that will be ablated later in the procedure, as can be seen in FIG. 11B.

[0067] Step 1006 in FIG. 10 involves moving the end-effector burr (or other tool attached to the end of the end-effector) down (distally) the femoral canal and picking, logging, or capturing points on the intact bone surface on the medial portion of the bone. The bone surface can also be detected automatically by monitoring the state of the motors in the system to determine when contact with a hard surface is made. An Iterative Closest Point (ICP) calculation is then performed with the combined new and existing point cloud data. The registration transformation is then updated. As observed in FIG. 11C , the surgeon advances the burr 1114 through the undercut haptic volume 1110 until the burr 1114 contacts the medial bone surface 1106. The surgeon captures, logs, or picks up points 1116 on the medial bone surface 1106. The locations of these points are used to update the registration transformation. Additionally or alternatively, the system may automatically detect when the bar TCP contacts the inner intact cortical bone surface, or this may be measured using a force / torque sensor (or other type of sensor) attached to the bar end effector.

[0068] Step 1008 of Figure 10 includes finalizing the resection of the femoral canal to the planned resection volume or haptic volume for placement of the stem of the femoral implant component using the updated bone registration transformation. As can be seen in Figure 11D, the femoral canal has been sufficiently resected to the full resection volume 1112 according to the surgical plan.

[0069] Another femur registration method 1200 is shown in Figures 12 and 13A-13D. As can be seen in Figure 12, the registration method 1200 may include, in step 1202, segmenting the lateral bone surface of the proximal femur and determining the femoral canal axis of the femoral canal or the Z-axis of the femoral anatomy within a bone model constructed from medical images of the proximal femur. In addition, step 1202 may also include picking up a point cloud on the lateral surface of the proximal femur for bone registration. This particular femur registration method 1200 does not include segmentation of the medial bone surface. As can be seen in Figure 13A, a medical image 1300 of a plurality of medical images of a patient's proximal femur 1302 has been acquired. The lateral bone surface 1304 of the proximal femur 1302 in the medical image 1300 is segmented, and the Z-axis 1306 of the femoral anatomy of the femoral canal is determined from the medical images. The figure also shows points 1308 of a point cloud on the proximal femur 1302. The points 1308 are spaced along the femoral head, femoral neck, and a portion of the greater trochanter.

[0070] Step 1202 of alignment method 1200 occurs preoperatively, while steps 1204-1208 occur intraoperatively. Step 1204 of FIG. 12 involves resecting the proximal femur with an end effector burr within a volume smaller than the fully resected haptic volume for implantation of the femoral implant component stem. The relatively small volume of resection in step 1204 is intended to clear a cavity for point pickup. Additionally, in step 1204, the surgeon may insert a tracker mechanism into the medullary canal. As seen in FIG. 13B, an initial volume 1310 within the femoral canal is resected via the end effector burr. The initial volume 1310 is smaller than the full resection volume 1312 that will be used for implantation of the femoral implant component stem. After the initial volume 1310 is resected, a tracker mechanism or tool 1314 is inserted into the femoral canal. 13B, the tracker mechanism 1314 includes a distal expansion mechanism, a shaft extending proximally from the distal positioning mechanism, and a tracker at the proximal end of the tracker mechanism. The tracker mechanism 1314 can be inserted into the femoral canal such that the distal positioning mechanism extends through the initial volume 1310 and into the bone of the femoral canal.

[0071] Step 1206 of FIG. 12 may include aligning the tracker mechanism 1314 with the medial cortical bone surface of the femur. Referring to FIG. 13C, this shows the tracker mechanism 1314 in a laterally expanded orientation within the femoral canal such that the shaft is approximately parallel to the Z-axis 1306 of the femoral anatomy. As can be seen in the figure, the distal positioning mechanism 1314 may include longitudinally extending members (parallel to the shaft) configured to expand radially outward to contact the medial cortical bone surface of the femur 1302. The members may have markers capable of being viewed under medical imaging to verify that the members are in contact with the cortical bone surface of the femur. As can be seen in the figure, when the members are in contact with the cortical bone surface, the shaft extending proximally from the distal positioning mechanism is parallel to the Z-axis 1306 of the femoral anatomy. In certain examples, the location of the bone contact points can be tracked inside the tracker mechanism 1314. The mechanism 1314 can include two, three, or even more contact points that have the ability to center the tool within the canal to align the midpoint at any given location. In such examples, a tool axis may not be required. In certain examples, the contact points on the tracker mechanism 1314 could be spring-expandable and actively track and map the interior wall of the bone as the tool is inserted into the canal.

[0072] Also, referring back to FIG. 12, the registration method 1200 may include, in step 1206, performing an Iterative Closest Point (ICP) calculation using the existing point cloud and determining the Z-axis of the femoral anatomy, and updating the registration transformation accordingly.

[0073] Step 1208 of Figure 12 may include completing bone preparation by removing the tracker mechanism 1314 and resecting the remainder of the femoral canal to a final resection volume that may have been updated based on the registration transformation. As observed in Figure 13D, the proximal femur 1302 may be sufficiently resected to a final resection volume 1316 for implantation of the stem of the femoral implant component.

[0074] FIG. 13E illustrates another femoral alignment method 1330. As can be seen in FIG. 13E, the alignment method 1330 may include the following operations or steps. In a particular example, the method 1330 may include step (1) of planning implant placement relative to a computer model of the patient's bone in an imaging coordinate system. The implant planning in (1) may provide a planned initial femoral canal preparation (2a) (used in canal alignment) and a planned full preparation (2b) in the imaging coordinate system (to receive the implant stem), because the two planned preparations of the femoral canal may be related to the overall implant plan. Differences (e.g., volumetric differences) between the full preparation (2b) and the canal preparation (2a) may also be calculated in the imaging space (2c).

[0075] Continuing with method 1330 of FIG. 13E, after implant planning (otherwise referred to as preoperative planning) (1), the surgeon can align the proximal femur (3) using any known alignment method. From the proximal femur alignment (3), a proximal alignment transform (4) to the bone coordinate system (bone CS-A) is calculated. Using the proximal alignment transform from (4), the planned femoral canal preparation from (2) is transformed to bone CS-A (5). Then, knowing the femoral canal preparation plan in bone CS-A from (5), the system can prepare the canal in bone CS-A (6) by physically burring the proximal canal of the femur according to the planned canal preparation determined in (2a).

[0076] With the proximal femoral canal now burred or otherwise prepared, the surgeon can now align the medial bone (7) exposed by the burring. The proximal alignment in (3) can be combined with the medial bone alignment in (7) to calculate a full bone alignment transformation for bone CS-B (8). With the full bone transformation from (8), the full bone preparation plan from (2a) is transformed to bone CS-B (9).

[0077] The decision boxes at 10 define where the design can be split between being fully prepared or only partially prepared.

[0078] In Example #1, a full bone preparation is prepared (by ignoring previously prepared canals). Then, knowing the full preparation plan in bone CS-B from (9), the system can prepare the proximal femur according to the full preparation plan in bone CS-B (11) by physically burring the proximal femoral canal according to the full preparation plan from (2b). Bone alignment and preparation are complete in this first example.

[0079] Below, we will explain examples #2 and #3.

[0080] The decision boxes in (16) define where the design can be split between proximal registration (bone CS-A) and full registration (bone CS-B) and the remaining bone preparation with or without correction for the transformation.

[0081] Example #2: Preparing the remaining bone with transformation correction. The difference between bone CS-A from (4) and bone CS-B from (8) is calculated. By knowing the above transformation difference, the femoral canal preparation in bone CS-A (5) can be transformed to bone CS-B (13). The remaining bone in bone CS-B (14) can be calculated by subtracting the canal preparation in bone CS-B (13) from the full planned preparation in bone CS-B (9). Thus, by knowing the remaining bone in bone CS-B, the system can prepare the remaining bone in bone CS-B (15) by burring the remaining bone in the proximal femoral canal according to the full preparation plan. Bone alignment and preparation are complete in this second example.

[0082] Example #3: Preparing the remaining bone without transformation correction. The planned remaining bone from (2c) is transformed into bone CS-B by knowing the transformation from (8). The system can then prepare the assumed remaining bone in bone CS-B (17) under the assumption that the difference between bone CS-A and bone CS-B is minimal and any unprepared bone due to the difference will be floating and can be removed from the canal. Bone alignment and preparation are complete in this third example.

[0083] FIG. 13F illustrates another femoral alignment method 1340. The first step 1342 of the method 1340 is pre-operative planning of an arthroplasty procedure, such as a total hip replacement. More specifically, step 1342 may include planning implant placement of a femoral implant relative to the patient's femur in pre-operative coordinates. This may include selecting implant size, shape, type, and manufacturer, among other variables. Additionally, pre-operative planning of the implant may include virtually positioning and orienting an implant model (e.g., a virtual three-dimensional implant model representing the physical implant provided by the manufacturer) relative to a patient bone model (e.g., a virtual three-dimensional bone model representing the patient's physical femur). The implant model may be provided by the manufacturer. The patient bone model may be generated from a pre-operative scan of the patient's leg. The patient bone model may be generated from a statistical model, a generic model, or any other type of model that represents or approximates the shape, size, and configuration of the patient's physical bone.

[0084] Once the final implant position and orientation have been determined to achieve a particular surgical outcome, a surgical plan can be determined to achieve the final implant position and orientation, for example, the final implant position and orientation will determine the corresponding position and orientation of bone to be removed from the femoral canal so that the stem of a femoral implant can be precisely positioned therein to achieve the desired or planned final implant position and orientation.

[0085] As part of the pre-operative planning step 1342, the method 1340 may also include planning or determining an initial canal preparation plan in step 1344. The initial canal preparation plan may also be referred to as the first bone removal plan of the surgical plan. In an actual, physical surgery, the femoral canal would be prepared, for example, by longitudinally drilling a hole where the stem of a femoral implant will ultimately be positioned. As described herein, the femoral canal would be prepared in at least two steps: initial canal preparation for alignment purposes and final canal preparation for implantation of the femoral implant. Determining the initial canal preparation plan in step 1344 may include determining coordinate locations for partial bone removal of the femoral canal. Step 1344 may also include determining a cutting path for a surgical device to facilitate bone removal from the femoral canal. The coordinate locations and cutting path may be defined in a coordinate system relative to the pre-operative bone model used to plan the final implant position and orientation. As described herein, the initial canal preparation plan may include only partial canal preparation, which involves less bone removal (e.g., less depth, less diameter) than the full canal preparation required for implantation of the femoral implant stem.

[0086] One reason the initial canal preparation plan results in partial bone removal from the femoral canal rather than full preparation of the femoral canal is that the partial bone removal allows for an additional alignment step with data from the femoral canal that occurs before full preparation of the femoral canal. This additional alignment of the internal femoral canal can lead to a more accurate alignment process and, therefore, a more accurate full preparation of the femoral canal. For at least these reasons, the preoperative plan for bone removal can be divided into at least a first bone removal plan that includes a plan for partial removal of bone from the femoral canal (for alignment purposes) and a second bone removal plan that includes a plan for full removal of bone from the femoral canal to achieve the preoperatively planned final implant position and orientation.

[0087] The next step 1346 of method 1340 may include planning or determining a final canal preparation plan. The final canal preparation plan may also be referred to as a second bone removal plan of the surgical plan. Alternatively, the final canal preparation plan may be referred to as a post-alignment canal preparation plan. This step 136 of method 1340 includes planning for femoral canal preparation beyond the initial canal preparation from step 1344. In certain examples, this step 1346 includes planning for femoral canal preparation such that the canal is sufficiently drilled to accept the stem of a femoral implant.

