WO2025006323A1 - Locating features at pre-defined locations relative to a bone cut surface - Google Patents

Abstract

A system for locating a feature relative to a cut surface is provided. The feature has a pre-defined location relative to the cut surface. The system includes a tool having a tool tip and a tracking element. A display is provided that is capable of providing a visual representation. A computer comprising a processor, configured to: display on the display a visual representation of a resected view of a bone cut surface and a location of a feature having a pre-defined location relative to the bone cut surface, providing feedback on the display of a tool tip physical location relative to the location for the feature A method for locating a feature on a bone cut surface is also provided.

Description

LOCATING FEATURES AT PRE DEFINED LOCATIONS RELATIVE TO A BONE CUT SURFACE

RELATED APPLICATIONS

[0001] This application claims priority benefit of US Provisional Application Serial Number 63/523,173 filed 26 June 2023; the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to computer assisted surgery, and more specifically to systems and methods that decrease the surgical time required to align a cut guide for preparing a bone for a joint implant.

BACKGROUND OF THE INVENTION

[0003] Total joint arthroplasty (TJA) is an orthopedic surgical procedure in which the worn or otherwise compromised articular surfaces of the joint are replaced with prosthetic components, or implants. A TJA procedure for a knee implant is commonly referred to as total knee arthroplasty (TKA) in which the articulating surfaces of a knee joint are replaced with prosthetic components, or implants. TKA requires the removal of worn or damaged articular cartilage and bone associated with a distal femur and proximal tibia in the area of the knee joint surfaces in need of being replaced. The removed cartilage and bone are then replaced with synthetic implants, typically formed of metal or plastic, to create new joint surfaces.

[0004] One of the most difficult aspects of TKA is the accurate removal of bone, referred to as bone cuts or bone resections, to form the cut surfaces on the remaining bone in the desired position and orientation (POSE), which in turn determines the final placement of the implants within the joint since the contact surfaces of the implant are mounted to the cut surfaces. Generally, surgeons plan and create the bone cuts such that the final placement of the implants restores the mechanical axis or kinematics of the patient's leg prior to the wear, while preserving the balance of the surrounding knee ligaments. Even small implant alignment deviations outside of clinically acceptable ranges correlate to less than optimal outcomes that result in increased rates of revision surgery. In TKA, creating the bone cuts to correctly align the implants is especially difficult because the femur requires at least five planar bone cuts to receive a traditional, faceted interface femoral prosthesis. The planar cuts on the distal femur must be aligned in five degrees of freedom to ensure a proper orientation: anterior-posterior translation, proximal-distal translation, external-internal rotation, varus-valgus rotation, and flexionextension rotation. Any malalignment in any one of the planar cuts or orientations may have drastic consequences on the final result of the procedure and the wear pattern of the implant. The results of such misalignment might include discomfort, limited range of motion, revision, and reduced implant longevity.

[0005] A typical TKA procedure involves the use of manual tools including the use of several cutting guides, also referred to herein as cutting blocks or jigs, to form the cut surfaces. These guides require reference to various anatomical landmarks and often include the use of an intramedullary rod in order to align the cut guides to form the cut surfaces in a desired POSE. These manual tools are cumbersome, require considerable surgical experience, are time intensive to deploy, and are not always accurate.

[0006] Despite the aforementioned limitations, these cutting guides do provide a few advantages. For one, the cutting guides typically include one or more guide slots to restrict or align a bone removal device, such as an oscillating saw, in the desired POSE for making a bone cut, and those guide slots help stabilize the bone removal device during cutting to ensure the bone removal device does not deflect from the desired plane. Second, a single cutting guide may include multiple guide slots (referred to herein as an N-in-1 cutting block) which can define more than one cutting plane to be accurately resected, such as a 4-in-l block, 5-in-l block . . . N- in-1 block. Thus, the surgeon can resect two or more planes once the cutting guide is accurately oriented on the bone. Still another advantage is that the guide slots and the working end of the oscillating saw are typically planar in shape and relatively thin, which make them ideal for creating planar cut surfaces. The advantages of using a cutting guide are apparent, however, the cutting guide still needs to be accurately positioned on the bone prior to executing the cut. In fact, it is the alignment of the guide slots in a desired POSE with respect to the bone that remains one of the most difficult, tedious, time consuming, and critical tasks during TKA procedure. A conventional TKA procedure may take approximately 60 minutes to complete with an inordinate amount of this time devoted to cut guide placement.

[0007] To overcome the tedious task of manually aligning cutting guides on the bone, several robotic surgical systems have been developed to accurately form the cut surfaces including the TSolution One® Surgical System (THINK Surgical, Inc., Fremont, CA) and the RIO Robotic Arm. The TSolution One® Surgical System aids in the planning and execution of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Other robotic systems may assist in robotically aligning a cutting guide in a desired POSE such as the hand-held robotic surgical system described in U.S. Pat. No. 11,457,980 and incorporated herein by reference in its entirety. The system includes a hand-held robotic device that robotically aligns a pin with a virtual plane having a pre-determined location relative to the bone. The pins are inserted in the bone coincident with the virtual plane. A cut guide having a guide slot is then clamped onto the pins.

The location of the virtual plane, and therefore the pins inserted in the bone coincident with the virtual plane, is defined such that when the cut guide is clamped onto the pins, the guide slot is aligned with the desired POSE to form the distal cut surface. After the distal cut surface is formed, the hand-held robotic device aligns a pin with a second virtual plane to insert pins in the distal cut surface. An alignment guide having a pair of holes is placed on the pins, where the position of holes corresponds to the desired location to guide a drill for drilling the peg holes for receiving the pegs of a 4-in-l block. However, this second step requires the use of the hand-held device to insert additional pins in the bone and an additional guide to clamp onto the pins to drill the peg holes, which increases the amount of sterile hardware needed for a procedure. Several other robotic systems may have steps that also increase the surgical time.

[0008] One way to control medical costs is to improve the efficiency of medical procedures. By decreasing the time required for a given medical procedure, the number of procedures performed in a given facility may be increased. For example, a surgical suite may be able to accommodate an additional procedure per day with even a slight improvement in a repetitive surgical procedure.

