Patent Publication Number: US-2022233243-A1

Title: Surgical planning guidance and learning

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/894,461, filed Feb. 12, 2018, which is a continuation of U.S. patent application Ser. No. 14/145,619, filed Dec. 31, 2013, which claims the benefit of and priority to U.S. Provisional Patent Application No. 61/747,765, filed Dec. 31, 2012, each of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     The present invention relates generally to surgical planning in connection with computer-assisted surgeries. More particularly, the embodiments described herein relate to the interactions between a user and an interface of a surgical planning system. 
     Planning systems for computer-assisted surgical systems produce surgical plans based on input information. To develop the surgical plan, the planning system applies an algorithm to the input information. For example, during planning of a total knee arthroplasty, input information may include information related to the patient&#39;s bone structure and other physical characteristics. The surgical plan developed by the planning system shows where any implants, such as a femoral component and a tibial component, should be placed. 
     After the surgical plan has been produced, the user (e.g., a surgeon, other medical practitioner, or a technical specialist) can customize the plan based on the user&#39;s additional knowledge. However, in conventional planning systems, the user may not know how the planning system arrived at the surgical plan. In other words, the user does not understand the algorithm applied to the input information to develop the surgical plan. A lack of knowledge related to the underlying algorithm used by the planning system may make it more difficult for the user to effectively modify the surgical plan (e.g., the planned implant placement or other specifics related to the surgical plan). 
     SUMMARY 
     The methods described herein guide a user during surgical planning in a manner that provides the user with information related to an initial surgical plan, thereby improving the transparency of the planning system relative to conventional planning systems. In addition, the methods for guiding a user described herein allow the user to customize the initially developed surgical plan. 
     In accordance with one aspect, the present disclosure relates to a method for guiding a user during surgical planning. The method includes receiving input information; developing an initial surgical plan based upon the input information; and guiding a user by providing suggested actions to the user. If the user performs the suggested actions, the suggested actions lead the user to the initial surgical plan. The method further includes providing the user with an option to deviate from one or more of the suggested actions by performing non-suggested actions, wherein deviation from one or more of the suggested actions leads to development of a final surgical plan that is different from the initial surgical plan. 
     According to another aspect, the present disclosure relates to a system for guiding a user during surgical planning. The system includes a processing circuit configured to receive input information; apply an algorithm to the input information to develop an initial surgical plan; and display on a display device a plurality of icons in sequence, each of the plurality of icons having a distinguishing characteristic configured to alert the user to select each of the plurality of icons. If the user selects each of the plurality of icons having a distinguishing characteristic, the selections lead the user to the initial surgical plan. The processing circuit is further configured to customize the initial surgical plan to create a final surgical plan upon user selection of a displayed icon without a distinguishing characteristic. 
     The invention is capable of other embodiments and of being practiced or being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements, in which: 
         FIG. 1A  is a representation of a display screen during a first step of guiding a user during surgical planning according to a first exemplary embodiment. 
         FIG. 1B  is a representation of a display screen during a second step of guiding a user during surgical planning according to the first exemplary embodiment. 
         FIG. 1C  is a representation of a display screen during a third step of guiding a user during surgical planning according to the first exemplary embodiment. 
         FIG. 1D  is a representation of a display screen during a fourth step of guiding a user during surgical planning according to the first exemplary embodiment. 
         FIG. 1E  is a representation of a display screen during a fifth step of guiding a user during surgical planning according to the first exemplary embodiment. 
         FIG. 1F  is a representation of a display screen after completion of guiding a user during surgical planning according to the first exemplary embodiment. 
         FIG. 2A  is a representation of a display screen during a first step of guiding a user during surgical planning according to a second exemplary embodiment. 
         FIG. 2B  is a representation of a display screen during a second step of guiding a user during surgical planning according to the second exemplary embodiment. 
         FIG. 2C  is a representation of a display screen after completion of guiding a user during surgical planning according to the second exemplary embodiment. 
