Patent Publication Number: US-2023157764-A1

Title: Systems and methods for patient-based computer assisted surgical procedures

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/087,284 entitled “Systems and Methods for Patient-Based Computer Aided Surgical Procedures,” filed Apr. 14, 2011, which claims the benefit of priority of U.S. Provisional Patent Application No. 61/324,207 filed Apr. 14, 2010, and U.S. Provisional Patent Application No. 61/324,692 filed Apr. 15, 2010. The disclosures of each of the foregoing applications are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Orthopedic implants are used for resurfacing or replacing joints, such as knees, hips, shoulders, ankles, and elbows that typically experience high levels of stress and wear or traumatic injury. Implants used to replace these joints must be strong and able to withstand the daily stress and wear at these joints, especially for weight-bearing knee and hip replacements. But providing a sufficiently strong implant that also fits properly is challenging. Traditional orthopedic implants are made from polymer, ceramic, metal or other appropriate material and formed so that they fit the patient&#39;s bone securely. In knee replacement surgeries, for example, typical approaches involve cutting the end of the tibia and/or femur, then fitting a new implant to the cut end. The size of the implant is typically determined by the surgeon based on hand measurements and visual estimates. The size and fit between the bone and implant can vary—in some cases being too loose, and in others too tight. 
     Computer assisted methods have been developed that provide a graphical image of the resected bone and design software that allow the surgeon to install the implant to fit the surgical site more precisely. During a computer-assisted surgery (CAS), a surgeon registers the patient&#39;s anatomical site by touching various landmarks around the patient&#39;s joint using a registration tool. Once the registration process is completed, the surgeon uses a surgical tool (e.g., cutter) to resect the bone in the patient&#39;s joint. The surgical tool may be guided by a computer assisted system. 
     There are, however, drawbacks to conventional registration processes. A surgeon typically uses a foot pedal or needs an assistant&#39;s help during the registration process. The surgeon is required to hold the registration tool steady against a smooth bone surface. While the surgeon is holding the tool, the surgeon&#39;s assistant notifies the computer what registration point the surgeon is registering. Also, to register a single point the surgeon may need to change the orientation of the registration tool in various angles with respect to the registration point to ensure that a tracking camera accurately captures the location. This registration process is tedious, time-consuming, and prone to errors. 
     Conventional CAS systems also include a reference array, which is made of light-reflective material that can be viewed on video camera and used to track the position of a surgical tool during the surgery. The reference array is positioned on the patient or near the patient, but it can be bumped easily and misaligned if anyone moves the operating table or pushes the reference array. When that happens, the patient&#39;s anatomic location needs to be re-registered, which prolongs the surgery time. Unfortunately, the surgeon may find it difficult to re-locate the same anatomical landmark sites registered previously, and therefore it may be difficult to re-register the site, possibly reducing the accuracy of the surgical procedure. 
     In some cases, a surgeon defines a bone cutting boundary pre-operatively based on the 3D model of a patient&#39;s joint or MRI or CT image of the patient. Therefore, the accuracy of the surgical procedure may depend on how well the registered bone (which is based on 3D model or an image of the patient) matches the physical bone. That matching can be difficult to achieve. There is a need for a registration process that allows the surgeon to repeatedly and more efficiently register a patient&#39;s bone for surgery. 
     SUMMARY 
     Disclosed herein are surgical systems and methods that provide a 3D model of a patient&#39;s affected area using imaging devices. The systems and methods (and various related apparatuses) use the model to determine an optimal implant and/or optimal implant position through virtual implantation and biomechanical simulation techniques. The techniques, in some implementations, create patient-matched instrumentation that conforms in one spatial orientation to the patient&#39;s anatomy, placing the patient-matched instrumentation on the patient&#39;s anatomy, registering a surgical tool with the patient-matched instrumentation while the patient-matched instrumentation remains in contact with the patient&#39;s anatomy, acquiring information about a relative position and/or orientation of the surgical tool, and associating the surgical tool with a computer. The computer preferably uses a controller, tracking hardware, tracking software, and a file containing information about one or more pre-planned anatomical modifications. The controller serves to instruct the surgical tool to perform or not perform one or more surgical functions according to the position of the surgical tool relative to the patient during surgery. Information about the surgical procedure to be performed is stored in the computer and is used in conjunction with the registration information obtained by the patient-matched instrumentation to control the one or more surgical functions of the tool. 
     Also disclosed are embodiments of patient-matched instrumentation which may be used to acquire registration information. 
     Certain embodiments include a patient-matched surgical guide for registering a location of a patient&#39;s bone, for example a tibia. By registering the location of the bone, the surgeon can more easily make appropriate cuts within the bone to prepare it for implant placement or other surgery. The surgical guide includes an inner surface that conforms to the patient&#39;s bone and a body having a registration site that receives a registration tool of a medical device for communicating the location of that registration tool to a processor. The registration site includes one or more registration points that correspond to one or more reference markers shown or described in an image of the patient&#39;s bone, for example, a computer image. The registration sites are easy to spot on the surgical guide. So, if the surgeon needs to re-register the device during surgery, he or she can easily find the reference markers on the registration site, rather than having to remember the location of the registration marker on the bone itself. 
     The image of the patient&#39;s bone is used to create a three-dimensional model of the patient&#39;s bone, and the registration points chosen so as to correspond to related reference markers of the three-dimensional model of the patient&#39;s bone. The markers preferably define a spatial relationship with respect to the articulating surfaces of the patient&#39;s bone. For example, a point may be created in the body of a polymer guide at a location that is chosen to overlay a pre-selected site on the resected femur, when the guide is interfitted to the resected femur end. The surgeon selects the reference marker site in the graphical computer image of the bone then generates the guide body with a point that corresponds to that site. 
     The patient-matched guide has a surface that interfits with the anatomical location which will be cut during the surgery. The surface may be structured so that it interfits with the guide in a single spatial orientation, for ease of alignment. The surface may be partially spherical. 
     The guide is also preferably prepared from a graphical image of the patient&#39;s bone, which is taken by creating a graphical image of the surgery site, and then using that image to create a three-dimensional model. In certain embodiments, the image is of a virtual surgery model, and a physical model is created from that virtual model by rapid prototyping. 
     Certain embodiments include a system for registering a location of a patient&#39;s anatomic portion using a guide that is structured as a patient-matched block. The block has an anatomy-facing surface that conforms to a patient&#39;s bone and a connector. A mount attaches to the bone and the connector and is configured to receive an array to communicate a location of the bone to a computer assisted surgical system. The mount may be positioned in a fixed spatial relationship with respect to the anatomy-facing surface. The mount may be included on a cutting tool that interfaces with the registration site. 
     In certain embodiments, a system is provided for performing a computer-assisted surgical procedure for implanting a prosthetic device to a patient. The system includes a patient-matched block having a registration site and an inner surface that is configured to conform to a patient&#39;s bone. The system includes a surgical tool with a cutting tip that interfaces with the registration site to identify a location of the registration site, and a processor that tracks the location of the tool with respect to the location of the patient&#39;s bone. In certain implementations, the cutting tip includes a center that corresponds to the registration point of the patient-matched block. 