[0088] Step 1346 may include several sub-steps, such as planning a broachless femoral preparation plan in step 1348, planning a single broach preparation plan in step 1350, planning a full canal preparation plan in step 1352, and planning only a canal preparation plan for the remainder of the bone in step 1354. Each of these sub-steps will be described below.

[0089] In determining the final canal preparation plan in step 1346, the method may include a broachless preparation plan in step 1348, in which the femoral canal is planned to be prepared entirely robotically, without manual broaching by the surgeon. As a result, no portion of the bone is left for manual preparation by the surgeon; in other words, the entire final preparation plan (whether the entire canal prep or only canal prep of the remaining portion of the bone) is prepared robotically.

[0090] As an alternative to broachless preparation planning, the final canal preparation plan may include a single-broach preparation plan in step 1350, in which the femoral canal is planned to be prepared partially robotically, with the final broach being performed manually by the surgeon. As a result, a small portion of the bone removal required to place the implant is left separate from the final canal preparation plan so that the surgeon can manually perform the final broach. In traditional (non-robotic) surgery, the surgeon may use a series of broaches of increasing size to prepare the femoral canal. In this case, a final (single) broach may be utilized because the final canal preparation plan is being performed robotically, without the need for a broach. Allowing the surgeon to perform the final broaching of the femoral canal allows the surgeon to make any final adjustments to the implant fit and may also reduce the possibility of removing excess bone from the canal via robotic preparation, since the surgeon can attempt to fit the implant while broaching.

[0091] Also, apart from determining whether the final canal preparation plan will include a broachless plan in step 1348 or a single broach plan in step 1350, the final canal preparation plan 1346 may include a determination of whether to plan the entire femoral canal preparation (including bone removal from the area of ​​the initial canal preparation) in step 1352 or whether to plan the preparation of only the remaining portion of the bone in the bone canal (bone not removed by the initial canal preparation) in step 1354.

[0092] In step 1352, the final canal preparation plan may include planning the overall femoral canal preparation. This may include the femoral canal preparation previously prepared by the initial canal preparation plan. The difference is that the second registration will involve relatively more registration data (e.g., registration data from both the inner canal and outer surfaces of the femur) compared to the first registration, potentially increasing the accuracy of mapping the surgical plan from the preoperative coordinate system to the surgical coordinate system, including the second bone removal plan. Therefore, there may be an improvement to the accuracy of the location of bone removal following the second registration. Therefore, the overall femoral canal preparation planning step may benefit from re-milling or re-removing a portion of the bone originally planned to be removed in the initial canal preparation plan.

[0093] In addition to re-removing a portion of the bone originally planned to be removed in the initial canal preparation plan in step 1344, the planning step for the overall femoral canal preparation in step 1352 may include planning coordinate locations for bone removal of the remaining portion of bone sufficient for implantation of the stem of a femoral implant. Note that the final canal preparation plan that includes the overall femoral canal preparation in step 1352 may include a broachless preparation plan in step 1348 or a single broach preparation plan in step 1350.

[0094] In step 1354, the final canal preparation plan may include planning the preparation of only the remaining bone portions of the femoral canal. This may include preparation of the femoral canal that was not previously prepared by the initial canal preparation plan. In certain instances, there may not be a significant improvement in accuracy from the second alignment, and therefore the increase in time required to re-prepare the bone as performed in the overall canal preparation plan in step 1352 may not be worth the slight increase in accuracy. However, if there is a large increase in accuracy improvement from the second alignment, this may signal that overall canal preparation is beneficial.

[0095] The planning step for preparing only the bone remainder of the femoral canal in step 1354 may include planning coordinate locations for bone removal of the bone remainder sufficient for implantation of the femoral implant stem. Note that the final canal preparation plan including preparation of only the bone remainder of the femoral canal in step 1354 may include a broachless preparation plan in step 1348 or a single broach preparation plan in step 1350.

[0096] In one example, the final canal preparation plan can include a plan for preparing the entire femoral canal with a broachless preparation plan according to step 1352 and according to step 1348. In one example, the final canal preparation plan can include a plan for preparing the entire femoral canal with a single broach preparation plan according to step 1352 and according to step 1350. In one example, the final canal preparation plan can include a plan for preparing only the remaining portion of the bone in the femoral canal with a broachless preparation plan according to step 1354 and according to step 1348. In one example, the final canal preparation plan can include a plan for preparing only the remaining portion of the bone in the femoral canal with a single broach preparation plan according to step 1354 and according to step 1350.

[0097] After pre-operative planning is complete, the surgery can begin in step 1342. As part of the surgery, a femur tracker can be placed or coupled to the patient's bone in step 1356. The femur tracker provides a reference for the surgical navigation system so that the surgical robot has spatial knowledge of the vicinity of the patient's bone within the surgical coordinate system.

[0098] Once the trackers are in place, the proximal femur is aligned (by assuming it is already dislocated from the hip joint) in step 1358. More specifically, the femoral head can be aligned by collecting, logging, or capturing points with a surgical device (e.g., a tracked pointer, an end effector of a robotic arm) on the external surface of the femoral head. The captured points (also referred to as alignment data) can be stored in a point cloud of data and spatially oriented relative to one another according to their location on the external surface of the femoral head. A sufficient number of points are collected to approximate the shape of the surfaces to be aligned.

[0099] The surgical navigation system has the ability to spatially locate the captured points relative to the femur tracker. The internal canal preparation plan from step 1344 is defined relative to a pre-operative bone model representing the patient's femur. Thus, the goal of registration is to accurately transform or map the pre-operative surgical plan (e.g., internal canal preparation plan) into surgical coordinate space relative to the actual femur in the same position and orientation that the surgical plan was in relative to the pre-operative bone model. As a result, the surgical robotic arm and the surgical plan exist in the same coordinate system, and the robotic arm can be operated to execute the surgical plan on the actual patient's bone to achieve the pre-operatively planned femur preparation in step 1342.

[0100] Once points have been captured on the proximal femur, the system computer calculates a registration transformation based on the captured points on the proximal femur in step 1360. The registration transformation is a mathematical algorithm that maps coordinate points associated with the initial canal preparation plan from the pre-operative coordinate system to captured points on the physical femur in the surgical coordinate system. With the registration transformation, the surgical plan including the initial canal preparation plan from step 1344 is transformed or mapped to the surgical coordinate system in step 1362.

[0101] With the initial canal preparation plan defined within the surgical coordinate system, method 1340 now includes, at step 1364, preparing an initial canal in the proximal femur according to the initial canal preparation plan. As described with reference to step 1344, the initial canal preparation plan may include less than full preparation of the femoral canal for implantation of the implant stem. For example, the robotic arm of a surgical robot may be used to drill or mill through the greater trochanter and into the central canal (i.e., the femoral canal). The bone may be milled distally, for example, until the medial surface of the cortical bone is reached. Cortical bone is much harder than the cancellous bone associated with it; therefore, it is easily identified during the procedure. The medial cortical bone is also easily identified within the preoperative bone model. Thus, the medial cortical bone provides an area for registration that can be matched with a registration point on the proximal femur. The combined points may be advantageous for generating a relatively accurate registration transformation because the points are spaced apart and on different surfaces of the bone (medial and lateral). Registration of the proximal femur and central canal is possible because the femoral head is still intact (i.e., has not yet been resected).

[0102] After the initial, partial preparation of the central canal, the method 1340 may include, in step 1366, aligning the inner canal. The inner canal can be aligned in several ways. As one example, a surgical device (e.g., a tracked probe, an end effector of a surgical arm, any of the devices described above) can be used to collect, log, or capture points on the inner cortical bone surface of the femoral canal. As another example, a surgical device (e.g., a tracked probe, an end effector of a surgical arm, any of the devices described above) can be used to collect, log, or capture orientation data associated with the femoral canal. The orientation data may be an axis, such as the longitudinal axis of the femoral canal. The captured points and / or orientation data can be defined as alignment data. The alignment data can be stored in a computer as a point cloud of data.

[0103] Once the medial bone is aligned, method 1340 may include calculating an alignment transformation using alignment data (e.g., captured points) from the femoral canal and alignment data (e.g., captured points and / or orientation data) from the exterior surface of the proximal femur. Because the second alignment transformation in step 1368 includes additional data from the medial canal compared to the first alignment in step 1360, the alignment transformation may have improved accuracy compared to the first alignment transformation.

[0104] In step 1370, method 1340 may include transforming or mapping the final canal preparation plan from step 1346 to the surgical coordinate system based on the calculated registration transformation of step 1368. This step maps coordinate locations and / or instructions for bone removal for the final preparation plan from the pre-operative coordinate system to the surgical coordinate system in the same location and orientation that the surgical plan was oriented and positioned relative to the pre-operative bone model. As a result, the final canal preparation plan, along with the patient's femur and the surgical robot, is located within the surgical coordinate system.

[0105] Following the step of transforming the final canal preparation plan to the surgical coordinate system, method 1340 may include preparing the femur according to the final canal preparation plan in step 1372. The manner in which the femur is prepared depends on the parameters of the final canal preparation plan preoperatively defined in step 1346. In the case of preoperatively planned global canal preparation in step 1352, physical preparation of the global canal will occur in step 1374. In this step, the global femoral canal may be milled or otherwise removed. This includes milling the previous portion of bone previously removed in step 1364, as well as preparing the remaining portion of bone not previously removed. As described above, the initial canal preparation in step 1364 was only a partial preparation of the femoral canal for the purpose of aligning the surfaces or axes of the bone associated with the canal. The final femoral canal preparation involves removing enough bone to accept the stem of a femoral implant. As described above, the global canal preparation may utilize a second registration involving data from the external and internal locations of the femur. Thus, the global femur preparation may still remove bone from the originally prepared portion of the femur because coordinates may have changed due to the subsequent registration.

[0106] In the case of preoperatively planned preparation of only the remaining bone portion of the femoral canal in step 1354, physical preparation of the remaining bone portion will occur in step 1376. In this step, the remaining portion or portions of the bone in the femoral canal that were not previously removed are prepared (i.e., removed) to create a path for the stem of the femoral implant. This may include milling only the portion of bone that was not previously removed into the femoral canal. This step may include substep 1378 of determining whether to use a first registration transformation calculated from points on the exterior of the proximal femur or a second registration transformation calculated from points on the exterior of the proximal femur and femoral canal data obtained from the femoral canal.

[0107] Following physical preparation of the femoral canal and prior to resection of the femoral head, method 1340 may include, in step 1380, marking the femoral neck in preparation for manual resection of the neck. In robotic hip surgery, a femoral tracker may be coupled to the femoral head. Consequently, robotic navigation ceases functioning when the femoral head is resected because the tracker can no longer accurately identify the location of the remainder of the femur. For at least this reason, the femoral neck is marked (e.g., etched) via robotically controlled and navigated guidance to provide guidance to the surgeon in manually resecting the neck. The femoral neck mark may be an etch or burr into the bone along the planned resection plane. The etch or burr may be a cut into the bone that does not completely resect the bone. That is, the cut into the bone may not extend all the way through the cortical bone. Instead, the cut provides a visible mark for the surgeon to use or verify correct placement of the saw blade.

[0108] Manual preparation of the femur is shown in step 1382. Resection of the neck is shown in step 1384, which may include the surgeon using a bone saw, with or without an additional guide or jig, to manually resect the femoral head at the neck. If the final canal preparation included a single broach preparation plan in step 1350, the surgeon may then broach the femoral canal in step 1386. Because the navigated robot has prepared the remainder of the femoral canal preparation, the surgeon uses a single broach to remove the final remaining portion of bone, the only remaining portion of manual canal preparation before implant try-in and implant fitting. This provides the surgeon the opportunity to make minor adjustments to the femoral canal and / or try-in the implant as they broach to provide a precise implant fit.

