Patent Publication Number: US-2022218423-A1

Title: Robot specific implant designs with contingent manual instrumentation

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/875,173, filed May 15, 2020; that in turn claims priority benefit of U.S. Provisional Application Ser. No. 62/850,365, filed May 20, 2019, the contents of both of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to the field of robotic orthopedic surgery, and more particularly to robot specific implant designs that exploit a robot&#39;s ability to create precise bone cuts. The present invention further provides one or more contingent manual instruments to complete the bone cuts. 
     BACKGROUND 
     Total knee arthroplasty (TKA) is a surgical procedure in which the articulating surfaces of the knee joint are replaced with prosthetic components, or implants. TKA requires the removal of worn or damaged articular cartilage and bone on the distal femur and proximal tibia. The removed cartilage and bone are then replaced with synthetic implants, typically formed of metal or plastic, to create new joint surfaces. The position and orientation (POSE) of the removed bone, referred to as bone cuts or resected bone, determines the final placement of the implants within the joint. Generally, surgeons plan and create the bone cuts so the final placement of the implants restores the mechanical axis or kinematics of the patient&#39;s leg while preserving the balance of the surrounding knee ligaments. Even small implant alignment errors outside of clinically acceptable ranges correlate with worse outcomes and increased rates of revision surgery. 
     Current TKA femoral implants are designed to be installed using specific manual instrumentation (e.g., cutting guides, cutting blocks, alignment fixtures). Due to the requirements of the manual instrumentation and complexity of the procedure, the number of bone cuts to create the new joint surfaces is limited and can remove more bone than is needed to secure the implant to the bone. Most commonly, the number of bone cuts is limited to five planar cuts.  FIG. 1  illustrates a patient&#39;s distal femur  10  and a contour matching femoral prosthesis  12  for a TKA procedure, where the five femoral cut planes include the anterior cut plane  14 , anterior chamfer cut plane  16 , the distal cut plane  18 , the posterior chamfer cut plane  20 , and the posterior cut plane  22 . It should be appreciated that the resulting five mating planes of the current implant designs compromise the bone through increased bone removal in order to reduce to the complexity of the surface preparation with these manual instruments. 
     Robotic surgery can overcome these limitations of the manual instruments. While a human can control a tool with unidirectional precision, a computer controlled robot can operate in a controlled manner in two or more degrees of freedom, and six degree of freedom controlled movement is routine now for robots. As a result, the robot can be controlled in several degrees of freedom to create planar, as well as non-planar bone cuts. The resolution of the bone cuts are also improved well beyond what a surgeon can do with manual instruments. However, the vast majority of implants are still designed and manufactured to accommodate manual bone preparation. As robotic-assisted surgery becomes more mainstream, there is an opportunity to improve the implant designs to exploit the robot&#39;s ability to create more precise and intricate bone cuts. These implant designs are referred to herein as robot specific implant designs. 
     With any robot specific implant design, there needs to be a contingency in the event the robotic surface preparation is aborted. A robotic surgical procedure may be aborted for a variety of reasons including hardware/software faults, unexpected bone geometries, poor bone quality, unexpected boney or soft tissue features, and/or at the discretion of the surgeon. In the event the procedure is aborted, the surgeon will need to complete the surgery manually for the robot specific implant designs. 
     Thus, there exists a need for a system and method to improve the design of an implant to exploit a robot&#39;s ability to create precise bone cuts. There is a further need for a system and method to create the bone cuts for the robot specific implant designs. There is an even further need to provide manual instrumentation for the robot specific implant designs. 
     SUMMARY 
     A method for creating planar bone cuts on a bone to receive a total knee arthroplasty (TKA) femoral implant is described herein. A surgical plan is generated having instructions for a robotic surgical device to create six or more planar bone cuts on the bone. The instructions are executed with the robotic surgical device. The execution of the instructions is aborted before the completion of the six or more planar cuts and the remaining planar cuts are created using manual instruments. After the six or more planar cuts are created, a TKA implant having six or more planar mating surfaces may be installed on the bone. 