     Systems disclosed herein may use a computer having tracking hardware, tracking software, and a controller for guiding the surgical tool according to a file containing a surgical plan. The systems may include one or more files that include data that identifies the location of one or more registration sites on the guide (e.g., the patient-matched block) relative to the patient&#39;s bone. In certain implementations, a tracking receiver is provided for communication with the processor, the tracking receiver being configured to identify the location of the registration site by identifying the location of an array attached to a registration tool. The tracking receiver may be structures as an array. The tracking receiver may be mounted to a housing. The housing may be located on the cutting tool. The array may be included as part of a housing that mounts the patient-matched block to the patient. 
     Methods of use and methods of operation are also contemplated. Certain embodiments include a method of performing a computer-assisted surgical procedure for implanting a prosthetic device to a patient. Such method includes the steps of creating a three-dimensional model of a portion of the patient&#39;s bone, determining an optimal implant or implant position, and creating a body (e.g., a patient-matched block) that conforms to a portion of the bone, the body having a registration site that corresponds to a predetermined location on the bone. In certain implementations, methods include placing a patient-matched block on the patient&#39;s body, registering a surgical tool by touching a portion of the surgical tool to the registration site, defining a cutting boundary in relation to the patient&#39;s anatomy, and removing a portion of the patient&#39;s anatomy by making cuts within the cutting boundary. 
     In certain methods, a virtual implantation file is created. The file includes processor instructions for establishing a cutting boundary and representing that boundary electronically. The cutting boundary may be displayed on a monitor. If a cutting tool crosses the boundary, the imaging devices detect the crossing and signal to the processor to warn the surgeon. 
     In certain implementations, methods are provided operating a surgical alignment guide. Such methods include providing a patient-matched block, the block having at least one registration site and an inner surface that conforms to an anatomic portion of the patient. Such methods may further provide a surgical tool with an alignment point or tip that interfaces with the registration site. The methods may also involve positioning the alignment point with respect to the at least one registration site to align the guide and the tool. 
     Tracking tools may be used. In certain implementations, the methods involve tracking the position of a surgical tool relative to a reference array to identify the position of the tool. In certain implementations, a processor defines a cutting boundary having one or more pre-planned optimized resections of the patient&#39;s anatomy. The location of the surgical tool is tracked relative to the cutting boundary. 
     In certain implementations, the surgeon removes a portion of the patient&#39;s bone positioned within the cutting boundary by tracking the position of the surgical tool with respect to the patient&#39;s bone and cutting the bone along a path defined by a processor. 
     In certain embodiments, a method is provided for implanting a prosthetic device in a patient. The methods include applying a patient-matched surgical apparatus about a portion of a patient&#39;s bone, the apparatus having an inner surface that conforms to the bone portion and an alignment site that receives a registration tool. In certain implementations, the methods include joining the alignment site with a registration tool and tracking a location of a surgical tool with respect to the patient&#39;s bone by detecting the position of the surgical tool with respect to an array. 
     In various implementations, a registration tool is used. The registration tool may be formed with or include a distal tip of a surgical tool. In certain implementations, the registration tool is a distal tip of a surgical tool. In certain implementations, two or more arrays are used to help electronically define the cutting boundary. A first array is mounted to the patient or at some site in the surgery room nearby, and the surgical tool includes a second array. 
     In certain implementations, a registration tool includes a connector that interfaces with the alignment site. The registration tool may interfit directly with an array or indirectly via an adaptor for receiving the array. 
     Certain systems may also be used or provided, having a patient-matched surgical apparatus with an inner surface that conforms to the patient&#39;s bone and an alignment site, a registration tool configured to interface with the alignment site to identify the location of the patient&#39;s bone, and a processor that tracks a location of a surgical tool with respect to an array. 
     Further features, aspects, and advantages of various embodiments are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments and together with the description, serve to explain various examples of the disclosed methods and systems. In the drawings: 
         FIG.  1    shows a step of scanning a patient to obtain patient image data; 
         FIG.  2 A  shows MRI patient image data according to some embodiments; 
         FIG.  2 B  shows CT patient image data according to other embodiments; 
         FIG.  3    shows a step of segmenting patient data; 
         FIG.  4    shows a step of assembling segmented patient data; 
         FIG.  5    shows a step of creating a patient model using segmented patient data; 
         FIG.  6    shows a step of creating or selecting an implant from a database of implants, based on the patient model; 
         FIG.  7    shows a step of performing a virtual surgical step on the patient model to create an incomplete virtual surgery model; 
         FIG.  8    shows a step of performing one or more other surgical steps on the patient model to create a completed virtual surgery model; 
         FIG.  9    shows a step of loading a completed virtual surgery model into a biomechanical simulator and running iterative simulations; 
         FIG.  10    shows a step of evaluating performance characteristics to determine the best implant and/or best positioning of an implant by iteratively performing the steps shown in  FIGS.  6 - 9   ; 
         FIGS.  11 - 12    show portions of a surgical system according to some embodiments; 
         FIGS.  13 - 14    show a step of registering position information of a surgical system component according to some embodiments; 
         FIG.  15    shows a step of modifying anatomy based on obtained registration information and one or more pre-planned resections according to some embodiments; 
         FIGS.  16 - 19    show surgical cutting steps using a surgical tool having a controlled functionality; 
         FIG.  20    shows registration features of a surgical system according to some embodiments; 
         FIGS.  21 A-D  schematically illustrate a method of using a surgical system according to some embodiments; 
         FIGS.  22 - 42    illustrate a surgical system and its use according to certain embodiments; 
         FIG.  43    schematically illustrates a method of using a surgical system shown in  FIGS.  22 - 42   ; 
         FIG.  44    schematically illustrates a method according to some embodiments; and 
         FIG.  45    shows a surgical robot according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The figures illustrate certain implementations of systems and methods used to perform a computer assisted surgical procedures using a patient-matched alignment guide. The patient-matched alignment guide helps a surgeon more accurately register a patient&#39;s bone during a computer-assisted surgical procedure. The patient-based alignment guide also helps to speed up the registration process compared to a manual registration process. In certain implementations, the patient-matched alignment guide includes an inner surface that conforms to the patient&#39;s bone and a body having a registration site that receives a registration tool of a medical device for communicating the location of that registration tool to a processor. 
     Referring to the accompanying drawings in which like reference numbers indicate like elements,  FIG.  1    illustrates a step of scanning a patient  20  to obtain patient information. Devices for obtaining patient information may include, for instance, X-ray, computerized tomography (CT), magnetic resonance imaging (MRI), ultrasound, or other similar imaging devices. A patient  20  is subjected to scanning  10  and may be held still by a platform  12  or one or more jigs or fixtures (not shown) to reduce imaging artifacts. Image data of an affected area  22  of the patient is collected. While the particular embodiments shown and described herein generally relate to knee joints, it should be understood that the methods disclosed may be advantageously used in conjunction with any surgical procedure. For instance, the systems and methods described herein may be equally applicable to arthroplasty or reconstruction of the hip, foot, arm, elbow, shoulder, neck, spine, cranio-maxiofacial (CMF) regions, and extremities, without limitation. 
       FIGS.  2 A and  2 B  show patient data according to two exemplary embodiments.  FIG.  2 A  shows an MRI scan image slice  30 , and  FIG.  2 B  shows a CT scan image slice  30 ′. 