[0109] The following is a description of an example system that implements method 1340 of FIG. 13F. The system can align a surgical device, such as a surgical robot, with a patient's bone, such as a femur. The femur can include an external surface, such as a femoral head, neck, and greater trochanter. The femur can also include an internal canal or femoral canal. The surgical device and the femur are located in the same surgical coordinate system (e.g., an operating room). The system can include at least one computing device in communication with a surgical navigation system and the surgical device. The surgical navigation system can include a tracking device and at least one tool (e.g., a tracked probe, a surgical robot, and / or a tracking array positioned on the patient) configured to be tracked during its motion by the tracking device. The surgical navigation system is also configured to track the surgical device and / or the tracking array on the surgical device. The at least one computing device stores a surgical plan in a virtual coordinate space. The surgical plan may include data from the pre-operative planning of implant placement from step 1342 of method 1340 of Figure 13F. The surgical plan may also include an initial canal preparation plan, also referred to as a first bone removal plan, in step 1344 of method 1340 of Figure 13F. The surgical plan may also include a final canal preparation plan, also referred to as a second bone removal plan, in step 1346 of method 1340 of Figure 13F. The second bone removal plan may include plans for a broachless preparation plan in step 1348, a single broach preparation plan in step 1350, an overall canal preparation plan in step 1352, and / or a bone remainder preparation plan in step 1354, in addition to other steps such as a neck etching plan.

[0110] The at least one computing device is configured to perform the steps of: a) receiving external bone alignment data corresponding to locations on the external surface of the femur. This bone alignment data may correspond to the proximal bone alignment from step 1358 of method 1340 of FIG. 13F. For example, a surgeon may capture, collect, or log points on the patient's proximal femur (e.g., head, neck) using a tracked probe that is tracked by a surgical navigation system in a surgical coordinate system. The at least one computing device is then configured to b) calculate a first alignment transformation based on the external bone alignment data. This step may correspond to step 1360 of method 1340 of FIG. 13F. The at least one computing device may then c) transform a first bone removal plan of the surgical plan to the surgical coordinate system based on the first alignment transformation. This step may correspond to step 1362 of method 1340 of FIG. 13F. The at least one computing device may also d) receive internal bone canal alignment data corresponding to at least one of location or orientation data from an internal canal of the femur. This step may correspond to step 1366 of method 1340 of Figure 13F. For example, a surgeon may capture, collect, or log points on a patient's partially prepared medial femoral canal for evaluation and alignment purposes to provide further alignment data that may be used in the final preparation of the femoral canal.

[0111] The at least one computing device may also e) calculate a second registration transformation based on both the external bone registration data and the internal bone registration data. This step may correspond to step 1368 of method 1340 of Figure 13F. And the at least one computing device may f) transform a second bone removal plan of the surgical plan to the surgical coordinate system based on the second registration transformation. This step may correspond to step 1370 of method 1340 of Figure 13F.

[0112] Additionally or alternatively, the exemplary system described in the previous paragraph may be described as a computer-implemented method of aligning a surgical device with a patient's bone (e.g., femur). The computer-implemented method may include, among other things, at least one computer-implemented step in steps a) through f).

[0113] Additionally or alternatively, the exemplary system described in the previous paragraph may also be described as one or more tangible computer-readable storage media storing computer-executable instructions for executing a computer process on a computing system, such as at least one computing device described in the previous paragraph. The computer process may include, among other things, steps a) through f) described with reference to the at least one computing device.

[0114] Pelvis Tracking and Alignment 1. Overview 5, an acetabular tracking array is attached to the pelvis 12 to enable the tracking device 8 to track the motion of the pelvis 12. In step S5, a checkpoint can be attached to the pelvis 12 for use in the surgical procedure to verify that the acetabular tracking array is not moving relative to the pelvis 12. The checkpoint can be, for example, the checkpoint described in U.S. Patent Application No. 11 / 750,807, filed May 18, 2007 (U.S. Patent Application Publication No. 2008 / 0004633), which is incorporated herein by reference in its entirety.

[0115] In step S6, the pelvis 12 is registered to correlate the pose of the pelvis 12 (physical space) with the three-dimensional model 512 of the pelvis 12 in the navigation system 7. In a particular embodiment, shown in FIG. 6 , the registration is achieved using a tracked navigation probe 56 to collect points on the pelvis 12 (physical space), which are then mapped to corresponding points on the three-dimensional model 512 of the pelvis 12 (image space). In a particular embodiment, the registration can be achieved using a tool coupled to the end effector 40 of the robotic arm 30. In a particular embodiment, the registration can be achieved by any tool or device that is tracked by the navigation system 7. Subsequent sections of this application describe two methods for registering the three-dimensional model 512 of the pelvis (image space) with the pelvis 12 (physical space).

[0116] 2. Pelvic alignment method As shown in FIG. 6 , the display device 9 can show a representation 512 of the pelvis 12 that includes one or more registration points 516. The registration points 516 assist the surgeon in understanding where on the actual anatomical structures to collect points with the tracked probe. The registration points 516 can be color-coded to further assist the surgeon. For example, registration points 516 on the pelvis 12 that are to be collected next with the tracked probe can be colored yellow, while registration points 516 that have already been collected can be colored green, and registration points 516 that will be collected later can be colored red. After registration, the display device 9 can show the surgeon how well the registration algorithm fit the physically collected points to the representation 512 of the pelvis 12.

[0117] For example, as shown in FIG. 7 , error points 518 can be displayed to indicate how much error exists in the alignment between the surface of the representation 512 and the corresponding surface of the physical pelvis 12. In one embodiment, the error points 518 can be color-coded, for example, with the error points 518 representing the smallest error displayed in green and the error points 518 representing increasing amounts of error displayed in blue, yellow, and red. As an alternative to color-coding, the error points 518 representing different degrees of error could have different shapes or sizes. Verification points 519 can also be displayed. The verification points 519 indicate to the surgeon where points should be collected with the tracked probe to verify the alignment. When the alignment points 519 are collected, the software of the navigation system 7 displays the error (e.g., numerically in millimeters) between the actual points collected on the anatomical structures and the registered location of the representation 512 in physical space. If the alignment error is excessive, the surgeon realigns the pelvis 12 by repeating the alignment step of step S6.

[0118] This type of registration method requires the surgeon to continually switch his or her focus from the display device 9 showing a representation 512 of the pelvis 12 including one or more registration points 516 to the patient's physical pelvis 12 to gather accurate points. Focus switching takes time, and accurate estimation of the location of the registration points 516 on the patient's physical pelvis 12 takes even more time. In such a registration method described in this section, at least 43 points can be acquired to complete an accurate registration.

[0119] A further pelvic registration method S6 involving determining the center of rotation of the acetabulum based on preoperative images and intraoperative point collection is described in related International Patent Application No. PCT / US2017 / 049466, filed August 30, 2017, which is incorporated herein by reference in its entirety. The described method may reduce the total number of points collected compared to the registration methods described above. For example, the method described in this section allows a surgeon to complete accurate registration with 32 or fewer points. Additionally, many of the registrations described in this section are region-based point collection rather than point-based point collection. Region-based point collection allows the surgeon to collect points within a region of the patient's bone rather than precise points identified on the 3D bone model 512. This allows the surgeon to focus on the patient's anatomy and collect points within an allowed region on the top of the bone without having to switch his or her focus to the display screen 9 and back to the patient's physical pelvis 12. Collecting points within an allowed region increases accuracy because it is easier for the surgeon to collect points within a region that encompasses many possible locations of an acceptable point compared to a single acceptable point.

[0120] 3. Pelvis positioning method using the Z-axis of the imaging table and the Z-axis of the surgical table 14A-14B and 15A-15C, which illustrate a pelvic registration method 1400 utilizing acetabular center of rotation data and patient positioning data from a patient during a preoperative imaging scan (e.g., CT, MRI) and while positioned in the operating room. More specifically, registration method 1400 assumes a reclining patient orientation, e.g., supine on an imaging table for a preoperative imaging scan (e.g., CT, MRI), that is the same or similar to the orientation of the same patient lying in the same position (e.g., supine in this example) on an operating room table. This patient orientation data or patient positioning data can be used in conjunction with acetabular center of rotation data, which may be determined from the preoperative imaging scan and from capturing points on the patient's acetabulum intraoperatively, in registering a three-dimensional bony model of the patient's pelvis with the patient's physical pelvis in the operating room.

[0121] Referring first to FIGS. 14A and 14B, which illustrate example steps of a registration method 1400. In step 1402 of FIG. 14A, the registration method 1400 may include generating a preoperative image scan of a patient. The image scan may be generated via a variety of imaging modes, including computed tomography (CT), magnetic resonance imaging (MRI), and X-ray, among others. To generate the image scan, a patient 1500 lying supine on an imaging table 1502 may be imaged via an imaging arm 1504 of an imaging device 1506, as seen in FIG. 15A. In step 1404 of the registration method 1400 of FIG. 14A, the image scan may be segmented along the bone outlines in the image. Once all image scans have been segmented, in step 1406 of FIG. 14A, a three-dimensional bone model of the diseased area (e.g., the ilium and femur) may be generated from the segmented image scan. As an alternative to generating a 3D bone model from segmented image scans, a general or static 3D bone model can be generated that represents the patient's bones.

[0122] At this point, the pre-operative steps of the registration method 1400 diverge: steps 1408, 1410, and 1412 may refer to the patient positioning data portion of the registration method 1400, while step 1414 may refer to the center of rotation calculation portion of the method 1400.

[0123] In step 1408 of FIG. 14A , the Z-axis, long axis, or superior-inferior axis can be identified from the scanned image or from the three-dimensional bone model. As seen in FIG. 15A , the Z-axis 1508 extends longitudinally down the table and from the head to the toes of the patient 1500. The Z-axis 1508 can be identified in the scanned image as the axis along which the imaging table 1502 extends in relation to the imaging arm 1504. For example, in a CT scan, the imaging table 1502 can be motorized to translate the table 1502 and the patient 1500 positioned thereon through an opening or throughway 1510 in the imaging arm 1504 along the Z-axis 1508. In this orientation, the scan can be directed perpendicular to the Z-axis 1508. The Z-axis 1508 can be identified in a coordinate system by the bone model.

[0124] 14, the registration method 1400 may include determining a pelvic axis 1512 (or reference vector) of the patient 1500 from the scanned image or bone model. The pelvic axis 1512 may be the axis that bisects the patient's pelvis between the pubic symphysis and is generally equidistant between the pair of anterior superior iliac spines on opposing ilia. Various methods described herein and known in the art can be used to determine the pelvic axis 1512.

[0125] In step 1412 of Figure 14A, the alignment method 1400 may include determining an angular offset between the Z axis 1508 and the pelvic axis 1512. The angular offset 1514 can be observed in Figure 15C, which will be described below.

[0126] At step 1414 of FIG. 14A , the registration method 1400 may include determining the center of rotation of the acetabulum from the bone model. Determining the center of rotation may be performed by any method described herein or known in the art. An exemplary method for determining the center of rotation of a patient's acetabulum within a bone model generated from preoperative images is described in International Patent Application No. PCT / US2017 / 049466, filed August 30, 2017, which is incorporated herein by reference in its entirety. Another exemplary method for determining the center of rotation of a patient's acetabulum is via kinematic or motion analysis of the patient's femur in relation to the pelvis.

[0127] Referring to FIGS. 14B and 15B, steps of a registration method 1400 that may occur during surgery are shown. In step 1416 of FIG. 14B, the registration method 1400 may include placing a tracker on the patient's pelvis. As seen in FIG. 15B, the patient 1500 is positioned in an operating room, in this case lying supine on an operating room table 1520. The patient 1500 may also be lying in a lateral position on the table 1520, and it can be reasonably assumed that the change from supine to lateral is approximately a pure rotation about the patient's 1500 long axis. A robotic arm 1518 may be located near the operating room table 1520. As seen in the figure, the tracker 1516 may be placed on the diseased side of the pelvis.