[0009] Thus, while there have been several advancements to form the cut surfaces on a bone for mounting an implant in joint replacement surgery, there continues to be a need for improved methods and systems that reduce the time required to perform a surgical procedure.

SUMMARY OF THE INVENTION

[0010] A system for locating a feature relative to a cut surface is provided. The feature has a pre-defined location relative to the cut surface. The system includes a tool having a tool tip and a tracking element. A display is provided that is capable of providing a visual representation. A computer comprising a processor, configured to: display on the display a visual representation of a resected view of a bone cut surface and a location of a feature having a pre-defined location relative to the bone cut surface, providing feedback on the display of a tool tip physical location relative to the location for the feature.

[0011] A method for locating a feature on a bone cut surface is also provided that includes a visual representation of a resected view of a bone cut surface and a location of a feature having a pre-defined location relative to the bone cut surface being displayed on a display. Feedback is provided on the display of a tool tip physical location relative to the location of the feature.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is further detailed with respect to the following drawings that are intended to show certain aspects of the present of invention, but should not be construed as limit on the practice of the invention, wherein:

[0013] FIG. 1 depicts a surgical system to perform a procedure on a bone in accordance with embodiments of the invention;

[0014] FIGS. 2A and 2B are a detailed view of the hand-held device in accordance with embodiments of the invention;

[0015] FIG. 3 depicts the hand-held device aligning pin for inserting a set of pins coincident with a virtual plane having a pre-determined location relative to a femoral bone in accordance with embodiments of the invention;

[0016] FIG. 4 depicts a cut guide clamped onto the set of pins aligned in FIG. 3 in accordance with embodiments of the invention; [0017] FIG. 5 depicts the use of a digitizer on a formed distal cut surface to locate a set of pre-defined locations for peg holes with use of a graphical user interface (GUI) on a display in accordance with embodiments of the invention;

[0018] FIGs. 6 A and 6B depict a prior art 4-in-l cut block for use in embodiments of the invention;

[0019] FIG. 7 depicts use of a drill guide to assist in forming peg holes normal to the distal surface in accordance with embodiments of the invention;

[0020] FIG. 8 depicts the 4-in-l cut block mounted on the distal cut surface in accordance with embodiments of the invention; and

[0021] FIG. 9 is a flowchart of a method according to embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention has utility as a method and system for increasing the throughput of aligning cutting guides for preparing bones for joint implants. The resultant increase in joint implant surgical throughput results in more efficient utilization of medical facilities. A robotic surgical device may be used to ensure the accuracy in forming one or more cut surfaces on the bone and the embodiments described herein may be utilized to increase the efficiency (e.g., decrease the surgical time) in aligning any other cutting guides during the procedure.

[0023] Some embodiments of the present invention utilize feedback as to the location of a digitizer tip relative to representation of a cut surface to identify pre-defined locations for one or more features to be formed in a cut surface on a bone. The feedback may be provided in real time. “Real time” is the context of inventive feedback is intended to mean that a human user perceives the updates as happening with little or no lag time relative to a command or physical movement. It is appreciated that while total knee arthroplasty (TKA) and the use of a 4-in-l cutting block is used to illustrate the inventive system and method, other surgical procedures for joint replacements involving the hip, shoulder, elbow, jaw, as well as for other structures in the body including the vertebra of the spine may benefit from the concepts presented herein. It is further appreciated that while the feedback of the digitizer tip position relative to a cut surface is used to identify the location for the 4-in-l block peg holes, the method could also apply to locate any feature (e.g., location of a keel hole to be formed in a proximal cut surface on a tibia, location for inserting pins, screws, or other hardware in a cut surface formed on a bone) that has a pre-defined location relative to a cut surface.

[0024] The present invention will now be described with reference to the following embodiments. As is apparent by these descriptions, this invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. The bone as depicted can be that of a living subject, a cadaver, or training model, regardless of whether belonging to, or representative of a human or animal. For example, features illustrated with respect to one embodiment can be incorporated into other embodiments, and features illustrated with respect to a particular embodiment can be deleted from that embodiment. In addition, numerous variations and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention. Hence, the following specification is intended to illustrate some particular embodiments of the invention, and not to exhaustively specify all permutations, combinations, and variations thereof. [0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety.

[0027] The following description provides examples related to knee replacement; however, it should be appreciated that the embodiments described herein are readily adapted for use in a myriad of applications where it is desirous to position implants for joint replacement procedures in other portions of the body.

[0028] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

Definitions

[0029] Unless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below.

[0030] As used in the description of the invention and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0031] Also, as used herein, “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”). [0032] As used herein, the term “bone data” refers to data related to one or more bones. The bone data may be determined: (i) prior to making modifications (e.g., bone cuts, insertion of a pin or screw, etc.) to one or more bones, referred to as pre-operative bone data; and/or (ii) determined after one or more modifications have been made to a bone, referred to as postmodification bone data. The bone data may include: the shapes of the one or more bones; the sizes of the one or more bones; angles and axes associated with the one or more bones (e.g., epicondylar axis of the femoral epicondyles, longitudinal axis of the femur, the mechanical axis of the femur); angles and axes associated with two or more bones relative to one another (e.g., the mechanical axis of the knee); anatomical landmarks associated with the one or more bones (e.g., femoral head center, knee center, ankle center, tibial tuberosity, epicondyles, most distal portion of the femoral condyles, most proximal portion of the femoral condyles); bone density data; bone microarchitecture data; and stress/loading conditions of the bone(s). By way of example, the bone data may include one or more of the following: an image data set of one or more bones (e.g., an image data set acquired via fluoroscopy, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, other x-ray modalities, laser scan, etc.); three- dimensional (3-D) bone models, which may include a virtual generic 3-D model of the bone, a physical 3-D model of the bone, a virtual patient- specific 3-D model of the bone generated from an image data set of the bone; and a set of data collected directly on the bone intra-operatively commonly used with imageless CAS devices (e.g., laser scanning the bone, painting the bone with a digitizer).

[0033] As used herein, the terms “computer-assisted surgical device” and “CAS device” refer to devices used in surgical procedures that are at least in part assisted by one or more computers.