         FIG. 3A  is a representation of a display screen during a first step of guiding a user during surgical planning according to a third exemplary embodiment. 
         FIG. 3B  is a representation of a display screen during a second step of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 3C  is a representation of a display screen during a third step of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 3D  is a representation of a display screen during a fourth step of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 3E  is a representation of a display screen during a fifth step of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 3F  is a representation of a display screen during a sixth step of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 3G  is a representation of a display screen after completion of guiding a user during surgical planning according to the third exemplary embodiment. 
         FIG. 4A  is a representation of a display screen during a first step of guiding a user during surgical planning according to a fourth exemplary embodiment. 
         FIG. 4B  is a representation of a display screen during a second step of guiding a user during surgical planning according to the fourth exemplary embodiment. 
         FIG. 4C  is a representation of a display screen during a third step of guiding a user during surgical planning according to the fourth exemplary embodiment. 
         FIG. 4D  is a representation of a display screen during a fourth step of guiding a user during surgical planning according to the fourth exemplary embodiment. 
         FIG. 4E  is a representation of a display screen during a fifth step of guiding a user during surgical planning according to the fourth exemplary embodiment. 
         FIG. 4F  is a representation of a display screen after completion of guiding a user during surgical planning according to the fourth exemplary embodiment. 
         FIG. 5  is a perspective view of an embodiment of a surgical system according to an exemplary embodiment. 
         FIG. 6  is a block diagram of a model surgical system according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting. 
       FIGS. 1A-4F  provide various representations of a user display during different exemplary embodiments described herein. In each of the exemplary embodiments, input information has been received (e.g., by a surgical planning system) and an algorithm has been applied to the input information to develop an initial surgical plan. Input information may relate to the patient&#39;s bone structure or other physical characteristics. Imaging techniques, such as CT, MRI, or ultrasound, may be used to obtain three-dimensional representations of the patient&#39;s anatomy, such as the representations of the femur and tibia shown in  FIGS. 1A-4F . General surgical planning and navigation, including haptic control and feedback, may be performed by a computerized surgical system such as that depicted in  FIGS. 5 and 6  (and described below), and as described in U.S. Pat. No. 8,010,180 “Haptic Guidance System and Method” to Quaid et al., which is incorporated herein by reference in its entirety. 
       FIGS. 1A-4F  provide examples of guiding a user during surgical planning by providing a plurality of suggested actions to the user. The user is guided via a display screen, shown in various exemplary embodiments as graphical user interface (GUI)  2 , to perform the suggested actions. The suggested actions may correspond to steps of an algorithm used by a planning system to develop an initial surgical plan. Guiding a user in this manner allows the user to 1) learn how the initial surgical plan was developed by the planning system, and 2) customize the initial surgical plan during the user-guidance process. If the user performs the suggested actions, the suggested actions will lead the user to the initial surgical plan. However, the user has the option to deviate from one or more of the suggested actions by performing non-suggested actions. Deviation from one or more of the suggested actions leads to development of a final surgical plan that is different from the initial surgical plan. 
     In connection with guiding a user, the GUI  2  illustrated in  FIGS. 1A-4F  may display a series of icons in sequence, each of the icons having a distinguishing characteristic intended to alert the user to select the icons. If the user selects the icons having a distinguishing characteristic, the selections will lead the user to the initial surgical plan. However, the user can customize the initial surgical plan by selecting a displayed icon without a distinguishing characteristic. 
     In accordance with one embodiment, GUI  2  provides virtual representations of a femoral component  4  and a tibial component  6  on virtual models of a patient&#39;s femur and tibia, respectively. References herein to femoral component  4  and tibial component  6  are understood to be references to the virtual representations of these components as shown on a GUI  2 . 