     A method to design an implant and execute a robotic surgical procedure is described herein. Pre-operative bone data of a bone is provided to a computer having a pre-operative planning software program. A position for an implant having six or more planar surfaces is planned relative to the pre-operative bone data. A set of instructions is generated for a robotic surgical device to create six or more corresponding planar bone cuts to mate with complementary planar surfaces of the implant. The set of instructions are then executed with the robotic surgical device. 
     A surgical system is described herein. The surgical system includes a robotic arm, a computing system, and one or more contingent manual instruments. The robotic arm controls an end-effector. The computing system has one or more processors and memory. The memory stores a surgical plan having instructions for the robotic arm to actuate the end-effector to create six or more planar bone cuts on a bone. The one or more processors executes the instructions to control the robotic arm to create the six or more planar bone cuts with the end-effector. The one or more contingent manual instruments, each alone or in combination, create any remaining planar bone cuts in the event the execution of the instructions is aborted prior to the completion of the six or more planar bone cuts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  depicts a prepared bone to receive a prior-art femoral TKA implant; 
         FIGS. 2A and 2B  depict a robot-specific femoral TKA implant having seven planar bone-contacting surfaces in accordance with embodiments of the invention, where  FIG. 2A  is a perspective view thereof, and  FIG. 2B  is a side view thereof; 
         FIGS. 3A to 3C  depict cut blocks to manually prepare the bone for a robot-specific femoral TKA implant in the event of an aborted robotic procedure in accordance with embodiments of the invention, where  FIG. 3A  is a top perspective view of a first cut block,  FIG. 3B  is a bottom perspective view of the first cut block, and  FIG. 3C  is top perspective view of an embodiment of a second cut block; 
         FIGS. 4A and 4B  depict cross-sectional views of the first cut block ( FIG. 4A ) and second cut block ( FIG. 4B ) of  FIGS. 3A to 3C  on a distal cut plane of a femur in accordance with embodiments of the invention; 
         FIG. 5  depicts a prepared bone to receive a robot-specific femoral TKA implant in accordance with embodiments of the invention; and 
         FIG. 6  depicts a robotic surgical system to prepare a bone to receive a robot-specific femoral TKA implant in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention has utility as a system and method to improve the design of an implant to exploit a robot&#39;s ability to create more precise and intricate bone cuts. The improved robotic implant designs confer a better fit and alignment on the bone, while preserving additional bone when compared to manual procedures. Further, the present invention provides the user with fallback manual instrumentation in the event the robotic procedure needs to be aborted. 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. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, features illustrated with respect to one embodiment can be incorporated into other embodiments, and features illustrated with respect to a particular inventive embodiment may be deleted from the 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. 
     Further, it should be appreciated that although the systems and methods described herein make reference to total knee arthroplasty, the systems and methods may be applied to other robotic-assisted surgical procedures involving other bones and joints in the body illustratively including the hip, ankle, elbow, wrist, skull, and spine, as well as revision of initial repair or replacement of any of the aforementioned bones or joints. 
     All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. 
     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 of from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4. 
     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. 
     Unless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below. 
     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. 
     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”). 
     As used herein, the term “digitizer” refers to a device capable of measuring, collecting, designating, or recording the position of physical coordinates in three-dimensional space. For example, the ‘digitizer’ may be: a “mechanical digitizer” having passive links and joints, such as the high-resolution electro-mechanical sensor arm described in U.S. Pat. No. 6,033,415; a non-mechanically tracked digitizer probe (e.g., optically tracked, electromagnetically tracked, acoustically tracked, and equivalents thereof) as described in, for example, U.S. Pat. No. 7,043,961; a digitizer probe as described in U.S. Pat. No. 8,615,286; or an end-effector of a robotic device. 
     As used herein, the term “digitizing” refers to the collecting, measuring, designating, and/or recording of physical points in space with a digitizer. 