Examples of CAS devices illustratively include tracked/navigated instruments and surgical robots. Examples of a surgical robot illustratively include robotic hand-held devices, serial-chain robots, bone mounted robots, parallel robots, or master-slave robots, as described in U.S. Patent Nos. 5,086,401; 6,757,582; 7,206,626; 8,876,830; 8,961,536; 9,707,043; and 11,457,980; which patents and patent application are incorporated herein by reference. The surgical robot may be active (e.g., automatic/autonomous control), semi-active (e.g., a combination of automatic and manual control), haptic (e.g., tactile, force, and/or auditory feedback), and/or provide power control (e.g., turning a robot or a part thereof on and off). It should be appreciated that the terms “robot” and “robotic” are used interchangeably herein. The terms “computer-assisted surgical system” and “CAS system” refer to a system comprising at least one CAS device and may further include additional computers, software, devices, or instruments. An example of a CAS system may include: i) a CAS device and software (e.g., cutting instructions, pre-operative bone data) used by the CAS device); ii) a CAS device and software (e.g., surgical planning software) used with a CAS device; iii) one or more CAS devices (e.g., a surgical robot); iv) a combination of i), ii), and iii); or iv) any of the aforementioned with additional devices or software (e.g., a tracking system, tracked/navigated instruments, tracking arrays, bone pins, rongeur, an oscillating saw, a rotary drill, manual cutting guides, manual cutting blocks, manual cutting jigs, etc.).

[0034] Also referenced herein is a “surgical plan.” A surgical plan is generated using planning software. The surgical plan may be generated pre-operatively, intra-operatively, or pre- operatively and then modified intra-operatively. The planning software may be used to plan the location for an implant with respect to a bone and/or plan a location to make one or more modifications (e.g., bone cuts, location for inserting bone pins) to the bone. The planning software may include various software tools and widgets for planning the surgical procedure. This may include, for example, planning: (i) a location for of implant data (e.g., a 3-D implant model) with respect to bone data (e.g., a 3-D bone model) to define a location for the implant with respect to the bone; (ii) a location for one or more bone cuts to be made relative to bone data to define the locations for one or more cuts to be made on the bone, and/or (iii) one or more locations for inserting hardware (e.g., bone pins, screws) relative to bone data. All of which may be used to define locations for robot operating instructions (e.g., a cut-file, a virtual plane, virtual boundary, a virtual axis) with respect to the bone data, where a CAS device is directed to align an end-effector (e.g., the hardware, a burr, end-mill, drill bit) with the location of the robot operating instructions when registered to the bone.

[0035] As used herein, the term “digitizer” refers to a device capable of measuring, collecting, recording, and/or designating the position of physical locations (e.g., points, lines, planes, boundaries, etc.) in three-dimensional space. By way of example but not limitation, a “digitizer” may be: a “mechanical digitizer” having passive links and joints, such as the high-resolution electro-mechanical sensor arm described in U.S. Patent No. 6,033,415 (which U.S. patent is hereby incorporated herein by reference); a non-mechanically tracked digitizer probe (e.g., optically tracked, electromagnetically tracked, acoustically tracked, and equivalents thereof) as described for example in U.S. Patent 7,043,961 (which U.S. patent is hereby incorporated herein by reference); an end-effector of a robotic device; or a laser scanner.

[0036] As used herein, the term “digitizing” refers to the collecting, measuring, designating, and/or recording of physical locations in space with a digitizer.

[0037] As used herein, the term “registration” refers to: the determination of the spatial relationship between two or more objects; the determining of a coordinate transformation between two or more coordinate systems associated with those objects; the mapping of an object onto another object; and a combination thereof. Examples of objects routinely registered in an operating room (OR) illustratively include: CAS systems/devices; anatomy (e.g., bone); bone data (e.g., 3-D virtual bone models); a surgical plan (e.g., location of virtual planes defined relative to bone data, cutting instructions defined relative to bone data); and any external landmarks (e.g., a tracking array affixed to a bone, an anatomical landmark, a designated point/feature on a bone, etc.) associated with the bone (if such landmarks exist). Methods of registration known in the art are described in U.S. Pat. No. 6,033,415; 8,010,177; 8,036,441; and 8,287,522; and 10,537,388. In particular embodiments with orthopedic procedures, the registration procedure relies on the manual collection of several points (i.e., point-to-point, point- to-surface) on the bone using a tracked digitizer where the surgeon is prompted to collect several points on the bone that are readily mapped to corresponding points or surfaces on a 3-D bone model. The points collected from the surface of a bone with the digitizer may be matched using iterative closest point (ICP) algorithms to generate a transformation matrix. This transformation matrix and various other transformation matrices provides the mathematical locational relationships between: (i) one or more targets or boundaries defined in a surgical plan (e.g., a pre-defined location for a targeted virtual plane that was defined with respect to bone data, a predefined location of cutting instructions that was defined with respect to bone data); (ii) the coordinate system of a tracking array affixed to the bone (if present); (iii) a CAS device (e.g., the base coordinate system of the CAS device, or a coordinate system of a tracking array affixed to the CAS device and, if needed, calibration data and/or kinematic data that define the location of an end-effector relative to the tracking array); and any other coordinate system or object required to perform the procedure. In other embodiments, the registration is performed using image or imageless registration. [0038] As used herein, the term “display” is intended to encompass a variety of the digital devices that during operation provide an image recognizable to human viewing. Digital devices operative herein as displays illustratively include a graphical user interface (GUI), a computer monitor, a holographic display, a mobile display, a smartphone display, a video wall, a headmounted display, a heads-up display, a virtual reality headset, a broadcast reference monitor, any of the aforementioned with a touchscreen capability, and a combination thereof.

[0039] Referring now to the figures, FIG. 1 is an embodiment of an inventive computer- assisted surgical system shown generally at 100 for implementing improved methods that increases the throughput for aligning cut guides on a bone for preparing one or more bones for joint implants. A 2-DoF device 102, as shown in greater detail in FIGs. 2A and 2B, is provided for maintaining alignment of an end-effector 206 coincident with a virtual plane, a computing system 104, and a tracking system 106. In other inventive embodiments, an end effector extends from a robotic arm. The computing system 104 generally includes hardware and software for executing a medical procedure. By way of example but not limitation, in one preferred form of the present invention, the computing system 104 is configured to control the actuation of the working portion 204 relative to the hand-held portion 202 of the 2-DoF 102 device to maintain alignment of the end-effector axis 207 (FIG. 2B) coincident with a virtual plane defined in a surgical plan. The working portion 204 in operation aligns an end-effector for modifying the subject bone. The computing system 104 may generate control signals to accurately maintain the end-effector axis 207 coincident with a virtual plane defined in the surgical plan based on: a) the location of the virtual plane registered to the location of the bone; b) the tracked location of the bone; and c) the tracked POSE of the 2-DoF device 102. The computing system 104 in some inventive embodiments includes a non-transitory memory in which data, software, or a combination thereof are stored.