[0128] In step 1418 of Figure 14B, the registration method 1400 may include positioning or aligning the patient 1500 on the operating room table 1520 in the same orientation as the patient is lying on the imaging table 1502, as seen in Figure 15B. In step 1420, the registration method 1400 may include collecting two points 1522 on the operating room table 1520 along a long edge 1524 of the table 1520. In step 1422 of the method 1400, a vector 1526 may be calculated between the two points 1522. This vector 1526 may be similar to the Z axis 1508 of the scanned image, in that the patient 1500 is likely lying in a supine position in the same orientation on the imaging table 1502 and the operating room table 1520. Vector 1526 can be determined and stored by the system in a common coordinate system using positioning data for tracker 1516. Additionally or alternatively, a pointer or tracked probe can be used to identify the table axes. For example, a pointer can be positioned in space so that it aligns with the long edge 1524 of table 1520 and the system can capture the axis of the pointer. Additionally or alternatively, the pointer could be aligned with the patient by, for example, placing the pointer along the patient's midline with its pointed tip facing the patient's head. This method would also work with a patient in a recumbent position.

[0129] Step 1424 of the registration method 1400 of Figure 14B may include defining an registration constraint such that the patient's pelvis is angled relative to a vector 1526 (or the long axis of the OR table 1520) on an operating room table 1520 by an angular offset 1514, as shown in Figure 15C. The angular offset 1514 may be defined as the angle between the Z axis 1508 and the pelvic axis 1512 (by assuming that the vector 1526 and the pelvic axis 1512 lie in a common coordinate system), or alternatively, the angular offset 1514 may be defined as the angle between the vector 1526 on the OR table 1520 and the pelvic axis 1512.

[0130] In step 1426 of FIG. 14B, the registration method 1400 may include determining the center of rotation of the patient's pelvis. The center of rotation 1528 is shown in FIG. 15B. This step 1426 may be accomplished via any method known in the art, and may be accomplished via the method described in International Patent Application No. PCT / US2017 / 049466, filed August 30, 2017, which is incorporated herein by reference in its entirety. In the aforementioned PCT application, a method is described for picking points on the patient's acetabulum and forming a sphere based on the points. From the sphere, the center of rotation can be determined.

[0131] Once the center of rotation has been found in step 1426, and once the registration constraints correlating to the angular offsets have been found in step 1424, a registration transformation can be utilized in step 1428 of Figure 14B. The registration transformation merges the bone model (determined from pre-operative image scans of the patient's body) with the patient's physical body on the operating room table 1520 so that the robotic arm 1518 of Figure 15C can be used to move relative to the patient's body in a controlled manner and according to a predetermined plan.

[0132] By knowing the center of rotation of the patient's pelvis in step 1426, the position of the pelvis in the coordinate system is effectively locked during the registration transformation. However, knowing only a single fixed point (center of rotation) means that the pelvis is not constrained to rotate along three axes within this coordinate system. Therefore, more information is needed to merge the bone model and the physical pelvis. The registration transformation can use the registration constraint of step 1428 by locking the orientation of the patient's pelvis with respect to vector 1526 during registration. Because vector 1526 contains coordinates in three directions (x, y, z), the orientation of the pelvis can be determined when combining information from vector 1526 and center of rotation 1528.

[0133] Additionally or alternatively, the surgical registration method may be as shown in Figures 14C and 15D-15E. Figure 14C shows a flowchart illustrating example steps in a surgical registration method 1440. Figure 15D shows an overhead view of a patient 1500 on an imaging table 1502 immediately prior to undergoing an imaging event (e.g., CT, MRI). Figure 15E shows the patient 1500 on an operating room table 1520 immediately prior to undergoing a surgical procedure. The registration method 1440 obtains information regarding the preoperative position and orientation of the patient 1500 on the imaging table 1502 and assumes that certain information regarding the patient's position and orientation will be consistent when the patient lies on the operating room table 1520.

[0134] Referring to FIG. 14C , in step 1442, an image scan of the patient 1500 is generated. The image scan may be CT, X-ray, or MRI, among other imaging modes. In step 1444, the center of rotation (COR) of the acetabulum may be determined relative to an imaging coordinate system. The imaging device may include its own coordinate system (x, y, z) based, for example, on the translation of the imaging table 1502 (as seen in FIG. 15D , the table 1502 lies in the xz plane). That is, the table 1502 may translate in the z direction to move the patient and table within the opening 1510 of the imaging arm 1504 of the imaging device 1506. Additionally, the table 1502 may translate in the x and y directions to center the patient and table within the opening 1510 of the arm 1504.

[0135] The COR of the acetabulum can be identified, for example, by selecting the COR in multiple coordinate views (e.g., coronal, sagittal, axial) or by a user selecting the COR in an image scan. Additionally or alternatively, method 1440 may include, among other things, generating a three-dimensional bone model of the patient's bone from the image scan, a statistical bone model, or a generic bone model. Any method known in the art or described herein can then be used to identify the COR from the bone model in the imaging coordinate system. Note that the COR may be the three-dimensional location (x, y, z) of one or more points relative to the origin (0,0,0) of the imaging coordinate system.

[0136] Moving to the intraoperative portion of method 1440, in step 1446 of Figure 14C and also as seen in Figure 15E, patient 1500 is positioned on OR table 1520. In step 1448, pelvis tracker 1516 is attached to the patient's diseased pelvis.

[0137] In step 1450, the XYZ coordinates of the operating room table 1520 are identified. More specifically, at least three points 1530, 1532, and 1534 are identified on the table 1520, where two points 1530 and 1532 are located on the same side of the table (e.g., the edge of the table so as to be at the same point on the x-axis) and one point 1534 is located on the opposite side of the table 1520. The two points 1530 and 1532 can be oriented or aligned with the OR table axis or the z-axis, as shown in FIG. 15E. All points 1530, 1532, and 1534 can be positioned at the same location along the y-axis. In other words, the three points 1530, 1532, and 1534 can be positioned at the same height relative to a plane defined by the top of the OR table 1520. Three points 1530, 1532, 1534 can be captured or logged by the system's tracked probe and identified relative to the position of the pelvis tracker 1516 in the intraoperative coordinate system. As an alternative to collecting points 1530, 1532, 1534 on the OR table 1520, the table axes (x, y, z) can be determined by sequentially translating the table along the corresponding axes to identify the applicable vectors. In certain instances, it may be advantageous to determine points 1530, 1532 before a major leg manipulation (e.g., before a femur dislocation) to ensure the patient has not moved.

[0138] In step 1452, the XYZ coordinates of the center of acetabulum (COR) can be determined in the intraoperative coordinate system relative to the anatomical tracker 1516 or another point. The COR can be determined based on any method described herein or known in the art. In certain examples, the COR can be determined from a series of motion analyses. In certain examples, the COR can be determined based on a point-pickup method after the femoral head has dislocated from the acetabulum.

[0139] At this point, at least the following points have been identified in the intraoperative coordinate system: points 1530, 1532, and 1534 located on the OR table 1520, and the COR of the patient's acetabulum. And at least the following points have been identified in the preoperative imaging coordinate system: the COR of the acetabulum, as well as coordinate axes (x, y, z) that correlate to the translational motion of the imaging table 1502.

[0140] 14C, a six degree of freedom (DOF) transformation is then computed between the imaging coordinate points and the intraoperative coordinate points to align the preoperative image with the intraoperative position of the patient 1500. As a result, a handheld surgical device, such as a robotic arm or an autonomous or haptically driven device, may be able to identify the patient's position and orientation for the performance of the surgical procedure.

[0141] Additionally or alternatively, surgical registration methods may be those shown in Figures 14D and 15F-15G. Figure 14D shows a flowchart illustrating exemplary steps in a surgical registration method 1460. Figure 15F shows an overhead view of a patient 1500 on an imaging table 1502 immediately prior to undergoing an imaging event (CT, MRI). Figure 15G shows the patient 1500 on an operating room table 1520 immediately prior to undergoing a surgical procedure. The registration method 1460 obtains information regarding the preoperative position and orientation of the patient 1500 on the imaging table 1502 and assumes that certain information regarding the patient's position and orientation will be consistent when the patient lies on the operating room table 1520.

[0142] Referring to FIG. 14D, in step 1462, an image scan of the patient 1500 is generated. The image scan may be CT, X-ray, or MRI, among other imaging modes. In step 1464, the center of rotation (COR) of the acetabulum may be determined relative to an imaging coordinate system. The imaging device may have its own coordinate system (x, y, z) based, for example, on the translational motion of the imaging table 1502 (as seen in FIG. 15F, the table 1502 lies in the xz plane). That is, the table 1502 may translate in the z direction to move the patient and table within the opening 1510 of the imaging arm 1504 of the imaging device 1506. Additionally, the table 1502 may translate in the x and y directions to center the patient and table within the opening 1510 of the arm 1504.

[0143] The COR of the acetabulum can be identified, for example, by selecting the COR in multiple coordinate views (e.g., coronal, sagittal, axial) or by a user selecting the COR in an image scan. Additionally or alternatively, method 1460 may include, among other things, generating a three-dimensional bone model of the patient's bone from the image scan, a statistical bone model, or a generic bone model. Any method known in the art and described herein can then be used to identify the COR from the bone model in the imaging coordinate system. Note that the COR may be the three-dimensional location (x, y, z) of one or more points relative to the origin (0,0,0) of the imaging coordinate system.

[0144] Moving to the intraoperative portion of method 1460, in step 1466 of Figure 14D and also as seen in Figure 15G, patient 1500 is positioned on OR table 1520. In step 1468, pelvis tracker 1516 is attached to the patient's diseased pelvis.

[0145] In step 1470, the XYZ coordinates of the operating room table 1520 are identified. More specifically, at least two points 1530, 1532 are identified on the table 1520, where the two points 1530, 1532 are located on the same side of the table 1520 (e.g., the edge of the table so that they are at the same point on the X axis). The two points 1530, 1532 can be oriented or aligned with the OR table axis or the Z axis, as shown in FIG. 15G. The points 1530, 1532 can be positioned at the same location along the y axis. In other words, the two points 1530, 1532 can be positioned at the same height relative to a plane defined by the top of the OR table 1520. The two points 1530, 1532 can be captured or logged by a tracked pointer of the system and identified relative to the position of the pelvic tracker 1516 within the intraoperative coordinate system. As an alternative to collecting points 1530, 1532 on the OR table 1520, the table axes (x, y, z) can be determined by sequentially translating the table along the corresponding axes to identify the applicable vectors. In certain instances, it may be advantageous to determine points 1530, 1532 before a major leg manipulation (e.g., before a femur dislocation) to ensure that the patient has not moved.

[0146] In step 1472, the XYZ coordinates of the center of acetabulum point (COR) can be determined in the intraoperative coordinate system relative to the anatomical structure tracker 1516 or another point. The COR can be determined based on any method described herein or known in the art. In certain examples, the COR can be determined from a series of motion analyses. In certain examples, the COR can be determined based on a point-pickup method after the femoral head has dislocated from the acetabulum.

[0147] At this point, at least the following points have been identified in the intraoperative coordinate system: points 1530, 1532 located on the OR table 1520, as well as the COR of the patient's acetabulum. And at least the following points have been identified in the preoperative imaging coordinate system: the COR of the acetabulum, as well as coordinate axes (x, y, z) that correlate to the translational motion of the imaging table 1502.

[0148] 14D, a six degree of freedom (DOF) transformation is then computed between the imaging coordinate points and the intraoperative coordinate points to register the preoperative image with the intraoperative position of the patient 1500. This may enable a robotic arm or handheld surgical device, such as an autonomous or haptically driven device, to identify the patient's position and orientation for the performance of the surgical procedure.