       FIG.  3    shows a step within a segmentation process. One  30   a  of a plurality of image slices is imported into a computer having segmentation software such as MIMICS. MIMICS is a registered trademark of Materialise Inc. headquartered at Technologielaan 15, 3001 Leuven, Belgium. Regions of bone, cartilage, and soft tissues are separated in the image slice  30   a , as well as in the remaining plurality of image slices. In the particular embodiment shown, a knee image  30   a  slice is segmented to separate femoral bone and cartilage  31   a  from tibial bone and cartilage  35   a  and soft tissues such as cruciate ligaments  32   a , quadriceps tendon  33   a , and patellar ligament  34   a . Segmentation may be automatic, manual, or a combination thereof. 
       FIG.  4    shows a plurality  40  of segmented image slices  30   a - f  each having segmented portions  31   a - f . The plurality of segmented image slices  30   a - f  are imported into modeling software to create a 3D model  50  of the patient&#39;s affected anatomy as shown in  FIG.  5   . The 3D model  50  may serve as a working model for use in biomechanical simulations as will be discussed hereinafter. The 3D model  50  may incorporate bone, cartilage, and/or soft tissues derived from the patient scan. In the particular embodiment shown, the 3D model  50  is a model of patient&#39;s affected knee joint and includes a bone, cartilage, and cruciate ligament model comprising characteristics of an individual patient&#39;s femur  51 , tibia  55 , fibula, lateral collateral ligament  56 , and medial collateral ligament  57 . In this case, anterior and posterior cruciate ligaments are omitted from the 3D model  50  because a bicruciate-stabilized implant is used. A series of reference point markers  59   a - f  may be incorporated into the model, each marker  59   a - f  defining spatial relationships between the markers and anatomic landmarks or features present in the 3D model  50 . The locations of these markers  59   a - f  are selected to correspond with certain anatomic landmarks or articulating surfaces of the femur  51  and tibia  55 . More particularly, the markers  59   a - 59   c  may be selected to correspond to the anatomic surfaces of the medial and lateral condyles of femur and medial and lateral epicondyles of the femur. One of the reference point markers  59   a - 59   c  may correspond to the distal condylar line of the femur, the Whiteside line, or the mechanical axis of the leg. Additional reference point markers  59   c - 59   f  that correspond to the tibial anatomical landmarks such as medial and lateral condyles of tibia and tibial tuberosity may be selected. Other reference points could be used, for example one or more of the anatomic axis, mechanical axis, A-P depth, M-L width, joint line, ACL attachment, tibial sulcus, medial malleolus, posterior condylar axis, and distal femoral condyle. 
       FIG.  6    illustrates the step of selecting  560  an implant  530 , such as a femoral component of a knee prosthesis from a series  500  of implants  510 ,  520 ,  530  according to some embodiments. The prosthesis components may comprise articulating surfaces  512 ,  522 ,  532  having different geometries and/or bone-facing surface portions  514 ,  524 ,  534  having different geometries. The selection  560  may be provisionally determined by computer software, by an engineer, by a health care provider, sales associate, or technician based on parameters of the 3D model  50 . In certain implementations, the implant  530  is created based on the patient model  50 . The bone-facing surface portions  514 ,  524 ,  534  may be shaped specifically to conform to follow the patient&#39;s unique joint shape and localized contours along the surface of the joint. In certain implementations, the implant  530  is selected from a library that is pre-loaded with implants with varying shape and size. 
     As shown in  FIG.  7   , the 3d patient model  50  may be converted to an incomplete virtual surgery model  60  comprising one or more surgical modifications to the 3D patient model  50 , based on the implant selection  560  and the attributes  532 ,  534  of the selected implant  530 . The incomplete virtual surgery model  60  may comprise, for instance, one or more virtual resections or cuts  63 ,  62  to a femur  61  and tibia  65 , respectively. In certain embodiments, one or more reference point markers  69   a - f  are maintained in the same spatial locations relative to the anatomic portions  61 ,  65 ,  66 ,  67  of the model  60  as the markers  59   a - f  in the 3D patient model  50 . For instance, markers  69   a - f  may define additional spatial relationships between the markers  69   a - f  and provisionally determined virtual resections or cuts  62 ,  63  of the tibia  65  and femur  61 . In certain embodiments, the point markers  69   a - f  are picked after the virtual resections or cuts are determined in respect to the computer model. In certain embodiments, one or more reference point markers  69   a - f  may be selected so as to define a cutting a plane. In certain embodiments, one or more of the reference point makers  69   a - f  corresponds to one or more locations of a pin hole disposed on a patient-matched instrument (e.g., cutting block). In certain implementations, the patient-matched instrument may include a slot for receiving a cutting blade for making a distal resection and two pin holes for preventing the rotation of the instrument once fitted to the patient&#39;s bone. In alternative implementations, one or more additional or alternative reference markers could be used to designate locations in the bone or bone model for making one or more holes or cuts within the patient&#39;s bone to help assist with registration of a cutting device if the patient-matched device is removed during surgery. One or more such markers could be identified in the model  50  or virtual surgery model  60  to correspond to one or more pin holes, slots or other cuts to be made in the patient&#39;s bone to assist in the registration and guiding of the surgical tool. For example, one or more alternative markers could be included in a model to denote a place for inserting one or more holes in the patient matched device (e.g., a patient-matched block  200 ) and correspondingly in the patient&#39;s bone overlaid by the patient matched device. For example one or more holes such as  2004  or  2006  of  FIG.  23    et seq. (discussed below) could be placed within the patient-matched block, and corresponding holes drilled or cut into the patient&#39;s bone in locations directly beneath the block under such holes. After inserting such holes, if the block is removed prior to the resection, the health care provider could use the holes or slots in the bone as reference points for re-registration of the tool or guiding the tool to make cuts during the resection. 
     As shown in  FIG.  8   , the virtual surgery model  60  may be converted to a completed virtual surgery model  70  comprising one or more surgical modifications  63 ,  62  to the 3D patient and incomplete virtual surgery models  50 ,  60  based on the implant selection  560  and the attributes  532 ,  534  of the selected implant  530 . The completed virtual surgery model  70  may comprise, for instance, one or more implant components such as a femoral component  78   a , a tibial articular insert component  78   b , and a tibial baseplate component  78   c . One or more reference point markers  79   a - f  are maintained in the same spatial locations relative to the anatomic portions  71 ,  75 ,  76 ,  77  of the completed virtual surgery model  70  as the markers  59   a - f ,  69   a - f  in the 3D patient and incomplete virtual surgery models  50 ,  60 . For instance, markers  79   a - f  may define additional spatial relationships between the markers  79   a - f  and a provisionally determined virtual articular surfaces and bone facing interface surfaces of the implant components  78   a - c.    
     As shown in  FIG.  9   , the completed virtual surgery model  70  may be imported into biomechanical simulation software such as KNEESIM by LIFEMOD to determine one or more predicted performance characteristics of the implant components  78   a - c . “LifeMOD” and “KneeSIM” are trademarks of LifeModeler, Inc., 2730 Camino Capistrano, Suite 7, San Clemente, Calif. The simulation model  80  may be iteratively run with different completed virtual surgery models  70 —each completed virtual surgery model  70  incorporating different implant selections  560 . Selections  560  may have different implant attributes including differences in size, articular geometry  512 ,  522 , and bone facing attachment geometries  514 ,  524 . Alternatively, the simulation model  80  may be iteratively run with different completed virtual surgery models  70 , each incorporating different implant positioning. For instance, in each completed virtual surgery model  70 , one or more implant components  78   a - c  may be spatially oriented differently relative to the patient&#39;s anatomy  71 ,  75 ,  76 ,  78 . Biomechanical simulation model  80  may further comprise soft tissues representative of the patient&#39;s own anatomy, such as the quadriceps muscle and tendon  73 , patellar tendon  74 , and collateral ligaments  76 ,  77 . 