[0040] The computing system 104 of the computer-assisted surgical system 100 may include: one or more device computers (108, 109); a planning computer 110; a tracking computer 111; and peripheral devices. Each computer may include one or more processors and/or one or more units of non-transitory computer-readable media. As used herein, non-transitory and non-volatile in the context of computer media are considered to be synonyms. In some inventive embodiments, a device computer 109 is mounted on or in the 2-DoF device 102. Processors operate in the computing system 104 to perform computations and execute software associated with the inventive system and method. The device computer(s) (108, 109), the planning computer 110, and the tracking computer 111 may be separate entities as shown in FIG. 1, or it is also contemplated that operations may be executed on one (or more) computers depending on the configuration of the computer-assisted surgical system 100. For example, the tracking computer 111 may have operational data to control the 2-DoF device 102 without the need for a device computer (108, 109). Furthermore, if desired, any combination of the device computers (108, 109), planning computer 110, and/or tracking computer 111 may be connected together via a wired or wireless connection. In addition, the data gathered by, and/or the operations performed by, the tracking computer 111 and device computer(s) (108, 109) may work together to control the 2-DoF device 102 and, as such, the data gathered by, and/or the operations performed by, the tracking computer 1 11 and device computer(s) (108, 109) to control the 2-DoF device 102 may be referred to herein as a “control system.” It is further appreciated that one or more of the computers may be readily located remote from the surgical site. Cloud-based computation is also contemplated in the present invention. [0041] The peripheral devices allow a user to interface with the computing system 104 and may include, but are not limited to, one or more of the following: one or more user-interfaces, such as a display 112 to display a graphical user interface (GUI); and user-input mechanisms, such as a keyboard 114, a mouse 122, a pendent 124, a joystick 126, a wearable hand or head machine interface device, or a foot pedal 128. If desired, the display 112 may have touchscreen capabilities, and/or the 2-DoF device 102 may include one or more input mechanisms (e.g., buttons, switches, etc.). Another peripheral device may include a tracked digitizer probe 130 to assist in the registration process. Tracking array 120c is assembled to the digitizer probe 130 to permit the tracking system 106 to track the POSE of the digitizer probe 130 in space. The digitizer probe 130 may further include one or more user input mechanisms to provide input to the computing system 104. For example, a button on the digitizer probe 130 may allow the user to signal to the computing system 104 to digitize a point in space to assist in registering the bone to a surgical plan.

[0042] The device computer(s) (108, 109) may include one or more processors, controllers, software, data, utilities, and/or storage medium(s) such as RAM, ROM or other non-volatile or volatile memory to perform functions related to the operation of the 2-DoF device 102. By way of example but not limitation, one or more of the device computers (108, 109) may include software to control the 2-DoF device 102, e.g., generate control signals to move the working portion 204 relative to the hand-held portion 202 to a targeted POSE, receive and process tracking data, control the rotational or oscillating speed of the end-effector 206 by controlling motor 205, execute registration algorithms, execute calibration routines, provide workflow instructions to the user throughout a medical procedure, as well as any other suitable software, data or utilities required to successfully perform the procedure in accordance with embodiments of the invention. In still other inventive embodiments, the device computer (108) is equipped with an alignment alert in lieu of, or in concert with, the aforementioned controls. By way of example, an alignment alert includes an auditory tone, laser projection, vibration in device 102, or a combination thereof that notifies a surgeon as to a correct POSE for a tool to perform a given function. A laser light projection is well-suited to indicate a needed POSE in those instances when a conventional tool decoupled from the control system holds an end effector.

[0043] In some inventive embodiments, the system 100 may include a first device computer 108 located separate from the 2-DoF device 102 and a second device computer 109 housed in the 2-DoF device 102 to provide on-board control. The first device computer 108 may be dedicated to the control of the surgical workflow via a GUI, the registration process and the associated calculations, the display of 3-D models and 3-D model manipulation or animation, as well as other processes. The second device computer 109, also referred to herein as an on-board device computer, may be dedicated to the control of the 2-DoF device 102. For example, the on-board device computer 109 may compute and generate the control signals for the actuator motors (210a, 210b) based on: i) received signals/data corresponding to the real-time POSE of the 2- DoF device from the tracking system; and ii) received signals/data corresponding to the real-time POSE of the virtual plane computed by first device computer 108. The on-board device computer 109 may also send internal data (e.g., operational data, actuator/screw position data, battery life, etc.) via a wired or wireless connection. In some inventive embodiments, wireless optical communication is used to send and receive the signals/data described herein. Details about bi-directional optical communication between a 2-DoF device 102 and a tracking system