[0149] D. Robot Arm Alignment 5, after aligning the pelvis in step S6, the robotic arm 30 can be aligned in step S7. In this step, the robotic arm 30 is aligned to correlate the pose of the robotic arm 30 (physical space) with the navigation system 7 (image space). The robotic arm 30 can be aligned, for example, as described in U.S. Patent Application No. 11 / 357,197, filed February 21, 2006 (U.S. Patent Application Publication No. 2006 / 0142657), which is incorporated herein by reference in its entirety.

[0150] E. Preparing the Acetabulum and Performing the Surgical Procedure During surgery, a surgeon can use the robotic arm 30 of FIG. 3 to facilitate a joint replacement procedure, such as reaming bone and implanting an acetabular cup for a total hip replacement or hip resurfacing procedure. As described above, the robotic arm 30 includes surgical tools configured to be coupled to a cutting element (for reaming) and to engage a prosthetic component (for impaction). For example, as seen in FIG. 3B , for reaming, the end effector 40 can be coupled to a motion member 100, which is coupled to the cutting element. Similarly, for impaction, the end effector 40 can be coupled to another motion member, which is engaged with a prosthetic component. The robotic arm 30 can be used to ensure proper positioning during reaming and impaction.

[0151] In step S8 of FIG. 5 , the surgeon resurfaces the acetabulum 22 using a reamer, such as the motion member 100 coupled to the robotic arm 30 of FIG. 3B . As described above in connection with the motion member 100, the surgeon couples an appropriate motion member (e.g., a straight or offset reamer) to the end effector 40, connects a cutting element to the received motion member, and manually manipulates the robotic arm 30 to ream the acetabulum 22. During reaming, the robotic arm 30 provides tactile (force feedback) guidance to the surgeon. The tactile guidance limits the surgeon's ability to manually move the surgical tool to ensure that the actual bone cut corresponds in shape and location to the planned bone cut (i.e., the cut is consistent with the surgical plan). In certain instances, an autonomous or handheld system may function within a defined virtual boundary without tactile feedback or guidance.

[0152] In step S9 of Figure 5, the surgeon verifies that the alignment (i.e., geometric relationship) between the acetabular tracking array and the pelvis 12 is still valid by contacting the tracked probe with the pelvic checkpoints, as described, for example, in U.S. Patent Application No. 11 / 750,807, filed May 18, 2007 (U.S. Patent Application Publication No. 2008 / 0004633), the contents of which are incorporated herein by reference in their entirety. If the alignment deteriorates (e.g., due to the acetabular tracking array being bumped during reaming), the pelvis 12 is realigned. Alignment verification can be performed any time the surgeon desires to check the integrity of the acetabular alignment.

[0153] In step S10 of Figure 5, the prosthetic component 316 is implanted on the reamed acetabulum 22 using an impactor tool. In the same manner as described above in connection with step S8 (reaming), during the implantation step S10, the display device 9 can show the planned pose 500, the activation area 510, the representations of the anatomical structures 512, 514, and the representations of the surgical tools, as seen in Figure 4. Also, as described above in connection with step S8, if the surgeon moves the end effector 40 to override the haptic feedback, the controller can initiate automatic control of the surgical tools to substantially align at least one aspect of the actual pose with a corresponding desired aspect of the target pose.

[0154] 5, in step S11, the surgeon places the femoral component on the femur 14, and in step S12, the surgeon determines leg length and femoral offset. At any point in the surgical procedure, the display device 9 can show data related to progress and / or results. For example, data related to the actual position of the reamed acetabulum 22 (or implanted acetabular cup) after reaming in step S8 and / or impaction in step S10 may include, for example, numerical data representing the error between the actual and planned locations in three orthogonal planes of the patient's anatomy (i.e., medial / lateral, superior / inferior, and anterior / posterior).

[0155] V. Tools and Methods for Bone Alignment of the Femur, Pelvis, and Vertebrae, In addition to Other Bones Point-pickup-based bone registration is one method of registration in navigated and robotic-assisted orthopedic surgery. During a surgical procedure, an incision is made at a surgical site (e.g., hip, knee). A localization pointer or tracked probe is used to pick up a digitized point cloud (a set of data points in a coordinate system representing the surface contours) on the bone area of ​​the patient's body that is accessible through the incision. Using point pairs and an Iterative Closest Point (ICP) algorithm, the patient point cloud data in "tracker space" (a coordinate system having position data corresponding to trackers on the patient's body and a point cloud of collected points of the patient) is transformed into a three-dimensional bone model of the patient's bone formed from segmented medical images or otherwise. The accurate registration transformation is determined as the least root-mean-square of the point cloud fitting.

[0156] In the context of point-pickup-based registration (femoral, pelvic, or other), intraoperatively picking up points on a bone surface with a probe generally requires the surgeon to have access to the bone through an initial incision at the surgical site. Due to the small incision area, especially in minimally invasive surgery, it can be difficult to ensure six-degree-of-freedom accuracy in registration when relying on point cloud data collected only within the surgical incision. To increase the accuracy of such registration, points can be added to the point cloud away from the surgical site. For example, in a total hip replacement procedure, the surgeon can capture points on the patient's acetabulum and also capture points on the iliac crest surface of the patient's ilium to increase registration accuracy. Still, in the context of total hip replacement, the surgeon can pick points on the proximal femur (e.g., the femoral head) and, in addition, can capture points on the distal or mid-distal femoral surface to increase registration accuracy. However, the iliac crest and distal femur are not present within the initial surgical incision.

[0157] To pick up such distant points (i.e., not within the initial surgical incision) on the iliac crest and distal femur, the surgeon may need to make additional incisions (e.g., stab incisions) away from the initial incision for the sole purpose of contacting one or more of the patient's bones with a tracked probe or locating pointer in a pressure-contact state. Making additional incisions into the patient's body may not be ideal because there is an increased chance of infection, pain, scarring, and time associated with such methods.

[0158] Described herein with reference to Figures 16A-16C are registration tools and methods for use in zones of a patient's body away from the surgical site (i.e., outside the surgical incision) and without further incisions into the patient's skin. As seen in Figure 16A, needles 1 of varying lengths and diameters, such as acupuncture needles or syringe needles, can be used to digitize points on hard bone surfaces without incisions through the patient's skin. The diameter of needle 1 can be small enough to easily penetrate the patient's skin, soft tissue, and cartilage without adverse effects on the patient's comfort. By using needle 1, bone registration points can be picked up in anatomical regions that are not typically accessible through intra-wound point pick-up methods, particularly MIS.

[0159] As seen in FIG. 16B, which is an anterior view of a femur 6 according to the present disclosure, one or more needles 1 a can be inserted into soft tissue 7 through one of multiple holes in a needle fixture or template 2. The needle fixture 2 can guide the needle 1 a through the skin, and the needle 1 a can stop at the hard bone surface of the femur 6. A passive or active location marker can be attached to the needle 1 a to navigate the position of the needle's top via one or more cameras 10 (e.g., optical cameras). A needle tracker 3 a can be coupled to the needle fixture 2. However, the needle tracker 3 a may not be necessary if the needle tip is tracked. The fixture 2 can have multiple functions, including (1) compressing the soft tissue, (2) guiding the insertion of the needle 1 a, and (3) measuring the position of the needle tip relative to the needle tracker 3 a via a transform 8 a.

[0160] Still referring to Figure 16B, bone tracker 4 can be rigidly attached to the hard bone surface of femur 6 by clamps or bone pins 5. The position of the needle tip within the space of bone tracker 4 can be determined through transformation 9a. Needle fixture 2, together with needle tracker 3a, can be freely moved to different anatomical locations of the bone to digitize points on bone surface 6 and add these points to a point cloud. Camera 10 can track the positions of bone tracker 4 and needle tracker 3a.

[0161] As seen in FIG. 16C, an anterior view of a femur 6 according to the present disclosure, the proximal end of needle 1b is attached to a mechanical tracker 3b to navigate the position of the needle tip (distal end of the needle) within the space of the mechanical tracker 3b through a transform 8b. The mechanical tracker 3b can be attached to a bone clamp 5 or another reference location. The mechanical tracker 3b can be aligned to the optical tracker 4 through a transform 9b. The mechanical tracker 3b can report the position of each joint via, for example, an encoder or a fiber optic tracker. A camera (e.g., an optical camera) can track the movement of the optical tracker 4. The position of the needle tip within the space of the bone tracker 4 is then further determined through a transform 9b. The needle fixture 2 and tip center point (TCP) of the mechanical tracker 3b can be freely moved to different anatomical locations of the bone to digitize multiple points on the bone surface 6 and add those points to a point cloud.

[0162] In a particular example, alignment system 1700 can be utilized as seen in Figures 17A-17C, where Figure 17A shows an anterior view of a femur 4 being aligned by alignment system 1700 in the context of a total hip replacement, Figure 17B shows an anterior view of a femur 4 being aligned by alignment system 1700 in the context of a total knee replacement, and Figure 17C shows an anterior view of a tibia 5 being aligned by alignment system 1700 in the context of a total knee replacement.

[0163] As seen in FIG. 17A , the proximal end of the femur 4 can be subjected to point pickup via a tracked pointer through an incision in the patient at the surgical site (e.g., in the hip region). In the case of a total hip replacement, the femoral head can be exposed and easily accessible for point pickup via a tracked pointer to generate a point cloud of data used in the registration process. To increase the accuracy of the registration transformation, the registration system 1700 includes a needle template 2 containing multiple through-holes, a needle tracker 3, and tracking needles 1 a, which are used on the shaft of the femur 4 approximately midway between the proximal femoral head and the distal femoral condyle. The needle template 2 can be pressed against the patient's skin, and the needle template 2 can be used to guide one or more needles 1 a into the patient's skin until they contact the bone surface of the femur. An optical camera (not shown) can detect the position of the needle template 2 and the corresponding position of the needle inside one of the through holes of the template 2 .

[0164] Therefore, when the registration transformation is performed, the system can use point cloud data associated with surface points on the femoral head and on the bone surface of the mid-distal femur to increase the accuracy of the process.

[0165] As seen in FIG. 17B , the distal end of the femur 4 can be subjected to point pickup via a tracked pointer through an incision in the patient at the surgical site (e.g., the knee region). In the case of a total knee arthroplasty, the femoral condyles can be exposed and easily accessible for point pickup via a tracked pointer to generate a point cloud of data used in the registration process. To increase the accuracy of the registration transformation, the registration system 1700 includes a needle template 2 containing multiple through-holes, a needle tracker 3, and a tracking needle 1 a, which are used on the shaft of the femur 4 approximately midway between the proximal femoral head and the distal femoral condyle. The needle template 2 can be pressed against the patient's skin and used to guide the needle 1 a into the patient's skin until it contacts the bone surface of the femur. An optical camera (not shown) can detect the position of the needle template 2 and the corresponding position of the needle within one of the through-holes in the template 2.

[0166] Therefore, when the registration transformation is performed, the system can use point cloud data associated with surface points on the femoral condyles and on the bone surfaces of the mid-distal femur to increase the accuracy of the process.

[0167] As seen in FIG. 17C , the proximal end of the tibia 5 can be subjected to point pickup via a tracked pointer through an incision in the patient at the surgical site (e.g., the knee region). In the case of a total knee arthroplasty, the proximal tibia (e.g., the tibial plateau) can be exposed and easily accessible for point pickup via a tracked pointer to generate a point cloud used in the registration process. To increase the accuracy of the registration transformation, the registration system 1700 includes a needle template 2 containing multiple through-holes, a needle tracker 3, and a tracking needle 1 a, which are used on the shaft of the tibia 5 approximately midway between the proximal and distal tibia. The needle template 2 can be pressed against the patient's skin and used to guide the needle 1 a into the patient's skin until it contacts the bone surface of the tibia. An optical camera (not shown) may detect the position of the needle template 2 and the corresponding position of the needle within one of the through-holes of the template 2 .