     The GUI  2  also displays criteria in the form of a list  8 . The criteria are related to the surgical plan shown on the current display of GUI  2 . Each of the criteria is associated with one or more acceptable values. Acceptable values for any particular criterion may be values below a maximum threshold, above a minimum threshold, or within a predefined range. Some examples of displayed criteria, as can be seen in  FIGS. 1A-4F , include femoral notching and sizing, femoral rotation, femoral overhang, tibial overhang and sizing, tibial rotation, tibial slope, limb alignment and joint line, extension and flexion gaps, and mid-flexion gap and stability. These criteria relate to surgical planning of a total knee arthroplasty (the example used in the exemplary embodiments of  FIGS. 1A-4F ). However, the criteria may be chosen to be applicable to any planned surgical procedure. 
     Each of the criteria in list  8  includes a corresponding indicator  10  configured to provide the user with information related to the particular criterion. The information provided by indicator  10  may relate to whether the corresponding criterion has an acceptable value. The indicators  10  may be circular images configured to provide information via a display feature. Each indicator  10  may be configured to change its display feature to convey information. In one embodiment, if a certain criterion has an acceptable value during a stage of user-guidance, the corresponding indicator indicates acceptability by displaying a first display feature, such as a checkmark. For example, in  FIG. 1A , femoral overhang and several other criteria have acceptable values and are therefore marked with an indicator  10   a  having a first display feature (e.g., a checkmark). However, if a certain criterion does not have an acceptable value during a stage of user-guidance, the corresponding indicator will display a second display feature, such as being filled in. In  FIG. 1A , the femoral notching and sizing criterion and the extension and flexion gaps criterion do not have acceptable values. These criteria are therefore marked with a indicator  10   b  having a second display feature (e.g., a filled interior). Criteria that are within a predefined range of an acceptable value may be marked with an indicator having a third display feature, such as a shaded interior. In  FIG. 1A , the tibial slope criteria is within a predefined range of an acceptable value, so the indicator  10   c  associated with tibial slope has a shaded interior. Thus, the indicators  10   a,    10   b,  and  10   c  can provide information related to the current values of the criteria in list  8  by displaying different features. Any type of display features may be utilized to convey information to a user. 
     In one embodiment, the indicators  10  provide information related to changes in the values of the criteria in list  8  by changing color in connection with changes to the criteria values. Thus, the first, second, and third display features can be different colors. The indicators  10  may change color when the user performs suggested or non-suggested actions that change one or more of the criteria. A change of a criterion value may be, for example, a change from an unacceptable value to a value within a certain range of an acceptable value. The corresponding indicator indicates this change by changing from an indicator  10   b  having a second color (e.g., red) to an indicator  10   c  having a third color (e.g., yellow). Alternatively, a change in criterion value may be a change from a value within a certain range of an acceptable value to an acceptable value. The corresponding indicator indicates this change by changing from an indicator  10   c  having a third color (e.g., yellow) to an indicator  10   a  a having a first color (e.g., green). 
     GUI  2  further includes a plurality of icons  12   a - 12   j.  A user may select (e.g., touch, mouse click, etc.) the icons to cause additional information to be displayed. Various types of information that may be displayed to a user include or relate to: 3D flex pose capture (icon  12   a ), limb alignment (icon  12   b ), gap graphs (icons  12   c  and  12   h ), virtual models of implants (icon  12   d ), planned bone resections (icon  12   e ), CT scan overlay (icon  12   f ), alignment axes (icon  12   g ), trace points (icon  12   i ) and over/under hang (icon  12   j ). 