     The iterative and autonomous nature of the biomechanical simulation software is advantageous because it facilitates an optimization of any one or more of: implant selection  560 , implant orientation relative to the patient&#39;s anatomy, and surgical steps (e.g., positioning one or more bone cuts  62 ,  63 ). This is illustrated in  FIG.  10   . An iterative model  90  may be created by importing a set of parameters into one or more of the models  50 ,  60 ,  70 ,  80 . Parameters may include, for instance, information relating to a series of implants  98   a ,  98   b  having similar bone-facing surface geometries ( 95   a ,  95   b ), one or more different bone-facing surface geometries ( 95   a ,  96 ), or one or more different articular surfaces ( 92   a ,  92   b ). As with other models  50 ,  60 ,  70 ,  80 , the iterative model  90  may also incorporate one or more reference point markers  99   a - f  which are maintained in the same spatial locations relative to the anatomic portions  91  of the iterative model  90  as the markers  59   a - f ,  69   a - f ,  79   a - f  in the other models  50 ,  60 ,  70 . For instance, markers  99   a - f  may define additional spatial relationships between the markers  99   a - f  and anatomy  91  or between the markers  99   a - f  and one or more iterative model  90  attributes  92   a ,  98   a ,  95   a ;  92   b ,  98   b ,  95   b ;  96 . Biomechanical simulation, along with the preparation of the model  70  and formation of the physical model (e.g., block  200 ) could be performed before surgery. 
       FIG.  11    shows a surgical system  2000  according to some embodiments. A patient-matched instrumentation block  200  is created using information obtained from one or more of the models  50 ,  60 ,  70 ,  80 ,  90  referenced above. The block  200  incorporates a body having a plurality of registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244 , and a surface  202  including at least three points of contact which conforms to an anatomic portion of an affected area  22  of the scanned patient  20 , for instance, the patient&#39;s distal femur  100 . The surface  202  may be manufactured from the 3D model  50  ( FIG.  5   ) of the patient. The block  200  fits to the anatomic portion of the affected area  22  in only one spatial orientation. More specifically, the surface  202  is structured specifically to match the patient&#39;s bone surface such that when the surgeon places the block  200  on the patient&#39;s joint, the patient&#39;s bone surfaces interface with the surface  202  to temporarily fix the block  200  in place with respect to the patient&#39;s bone, but because of the shape and contouring of the block, which corresponds to the bone, the block fits on the bone in only one orientation. Once fitted, the block  200  does not move or rotate with respect to the patient&#39;s bone until the surgeon physically removes the block  200  from the patient&#39;s bone. This allows the surgeon to take off the block  200  and re-fit the block  200  exactly the same way if he or she needs to re-mount the block  200  to re-register the patient&#39;s bone surface. 
     In the embodiment shown, the registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244  have generally partially spherical surfaces having center registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  which correspond to the one or more reference markers  59   a - f ,  69   a - f ,  79   a - f ,  99   a - f  in models  50 ,  60 ,  70 ,  80 ,  90  (described above). The block  200  is created by taking one or more of the models  50 ,  60 ,  70 ,  80 ,  90  and determining the locations of the registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244  that correspond to one or more reference markers  59   a - f ,  69   a - f ,  79   a - f ,  99   a - f  found in the selected model. This allows the block  200  to function as a physical surgical template that aligns virtual anatomy with the actual anatomy of the patient. In some instances, the registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  of each registration portion may define one or more reference planes, such as an anterior coronal plane  240  or a distal transverse plane  260 . For example, femoral patient-matched instrumentation blocks  200  configured for use with the knee joint may comprise center registration points define other anatomical landmarks such as a mechanical axis  232  of the joint, an anatomic axis  234  of the joint, Whiteside&#39;s line  250 , the epicondylar axis ( 252 ), or the like. 
     A surgical tool  300  comprising a body  320 , tracking member  370 , and a rotatable, reciprocating, or vibratory cutting member  310  is provided. The cutting member  310  is adapted for communication with the block  200  at a plurality of locations (i.e., at each registration portion). The tracking member  370  may be provided, for example, as an array having one or more three fiducial marker members  372  which can be tracked in space by a receiver  1010  as will be described later. Alternatively, while not shown tool  300  may comprise a receiver  1010  mounted thereto, in lieu of an array, which senses other arrays in the surgical field. 
     In the particular embodiment shown, the cutting member  310  has a center  312  that corresponds identically to center registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  of the registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244 . A registration step may include placing the cutting member  310  into each registration portion  210 ,  212 ,  214 ,  240 ,  242 ,  244  of the block  200  in order to communicate spatial positioning information about the tool  300  and cutter  310  relative to both the block  200  and the patient&#39;s anatomy  100  to a computer  1020  having a controller. It should be understood that while the cutter  310  and registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244  are shown to comprise spherical surface portions, other shapes (e.g., conical, cylindrical), could be used, so long as the cutter  310 ,  312  is configured to properly register with registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  associated with the block  200 . 
       FIG.  12    shows a transverse cross-sectional view of block  200  and the relative relationships between registration portions  210 ,  212 ,  214 ,  240 ,  242 ,  244 , registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245 , anatomy  100 ,  102 , and one or more pre-planned optimized resections  130 . Because the registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  are derived from and correspond to the reference markers  59   a - f ,  69   a - f ,  79   a - f ,  99   a - f  of models  50 ,  60 ,  70 ,  80 ,  90 , one or more optimized surgical steps can be transferred from the virtual models  50 ,  60 ,  70 ,  80 ,  90  to the patient&#39;s actual anatomy, using the block  200  as a surgical template for aligning virtual anatomy with actual anatomy. For instance, the spatial relationships between an optimized virtual resection  63  relative to marker  69   c  (determined from the virtual surgery model  60  and validated for best performance using simulation models  80 ,  90 ) may directly equate to the spatial relationships between a planned actual resection  130  relative to registration points  245  on the block  200 . 
       FIGS.  13  and  14    show one of a plurality of registration steps using the block  200 . The cutter  310  is placed into one  244  of the plurality of registration portions, such that the cutter center  312  is aligned with the registration point  245  of the registration portion  244 . The tool  300  holding the cutter  310  may be rotated around at various angles keeping the cutter  310  within the registration portion  244  to ensure a proper registration. It should be known that a separate smooth spherical ball registration tip identical in size and shape to the cutter  310  can be used in lieu of cutter  310 , in order to accomplish the same registration function and reduce the possibility of teeth on the cutter  310  cutting into or damaging the block  200 . During registration steps, information pertaining to relative spatial relationships  294 ,  292  between the cutter  310  and anatomical portions such as an articular surface  102  or one or more pre-planned optimized resections  130  located below uncut bone  110  may be transferred to a computer  1020  having a controller, or to a stand-alone computer and controlling device located on or inside the tool  300 . The surgeon may input information into the computer  1020  regarding which registration point  245  or registration portion  244  is being registered at any given time. It should be noted that the one or more pre-planned optimized resections  130 , while shown as a series of planar cuts, may comprise a series of curves, splines, irregularly-shaped surfaces, B-splines, and 3D surfaces to match or better suit a particular patient&#39;s anatomy. For instance, non-planar resections may be used with custom implants having matching non-planar attachment surfaces, in order reduce the total amount of bone or cartilage removal necessary to accommodate a standard implant having planar resections. The one or more pre-planned optimized resections  130  may be focused around areas of deteriorated anatomy only, resulting in more minimally-invasive surgeries and better bone conservation. 