[0168] Therefore, when the registration transformation is performed, the system can use point cloud data associated with surface points on the proximal tibia and on the bone surfaces of the mid-distal tibia to increase the accuracy of the process.

[0169] The registration system 1700 described with reference to Figures 17A-17C can be used on the ilium, as seen in Figure 18. More specifically, while the acetabular rim 2 and acetabular articulating surface 1 may be accessible in a total hip replacement procedure, the iliac crest 4 and the area directly below the lip of the iliac crest (i.e., the portion of the back of the ilium between the iliac crest 4 and the anterior gluteal line) are generally not present within the surgical incision for conventional hip replacement procedures. As seen in Figure 18, the articulating surface 1 and acetabular rim 2 can be point-picked up via a tracked pointer through an incision in the hip region. From the articulating surface 1 and rim 2, the system may determine the center of rotation COR, for example, by the method described in International Patent Application No. PCT / US2017 / 049466, filed August 30, 2017, which is incorporated herein by reference in its entirety. To increase the accuracy of the registration transformation, the registration system 1700 includes a needle template 2 containing multiple through-holes, a needle tracker 3, and a tracking needle 1 a, which are used on the iliac crest near the anterior superior iliac spine. The needle template 2 may be pressed against the patient's skin in a pressure-contact state, and the needle template 2 may be used to guide the needle 1 a into the patient's skin until it contacts the bony surface of the ilium. An optical camera (not shown) may detect the position of the needle template 2 and the corresponding position of the needle within one of the through-holes of the template 2.

[0170] Therefore, when the registration transformation is performed, the system can use point cloud data associated with surface points on the acetabulum region of the ilium and on the iliac crest surface to increase the accuracy of the process.

[0171] Additionally or alternatively, the registration system 1700 can be used on other parts of the patient's body that can be segmented, such as the spine (L1, L2, L3, L4, L5). As seen in FIG. 19A, a lateral view of the ilium and spinal column, a tracking array can be positioned on the patient's ilium. Additionally, the registration system 1700 includes a needle template 2 including multiple through-holes, a needle tracker 3, and a tracking needle 1a, which can be used on the bony portions of the posterior surfaces of the vertebrae of the spine. The needle template 2 can be pressed against the patient's skin in a pressure-contact state, and the needle template 2 can be used to guide the needle 1a into the patient's skin until it contacts the bony surface of the vertebra. An optical camera (not shown) can detect the position of the needle template 2 and the corresponding position of the needle within one of the through-holes in the template 2.

[0172] Therefore, when the registration transformation is performed, the system can use point cloud data associated with the vertebrae along with other registration areas to increase the accuracy of the process. The methods described herein may be used on top of any bone and are not limited to leg bones and vertebrae. The needle-based registration method can be used on top of bones in the arms, hands, feet, upper body, and head, without limitation.

[0173] Referring to Figures 20A-20D, these respectively show an axial cross-sectional image of a vertebra 2000 and a bone anchor 2002 positioned therein, an axial cross-sectional image of a vertebra 2000 with a rotary bar 2004 partially positioned within the vertebra 2000, another axial cross-sectional image of a vertebra 2000 with a rotary bar 2004 partially positioned within the vertebra 2000, and an axial cross-sectional image of the bar 2004 extending through the vertebra 2000 to the far medial wall of the cortical bone 2006.

[0174] Accuracy in spinal alignment can be a challenge. Traditionally, tracker devices are positioned within the patient's pelvis so that the vertebrae (to which the surgical procedure is applied) can be separated from the tracker by several non-rigid joints. Thus, when the patient is positioned in the prone position (i.e., stomach-down), among other positions, there can be significant soft tissue pressing against the vertebrae, which can change the position of the vertebrae. Additionally, manipulation of adjacent vertebral segments can cause the vertebrae to shift slightly.

[0175] The purpose of the tools, systems, and methods described below is to confirm and improve alignment by identifying contact with the interior cortical bone of the vertebra 2000 after initial penetration of the outer surface of the vertebra 2000. To this end, FIG. 20A shows an axial cross-sectional image of the vertebra 2000 with a bone anchor 2002 positioned therein. As can be seen in the figure, the shank 2008 of the bone anchor 2002 extends through the pedicle 2010 of the vertebra 2000, initiating contact with the spinal cord 2012. The vertebra 2000 includes cortical bone 2006 (compact bone) on the outer portion or outer shell, including a cortical rim 2014 that surrounds the vertebral body, and cancellous bone 2016 (spongy or trabecular bone) that is interior to the cortical bone 2006. Cortical bone 2006 is harder and denser than cancellous bone 2016, which is more porous, weaker, and more brittle than cortical bone 2006. Cancellous bone 2016 makes up the shafts of long bones (e.g., femur, tibia). Cortical bone 2006 surrounds and protects the spinal cord 2012.

[0176] 20A , upon inserting the bone anchor 2002 into the vertebra 2000, the surgeon attempts to position the anchor 2002 as shown, where the shank 2008 remains within the vertebra 2000 (i.e., has not dislodged on either side of the cortical bone 2006). That is, the shank 2008 first penetrates through the cortical bone 2006 and then remains within the cancellous bone 2016. A conventional method for ensuring placement of the shank 2008 within the vertebra 2000 is for the surgeon to drill through the outer cortical layer of the vertebra 2000 near the pedicle 2010 and attempt to identify the cortical surface, or inner surface of the wall, by "feeling" the tip of the drill bit contacting the inner cortical surface. Once the surgeon detects contact with the inner wall of the cortical bone 2006, the surgeon knows not to proceed further with the drill.

[0177] During the registration procedure, once cortical contact is achieved, the point of contact between the bone and the bar 2004 can be used to update the alignment of the bone position. The surgeon can also update the screw insertion plan, if necessary. The load cell 2020 can detect the direction of contact of the bar 2004 with the bone to optimize the alignment improvement. The system can identify errors by comparing the contact position with the expected contact based on a surgical navigation system that tracks the position of the bar 2004 in relation to the patient's aligned position. If differences exist, the alignment could be updated using the contact point as an internal alignment point.

[0178] 20B-20D illustrate a system and method for aligning a vertebra 2000 using a bur 2004 of an end effector 2018 of a surgical robotic system (not shown in FIGS. 20B-20D but shown and described in this application). Generally, the bur 2004 can be used to create a path into the pedicle 2010. Once inside the bone, the bur 2004 can be shut off to prevent rotation. The surgeon can advance the bur 2004 through the cancellous bone 2016. A load cell 2020 on the end effector 2018 could indicate if the bur 2004 has contacted the cortical bone 2006. The load cell 2020 can be configured to identify and distinguish cancellous bone 2016 from cortical bone 2006 since each bone type has a different stiffness. The load cell 2020 can provide an audible or other (visual, tactile) notification of the contact of the bar 2004 with the cortical bone 2006. According to the tactile setting, the surgical robotic system can prevent the surgeon from advancing the bar 2004 further in the direction of the cortical bone 2006 once a certain stiffness value is reached.

[0179] As seen in FIG. 20B, the surgeon can insert the bur 2004 into the pedicle 2010 in the smallest neck region between the cortical bone 2006 around the spinal cord 2012 and the cortical canal 2022 around the exterior of the vertebra 2000. The bur 2004 can be moved from side to side (as indicated by the arrows in FIG. 20B) to intentionally contact the cortical wall 2006 and align its internal features. The bur 2004 can be pivoted about the entry point to minimize any disruption of the threaded area.

[0180] As seen in FIG. 20C , the surgeon can insert a burr 2004 into the pedicle 2010 in the smallest neck region between the cortical bone 2006 around the spinal cord 2012 and the cortical canal around the exterior of the vertebra 2000. The burr 2004 can be moved over the interior surface of the cortical canal 2022 (as indicated by the arrow in FIG. 20C ) to map out or create an alignment at its top. The identified surface on the cortical canal can then be compared to the model to refine or adjust the alignment.

[0181] 20D, the surgeon can insert the burr 2004 through the pedicle 2010 and through the cancellous bone 2016 until the burr 2004 contacts the far medial surface of the cortical edge 2014. If there is no contact with the burr 2004 in compression against the cortical bone 2006 in the cervical region of the pedicle 2012, contact between the medial surface of the cortical edge 2014 will be confirmed. When the load cell 2020 detects distant cortex, the system can report such contact and update or refine the alignment accordingly.

[0182] In addition to the system detecting when the bur 2004 contacts the cortical bone 2006, the system can also detect a potential breach of the cortical bone 2006. For example, once the bur 2004 contacts the cortical bone 2006, as determined by the load experienced by the load cell 2020 of the end effector 2018, any load experienced at its boundary wall that changes from the previous load (e.g., a sudden decrease in resistance / stiffness that signals a breach of the cortical wall) can be considered a potential breach of the cortical surface 2006.

[0183] In certain examples, a system and method for surgical registration may include the following: The system may align patient data collected during surgery of a vertebra 2000 with a computer model of the vertebra within a coordinate system. The vertebra 2000 may include a cortical bone shell 2006 having an outer surface and an inner surface, and cancellous bone 2016 interior to the cortical bone shell 2006. The vertebra 2000 may define a spinal canal 2022 bounded by the cortical bone shell 2006. In certain examples, the system may include a surgical navigation system and at least one computing device. The surgical navigation system may include a tracking device and at least one tool 2018 tracked by the tracking device. The at least one tool may include an end effector 2018 having a cutting element 2004 at its distal end and a load cell 2018 for sensing a load on the cutting element 2004. The computing device may be in communication with the surgical navigation system. The at least one computing device can then store a computer model of the vertebrae in the coordinate system.

[0184] In certain examples, the at least one computing device can receive load data relating to the load experienced by the cutting element 2004 at the distal end of the end effector 2018 as the cutting element 2004 contacts the cortical bone shell 2006 and the cancellous bone 2016. The at least one computing device can also identify, based on the load data, when the cutting element 2004 contacts the inner surface of the cortical bone shell 2006. The at least one computing device can also receive a point cloud of data associated with the vertebra 2000. The point cloud of data can include coordinate locations on the inner surface of the cortical bone shell 2006 collected via the cutting element 2004. The at least one computing device can also perform or update a transformation to align the point cloud of data associated with the vertebra 2000 with a computer model of the vertebra within a common coordinate system.

[0185] VI. Example Computing Systems 21 , a detailed description of an exemplary computing system 3000 having one or more computing units that may implement the various systems and methods described herein is provided. The computing system 3000 may be applied to any of the computers or systems used in pre- or intra-operative planning of arthroplasty procedures (e.g., alignment), or other computing or network devices. It should be understood that specific implementations of these devices may have different possible specific computing architectures, all of which are not specifically described herein but would be understood by those skilled in the art.

[0186] Computer system 3000 may be a computing system capable of executing computer programs to perform computer processes. Data and program files may be input to computer system 3000, and the computer system reads the files and executes the programs therein. Some of the elements of computer system 3000 are shown in FIG. 21 , including one or more hardware processors 3002, one or more data storage devices 3004, one or more memory devices 3008, and / or one or more ports 3008-3010. In addition, other elements that will be recognized by those skilled in the art may be included in computing system 3000 but are not explicitly depicted in FIG. 21 and will not be further described herein. The various elements of computer system 3000 may communicate with each other via one or more communication buses, point-to-point communication paths, or other communication means not explicitly depicted in FIG. 21 .

[0187] The processor 3002 may include, for example, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), and / or one or more internal level caches. There may be one or more processors 3002, such as a processor 3002 with a single central processing unit, or with multiple processing units capable of executing instructions and performing operations in parallel with each other, commonly referred to as a parallel processing environment.