106 are further described below. [0044] The planning computer 110 in some inventive embodiments is dedicated to planning the procedure. By way of example but not limitation, the planning computer 110 may contain hardware (e.g., processors, controllers, memory, etc.), planning software, data, and/or utilities capable of: receiving, reading, and/or manipulating medical imaging data; segmenting imaging data; constructing and manipulating three-dimensional (3D) virtual models; storing and providing computer-aided design (CAD) files such as 3-D implant models or other hardware CAD files; planning the POSE of implant models relative to bone data; defining the location of robot operating instructions (e.g., cut-files, virtual planes, virtual boundaries, virtual axes, virtual targets) relative to bone data; generating the surgical planning data for use with the system 100; and providing other various functions to aid a user in planning the surgical procedure. The final surgical plan data may include: one or more images of the bone or virtual models of the bone; bone registration data; subject identification information; the POSE of one or more pins, screws, implants, grafts, fixation hardware defined relative to the bone data; and/or the POSE of robot operating instructions defined relative to the bone data. The device computer(s) (108, 109) and the planning computer 110 may be directly connected in the operating room, or the planning computer 110 may exist as separate entities outside the operating room. The final surgical plan is readily transferred to a device computer (108, 109) and/or tracking computer 111 through a wired (e.g., electrical connection) or a wireless connection (e.g., optical communication, Wi-Fi, Bluetooth) in the operating room; or transferred via a non-transient data storage medium (e.g., a compact disc (CD), or a portable universal serial bus (USB drive)). As described above, the computing system 104 may comprise one or more computers, with multiple processors capable of performing the functions of the device computer 108, the tracking computer 111, the planning computer 110, or any combination thereof. [0045] The tracking system 106 of the present invention generally includes a detection device to determine the POSE of an object relative to the position of the detection device. In some inventive embodiments, the tracking system 106 is an optical tracking system such as the optical tracking system described in U.S. Pat. No. 6,061,644 (which is hereby incorporated herein by reference), having two or more optical detectors 107 (e.g., cameras) for detecting the position of fiducial markers arranged on rigid bodies or integrated directly on the tracked object. By way of example but not limitation, the fiducial markers (120a, 120b, 120c, 120d, 212) may include an active transmitter, such as a light emitting diode (LED) or electromagnetic radiation emitter; a passive reflector, such as a plastic sphere with a retro-reflective film; or a distinct pattern or sequence of shapes, lines or other characters. A set of fiducial markers (120a, 120b, 120c, 120d, 212) arranged on a rigid body, or integrated on a device, is sometimes referred to herein as a tracking array, where each tracking array has a unique geometry/arrangement of fiducial markers (120a, 120b, 120c, 120d, 212), or a unique transmitting wavelength/frequency (if the markers are active LEDS), such that the tracking system 106 can distinguish between each of the tracked objects.

[0046] In specific inventive embodiments, the tracking system 106 may be incorporated into an operating room light 118 as shown in FIG. 1, located on a boom, a stand, or built into the walls or ceilings of the operating room. The tracking system computer 111 includes tracking hardware, software, data, and/or utilities to determine the POSE of objects (e.g., bone structures, the 2-DoF device 102) in a local or global coordinate frame. The output from the tracking system 106 (i.e., the POSE of the objects in 3-D space) is referred to herein as tracking data, where this tracking data may be readily communicated to the device computer(s) (108, 109) through a wired or wireless connection. In a particular inventive embodiment, the tracking computer 106 processes the tracking data and provides control signals directly to the 2-DoF device 102 and/or device computer 108 based on the processed tracking data to control the position of the working portion 204 of the 2-DoF device 102 relative to the hand-held portion 202. In another inventive embodiment, the tracking computer 106 sends tracking data to a receiver located on the 2-DoF device 102, where an on-board device computer 109 generates control signals based on the received tracking data.

[0047] The tracking data is determined in some inventive embodiments using the position of the fiducial markers detected from the optical detectors and operations/processes such as image processing, image filtering, triangulation algorithms, geometric relationship processing, registration algorithms, calibration algorithms, and coordinate transformation processing.

[0048] Bi-directional optical communication (e.g., light fidelity or Li-Fi) may occur between the 2-DoF device 102 and the tracking system 106 by way of a modulated light source (e.g., light emitting diode (LED)) and a photosensor (e.g., photodiode, camera) regardless of the wavelengths employed. The 2-DoF device 102 may include an LED and a photosensor (i.e., a receiver) disposed on the working portion 204 or hand-held portion 202, where the LED and photosensor are in communication with a processor such as modem or an on-board device computer. Data generated internally by the 2-DoF device 102 may be sent to the tracking system 106 by modulating the LED, where the light signals (e.g., infrared, visible light) created by the modulation of the LED are detected by the tracking system optical detectors (e.g., cameras) or a dedicated photosensor and processed by the tracking system computer 111. The tracking system 106 may likewise send data to the 2-DoF device 102 with a modulated LED associated with the tracking system 106. Data generated by the tracking system 106 may be sent to the 2-DoF device

102 by modulating the LED on the tracking system 106, where the light signals are detected by the photosensor on the 2-DoF device 102 and processed by a processor in the 2-DoF device 102. Examples of data sent from the tracking system 106 to the 2-DoF device 102 includes operational data, surgical planning data, informational data, control data, positional or tracking data, pre-procedure data, or instructional data. Examples of data sent from the 2-DoF device 102 to the tracking system 106 may include motor position data, battery life, operating status, logged data, operating parameters, warnings, or faults.

[0049] It should be appreciated that in some embodiments of the present invention, other tracking systems are incorporated with the surgical system 100. By way of example but not limitation, the surgical system 100 may include an electromagnetic field tracking system, ultrasound tracking systems, accelerometers and gyroscopes, and/or a mechanical tracking system. The replacement of a non-mechanical tracking system with other tracking systems will be apparent to one skilled in the art in view of the present disclosure. In one form of the present invention, the use of a mechanical tracking system may be advantageous depending on the type of surgical system used such as the computer-assisted surgical system described in U.S. Pat. No. 6,322,567; assigned to the assignee of the present application and incorporated herein by reference in its entirety.

[0050] FIGS. 2A and 2B are schematic views showing the 2-DoF device 102 in greater detail. More particularly, FIG. 2A shows the 2-DOF device 102 in a first working POSE, and FIG. 2B illustrates the 2-DOF device 102 in a second working POSE. The 2-DoF device 102 includes a hand-held portion 202 (or handle) and a working portion 204. The hand-held portion 202 includes an outer casing 203 of ergonomic design which can be held and wielded by a user (e.g., a surgeon). In particular inventive embodiments, the 2-DoF device 102 is intended to be fully supported by the hands of the user in that there are no additional supporting links connected to the 2-DoF device 102 and the user supports the full weight of the 2-DoF device 102. The working portion 204 comprises an end-effector 206 having an end-effector axis 207. The endeffector 206 may be removably coupled to the working portion 204 (via a coupler (e.g., chuck)) and driven by a motor 205. The hand-held portion 202 and working portion 204 are connected to one another; for example, by a first linear actuator 207a and a second linear- actuator 207b in order to control the pitch and translation of the working portion 204 relative to the hand-held portion 202, as will hereinafter be discussed in further detail. In a particular inventive embodiment, the working portion 204 is removably coupled to the hand-held portion 202 to permit different types of working portions to be assembled to the hand-held portion 202. For example, a first working portion 204 may illustratively be a laser system having components to operate a laser for treating tissue, a second working portion 204 may illustratively be a drill for rotating a bone pin, and a third working portion 204 may illustratively be an oscillating saw.