       FIG.  14    illustrates the step of registering a surgical tool  300  and associated cutter  310  using a patient-matched block. After placing the block  200  on the patient&#39;s bone, one or more arrays  470  having one or more fiducial markers  472  may be secured to the patient&#39;s anatomy (e.g., the femur). The one or more arrays  470  are preferably provided adjacent to the patient&#39;s affected site (e.g., the distal femur). The surgeon places the cutter  310  of the tool  300  into one  244  of a plurality of registration portions  210 ,  212 ,  214 ,  242  and notifies the computer  1020  which registration portion is communicating with the cutter  310  at any given time. This may be done through a graphical user interface (GUI) or a keypad located on or communicating with the tool  300 . The center of the cutter  310  is then registered with one or more of the other registration portions  210 ,  212 ,  214 ,  242  until the desired virtual surgery model  60  is aligned with the patient&#39;s actual anatomy  22 . Since the center  312  of the cutter  310  essentially matches the spatial location of each registration point  211 ,  213 ,  215 ,  243 ,  245  on the block  200 , data regarding the spatial location  294  of each registration point  245  relative to the patient&#39;s anatomy  102  are stored into the computer  1020  in a first file. A second file containing a preoperative plan, information regarding one or more surgical procedure steps, and/or a 3D image file of the one or more pre-planned optimized resections  130  is also uploaded to the computer  1020 . The second file is representative of the virtual surgery model  60  and includes one or more reference markers  69   a - f  which are synonymous with each spatial locations  292  of each registration point  245  (the data being available at the time of manufacturing the block  200 ). Essentially, in the most basic sense, the second file serves as a virtual surgical blueprint for the patient-specific procedure and the first file serves as a calibration mechanism so that the surgical tool  300  can physically be used to implement the virtual surgical blueprint. 
     By relating the information obtained in the first file to the computer  1020 , the computer&#39;s processor can determine the actual physical position and orientation of the tool  300  and cutter  310  in 3D space relative to both the patient&#39;s actual anatomy and virtual surgery model  60 . The relative position and orientation of the tool  300  and cutter  310  in 3D space relative to the one or more pre-planned optimized resections  130  may also be determined using information contained within the second file and displayed on the GUI device as shown in  FIG.  15   . 
       FIGS.  15 - 19    graphically illustrate steps of making one or more pre-planned optimized resections  130 ′. After registration, the tool  300  is operated to turn, vibrate, or reciprocate the cutter  310 . The cutter  310  is then plunged into and through the anatomical surface  102  (e.g., articular surface) to remove portions  110  of bone, cartilage, and other anatomy between the cutter  310  and the one or more pre-planned optimized resections  130 ′. Realtime data regarding the spatial position  394  of the cutter  310  (e.g., center  312 ) relative to anatomy  102 ,  110  and one or more planned resections  130  is tracked via a tracking receiver  1010  and fed into a controller associated with computer  1020 . When a surface of the cutter  310  approaches, meets, or exceeds a surface boundary of the one or more pre-planned optimized resections  130 , the controller signals the tool  300  to retract the cutter  310  within the tool  300  or stop rotation of the cutter  310  so as to prevent cutting beyond the one or more preoperatively planned and optimized resections  130  as shown in  FIG.  18   . Alternatively, a display can warn the surgeon to reduce pressure or cutting in certain areas as the cutter  310  approaches, meets, or exceeds a surface boundary of the one or more pre-planned optimized resections  130 . 
     At the point in time during surgery when the closest distance  392  between the cutter center  312  and the one or more planned resections  130  equals the radius of the cutter  310  for the entire boundary surface of the one or more planned resections  130 , the step of modifying anatomy is finished, and the tool  300  can be removed from the surgical site. Thereafter, an implant  500  having attachment surfaces  534  matching the corresponding one or more planned resection surfaces  130  may be implanted. 
       FIG.  20    illustrates an alternative apparatus and method for registration of surgical tools according to some embodiments. Surgical tool  300  comprises an array  1375  attached thereto via mounting means  1350 . The array  1375  comprises at least three fiducial tracking markers  1372  similar to the embodiment shown in  FIGS.  11 ,  14 , and  15   . However, the array further comprises a plurality of location features  1382  provided thereon which are adapted to communicate with a plurality of location features  610 ,  620 ,  630  provided on a patient-matched block  600 . In certain embodiments, the location features  1382 ,  1384 , and  1386  are shaped and contoured such that when the array  1375  joins the block  600 , the inner and/or outer surfaces of the location features  1382 ,  1384 ,  1386  interfit with the location features  610 ,  620 ,  630  of the block  600  in only one orientation. In some embodiments, the location features are keyed to force the array  1375  to be positioned in one orientation only when the array  1375  engages the block  600 . The location features  1382 ,  1384 ,  1386  may be held in place within the location features  610 ,  620 ,  630  by friction. In use, after the block  600  is secured to the anatomy  100  (e.g., by pinning the block  600  using holes  630 ), the location features on the array  1375  may be joined with the location features  610 ,  620 ,  630  on the block  600  in only one possible configuration. Then, the surgeon instructs the computer  1020  to register the spatial position and orientation of the tool  300 . Because the dimensions of the cutter  310  for attachment to the tool is known and the cutter  310  may only be attached to the tool in one configuration, and the distance between each tracking fiducial marker  1372  and the center  312  of the cutter  310  can be determined, the computer  1020  can track the spatial orientation of the cutter  310  during a surgical procedure in real time. 
       FIGS.  21 A- 21 D  graphically illustrate a method of performing surgery  3000  according to some embodiments. A patient is scanned  3002  using imaging means such as CT, microCT, or MRI. Then, 2D image slices are saved  3004  and exported  3006  to segmentation software (e.g., MIMICS software). One or more portions of one or more of the image slices may be segmented  3008  in order to separate soft tissues from bone and cartilage. The resulting segmented 2D image slices may be combined  3009 ,  3012  into a single 3D file using software (e.g., MIMICS) and exported to CAD software  3010  to create a 3D patient model  50  for analysis and preoperative planning. The CAD software may also serve to smooth the single 3D file created from the segmented 2D image slices. 