[0188] Computer system 3000 may be a conventional computer, a distributed computer, or any other type of computer, such as one or more external computers provided via a cloud computing architecture. The described techniques are optionally implemented in software stored on one or more data storage devices 3004, stored on one or more memory devices 3006, and / or communicated via one or more of ports 3008-3010, thereby transforming computer system 3000 of FIG. 21 into a special-purpose device that implements the operations described herein. Examples of computer system 3000 include personal computers, terminals, workstations, mobile phones, tablets, laptops, personal computers, multimedia consoles, gaming consoles, set-top boxes, and the like.

[0189] The one or more storage devices 3004 may include any non-volatile data storage device capable of storing data generated or utilized within the computing system 3000, such as computer-executable instructions for executing computer processes, which may include instructions for both application programs and operating systems (OS) that manage various components of the computing system 3000. The data storage devices 3004 may include, without limitation, magnetic disk drives, optical disk drives, solid-state drives (SSDs), flash drives, and the like. The data storage devices 3004 may include removable data storage media, non-removable data storage, and / or external storage devices provided via a wired or wireless network architecture with such computer program products, including one or more database management products, web server products, application server products, and / or other additional software components. Examples of removable data storage media include compact disc read-only memories (CD-ROMs), digital versatile disc read-only memories (DVD-ROMs), magneto-optical disks, flash drives, and the like. Examples of non-removable data storage media include internal magnetic hard disks, SSDs, and the like. The one or more memory devices 3006 may include volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM), etc.) and / or non-volatile memory (e.g., read-only memory (ROM), flash memory, etc.).

[0190] A computer program product containing mechanisms for implementing systems and methods in accordance with the described technology may reside in data storage device 3004 and / or memory device 3006, which may be referred to as a machine-readable medium. It should be understood that a machine-readable medium may include any tangible, non-transitory medium capable of storing or encoding instructions to perform any one or more of the operations of the present disclosure for execution by a machine, or capable of storing or encoding data structures and / or modules utilized by or associated with such instructions. A machine-readable medium may include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more executable instructions or data structures.

[0191] In some implementations, computer system 3000 includes an input / output (I / O) port 3008 and one or more ports, such as a communications port 3010, for communicating with other computing, network, navigation, or robotic devices. It should be understood that ports 3008-3010 may be combined or separated, and that more or fewer ports may be included within computer system 3000.

[0192] I / O port 3008 may be connected to I / O devices or other devices that allow information to be input to and output from computing system 3000. Such I / O devices may include, for example, without limitation, one or more input or output devices, such as a robotic arm and a navigation and tracking system.

[0193] In one implementation, the input device converts human-generated signals, such as human voice, physical movement, physical touch or pressure, and / or the like, into electrical signals as input data into the computing system 3000 via the I / O port 3008. Similarly, the output device can convert electrical signals received from the computing system 3000 via the I / O port 3008 into signals that can be detected by a human when output, such as sound, light, and / or touch. The input device can be an alphanumeric input device including alphanumeric and other keys to communicate information and / or command selections to the processor 3002 via the I / O port 3008. The input device may be another type of user input device, including, without limitation, a direction and selection control device such as a mouse, trackball, cursor direction keys, joystick, and / or wheel, one or more sensors such as a camera, microphone, position sensor, orientation sensor, gravity sensor, inertial sensor, and / or accelerometer, and / or a touch-sensitive display screen ("touch screen"), and / or a tracking / probe device associated with a navigation and tracking system. The output device may include, without limitation, a display, a touch screen, a speaker, a haptic and / or tactile output device, and / or the like. In some implementations, the input device and the output device may be the same device, for example, in the case of a touch screen.

[0194] In one implementation, the communications port 3010 is connected to a network, allowing the computer system 3000 to receive network data useful in performing the methods and systems described herein, as well as to determine transmission information and network configuration changes. In other words, the communications port 3010 connects the computer system 3000 to one or more communications interfaces configured to send and receive information between the computing system 3000 and other devices via one or more wired or wireless communications networks or connections. Examples of such networks or connections include, without limitation, Universal Serial Bus (USB), Ethernet, Wi-Fi, Bluetooth, Near Field Communications (NFC), Long Term Evolution (LTE), etc. One or more such communication interface devices may be utilized via communication port 3010 to communicate with one or more other devices directly over a point-to-point communication path, over a wide area network (WAN) (e.g., the Internet), over a local area network (LAN), over a cellular (e.g., third generation (3G) or fourth generation (4G)) network, or over another communication means. Additionally, communication port 3010 may be in communication with an antenna or other link for transmitting and / or receiving electromagnetic signals.

[0195] In one example implementation, patient data, bone models (e.g., generic, patient-specific), conversion software, tracking and navigation software, registration software, and other software and other modules and services can be implemented by instructions stored on the data storage device 3004 and / or memory device 3006 and executed by the processor 3002. The computer system 3000 can be integrated with or otherwise form a part of the surgical system 100. The system can be configured to register patient data collected intraoperatively from a first bone with a computer model of the first bone within a common coordinate system. The first bone can be coupled to a second bone to form a joint, such as a hip, knee, shoulder, elbow, or ankle, among others. The system can include a surgical navigation system including a tracker and a tool (e.g., a navigation probe, the end of a surgical robotic arm) that is tracked during its movement by the tracker. Additionally, the system may include one or more computing devices in communication with the navigation system. The computing device may perform the following steps: 1) receiving first data points of patient data from first intraoperatively collected points on an articulation surface of a concave portion of a bone. The first data points may be collected using at least one tool. The first data points may correspond in location to a first articulation region on the computer model; 2) receiving second data points from intraoperatively collected points on a second first bone. The second data points may be collected using at least one tool. The second data points may correspond in location to a second virtual data point on the computer model; 3) determining an intraoperative center of rotation from the first data points. The intraoperative center of rotation may correspond to a physical center of rotation of the second bone relative to the first bone; and 4) comparing a first distance between the virtual center of rotation and the second virtual data point and a second distance between the intraoperative center of rotation and the second data point.and 5) performing a transformation using the patient data and the computer model to correspond in terms of position and orientation.

[0196] However, the system depicted in Figure 21 is one possible example of a computer system that may be used or configured in accordance with aspects of the present disclosure. It should be understood that other non-transitory, tangible computer-readable storage media that store computer-executable instructions for implementing the disclosed techniques on a computing system may be used.

[0197] In this disclosure, among others, the methods disclosed herein, such as those shown in FIG. 5, may be implemented as sets of instructions or machine-readable software. Furthermore, it should be understood that the specific order or hierarchy of steps in the disclosed methods is an example of an illustrative approach. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the methods may be rearranged while remaining within the disclosed subject matter. The accompanying method claims present elements of the various steps in a sample order, but are not necessarily meant to be limited to the specific order or hierarchy presented.

[0198] The described disclosure, including any of the methods described herein, may be provided as a computer program product, software, or computerized method, which may include a non-transitory machine-readable medium having instructions stored thereon that can be used to program a computer system (or other electronic device) to perform a process according to the present disclosure. A machine-readable medium includes any mechanism for storing information in a form (e.g., software, processing application) that is readable by a machine (e.g., a computer). A machine-readable medium may include, without limitation, magnetic storage media, optical storage media, magneto-optical storage media, read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), flash memory, or any other type of medium suitable for storing electronic instructions.

[0199] While the present disclosure has been described above with reference to various implementations, it should be understood that these implementations are for illustrative purposes only and that the scope of the present disclosure is not limited thereto. Many variations, modifications, additions, and improvements are possible. More generally, embodiments according to the present disclosure are described in the context of particular implementations. Features may be separated or combined in different blocks or described by different terminology in various embodiments of the disclosure. These and other variations, modifications, additions, and improvements may fall within the scope of the present disclosure as defined in the appended claims. For example, while the present description describes a method involving the hip, the present disclosure is equally applicable to other joints, including the shoulder, ankle, and spine, among others.

[0200] Generally, although the embodiments described herein are described with reference to specific embodiments, modifications thereto can be made without departing from the spirit and scope of the disclosure. Also, it should be noted that the term "including" as used herein is intended to be inclusive, i.e., "including but not limited to."