[0051] A tracking array 212, having three or more fiducial markers, is preferably rigidly attached to the working portion 204 in order to permit the tracking system 106 (FIG. 1) to track the POSE of the working portion 204. The three or more fiducial markers alternatively, may be integrated directly with the working portion 204. The 2-DoF device 102 may further include one or more user input mechanisms such as triggers (e.g., trigger 214) or button(s). The user input mechanisms may permit the user to perform various functions illustratively including: activating or deactivating the motor 205, activating or deactivating the actuation of the working portion 204 relative to the hand-held portion 202, notifying the computing system 104 to change from targeting one virtual plane to a subsequent virtual plane, and pausing the medical procedure.

[0052] Within the outer casing of the hand-held portion 202 is the first linear actuator 207a and the second linear- actuator 207b. Each linear actuator (207a, 207b) may include a motor (210a, 210b) to power a screw (216a, 216b) (e.g., a lead screw, a ball screw), a nut (218a, 218b), and a linear rail (208a, 208b). In some inventive embodiments, the motors (first motor 210a, second motor 210b) are electric servomotors that bi-directionally rotate the screws (216a, 216b). Motors (210a, 210b) may also be referred to herein as linear actuator motors. The nuts (218a, 218b) (e.g„ ball nuts, elongated nuts) are operatively coupled to the screws (216a, 216b) to translate along the screws (216a, 216b) as each screw is rotated by its respective motor (210a, 210b). A first end of each linear rail (208a, 208b) is coupled to a corresponding nut (216a, 216b) and the opposing end of each linear rail (208a, 208b) is coupled to the working portion 204 via hinges (220a, 220b) such that the hinges (220a, 220b) allow the working portion 204 to pivot relative to the linear rails (208a, 208b). The motors (210a, 210b) power the screws (216a, 216b) which in turn cause the nuts (218a, 218b) to translate along the axis of the screws (216a, 216b). Translation of nuts (218a, 218b) along ball screws (216a, 216b), respectively, causes translation of front linear rail 208a and back linear rail 208b, respectively, whereby to permit (a) selective linear movement of working portion 204 relative to hand-held portion 202, and (b) selective pivoting of working portion 204 relative to hand-held portion 202 of 2-DoF device 102. Accordingly, the translation “d” and pitch “a” (FIG. 2B) of the working portion 204 may be adjusted depending on the position of each nut (218a, 218b) on their corresponding screw (216a, 216b). A lineai- guide 222 (FIG. 2A) may further constrain and guide the motion of the linear rails (208a, 208b) in the translational direction “d”. In a particular embodiment, the nuts (216a, 216b) are elongated and couple directly to the working portion 204 via the hinges (220a, 220b), in which case the linear rails (208a, 208b) are no longer a component of the linear actuators (207a, 207b). It should be appreciated that other linear actuation mechanisms/components may be used to adjust the POSE of the working portion 204 relative to the hand-held portion 202 such as linear motors, pneumatic motors, worm drives and gears, rack and pinion gears, and other arrangements of motors and transmissions.

[0053] The 2-DoF device 102 may receive power via an input/output port (e.g., from an external power source) and/or from on-board batteries (not shown).

[0054] The motors (205, 210a, 210b) of the 2-DoF device 102 may be controlled using a variety of methods. By way of example but not limitation, according to one method of the present invention, control signals may be provided via an electrical connection to an input/output port. By way of further example but not limitation, according to another method of the present invention, control signals are communicated to the 2-DoF device 102 via a wireless connection, thereby eliminating the need for electrical wiring. The wireless connection may be made via optical communication. In certain inventive embodiments, the 2-DoF device 102 includes a receiver for receiving control signals from the computing system 104 (FIG. 3). The receiver may be, for example, an input port for a wired connection (e.g., Ethernet port, serial port), a transmitter, a modem, a wireless receiver (e.g., Wi-Fi receiver, Bluetooth® receiver, a radiofrequency receiver, an optical receiver (e.g., photosensor, photodiode, camera)), or a combination thereof. The receiver may send control signals from the computing system 104 directly to the motors (205, 210a, 210b) of the 2-DoF device 102, or the receiver may be in communication with a computer (e.g., an on-board device computer 109 as further described below) that processes signals received by the receiver and then generates the control signals for the motors (205, 210a, 210b) based on the received signals.

[0055] FIG. 3 depicts the hand-held device 102 aligning a set of pins (300a, 300b) coincident with a virtual plane "‘VP” having a pre-defined location relative to the femur “F”. The location of the virtual plane “VP” may be defined based on the planned location for forming the distal cut surface (shown in FIG. 4) on the bone. In some inventive embodiments, the location of the virtual plane “VP” is defined by translating the planned location for the distal cut surface by a numerical amount corresponding to the geometry of the cutting guide 302 (shown in FIG. 4) such that the guide slot 308 of the cut guide 302 aligns with the planned location for the distal cut surface “DC” when the cut guide 302 is coupled to the pins (300a and 300b). The hand-held device 102 aligns a pin coincident with the virtual plane for insertion of the pins in the bone by moving the working portion 204 relative to the hand-held portion 202 in response to control signals generated by the computing system 104. This is a highly accurate procedure and ensures the guide slot 308 of the cut guide 302 will align with the planned location for the distal cut surface “DC”. FIG. 3 shows two pins (300a and 300b) inserted in the bone coincident with the virtual plane “VP” for receiving a cutting guide 302.