     In certain embodiments, a custom implant and custom anatomical modification  130  is created based on the patient model  50 , or an ideal implant  530  may be selected  3014  from a database  500  of implants  510 ,  520 ,  530 . A computer model of the custom or selected implant, including attachment surfaces is loaded into the patient model, and positioned on the patient model in a first location and orientation  3016  via a virtual resection  3018  and virtual implantation  3020 ,  3022  as shown in  FIGS.  7  and  8   . In certain embodiments, the implant size is determined by fitting a trial implant for confirming the fit and sizing of an implant to be used. Optionally, biomechanical simulation software such as KNEESIM or LIFEMOD may then be used  3024 ,  3026 ,  3028  to determine one or more performance characteristics of the selected implant  530  if it is used on the patient  20  and oriented in the first location and orientation  3016  within the virtual 3D patient model  50  as shown in  FIG.  9   . If one or more of the performance characteristics are acceptable  3032 , then a patient-matched block  200  may be created. If one or more of the performance characteristics of the selected implant  530  are not acceptable, then another implant  510 ,  520  may be selected  3034  from the database  500 , or the same implant  530  may be virtually implanted  3036  in a second location and orientation using different virtual anatomical modifications  62 ,  63 , and the simulation model  80  may be run again. In some embodiments, the proposed computer model and/or data relating to the performance characteristics may be sent electronically to a health care provider. In other embodiments, a network access may be provided to allow a health care provider to access via a computer and/or network the proposed computer model and/or data relating to performance characteristics. In some embodiments, a user, such as an engineer, may act upon instructions or approval received from a health care provider relating to the proposed computer model and/or data relating to the performance characteristics. If approval is denied, then a message indicating disapproval is sent via the network or the computer model and modifications are made to the model or data, and re-sent. 
     Steps  3038 - 3048  describe creating a patient-matched block  200  having registration features  210 ,  212 ,  214 ,  240 ,  242 ,  244 . The registration features define registration points  211 ,  213 ,  215 ,  241 ,  243 ,  245  which are designed to receive and detect a location of a material removal implement, burr, bit, router, mill, or cutter  310  of a surgical tool  300  relative to a patient&#39;s anatomy  100  during surgery. Spatial relationships between registration points, articular surfaces  102 , and one or more pre-planned optimized resections  130  are pre-defined, stored into a computer file, and uploaded into a computer  1020  having a controller. The computer file is used to manufacture the block  200 , and may also be used during surgery to register in space, the relative spatial locations of the block  200 , tool  300 , cutter  310 , articular surface  102 , and all pre-planned anatomical modifications and resection profiles  130 . 
     The surgeon places  3050  the patient-matched block  200  onto the affected site  100  (e.g., arthritic bone) so that it fits in only one spatial orientation  3052 . The block  200  may be secured  3054  to the affected site  100  (e.g., with pins) so that a surgical tool  300  may be registered accurately with a computer-assisted surgery (CAS) system. The tool  300  provided in step  3056  may be registered by placing  3060 ,  3062  a portion of the tool (e.g., cutter  310 ) into each registration portion and simultaneously communicating  3064  information regarding the location of the surgical tool  300  to a computer  1020  while the surgical tool  300  is positioned at each registration portion of the block  200 . The center location  312  of the cutter  310  at each registration portion  211 ,  213 ,  215 ,  241 ,  243 ,  245  generally matches identical spatial reference points  69   a - f  within an electronic file containing one or more preoperatively-planned patient-optimized anatomical modifications to be made  130 ′ (See  FIG.  7   ). In step  3058 , the electronic file is uploaded to the computer  1020 , and registration information is processed  3068  with the electronic file to define  3070  a surgical cutting boundary and set control limits for the surgical tool  300 . Information relating to the surgical cutting boundary  130 ′ is sent to a controller associated with the computer  1020 . Tracking device  1010  determines real-time positioning of the tool  300  and cutter  310  and sends information regarding instant tool position to the controller. The tracking device  1010  may be a passive or active system. The system may utilize electromagnetic waves, infra-red, or ultrasound. In certain embodiments, the system is passive and uses infra-red. If the real-time position and orientation of the tool  300  places the cutter  310  shallower than the desired cutting boundary  130 ′, then the controller instructs the tool  300  to continue cutting  3072 . However, if the real-time position of the tool  300  places the cutter  310  adjacent to, on, or past the desired cutting boundary  130 ′, then the controller instructs  3074  the tool  300  to discontinue continue the cutting operation. For instance, the controller may instruct the tool  300  to retract the cutter  310  or reduce or eliminate current to the tool  300  when the computer-assisted tracking software determines that the cutter  310  is adjacent to, on, or past the desired cutting boundary  130 ′. 
     Once the anatomy is prepared  3076 , an implant  530  having attachment surfaces  534  matching the prepared anatomy  130  may be installed  3078 , and the surgical procedure is finished  3080  in a conventional manner. 
       FIGS.  22 - 43    illustrate an alternative surgical system and a method of its use. A patient-specific instrument is provided that is designed to conform at least in part to a contour of a patient&#39;s unique anatomy. For instance, as shown, a patient-specific instrument is provided as a distal femoral block  2000  comprising one or more mounting devices such as holes  2002 ,  2004 ,  2006  for receiving one or more surgical fasteners  2202 ,  2204 ,  2206 . The block  2000  has an anatomy-facing portion  2020  that includes a surface contact, line contact, or point contact with the patient&#39;s anatomy  9000  (e.g., distal femoral articular cartilage and bone). The block  2000  mates with the anatomy  1000  in only one spatial orientation within six degrees-of-freedom. Block  2000  includes an alignment site in the form of an adapter portion  2100  that mates with a complementary adapter portion  2460  of a mount  2400 . The housing receives an array or other imaging site, as discussed below, and thus the housing  2400  functions as a mount. The adapter portions  2100 ,  2460  may be structured as dovetail connections, tongue-in-groove connections, peg-in-hole connections, snap-fit connections, male/female connections, or any other known connections. The adapter portions may be self-securing or may be temporarily fixed together with one or more screws, magnets, or pins. Moreover, the adapter portions may be configured so that the mount  2400  can attach to the block  2000  from multiple directions. 
     The block  2000  may be held to the patient&#39;s native anatomy, or secured thereto using surgical fasteners  2202 ,  2204 ,  2206  as shown in  FIGS.  24  and  25   . Mount  2400  may then be secured to the block  2000  via adapter portions  2460 ,  2100  as shown in  FIGS.  26  and  27   . The mount is then secured to the patient&#39;s anatomy as shown in  FIGS.  28  and  29   . For example, the mount  2400  may have one or more bosses  2430 ,  2480  having apertures  2432 ,  2482  therein which are suitable for receiving surgical fasteners  2203 ,  2205 . Once mount  2400  is secured to the patient&#39;s anatomy, the block  2000  may be removed as shown in  FIGS.  30  and  31   . Small voids  9002 ,  9004 ,  9006  may exist where surgical fasteners  2202 ,  2204 ,  2206  are used. 
     Mount  2400  may comprise an extension portion  2450  and a mounting adapter for receiving an array  2500  having a complimentary mounting adapter  2510 . The mounting adapters  2410 ,  2510  preferably rigidly secure the array  2500  to the mount  2400  in only one relative spatial orientation within six degrees-of-freedom. Once the array  2500  is fitted to the mount  2400 , a location of the array  2500  is tracked and communicated to a processor of a computer assisted surgical system. Array generally comprises three or more fiducial markers  2502 ,  2504 ,  2506  visible to a receiver  1010  of a computer assisted surgical system which may be mounted to a platform  2518 . Mounting adapters may comprise portions of tracks, threaded connections, dovetail joints, ball detents, snap-fit releasable connections, quarter-turn fasteners, or magnetized male/female connections. 