       FIGS. 1A-1F  illustrate a first exemplary embodiment for guiding a user during surgical planning. In the embodiment of  FIGS. 1A-1F , the user is guided through steps relating to planning the placement of femoral and tibial components for a total knee arthroplasty. Referring to  FIG. 1A , a GUI  2  during a first step of guiding a user is shown. The GUI  2  provides a first suggested action to a user by displaying an icon having a distinguishing characteristic. The distinguishing characteristic is configured to alert the user to select the icon. In  FIG. 1A , icon  12   h  is marked with two distinguishing characteristics—an outline and a guiding arrow  14 . The outline may be shown in a specific color (e.g., pink), and the guiding arrow  14  may be shown in the same or different color. The distinguishing characteristic of icon  12   h  guides the user to select the icon  12   h.  Selecting the icon  12   h  causes additional information related to gaps between femoral component  4  and tibial component  6  to be displayed in the form of bar graphs  16 , as shown in  FIG. 1B .  FIG. 1B  illustrates GUI  2  during a second step of guiding a user during surgical planning. In  FIG. 1B , an expansion box  18  includes a distinguishing characteristic (e.g., an outline in a specific color) to guide the user to select the expansion box  18 . Selecting the expansion box  18  causes placement arrows  19  to appear, as shown in  FIG. 1C . 
     The GUI  2  next guides the user by suggesting how to adjust the placements of the femoral component  4  and tibial component  6  to achieve acceptable criteria values. The suggested action of  FIG. 1C  is selecting an icon to cause a change in placement of a virtual implant (in this step, the femoral component  4 ). The marked arrow  20  shown in  FIG. 1C  includes a distinguishing characteristic (e.g., an outline in a specific color) to guide the user to select the marked arrow  20 . When the user selects the marked arrow  20 , the placement of femoral component  4  shifts from the placement shown in  FIG. 1C  to the placement shown in  FIG. 1D . 
     As can be seen in  FIG. 1D , the shift of femoral component  4  caused the femoral notching and sizing criterion to have an acceptable value. To provide this information to the user, the femoral notching and sizing criterion in  FIG. 1D  is marked with an indicator  10   a  having a checkmark (in contrast, a filled-in indicator  10   b  corresponded to femoral notching and sizing in  FIG. 1C ). Colors may also be used in the relevant indicators to provide this information. The user can therefore see a direct cause and effect between shifting the placement of femoral component  4  and the femoral notching and sizing criterion having an acceptable value. 
     In  FIG. 1D , expansion box  18  includes a distinguishing characteristic (e.g., an outline in a specific color) to guide the user to select expansion box  18 . Selecting expansion box  18  causes placement arrows  19  to appear as shown in  FIG. 1E , allowing the user to adjust the placement of a virtual implant (in this step, tibial component  6 ). The user is guided to adjust the posterior slope of the tibial component  6  by selecting marked arrow  24 , which includes a distinguishing characteristic. Selecting marked arrow  24  adjusts the tibial component  6  to the placement shown in  FIG. 1F . The change in placement or orientation may be accomplished incrementally via several selections of arrow  24 . As shown in  FIG. 1F , this adjustment to the posterior slope (e.g., from 2.0° to 7.0°) caused both the tibial slope criterion and extension and flexion gaps criterion to have acceptable values, as shown by their associated checked indicators  10   a.  The GUI  2  indicates that the planning of femoral and tibial component placement is complete by displaying a completion icon  26 . 
     The actions suggested to the user (e.g., selecting marked arrows  20  or  24 ) are presented in a predetermined manner. If the user performs each suggested action of  FIGS. 1A-1F  (e.g., selects each of the plurality of icons having a distinguishing characteristic), the actions will lead the user to the initial surgical plan developed by applying an algorithm to input information. Thus, via GUI  2 , the user is guided through steps that, if followed, would lead the user to the initially developed surgical plan. This guidance illustrates to the user how the algorithm was applied to arrive at the initial surgical plan. The user guidance therefore provides transparency into how the initial surgical plan was developed. 
     However, the user has the option to deviate from one or more of the suggested actions by performing non-suggested actions, such as selecting a displayed icon without a distinguishing characteristic. Deviation from one or more of the plurality of suggested actions may lead to the development of a final surgical plan that is different from the initial surgical plan. In this manner, the user can customize the initial surgical plan to create a final surgical plan. The final surgical plan can differ from the initial surgical plan in one or more ways, such as in placement of a virtual implant, type of virtual implant, or size of virtual implant. For example, in the step shown by the GUI  2  in  FIG. 1C , one way the user can customize the initial surgical plan is by selecting the arrows surrounding marked arrow  20 , which do not have distinguishing characteristics. Selecting an arrow other than marked arrow  20  would customize the surgical plan by causing the femoral component  4  to shift to a different placement than the placement shown in  FIG. 1D  (which resulted from selecting marked arrow  20 ). The user guidance therefore allows the user to customize the initial plan in a straightforward and intuitive manner. 