     As used herein, the term “pre-operative bone data” refers to bone data used to pre-operatively plan a procedure before making modifications to the actual bone. The pre-operative bone data may include one or more of the following. An image data set of a bone (e.g., computed tomography, magnetic resonance imaging, ultrasound, x-ray, laser scan), a virtual generic bone model, a physical bone model, a virtual patient-specific bone model generated from an image data set of a bone, or a set of data collected directly on a bone intra-operatively commonly used with imageless computer-assist devices. 
     As used herein, the term “registration” refers to the determination of the POSE and/or coordinate transformation between two or more objects or coordinate systems such as a computer-assist device, a bone, pre-operative bone data, surgical planning data (i.e., an implant model, cut-file, virtual boundaries, virtual planes, cutting parameters associated with or defined relative to the pre-operative bone data), and any external landmarks (e.g., a tracking marker array) associated with the bone, if such landmarks exist. Methods of registration known in the art are described in U.S. Pat. Nos. 6,033,415; 8,010,177; and 8,287,522. 
     Also, referenced herein is a surgical plan. For context, the surgical plan is created, either pre-operatively or intra-operatively, by a user using planning software. The planning software may be used to plan the position for an implant relative to pre-operative bone data. For example, the planning software may be used to generate three-dimensional (3-D) models of the patient&#39;s bony anatomy from a computed tomography (CT), magnetic resonance imaging (MRI), x-ray, ultrasound image data set, or from a set of points collected on the bone intra-operatively. A set of 3-D computer aided design (CAD) models of the manufacturer&#39;s prosthesis are pre-loaded in the software that allows the user to place the components of a desired prosthesis to the 3-D model of the boney anatomy to designate the best fit, position, and orientation of the implant to the bone. The planning software may additionally or alternatively include tools to custom design an implant relative to boney features. 
     As used herein, the term “real-time” refers to the processing of input data within milliseconds such that calculated values are available within 10 seconds of computational initiation. 
     Also described herein are “robotic surgical systems”. A robotic surgical system refers to a system (or device) requiring computer control of an end-effector to aid in a surgical procedure. Examples of a robotic surgical systems include active and haptic, 1 to N degree(s) of freedom (DOF) hand-held surgical devices and systems, autonomous serial-chain manipulator systems, haptic serial chain manipulator systems, parallel robotic systems, master-slave robotic systems, etc., as described in, for example, U.S. Pat. Nos. 5,086,401; 7,206,626; 8,876,830; 8,961,536; and 9,707,043; and U.S. Pat. App. Pub. US20180344409A1, which patents, patent publications and patent applications are hereby incorporated herein by reference. A particular embodiment of a robotic surgical system as described in detail below. 
     Embodiments of the invention provide robot-specific femoral total knee arthroplasty (TKA) implants that exploit a robot&#39;s ability to create more precise and intricate bone cuts. The robot-specific femoral TKA implants have six or more planar bone-contacting surfaces to increase the contact surface area with the bone and to preserve additional bone when compared to femoral implants with five or less planar surfaces. Referring now to the figures,  FIGS. 2A and 2B  illustrate a robot-specific femoral TKA implant  30  having seven bone-contacting planar surfaces. The femoral TKA implant  30  includes a posterior plane  32 , a first posterior chamfer plane  34 , a second posterior chamfer plane  36 , a distal plane  38 , an anterior plane  40 , a first anterior chamfer plane  42 , and a second anterior chamfer plane  44 . Opposing the seven bone-contacting planar surfaces is the femoral articulating surface  46  that mates with and articulates against a tibial TKA implant, and may particularly articulate against a liner/spacer associated with the tibial TKA implant. Having a femoral TKA implant with six or more planar bone-contacting surfaces preserves more of the native bone in TKA procedure and increases the contact surface area between the implant and the bone for additional stability.  FIG. 2B  depicts this bone conservation between an implant having seven planar surfaces compared to an implant having five planar surfaces. The dotted lines represent the anterior chamfer plane  48  and posterior chamfer plane  50  of a conventional implant having five planar surfaces with respect to the robot-specific femoral TKA implant  30  having seven planar surfaces. The volumes, V 1  and V 2 , represent the additional volume of bone to be removed to receive a conventional implant compared to the robot-specific femoral TKA implant  30 . While,  FIGS. 2A and 2B  depict an implant with seven bone-contacting planar surfaces, it is appreciated that variants thereof, with six, eight, nine, or even ten+ bone-contacting surfaces are provided within the spirit and scope of the present invention; these are intended to be incorporated within the scope of the present invention. Furthermore, whiles  FIGS. 2A and 2B  depict all seven bone-contacting planes having edges that are parallel, it should be appreciated that some of the planes need not have parallel edges and as a result, define facets with edge intersections that are, for example orthogonal to a contiguous plane. 