     During the creation of the block  2000 , engineers strategically set the datum of the mounting adapter  2410  (and ultimately, the datum of the array  2500  and plane between markers  2502 ,  2504 ,  2506 ) to be in a fixed spatial relationship with respect to the conforming anatomy-facing surface profile  2020 . In this way, the patient-matched block  2000  serves to perform an “instantaneous” registration function, without requiring the surgeon to participate in the time-consuming steps of touching a surgical tool to various anatomical landmarks as conventionally required. Moreover, the block  2000  allows an engineer or surgeon to actually replicate a preoperative surgical plan with more accuracy than conventional CAS methods, because the possibility of introducing error into the procedure from inaccurate manual registration techniques is eliminated. The datum established by the block positions the array  2500  at a known spatial orientation with respect to the patient&#39;s anatomy  9000 . 
     As shown in  FIGS.  35 - 37   , the surgical tool  1800  may be used to make one or more anatomical changes to the patient&#39;s anatomy  9000 . For example, as shown, tool  1800  includes a body  1820 , a tracking member  1870 , and a cutter  1810 . In certain embodiments, the cutter  1810  is rotable (e.g., a burr or end mill device) and is computer-controlled to assist the surgeon in making anatomical changes  9010 ,  9020  that closely match a preoperatively-defined surgical plan. The tracking member  1870  may be provided, for example, as an array having at least three fiducial markers  1872 ,  1874 ,  1876  which may be tracked in space by a receiver (e.g., receiver  1010  shown in  FIG.  15   ). When the tool  1800  moves the cutter  1810  to a location of the anatomy  9000  that approaches a pre-defined resection boundary  130 ′, a controller sends an input to the tool  1800  which provides a response from the tool  1800 . The input may comprise, for example, removing current to the tool  1800  or instructing the tool  1800  to retract the cutter  1810 , and the response from the tool  1800  may be, for instance, terminating further anatomical changes (e.g., stop cutting). 
     In the embodiments described above in  FIGS.  11 - 14   , the patient-matched block has one or more alignment sites (e.g.,  210 ,  212 ,  214 ,  240 ,  242 , and  244 ) that receives a registration tool (e.g., tip  310  of the surgical tool  300 ). The registration tool then joins the alignment sites and a location of the surgical tool is tracked with respect to the patient&#39;s bone by detecting the position of the surgical tool with respect to a reference array (e.g.,  470 ) positioned near or on the patient. In such implementations, the surgical tool  300  functions as both the registration tool and the cutter, and the registration and re-registration occurs by touching the distal tip of the cutter to the registration sites on the block. In the alternative implementations of  FIGS.  22 - 36   , the registration tool houses the reference array and uses a single registration site (e.g., adaptor portion  2100 ). The housing  2400  ( FIG.  26   ) is an example of such a registration tool. The housing  2400  connector (e.g., adaptor portion  2460 ) interfaces with a complimentarily shaped connector (e.g., the adaptor portion  2100  of the patient-matched block  2000  as shown in  FIG.  26   ) to align with respect to the block. The housing adaptor  2410  receives the array  2500  as shown in  FIG.  33   . A location of the surgical tool such as a surgical tool  1800  ( FIG.  36   ) can be tracked with respect to the patient&#39;s bone by detecting the position of the surgical tool with respect to the reference array  2500 . In this case, the reference array  2500  is directly engaged to the housing  2400 . Such implementation can eliminate the need to touch the site with the cutter for registration. The array mounted to the housing  2400  (aligned according to the patient-specific block) is registered by the processor, thereby automatically registering the location of the patient&#39;s bone. 
     Once the actual anatomical modification  9020  substantially matches anatomical changes  130 ′ outlined in the preoperatively-defined surgical plan, the array  2500  and mount  2400  may be removed from the anatomy  9000  as shown in  FIGS.  38 - 40    so that an implant  4000  may be installed. Anatomical voids  9003 ,  9005  may be present where surgical fasteners  2203 ,  2205  are used to secure the mount  2400  to the patient&#39;s anatomy  9000 . The implant  4000  may be a custom implant or standard implant. Anatomical modifications  9020  may optimize the placement of a standard implant in order to achieve best biomechanic performance for the patient. Implant  4000  may have an anatomic-facing portion (e.g., peg, keel, ridge, protuberance, porous ingrowth structure, or cement interface surface) that matches the anatomical modification  9020 . 
       FIG.  43    schematically illustrates the method illustrated in  FIGS.  22 - 42   . 
       FIG.  44    describes an alternative system and method wherein mount  2400 ′ may be integrally provided with an anatomy-facing portion configured to conform to and mate with a patient&#39;s anatomy  9000 ′ in one spatial orientation within six degrees-of-freedom. The anatomy-facing portion can conform to and mate with the patient&#39;s anatomy  9000 ′ via a surface contact, a line contact, or a point contact, such that a separate patient-matched block  2000  as shown and described in  FIGS.  23 - 31    is not necessary. The mount  2400 ′ is placed onto the patient&#39;s anatomy  9000 ′ in only one spatial orientation, and then is secured to the anatomy  9000 ′ with surgical fasteners  2203 ′,  2205 ′ as shown in  FIGS.  28 - 39   . The procedure is finished in a similar manner as described for  FIG.  43   . 
     Those with ordinary skill in the art will recognize that the markers, calibration methods, and tracking methods provided herein are merely illustrative, and other methods of finding coordinates on the workpiece and/or cutting tool surface can be used, including for example, ultrasound, fluoroscopic imaging, electromagnetic sensors, optical range sensors, mechanical arms, etc. 
     The tracking system can be, for example, as described in U.S. Pat. Nos. 5,828,770; 5,923,417; 6,061,644; and 6,288,785, the contents of which are incorporated herein by reference. Other tracking systems may be employed, such as radio-frequency (RF) tracking, ultrasound tracking, electromagnetic tracking, including “Flock of Birds” tracking, as those described in U.S. Pat. Nos. 4,849,692; 5,600,330; 5,742,394; 5,744,953; 5,767,669; and 6,188,355, the contents of which are incorporated herein by reference. 
     The systems and methods described herein may also be used in an automated robotic surgery.  FIG.  45    shows a surgical robot  5000  having a first arm  5002  for fitting the patient-matched instrumentation block  200  or  2000  to the patient&#39;s bone and a second arm  5004  configured to receive a cutting tool (e.g., surgical tool  300  as shown in  FIG.  11   ) for resecting the patient&#39;s bone according to a surgical plan. A technician may fit the block  200  to the first arm  5002 , the first arm  5002  being guided by the surgical robot  5000  to correctly align the block  200  with respect to the patient&#39;s bone. Once the block  200  is fitted to the patient&#39;s bone, the robot  5000  may register the location of the patient&#39;s bone by joining a registration tool (e.g., tool  300 ) operated by the second arm  5004  to one or more of the registration portions  210 ,  212 ,  214 ,  240 ,  242 , and  244  located on the block  200 . Alternatively, a technician or surgeon could places the block  200  directly on to the patient&#39;s bone and the surgical robot  5000  could register and resect the patient&#39;s bone according to a predefined surgical protocol and a cutting boundary. One example of the surgical robot  5000  may be the PiGalileo surgical navigation system sold by Smith &amp; Nephew, Inc. 