       FIGS. 2A-2C  illustrate a second exemplary embodiment for guiding a user during surgical planning.  FIG. 2A  shows GUI  2  during a first step of guiding the user and illustrates a suggested action of selecting an icon to cause a change in size of a virtual implant. In other embodiments, the suggested action can be selecting an icon to cause a change in type of a virtual implant, such as femoral component  4  or tibial component  6 . Specifically, the user is guided in  FIG. 2A  to select box  28 , which has distinguishing characteristics of an outline and a guiding arrow  14 . Selecting box  28  decreases the size of the femoral component  4 . As can be seen in  FIG. 2B , the femur size has been decreased from  6   w  ( FIG. 2A ) to  6 N ( FIG. 2B ). In  FIG. 2B , the user is guided to select icon  12   j,  which causes information related to over/under hang of femoral component  4  and tibial component  6  to appear in the form of outlines  30  ( FIG. 2C ). The user can therefore see how changing the size of femoral component  4  caused femoral overhang (a criterion shown in list  8  that had an unacceptable value in  FIG. 2A ) to have an acceptable value (as shown by the indicator  10   a  corresponding to femoral overhang in  FIGS. 2B and 2C ). The outline  30  associated with femoral component  4  in  FIG. 2C  shows the user that femoral component  4  is within the outline  30  in the medial and lateral directions. The user can use the outline  30  to evaluate whether he or she agrees with the suggested implant size.  FIG. 2C  also includes a completion icon  26  to demonstrate the completion of user guidance. 
     As in the first exemplary embodiment, although the user&#39;s actions (e.g., selecting box  28  to decrease the size of femoral component  4 ) in the embodiment of  FIGS. 2A-2C  are guided in a predetermined manner, the user has the option during each step of the process to adjust the initial surgical plan. For example, in the step shown by the GUI  2  in  FIG. 2A , the user could alternatively decide to shift the femoral component  4  in different directions to eliminate femoral overhang instead of making the femoral component  4  smaller. Alternatively, the user could decide that the amount of femoral overhang shown in the step of  FIG. 2A  is acceptable and decide not to adjust the placement or size of femoral component  4 . One of these alternative decisions by the user (e.g., any decision other than following the suggested action of decreasing the size of femoral component  4 ) would result in a final plan that is different from the initial surgical plan. In other words, the user is able to customize the initial surgical plan by deciding to take actions different from those suggested by the GUI  2 . 
       FIGS. 3A-3G  illustrate a third exemplary embodiment for guiding a user during surgical planning. Referring to  FIG. 3A , an indicator  10   b  having a second display feature corresponds to the extension and flexion gaps criterion, indicating that this criterion does not have an acceptable value. In other embodiments, the indicator may change color to indicate whether the associated criterion is acceptable or use other ways of indicating the same to the user. The exemplary embodiment of  FIGS. 3A-3G  leads the user through steps to adjust the femoral component  4  and tibial component  6  in a manner that will bring the extension and flexion gaps criterion to an acceptable value. 