     Given the additional planar surfaces of the robot-specific femoral TKA implant  30 , the bone is preferably prepared with a robotic surgical device. As the number of planar surfaces on the implant increases, the required resolution and precision to prepare the bone also increases. The robotic surgical device may prepare the bone by executing a set of instructions, where the set of instructions are based on at least one of: a geometry of the robot-specific femoral TKA implant (e.g., the boundaries of the implant, and/or the location of the planar surface); a geometry of the bone (e.g., the bone boundaries, a known volume of bone to be removed based on the geometry of the implant); a planned position of the robot specific femoral TKA implant relative to the femur (e.g., the intersecting lines or points between the implant with the bone); or a combination thereof. A user may plan the position of the implant relative to the bone in a pre-operative planning software program. The surgical plan may be generated by positioning a CAD model of the robot-specific femoral TKA implants relative to pre-operative bone data of the femur. The pre-operative planning program may further allow a user to custom design a robot-specific femoral TKA implant relative to the femur. The final surgical plan may include the set of instructions and the planned position of the implant relative to the femur to permit the robotic surgical device to execute the set of instructions on the femur in the planned location. In the operating room (OR), the bone is exposed and the surgical plan is registered with respect to the position of the bone in the coordinate system of the robotic surgical device. The set of instructions are then executed by the robotic surgical device to prepare the bone. After the bone is prepared, the robotic-specific femoral TKA implant is installed on the bone and the procedure is completed. 
     In certain circumstances, the robotic surgical procedure may need to be aborted before all of the planar surfaces are prepared on the bone. A robotic surgical procedure may be aborted for a variety of reasons including hardware/software faults, unexpected bone geometries, poor bone quality, unexpected boney or soft tissue features, and/or at the discretion of the surgeon. In the event the procedure is aborted, the surgeon needs to finish preparing the bone using manual instruments. In particular inventive embodiments, the manual instrumentation may include a set of cut blocks. Each version of the cut block includes a plurality of guide slots to guide a surgical saw to create the cut planes on the bone, where the angle and positioning of one or more of the guide slots on each cut block is different to create the different cut planes. For example, a first cut block may have guide slots positioned and angled to aid in creating the cut planes that contact the first anterior chamfer plane  42  and the first posterior chamfer plane  34  of the robot-specific femoral TKA implant  30 . A second cut block may have guide slots positioned and angled to aid in creating the cut planes that contact the second anterior chamfer plane  44  and the second posterior chamfer plane  36  of the robot-specific femoral TKA implant  30 . Additional versions of the cut blocks may be used to aid in the creation of additional cut planes (e.g., a third cut block to aid in the creation of two additional planes to receive a femoral TKA implant having 9 planes). 