     Various implementations and embodiments of the systems and methods disclosed herein (and any devices and apparatuses), and any combinations thereof, will be evident upon review of this disclosure. For example, certain embodiments include a patient-matched apparatus (for example a patient-matched block  200 ) for registering the location of a surgical tool. The apparatus includes an inner surface that conforms to an image of the patient&#39;s anatomic portion (such as a bone) and a body having one or more registration sites configured to receive a registration tool. The registration site may include one or more registration points corresponding to one or more reference markers described in the image of the patient&#39;s anatomic portion. The image may be disclosed, described or displayed as a computer image or any other graphical, electronic or other image. 
     The inner surface of any of the apparatuses may be configured to fit the patient&#39;s anatomic portion in a pre-determined spatial orientation, for example fitting the anatomic portion in only one spatial orientation. The registration site of any of the aforementioned patient-matched apparatuses may include a partially spherical surface. 
     Any of the registration tools disclosed herein or used in connection with any of the aforementioned patient-matched apparatuses or systems or methods may include a cutting member that interfaces with the registration site to identify a location of the registration site and communicates that location to a computer. The registration tool may communicate the location of the registration point relative to a reference array for storing into the computer in a first file. In various embodiments, the computer may include one or more of tracking hardware, tracking software, and a controller for guiding the surgical tool according to a second file containing a surgical plan. In the foregoing embodiments, the cutting member of the surgical tool may include a center that corresponds to the registration point of the patient-matched block or apparatus. The registration point of any of the patient-matched apparatuses may correspond to a reference marker. Any of the registration points may correspond to a reference marker of an iterative biomechanical simulation model of the patient. 
     In various implementations, a method is provided for operating a surgical alignment guide. The method includes the step of providing at least one registration site on a patient-matched apparatus. The apparatus may have an inner surface that conforms to a contour of an image of a patient&#39;s anatomic portion. The method may also include one or more of the steps of: providing a surgical tool with an alignment point configured to interface with the registration site; and align the alignment point with respect to the registration site for communicating the location of that registration site to a processor; tracking the position of the surgical tool relative to a reference array to identify the position of the surgical tool; defining a physical boundary for the surgical tool; guiding the operation of the surgical tool depending on the location of the surgical tool with respect to the physical boundary of the surgical tool; displaying a relative position of the surgical tool with respect to the physical boundary on a display device; communicating the position of the registration site to a processor via a tracking receiver; or any combination thereof. 
     In various implementations, a method is provided for manufacturing a surgical alignment guide. The method comprises one or more of the steps of: creating a computer model of a patient&#39;s joint based on an image of the patient&#39;s joint; creating at least one reference point on the computer model of the patient&#39;s joint; defining a spatial relationship between the reference point and a bone surface of the computer model of the patient&#39;s joint; creating a patient-matched alignment guide having at least one site that correspond to the reference point; creating an inner surface of the patient-matched alignment guide, the inner surface having a profile that conforms to a contour of the image of the patient&#39;s joint; or any combination thereof. 
     In various implementations, a system is provided for registering a location of a patient&#39;s anatomic portion using a patient-matched apparatus (such as a block). The system includes a patient-matched apparatus having a first connector and an anatomy-facing surface that conforms to an image of the patient&#39;s bone; and a mount having a second connector that mates with the first connector and is configured to receive an array to communicate a location of the array to a computer assisted surgical system. The mount may be positioned in a fixed spatial relationship with respect to the anatomy-facing surface. The systems may include a surgical tool having a second array configured to communicate a location of the surgical tool with respect to the first array. 
     In various implementations, a system is provided for operating a surgical alignment guide. The system includes a patient-matched surgical apparatus having an inner surface that conforms to an image of a patient&#39;s bone and an alignment site; a registration tool configured to interface with the alignment site to relate the position of the patient-matched surgical apparatus to a surgical tool; and a processor that tracks a location of the surgical tool with respect to an array. 
     In various implementations, a patient-matched surgical guide is disclosed for registering a location of a patient&#39;s bone. The surgical guide may include an inner surface that conforms to the patient&#39;s bone; and a body having a registration site that receives a registration tool of a medical device for communicating the location of that registration tool to a processor, wherein the registration site includes a registration point that corresponds to a reference marker described in an image of the patient&#39;s bone. The inner surface of the inner surface may be configured to fit a portion of the patient&#39;s bone in only one spatial orientation. In any embodiment of such guide, the registration site of the patient-matched surgical guide may include a partially spherical surface. In any embodiment of such guide, the image may be a three-dimensional model of the patient&#39;s bone, and the marker may define a spatial relationship with respect to the articulating surfaces of the patient&#39;s bone. In any embodiment of such guide, the image may be of a virtual surgery model. 
     In various implementations, a system is provided for registering a location of a patient&#39;s anatomic portion using a patient-matched block. The system includes a patient-matched block having an anatomy-facing surface that conforms to a patient&#39;s bone and a connector; and a mount that attaches to the bone and the connector and is configured to receive an array to communicate a location of the bone to a computer assisted surgical system. In any embodiment of such system, the mount may be positioned in a fixed spatial relationship with respect to the anatomy-facing surface. 
     In various implementations, a system is provided for performing a computer-assisted surgical procedure for implanting a prosthetic device to a patient. The system includes a patient-matched block having a registration site and an inner surface that is configured to conform to a patient&#39;s bone; a surgical tool with a cutting tip that interfaces with the registration site to identify a location of the registration site; and a processor that tracks the location of the tool with respect to the location of the patient&#39;s bone. In any embodiments of such system, a computer may be included and may have one or more of tracking hardware; tracking software; and a controller for guiding the surgical tool according to a file containing a surgical plan. In any embodiments of such system, the registration site of the patient-matched block may include a partially spherical surface having a center registration point. In any embodiments of such system, the cutting tip may include a center that corresponds to the registration point of the patient-matched block. In any embodiments of such system, the registration site may include a registration point that corresponds to a reference marker of a three-dimensional model of the patient&#39;s bone. The registration point may correspond to a reference marker of a completed virtual surgery model. In any embodiments of such system, a first file may be included and contain data of the location of the registration site of the patient-matched block relative to the patient&#39;s bone. In any embodiments of such system, a tracking receiver is in communication with the processor, the tracking receiver being configured to identify the location of the registration site. 
     In various implementations, a method of operating a surgical alignment guide is provided. The method includes one or more of the steps of: providing a patient-matched block, the block having at least one registration site and an inner surface that conforms to an anatomic portion of the patient; providing a surgical tool with an alignment point that interfaces with the registration site; aligning the alignment point with respect to the at least one registration site; tracking the position of the surgical tool relative to a reference array to identify the position of the tool; defining a cutting boundary having one or more pre-planned optimized resections of the patient&#39;s anatomy; or any combination thereof. 
     In various implementations, a system is provided for performing a computer-assisted surgical procedure for implanting a prosthetic device to a patient, the system comprising a patient-matched surgical apparatus having an inner surface that conforms to the patient&#39;s bone and an alignment site; a registration tool configured to interface with the alignment site to identify the location of the patient&#39;s bone; and a processor that tracks a location of a surgical tool with respect to an array. 
     In view of the foregoing, it will be seen that the several advantages are achieved and attained. As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. 
     Variations and modifications will occur to those of skill in the art after reviewing this disclosure. The disclosed features may be implemented, in any combination and subcombinations (including multiple dependent combinations and sub-combinations), with one or more other features described herein. The various features described or illustrated above, including any components thereof, may be combined or integrated in other systems. Moreover, certain features may be omitted or not implemented. 
     Examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and made part of this application.