[0056] FIG. 4 depicts the cutting guide 302 coupled (e.g., clamped) to the pins (300a, 300b), where the guide slot 308 is aligned with the planned location to form the distal cut surface “DC” in the femoral bone F. A saw blade 402 of a standard oscillating saw 400 is advanced through the guide slot 308 to form the distal cut surface “DC”. It is appreciated that the saw blade 402 is a subset of end-effectors previously denoted as 206. The guide slot 308 of the cutting guide 302 advantageously stabilizes the oscillating saw 400 during cutting to reduce any deflection in forming the distal cut surface “DC”. This further adds to the accuracy of the resulting bone cuts. It should be appreciated that the distal cut surface, in particular, requires a great degree of accuracy because the final POSE of the distal cut surface defines the varus-valgus rotation, flexion-extension rotation, and proximal-distal position of implant relative to the bone. The final POSE of the remaining cut surfaces, while important, do not have as much of an effect on the final implant position from a clinical perspective as the distal cut surface. As such, it is advantageous to use a robotic surgical device when forming this distal cut surface for the enhanced accuracy.

[0057] As shown in FIG. 5, in accordance with certain embodiments of an inventive method, after the distal cut surface “DC” is formed, the user moves a tool 500 around the distal cut surface “DC” to locate the pre-defined locations for the peg holes as will be discussed in regard to FIGs. 6A and 6B that will receive the pegs of a 4-in-l cut block 310 in the planned POSE. The tool 500 may be any tool having a tool tip 506 and a tracking element 502 for a tracking system to track movement of the tool 500 in space. The tracking element 502 may include a tracking array having a plurality of fiducial markers for an optical tracking system to track movement of the tool 500. In other inventive embodiments, the tracking element 502 may include an electromagnetic emitter, an acoustic emitter, or an attachment for a distal end of an electro-mechanical arm. In particular inventive embodiments, the tool 500 is a digitizer having a digitizer tip and a tracking array. A display 600 in some inventive embodiments also displays a graphical user interface (GUI) and the real-time position corresponding to that of the physical tool tip 506 relative to a computer representation of a resected view of a femoral bone model “RFM” and is particularly useful in addressing the problems of the prior art and serves to speed a surgical procedure. The resected view of the femoral bone model “RFM” may be an updated view of a femoral bone model now having the distal cut surface formed on the femoral bone model “FM” (e.g., the bone that was removed distal to the distal cut surface is subtracted from the femoral bone model to generate the resected view of the femoral bone model “RFM”). This resected view of the femoral bone model “RFM” may be a representation of the actual femur F with the formed distal cut surface “DC.’ In other inventive embodiments, only a representation of the distal cut surface is shown without any other bone model data (i.e., only a surface is shown without any other proximal information about the bone model). It is noted that in the system view of FIG. 1, the display 600 may be represented by the fixed display 112, or the display 600 may be a different display in communication with the computing system 104 and present in the operating room. The display 600 may take the form of a portable communication device, a monitor, a tablet, a wearable device, or a laptop. The display 600 may also be projected onto a wall or a lens of wearable eyewear or head gear. The GUI further displays the target locations of one or more features (e.g., peg holes) to be formed in the cut surface as shown by the “X’s” (602a and 602b). The “X” is intended to denote a cross hair, circle, arrow, words, a bullseye, or any other indicia of locality. The real-time location of the tool tip 506 may also be shown relative to the resected view of the femoral bone model “FM”, illustratively shown as a dot 604. A full or partial representation of the tool 500 may be indicated on the display as well as the real-time location of the representation relative to the resected view of the femoral bone model “FM”. Other metrics may also be shown in other windows (606, 608, 610) such as a distance of the tool tip 506 from the targets (602a, 602b), direction arrows to guide the user to the targets (602a, 602b), as well as any other useful information. Other forms of feedback may also be provided in lieu of or addition to the visual feedback on the display 600. This may include audio feedback, haptic feedback (e.g., a buzz when the tool tip 506 is positioned on the location of the target), or other visual feedback (e.g., a light on the tool 500 may turn green when the tool tip 506 is positioned on the location of the target and remain red while the user is moving the tool 500 to search for the target). Once the user has located the pre-defined location of the feature (here the location of the peg holes), the user may mark the area. The user may mark the area with a surgical marker or make a small impression or indent on the bone at the target’s location. In some inventive embodiments, the user may then take a standard drill 700 having a drill bit 702 (Shown in FIG. 7) and drill a peg hole at the target’s location.

[0058] The aforementioned feedback may be provided based on the following. First, the target locations for the features (e.g., peg holes) may be defined relative to bone data with planning software. The planning software is used to plan the POSE of an implant relative to a bone. This may be accomplished by positioning an implant model with respect to a 3-D bone model in a desired POSE. Based on the planned POSE of the implant relative to the bone, the planning software may determine the location for the virtual plane “VP” and the location for the peg holes such that when the cutting guide 302 is coupled to the pins (300a and 300b) and/or the pegs of the 4-in-l cut block are placed in the peg holes, the guide slots of the cutting guide 302 and the 4-in-l cut block align with the location for forming the cut surfaces on the remaining bone to mount the implant in the planned POSE. For example, in determining the location for the peg holes, the planning software knows the locations of the cut surfaces relative to the bone data based on the planned POSE of the implant relative to the bone data (e.g., the cut surfaces may be determined based on the interface locations between the contact surfaces of an implant model and a bone model). Then, the planning software, with the known geometry of the 4-in-l cut block (e.g., the location of the guide slots of the 4-in-l cut block are known relative to the pegs), as further described in FIGs. 6 A and 6B, defines the location for the peg holes relative to the cut surface to align the guides slots of the 4-in-l cut block with the planned locations for the cut surfaces. The defined locations for the peg holes with respect to the distal cut surface is then saved in the computing system 104. In the operating room (OR), the bone data, including the pre-defined locations for the peg holes, is registered to the bone. A tracking system tracks movement of the real-time location of the bone data registered to the bone and therefore the real- time location for forming the peg holes in the cut surface can be displayed on the display 600. The tool 500 and tool tip 506 is likewise tracked by the tracking system to determine the realtime location of the tool tip 506, and therefore the location of the tool tip 506 may be displayed relative to the pre-defined location for forming the peg holes in the cut surface.