       FIGS. 3A to 3C  illustrate an example of a first cut block  60  and a second cut block  80  to manually prepare the bone for a robot-specific TKA implant in the event of an aborted robotic TKA procedure, where  FIG. 3A  depicts a top perspective view of a first cut block  60 ,  FIG. 3B  depicts a bottom perspective view of the first cut block  60 , and  FIG. 3C  depicts a top perspective view of a second cut block  80 . The first cut block  60  is a body  62  having a top surface  64 , and a bottom surface  66  that contacts and lies against the distal cut plane on the femur. The first cut block  60  further includes a plurality of guide slots extending through the body  62  from the top surface  64  to the bottom surface  66 . The first cut block  60  in some inventive embodiments includes a posterior guide slot  68 , a first posterior chamfer guide slot  70 , a first anterior chamfer guide slot  72 , and an anterior guide slot  74 . The first cut block  60  in some inventive embodiments further includes a pair of pegs ( 76  and  78 ) projecting from the bottom surface  66  where the pair of pegs ( 76  and  78 ) fit into corresponding peg holes made on the distal cut plane. The position of the pegs ( 76  and  78 ) on the cut block  60  are at a known geometry relative to the guide slots such that when the cut block  60  is assembled into the peg holes made on the distal cut plane, the guide slots are aligned to aid in the creation of the planned cut planes. The posterior guide slot  68  and the anterior guide slot  74  are configured to guide a surgical saw to create the posterior cut plane  100  (as shown in  FIG. 5 ) and the anterior cut plane  106  (as shown in  FIG. 5 ), respectively. The first posterior chamfer guide slot  70  and the first anterior chamfer guide slot  72  are angled and positioned to guide a surgical saw to create the first posterior chamfer cut plane  102  (as shown in  FIG. 5 ) and the first anterior chamfer cut plane  104  (as shown in  FIG. 5 ), respectively. 
       FIG. 3C  illustrates a second cut block  80 . The second cut block  80  is a body  82  having a top surface  84 , and a bottom surface  85  (as shown in  FIG. 4B ) that contacts and lies against the distal cut plane on the femur in the same location as the first cut block  60 . The second cut block  80  further includes a plurality of guide slots extending through the body  82  from the top surface  84  to the bottom surface  85 . The second cut block  80  in some inventive embodiments includes a posterior guide slot  86 , a second posterior chamfer guide slot  88 , a second anterior chamfer guide slot  90 , and an anterior guide slot  92 . The second cut block  80  in some inventive embodiments further includes a pair of pegs (now shown) projecting from the bottom surface  85  similar to the pegs ( 76  and  78 ) described above. The position of the pair of pegs on the bottom surface  85  are known relative to the guide slots such that the guide slots align in the planned position when the pegs are inserted into the peg holes. The posterior guide slot  86  and the anterior guide slot  92  are configured to guide a surgical saw to create the posterior cut plane  100  (as shown in  FIG. 5 ) and the anterior cut plane  106  (as shown in  FIG. 4 ), respectively. The second posterior chamfer guide slot  88  and the first anterior chamfer guide slot  90  are angled and positioned to guide a surgical saw to create the second posterior chamfer cut plane  108  (as shown in  FIG. 5 ) and the second anterior chamfer cut plane  110  (as shown in  FIG. 5 ), respectively. 
       FIGS. 4A and 4B  depicts an example of the first cut block  60  and the second cut block  80  in use, where  FIG. 4A  is a cross-sectional view of the first cut block  60  on the distal cut plane of a femur F, and  FIG. 4B  is a cross-sectional view of the second cut block  80  on the distal cut plane of the femur F. In this example, the robotic surgical device was able to prepare the distal cut plane and the peg holes that receive the pegs of the cut blocks before the robotic procedure was aborted. In particular inventive embodiments, the set of instructions for the robotic surgical device are configured to have the robotic device create the distal cut plane and the peg holes first, prior to creating any of the other cuts. This acts as a contingency plan to permit the use of the cut blocks in the event of an abortion of the robotic procedure any time after the distal cut plane and peg holes are created. The first cut block  60  is then assembled onto the distal cut plane by placing the pair of pegs ( 76  and  78 ) into the peg holes. The surgeon can then create the posterior cut plane  100 , the first posterior chamfer cut plane  102 , the first anterior chamfer cut plane  104 , and the anterior cut plane  106  as shown in  FIG. 4B . Subsequently, the first cut block  60  is removed from the femur F, and the second cut block  80  is assembled to the distal cut plane by placing the pair of pegs into the peg holes. The surgeon may then create the second posterior chamfer cut plane  108  and the second anterior chamfer cut plane  110 .  FIG. 5  illustrates the fully prepared bone to receive the robot-specific femoral TKA implant  30 . Once prepared, the surgeon installs the robot-specific femoral TKA implant  30  on the bone and the procedure is completed. 