[0201] The structure and configuration of the systems and methods shown in the various exemplary embodiments are for illustrative purposes only. While only a few embodiments are detailed in this disclosure, many modifications (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, parameter values, mounting configurations, material use, color, orientation, etc.) are possible. For example, the positions of elements may be reversed or otherwise changed, and the characteristics or number of separate elements or positions may be modified or varied. Accordingly, all such modifications are intended to be within the scope of this disclosure. The order or sequence of any process or method steps may be modified or reordered according to alternative embodiments. Other substitutions, modifications, variations, and omissions may be made in the design, operating conditions, and configuration of the exemplary embodiments without departing from the scope of this disclosure. The above-described embodiments can be described as, but not limited to, the following examples. [Example 1] A system for aligning a device and a femur, the femur including an exterior surface and an interior canal, the femur and the device located within a common coordinate system, the system comprising: a navigation system and at least one computing device in communication with said device; The navigation system is configured to track the device, and the at least one computing device stores a surgical plan in a virtual coordinate space, and the at least one computing device: a) receiving external bone registration data corresponding to locations on the external surface of the femur; b) calculating a first registration transformation based on the external bone registration data; c) transforming a first bone removal plan of the surgical plan into the common coordinate system based on the first registration transformation; d) receiving internal bone canal registration data corresponding to at least one of location or orientation data from an internal canal of the femur; e) calculating a second registration transformation based on both the external bone registration data and the internal bone canal registration data; f) transforming a second bone removal plan of the surgical plan into the common coordinate system based on the second registration transformation. [Example 2] The system of Example 1, wherein the first bone removal plan is defined in the virtual coordinate space and has a first coordinate location for a first portion of bone removal from a virtual inner canal representing the inner canal of the femur. [Example 3] The system of Example 2, wherein the second bone removal plan is defined in the virtual coordinate space and has a second coordinate location for a second portion of bone removal from the virtual inner canal representing the inner canal of the femur. [Example 4] 4. The system of Example 3, wherein the first portion of bone removal from the first bone removal plan includes less bone removal from the virtual canal than the first and second bone removal plans combined. [Example 5] The system of Example 3, wherein the first bone removal plan includes only a partial femoral canal preparation plan that is less than the full canal preparation required for implantation of a femoral implant stem. [Example 6] The system of Example 3, wherein the first portion of bone removal from the first bone removal plan and the second portion of bone removal from the second bone removal plan are collectively comparable in volume to a full canal preparation plan. [Example 7] 7. The system of example 6, wherein the second bone removal plan includes a robotic bone removal portion and a manual bone removal portion. [Example 8] 8. The system of Example 7, wherein the manual bone removal portion is designed for a broach. [Example 9] 4. The system of Example 3, wherein the second coordinate location for the second portion of the bone removal comprises the first coordinate location for the first portion of the bone removal. [Example 10] The system of Example 3, wherein the second coordinate location for the second portion of bone removal from the second bone removal plan encompasses the first coordinate location for the first portion of bone removal from the first bone removal plan. [Example 11] 2. The system of Example 1, wherein the navigation system includes a tracking device and at least one tool configured to be tracked during its movement by the tracking device. [Example 12] The system of Example 1, wherein the surgical plan further includes a position and orientation for femoral neck etching, and the at least one computing device g) receives femoral neck etching data corresponding to physical marks on the femoral neck, the marks being less than a complete resection of the femoral neck. [Example 13] The system of Example 1, wherein the at least one computing device further: g) compares the first alignment transformation with the second alignment transformation, and progresses with one of the first alignment transformation or the second alignment transformation based on the comparison. [Example 14] 1. A computer-implemented method of aligning a device with a femur, the femur including an exterior surface and an interior canal, the device and the femur located within a common coordinate system, the computer-implemented method comprising: receiving external bone registration data corresponding to locations on the external surface of the femur; calculating a first registration transformation based on the external bone registration data; transforming a first bone removal plan of a surgical plan to the common coordinate system based on the first registration transformation, the first bone removal plan including a partial femoral canal preparation plan that is less than a full canal preparation plan required to accept a stem of a femoral implant; receiving internal bone canal alignment data corresponding to at least one of location or orientation data from the internal canal of the femur; calculating a second registration transformation based on both the external bone registration data and the internal bone canal registration data; transforming a second bone removal plan of the surgical plan to the common coordinate system based on the second registration transformation; A method comprising: [Example 15] 15. The computer-implemented method of Example 14, further comprising determining a planned implant placement of an implant model relative to a femoral bone model, the femoral bone model representing the femur. [Example 16] 16. The computer-implemented method of Example 15, further comprising determining a surgical plan to achieve the planned implant placement, the surgical plan comprising the first bone removal plan and the second bone removal plan. [Example 17] the first bone removal plan is planned in a virtual coordinate system relative to a femoral bone model representing the femur, the virtual coordinate system being different from the common coordinate system; 15. The computer-implemented method of Example 14, wherein transforming the first bone removal plan to the common coordinate system based on the first registration transformation comprises mapping the first bone removal plan to the femur in the common coordinate system at the same position and orientation that the first bone removal plan is in the virtual coordinate system relative to a bone model of the femur. [Example 18] the second removal plan is planned in a virtual coordinate system relative to a femoral bone model representing the femur, the virtual coordinate system being different from the common coordinate system; and 15. The computer-implemented method of Example 14, wherein transforming the second bone removal plan to the common coordinate system based on the second registration transformation comprises mapping the second bone removal plan to the femur in the common coordinate system at the same position and orientation as the second bone removal plan is in the virtual coordinate system relative to a bone model of the femur. [Example 19] 19. The computer-implemented method of Example 18, wherein the second bone removal plan includes bone removal from the internal canal of the femur, the second bone removal plan subsuming the bone removal from the first bone removal plan. [Example 20] 20. The computer-implemented method of Example 18, wherein a second bone removal plan includes removing additional bone beyond the bone in the first bone removal plan. [Example 21] 1. A system for registering patient data of a first bone in a first coordinate system with a surgical plan associated with the first bone in a second coordinate system different from the first coordinate system, the first bone having a head portion and a shaft portion extending from the head portion, the system comprising: a) at least one computing device in communication with a navigation system having a tracking device and at least one tool configured to be tracked during its movement by the tracking device, wherein the at least one computing device stores the surgical plan in the second coordinate system, the surgical plan having a virtual bone model representing the first bone, a first bone removal plan associated with the virtual bone model, and a second bone removal plan associated with the virtual bone model, and the at least one computing device: i) receiving a first point cloud of data associated with the first bone, the first point cloud of data having first data associated with the head portion of the first bone; ii) calculating a first registration transformation from a first point cloud of said data; iii) using the first registration transformation, transforming the first bone removal plan of the surgical plan into the first coordinate system at a position and orientation relative to the first bone such that the first bone removal plan existed in the second coordinate system relative to the virtual bone model; iv) receiving a second point cloud of data associated with the first bone, the second point cloud of data having second data associated with an interior portion of the shaft portion of the first bone; v) calculating a second registration transformation from both the first and second data point clouds; and vi) using the second registration transformation to transform the second bone removal plan of the surgical plan into the first coordinate system at a position and orientation relative to the first bone such that the second bone removal plan existed in the second coordinate system relative to the virtual bone model. [Example 22] The system of Example 21, wherein the first and second point clouds of data are collected intraoperatively via a surgical device that is tracked during its movement by the tracking device of the navigation system. [Example 23] 22. The system of example 21, wherein the first bone removal plan comprises a first plan for partial removal of bone from a virtual canal of the virtual bone model. [Example 24] The system of Example 23, wherein the second bone removal plan includes a second plan for full bone removal from the virtual canal of the virtual bone model, and the first and second bone removal plans are intended to prepare for implantation of a femoral implant stem. [Example 25] One or more tangible computer-readable storage media storing computer-executable instructions for executing a computer process on a computing system, the computer process comprising: a) receiving a plurality of image scans of a patient's pelvis; b) generating a three-dimensional bony model of the patient's pelvis from the plurality of image scans; c) identifying a scan axis associated with the plurality of image scans, the scan axis being defined along a long axis of a scanning table of an imaging device; d) identifying bony axes associated with the three-dimensional bone model of the patient's pelvis; e) determining an angular offset between the scan axis and the bone axis; f) determining a virtual center of rotation of at least one virtual bone relative to a three-dimensional bone model of the patient's pelvis; g) using the angular offset and the virtual center of rotation as constraints in a registration transformation utilized in a surgical registration procedure; A medium having: [Example 26] One or more tangible computer-readable storage media storing computer-executable instructions for executing a computer process on a computing system, the computer process comprising: a) receiving a point cloud of data from at least one tool of a surgical navigation system, the at least one tool being tracked during its movement by a tracking device of the surgical navigation system, the at least one tool being configured to store data points in the point cloud data, the point cloud of data having first and second data in a common coordinate system, the first data having pairs of points located on or near a surgical table, and the second data having a plurality of points corresponding to a concave portion of an articular surface, the articular surface being located between a first bone having the concave portion and a second bone having a convex portion; b) determining vectors between pairs of said points of said first data; c) determining a center of rotation from the second data, the center of rotation being of a second bone relative to the first bone; d) utilizing a registration transformation to register the point cloud of data with a three-dimensional computer model of at least one first bone, wherein the vector and the center of rotation are constraints in the registration transformation; A medium having: [Example 27] 1. A computer-implemented method for surgical registration, comprising: a) receiving a point cloud of data from at least one tool of a surgical navigation system, the at least one tool being tracked during its movement by a tracking device of the surgical navigation system, the at least one tool being configured to store data points in the point cloud data based on its position relative to the tracking device, the point cloud of data having first and second data in a first coordinate system, the first data having first and second coordinate points located on or near a surgical table, and the second data having one or more coordinate points corresponding to a center of rotation of a joint formed between a pair of bones; b) utilizing a registration transformation to align the point cloud of data with a plurality of coordinate points associated with a three-dimensional computer model of, or approximating, the bone pair and the joint, the plurality of coordinate points including one or more coordinate points corresponding to a center of rotation of the joint, the plurality of coordinate points being located in a second coordinate system; A method having the following. [Example 28] 28. The computer-implemented method of Example 27, wherein the first and second coordinate points located on or near the surgical table are aligned parallel to a long axis of the surgical table. [Example 29] 29. The computer-implemented method of Example 28, wherein the first data includes a third coordinate point located on or near the surgical table, the third coordinate point being located on an opposite side of the surgical table from the first and second coordinate points. [Example 30] 28. The computer-implemented method of Example 27, wherein the three-dimensional computer model of, or approximating, the bone pair and the joint is generated from a pre-operative image scan of the bone pair and the joint. [Example 31] 28. The computer-implemented method of Example 27, wherein the three-dimensional computer model of or approximating the bone pair and the joint comprises a generic bone model approximating the bone pair and the joint. [Example 32] 28. The computer-implemented method of Example 27, wherein the three-dimensional computer model of or approximating the bone pair and the joint comprises a statistical bone model approximating the bone pair and the joint. [Example 33] 1. A surgical registration system comprising: an alignment needle having a distal tip and a proximal light emitting diode (LED) light marker, the proximal LED light marker configured to be tracked by a tracking device of a surgical navigation system; a needle template having a template block having a plurality of through holes extending therethrough, the through holes being spaced apart from one another on the template block, and each of the plurality of through holes being configured to guide the alignment needle along a trajectory; an optical localization tracker coupled to the needle template, the optical localization tracker configured to be tracked by the tracking device of the surgical navigation system; A system having: [Example 34] 1. A system for registering intraoperatively collected patient data of a vertebra with a computer model of the vertebra in a coordinate system, the vertebra having a cortical bone shell with an outer surface and an inner canal, and cancellous bone within the cortical bone shell, and the vertebra defining a spinal canal bounded by the cortical bone shell, the system comprising: a) a surgical navigation system having a tracking device and at least one tool configured to be tracked during its movement by the tracking device, the at least one tool having an end effector having a cutting element at a distal end thereof and a load cell configured to sense a load on the cutting element; b) at least one computing device in communication with the surgical navigation system, the at least one computing device storing the computer model of the vertebrae in the coordinate system; wherein the at least one computing device i) receiving load data relating to the load experienced by the cutting element at the distal end of the end effector when the cutting element contacts the cortical bone shell and the cancellous bone; ii) identifying when the cutting element contacts the inner canal of the cortical bone shell based on the load data; iii) receiving a point cloud of data associated with the vertebra, the point cloud of data having coordinate locations on the inner canal of the cortical bone shell, the point cloud of data being collected via the cutting element at the distal end of the end effector; and iv) performing or updating a transformation to align the point cloud of data associated with the vertebra with the computer model of the vertebra in a common coordinate system.

Claims

1. 1. A system for registering patient data of a bone with a computer model of the bone in a coordinate system, the bone including a cortical bone shell having an outer surface and an inner surface, and an internal cancellous bone; a) a surgical navigation system including a tracking device and at least one tool configured to be tracked during its movement by the tracking device, the at least one tool including a cutting element at a distal end thereof and a load cell configured to sense a load on the cutting element; b) at least one computing device in communication with the surgical navigation system, the computing device storing a computer model of the bone in the coordinate system; i) receiving load data relating to the load experienced by the cutting element when the cutting element contacts the outer surface of the cortical bone shell, the underlying cancellous bone, and the inner surface of the cortical bone shell; ii) identifying, based on the load data, when the cutting element contacts the inner surface of the cortical bone shell; iii) receiving a point cloud of data associated with the bone, the point cloud of data including coordinate locations on an inner surface of the cortical bone shell, the point cloud of data being collected via the cutting element; iv) performing and updating a transformation to align the point cloud of data associated with the bone with a computer model of the bone in a common coordinate system; and A system comprising:

2. The system of claim 1 , wherein receiving the load data includes receiving stiffness data for each of an outer surface of the cortical bone shell, the internal cancellous bone, and an inner surface of the cortical bone shell.

3. The system of claim 2 , wherein identifying when the cutting element contacts an inner surface of the cortical bone shell based on the load data includes identifying a change in the stiffness.

4. The system of claim 3 , wherein the change in stiffness is based on a stiffness threshold.

5. The system of claim 1 , wherein the point cloud of data is collected intraoperatively by the surgical navigation system.

6. The system of claim 1 , wherein an inner surface of the cortical bone shell defines an inner canal bounded by the cortical bone shell.

7. The system of claim 6 , wherein the at least one computing device further identifies, based on the load data, when the cutting element contacts the inner canal bounded by the cortical bone shell.

8. The system of claim 7 , wherein receiving the point cloud of data includes receiving a coordinate location of the inner pipe.

9. The system of claim 1 , wherein the bone is a vertebra.

10. The system of claim 9 , wherein the vertebrae define an internal canal bounded by the cortical bone shell.

11. The system of claim 1 , wherein the at least one tool includes an end effector having the cutting element at a distal end thereof.

12. The system of claim 11 , wherein receiving the load data relates to a load experienced by the cutting element at a distal end of the end effector of the at least one tool.

13. The system of claim 11 , wherein receiving the load data comprises collecting a point cloud of the data through the cutting element at a distal end of the end effector of the at least one tool.

14. The system of claim 1 , wherein the at least one tool comprises a rotary burr coupled to a robotic arm.

15. The system of claim 1 , wherein the tracking device comprises an optical tracking system, a mechanical tracking system, or an electromagnetic tracking system.

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