[0059] FIG. 6A and FIG. 6B depict a prior art 4-in-l cut block 310 operative in the present invention and amenable to placement on the distal cut surface “DC” as created per the above description with respect to FIG. 4. FIG. 6A depicts a top perspective view of a cut block 310 and FIG. 6B depicts a bottom perspective view of the cut block 310. The cut block 310 is a body 312 having a top surface 314, and a bottom surface 315 that contacts and lies against the distal cut surface “DC” formed on the femur. The cut block 310 further includes a plurality of guide slots extending through the body 312 from the top surface 314 to the bottom surface 315. The cut block 310 in some inventive embodiments includes a posterior guide slot 316, a first posterior chamfer guide slot 318, a first anterior chamfer guide slot 320, and an anterior guide slot 322. The cut block 310 in some inventive embodiments further includes a pair of pegs (324a and 324b) projecting from the bottom surface 315 where the pair of pegs (324a and 324b) fit into corresponding peg holes made in the distal cut surface. The position of the pegs (324a and 324b) on the cut block 310 arc at a known geometry relative to the guide slots such that when the cut block 310 is assembled into the peg holes made on the distal cut surface, the guide slots are aligned in the planned POSE to aid in the creation of the remaining cut surfaces. A saw blade 402 of a standard oscillating saw 400 is advanced through the respective guide slots of the 4-in-l cut block 310 to form the posterior cut surface, the anterior cut surface, the posterior chamfer cut surface, and the anterior chamfer cut surface, respectively; yet with greater speed and accuracy. [0060] FIG. 7 depicts the use of a drill guide 800 to assist in forming the peg holes normal to the distal cut surface “DC” and adapted to receive pegs (324a, 324b). It is appreciated that resort to a drill guide 800 is not required and instead orthogonality is assured by other means that include a machinist square, plumb line, navigation, or other conventional techniques. The drill guide 800, if used, may include one or more elongated holes (802a, 802b) that can be aligned with the location of the target as located with the tool 500 in the previous step. The user may first place the elongated hole 802 over the location of the target and then re-confirm it is in the correct location by placing the tool tip 506 in the elongated holes (802a, 802b). The visual feedback on the GUI can be used to verify that the elongated holes (802a, 802b) are in the correct location (e.g., the representation of the tool tip 506 (e.g., the dot 604) overlaps the representation of the target (e.g., the “X” 602) when the tool tip 506 is placed within the elongated hole 802. The user, with or without the verification step, may then advance the drill bit 702 of the drill 700 through the elongated holes (802a, 802b) to form the peg holes. FIG. 8 depicts the 4-in-l cut block mounted on the distal cut surface “DC” by inserting the pegs (324a, 324b) of the 4-in-l cut block in the newly formed peg holes.

[0061] FIG. 9 is a flowchart of an inventive method 900 for locating and forming peg holes in a cut surface for receiving pegs of a cut block in a planned POSE. The inventive method affords advantages over a conventional procedure. The method begins with the user creating a distal cut surface in the bone to be fitted with an implant (Block 902). Subsequently a resected view of the distal cut surface on the bone is provided on a display. This may be provided as a 3- D model of the bone having the bone distal to the planned distal cut surface removed to show the resected view of the 3-D bone model. Also displayed on the resected view is a set of modeled peg holes demarcated on the resected view (Block 904). Real-time visual feedback is provided on the display of a tool tip being moved around the distal cut surface and the position of the tool tip relative to the location for the model peg holes (Block 906). Additional information provided on the display may include a distance measurement meter, crosshairs, arrows, or other visual indicia to guide the tool tip to a model peg hole location. The actual location of a peg hole is marked on the actual bone when the tool tip is coincident with a model peg hole location (Block 908). Holes are subsequently created at the marked locations (Block 910). In a specific inventive embodiment, the peg holes are drilled normal to the distal cut surface using a standard drill. To assist in drilling the holes normal to the surface, a drill guide having an elongated hole may be used and aligns with the marked spots to guide the drill bit into the bone and normal to the cut surface.

Other Embodiments

[0062] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the described embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes may be made in the function and arrangement of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.

Claims

1. A system for locating a feature relative to a cut surface, the feature having a predefined location relative to the cut surface, the system comprising: a tool comprising a tool tip and a tracking element; a display; and a computer comprising a processor, configured to: display on the display a visual representation of a resected view of a bone cut surface and a location of a feature having a pre-defined location relative to the bone cut surface; and providing feedback on the display of a tool tip physical location relative to the location for the feature.

2. The system of claim 1 wherein the display is a touchscreen.

3. The system of claim 1 wherein a graphical user interface (GUI) is displayed on the display.

4. The system of claim 4 wherein the GUI further comprises a distance measurement meter, crosshairs, direction arrows, bullseye, or other visual indicia for providing the feedback.

5. The system of claim 4 wherein the GUI provides real-time information.

6. The system of any one of claims 1 to 6 further comprising a tracking system.

7. The system of any one of claims 1 to 6 wherein the feature is a hole for receiving a portion of a cutting guide.

8. The system of any one of claims 1 to 6 wherein the feature is a hole for receiving a portion of an implant.

9. A method for locating a feature on a bone cut surface, the feature having a predefined location relative to the bone cut surface, the method comprising: displaying on a display a visual representation of a resected view of a bone cut surface and a location of a feature having a pre-defined location relative to the bone cut surface; and providing feedback on the display of a tool tip physical location relative to the location of the feature.

10. The method of claim 9 further comprising indicating when the tool tip physical location is coincident or is in proximity with the location of the feature.

11. The method of claim 9 wherein the feedback further comprises a distance measurement meter, crosshairs, direction arrows, or other visual indicia to guide the tool tip to the location of the feature.

12. The method of claim 9 wherein the feedback further comprises a dot on the display that moves in unison with the tool tip.

13. The method of any one of claims 9 to 12 wherein the feedback further comprises at least one of audio feedback or haptic feedback.

14. The method of any one of claims 9 to 12 wherein the feedback further comprises a light on the tool that changes colors when coincident with the location of the feature.

15. The method of claim 9 further comprising physically marking the location of the feature on the bone as an indicium.

16. The method of claim 15 wherein the bone is a femoral bone that is being prepared for a total knee arthroplasty (TKA).

17. The method of claim 9 wherein the feature, when formed in the cut surface is adapted to couple with a cutting guide.

18. The method of claim 17 wherein the cutting guide is a N-in-1 cut block.

19. The method of any one of claims 9 to 12 wherein the feature is a hole for receiving a portion of a cutting guide or an implant.

20. The method of claim 9 wherein the feedback is provided in real-time.

21. The method of claim 20 wherein the feedback speeds positioning of a cutting guide on the bone cut surface.