     It should be appreciated that various designs and/or configurations of one or more cut blocks may exist to finish preparing the bone. In a particular inventive embodiment, there is a single cut block having all the guide slots necessary to finish preparing the bone. This single cut block may illustratively include a posterior guide slot, a first posterior chamfer guide slot, a second posterior chamfer guide slot, an anterior guide slot, a first anterior chamfer guide slot, and a second anterior chamfer guide slot. Additional guide slots may be added depending on the number of planar surfaces of a robot-specific femoral TKA implant. In another inventive embodiment, a set of cut blocks are used as described above, but one or more guide slots from one guide block may be absent from another guide block. For example, the aforementioned second cut block  80  may not have the posterior guide slot  86  and anterior guide slot  92  because the first cut block  60  was able to aid in the creation of those cut planes. 
     It is further contemplated that other contingent manual instrumentation may be used in the event of an aborted robotic procedure. In a specific inventive embodiment, the manual instrumentation may include one or more 3-D printed cut guides. The 3-D printed cut guides may have one or more guide slots to guide a surgical saw in creating the cut planes. The 3-D printed cut guides further have a mating surface that is a negative match of a portion of the bone. The mating surface ensures the 3-D printed cut guide assembles to the bone in a desired position and orientation such that the guide slots are aligned in the planned location. 
     Robotic Surgical Device 
       FIG. 6  depicts a robotic surgical system  200  in the context of an operating room (OR) to prepare a bone to receive a robot-specific femoral TKA implant. The surgical system  200  includes a surgical robot  202 , a computing system  204 , and an optional tracking system  206 . The surgical robot  202  may include a movable base  208 , a manipulator arm  210  connected to the base  208 , an end-effector  211  located at a distal end  212  of the manipulator arm  210 , and a force sensor  214  positioned proximal to the end-effector  211  for sensing forces experienced on the end-effector  211 . The base  208  includes a set of wheels  217  to maneuver the base  208 , which may be fixed into position using a braking mechanism such as a hydraulic brake. The base  208  may further include an actuator to adjust the height of the manipulator arm  210 . The manipulator arm  210  includes various joints and links to manipulate the end-effector  211  in various degrees of freedom. The joints are illustratively prismatic, revolute, spherical, or a combination thereof. The end-effector  211  may be motor-driven end-mill, cutter, drill-bit, or other bone removal device. 
     The computing system  204  may generally include a planning computer  216 ; a device computer  218 ; an optional tracking computer  220 ; and peripheral devices. The planning computer  216 , device computer  218 , and tracking computer  220  may be separate entities, one-in-the-same, or combinations thereof depending on the surgical system. Further, in some embodiments, a combination of the planning computer  216 , the device computer  218 , and/or tracking computer  220  are connected via a wired or wireless communication. The peripheral devices allow a user to interface with the surgical system components and may include: one or more user-interfaces, such as a display or monitor  222  to display a graphical user interface (GUI); and user-input mechanisms, such as a keyboard  224 , mouse  226 , pendent  228 , joystick  230 , foot pedal  232 , or the monitor  222  that in some inventive embodiments has touchscreen capabilities. 