     Referring again to  FIG. 3A , expansion box  18  includes distinguishing characteristics of both an outline and a guiding arrow  14  to guide the user to select (e.g., touch, click on, etc.) expansion box  18 . When the user selects expansion box  18 , placement arrows  19  appear (as shown in  FIG. 3B ) that will allow the user to adjust the placement of femoral component  4 . The marked arrow  34  includes a distinguishing characteristic to guide the user to select the marked arrow  34 . When the user selects the marked arrow  34 , the placement of femoral component  4  shifts upward to the placement shown in  FIG. 3C . Correspondingly, measurements related to gaps between femoral component  4  and tibial component  6  are altered, as shown by the bar graphs  16 , and the extension and flexion gaps criterion now has an acceptable value (see  FIG. 3C ). However, the limb alignment and joint line criterion now has an indicator  10   c  having a third display feature, communicating to the user that the limb alignment and joint line criterion no longer has an acceptable value, but is within predetermined ranges of an acceptable value. The user will next be guided to make adjustments that will bring the limb alignment and joint line criterion to an acceptable value. 
     Accordingly, in  FIG. 3C , the user is guided to select marked arrow  36 , which shifts the femoral component  4  downward. As shown in  FIG. 3D , the bar graphs  16  indicate a corresponding change in the gaps between femoral component  4  and tibial component  6 . The limb alignment and joint line criterion is now at an acceptable value, as shown by the corresponding indicator  10   a,  but the extension and flexion gaps criterion is no longer at an acceptable value, as shown by the corresponding indicator  10   b.  Therefore, the planning system will guide the user to make adjustments that will bring the extension and flexion gaps criterion to an acceptable value. Accordingly, the user is guided in  FIG. 3D  to select marked arrow  38 . Selecting marked arrow  38  causes the tibial component  6  to move downward to the position shown in  FIG. 3E . The indicator corresponding to the extension and flexion gaps criterion changes from an indicator  10   b  having a second display feature to an indicator  10   a  having a third display feature to indicate to the user that the previous action (adjusting the tibial component  6 ) has brought the extension and flexion gaps criterion closer to an acceptable value. 
       FIG. 3E  guides the user to select expansion box  18 , which causes additional placement arrows  19  to appear, as shown in  FIG. 3F . In  FIG. 3F , the user is guided to select marked arrow  40 , which rotates the femoral component  4  to the placement shown in  FIG. 3G . This adjustment of femoral component  4  causes the extension and flexion gaps criterion to have an acceptable value, as indicated by the checked indicator  10   a  corresponding to the extension and flexion gaps criterion. In addition,  FIG. 3G  includes a completion icon  26 . 
       FIGS. 4A-4F  illustrate a fourth exemplary embodiment for guiding a user during surgical planning. Referring to  FIG. 4A , list  8  indicates that the extension and flexion gaps criterion and the mid flexion gap and stability criterion do not have acceptable values. Therefore, the embodiment of  FIGS. 4A-4F  will guide the user to adjust the femoral component  4  and tibial component  6  in a manner that will bring the criteria in list  8  to acceptable (or close to acceptable) values. 
     In  FIG. 4A , icon  12   b  has been selected to display information related to limb alignment in the form of a diagram  44 . The user is guided in  FIG. 4A  to select expansion box  18 , which includes the distinguishing features of an outline and a guiding arrow  14 . Selecting expansion box  18  causes placement arrows  19  to appear, as shown in  FIG. 4B . In  FIG. 4B , the user is guided to select marked arrow  42 . Selecting marked arrow  42  rotates femoral component  4  from the placement shown in  FIG. 4B  to the placement shown in  FIG. 4C . Correspondingly, the measurements related to gaps between femoral component  4  and tibial component  6  are altered, as shown by the bar graphs  16 , and the femoral varus angle has been altered (e.g., from 0.0° to 1.0°). Diagram  44  also illustrates the change in limb alignment between  FIG. 4B  and  FIG. 4C . In  FIG. 4C , the extension and flexion gaps criterion and the mid flexion gap and stability criterion are marked with indicators  10   c  having a third display feature, communicating to the user that these criteria are moving closer to acceptable values. The planning system will then guide the user to make adjustments to bring all criteria to acceptable values. 