     The planning computer  216  contains hardware (e.g., processors, controllers, and/or memory), software, data and utilities that are in some inventive embodiments dedicated to the planning of a surgical procedure, either pre-operatively or intra-operatively. This may include reading pre-operative bone data, displaying pre-operative bone data, manipulating pre-operative bone data (e.g., image segmentation), constructing three-dimensional (3D) virtual models, storing computer-aided design (CAD) files, providing various tools, functions, or widgets to aid a user in planning the surgical procedure, and generating surgical plan data. The final surgical plan may include pre-operative bone data, patient data, registration data including the POSE of a set of points defined relative to the pre-operative bone data, trajectory parameters, and/or a set of instructions to operate the surgical robot  202 . The set of instructions may include instructions for the surgical robot to modify a volume of bone to receive an implant. The set of instructions may illustratively be: a cut-file having a set of cutting parameters (e.g., cut paths, velocities) to automatically modify the volume of bone; a set of virtual boundaries defined to haptically constrain a tool within the defined boundaries to modify the bone; a set of boundaries coupled with power or actuation control of tracked surgical device to ensure the end-effector only removes bone within the boundaries; a set of planes or drill holes to drill pins or tunnels in the bone; or a graphically displayed navigated set of instructions for modifying the tissue. In particular embodiments, the set of instructions is a cut-file for execution by a surgical robot to automatically modify the volume of bone, which is advantageous from an accuracy and usability perspective. The surgical plan data generated from the planning computer  216  may be transferred to the device computer  218  and/or tracking computer  220  through a wired or wireless connection in the operating room (OR); or transferred via a non-transient data storage medium (e.g., a compact disc (CD), a portable universal serial bus (USB) drive) if the planning computer  216  is located outside the OR. 
     The device computer  218  in some inventive embodiments is housed in the moveable base  208  and contains hardware, software, data and utilities that are preferably dedicated to the operation of the surgical robotic device  202 . This may include surgical device control, robotic manipulator control, the processing of kinematic and inverse kinematic data, the execution of registration algorithms, the execution of calibration routines, the execution of the set of instructions (e.g., cut-files, the trajectory parameters), coordinate transformation processing, providing workflow instructions to a user, and utilizing position and orientation (POSE) data from the tracking system  206 . In some embodiments, the surgical system  200  includes a mechanical digitizer arm  205  attached to the base  208 . The digitizer arm  205  may have its own tracking computer or may be directly connected with the device computer  218 . The mechanical digitizer arm  205  may act as a digitizer probe that is assembled to a distal end of the mechanical digitizer arm  205 . In other inventive embodiments, the system includes a hand-held digitizer device  236  with a probe tip. 
     The optional tracking system  206  may be an optical tracking system that includes two or more optical receivers  207  to detect the position of fiducial markers (e.g., retroreflective spheres, active light emitting diodes (LEDs)) uniquely arranged on rigid bodies. The fiducial markers arranged on a rigid body are collectively referred to as a tracking marker array ( 238   a ,  238   b ,  238   c ,  238   d ), where each fiducial marker array has a unique arrangement of fiducial markers, or a unique transmitting wavelength/frequency if the markers are active LEDs. An example of an optical tracking system is described in U.S. Pat. No. 6,061,644. The tracking system  206  may be built into a surgical light, located on a boom, a stand  240 , or built into the walls or ceilings of the OR. The tracking system computer  220  may include tracking hardware, software, data, and utilities to determine the POSE of objects (e.g., bones B, surgical device  202 ) in a local or global coordinate frame. The POSE of the objects is collectively referred to herein as POSE data, where this POSE data may be communicated to the device computer  218  through a wired or wireless connection. Alternatively, the device computer  218  may determine the POSE data using the position of the fiducial markers detected from the optical receivers  207  directly. 
     The POSE data is determined using the position data detected from the optical receivers  207  and operations/processes such as image processing, image filtering, triangulation algorithms, geometric relationship processing, registration algorithms, calibration algorithms, and coordinate transformation processing. 
     The POSE data is used by the computing system  204  during the procedure to update the POSE and/or coordinate transforms of the bone B, the surgical plan, and the surgical robot  202  as the manipulator arm  210  and/or bone(s) (F, T) move during the procedure, such that the surgical robot  202  can accurately execute the surgical plan. 
     In another inventive embodiment, the surgical system  200  does not include an optical tracking system, but instead employs a mechanical arm  205  that may mechanically track a digitizer probe assembled to a distal link of the mechanical arm  205 . If the bone is not tracked, a bone fixation and monitoring system may fix the bone directly to the surgical robot  202  to monitor bone movement as described in U.S. Pat. No. 5,086,401. 
     OTHER EMBODIMENTS 
     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.