     Accordingly, in  FIG. 4C , the planning system guides the user to select marked arrow  46 . Selecting marked arrow  46  rotates tibial component  6  from the placement shown in  FIG. 4C  to the placement shown in  FIG. 4D  (e.g., incrementally depending upon the number of times marked arrow  46  is selected). Correspondingly, the measurements related to gaps between femoral component  4  and tibial component  6  are altered, as shown by the bar graphs  16 , and the tibial varus angle has been altered (e.g., from 0.0° to 1.0°). Diagram  44  illustrates the further change in limb alignment. In  FIG. 4D , the extension and flexion gaps criterion and the mid flexion gap and stability criterion continue to be marked with indicators  10   c,  showing that the criteria are close, but are not yet at acceptable values. Furthermore, the limb alignment and joint line criterion is now also marked with an indicator  10   c  having a third display feature. Therefore, in  FIG. 4D , the user is guided to select expansion arrow  18  in order to allow the user to again adjust the placement of femoral component  4 . Selecting expansion box  18  causes additional placement arrows  19  to appear as shown in  FIG. 4E . 
     In  FIG. 4E , the user is guided to select marked arrow  48 , which rotates the femoral component  4  from the placement shown in  FIG. 4E  to the placement shown in  FIG. 4F . In  FIG. 4F , the extension and flexion gaps criterion and the mid flexion gap and stability criterion are at acceptable values, as shown by the corresponding indicators  10   a  having a first display feature (e.g., being checked). However, the limb alignment and joint line criterion continues to have a corresponding indicator  10   c  having the third display feature showing that the criterion is close, but not yet at the desired value. Nonetheless, the planning system has arrived at the initial surgical plan created based on the input information, and  FIG. 4F  therefore displays a completion icon  26 . 
     In some conventional surgical planning systems, a surgical plan is created based on input information. The user is then provided with the surgical plan without having insight into the algorithm used by the planning system to develop the surgical plan. In each of the exemplary embodiments described herein, a planning system creates an initial surgical plan based on certain input information. However, in contrast to other conventional systems, the methods described herein guide the user through a series of steps, via GUI  2 , to lead the user to the initial surgical plan. The algorithm used by the planning system therefore becomes transparent to the user, and the user can easily see how the planning system arrived at the initial surgical plan. 
     This transparency provides users with the opportunity to customize the initial surgical plan in a straightforward manner. A user might desire to customize the surgical plan for a variety of reasons. For example, the user may have additional knowledge related to the specific patient (e.g., the patient&#39;s lifestyle or other factors that may affect the outcome of the surgical procedure), which may cause the user to want to modify the surgical plan in a particular way. As another example, the user may have years of experience performing similar surgical procedures, and may wish to modify the plan in a manner that he or she knows will lead to a more successful outcome. The methods described herein allow a user to more readily determine how to implement customizations by providing the user with awareness of the series of steps taken by the planning system, as well as providing the user with an opportunity to modify the surgical plan at each step. 
     Another advantage of the methods described herein relative to other planning systems is an improved user “buy in.” In conventional planning systems and methods, a user is simply provided with a solution (e.g., a surgical plan) and is not aware of how the system arrived at the solution. However, when a user is taken step-by-step through the process of arriving at an initial surgical plan, as described herein, the user is able to understand the algorithm relied on by the planning system. For example, when a user is guided according to the embodiment of  FIGS. 2A-2C , the user will understand that the initial surgical plan includes a femoral component  4  with a size of “6N” in order to obtain an acceptable value for femoral overhang. Similarly, when a user is guided according to the embodiment of  FIGS. 3A-3G , the user will understand that the femoral component  4  and tibial component  6  are placed to ensure acceptable values for the extension and flexion gaps criterion (as well as the other criteria in list  8 ). Because the user is provided with more knowledge regarding the algorithm applied by the surgical planning system, the user may be more comfortable relying on and implementing the surgical plan provided by the planning system. 
     Another advantage of the planning systems and methods described herein is the ability to improve the algorithm applied to input information over time by analysis of user input. User input may include, for example, any user actions, such as input of information or modifications or customizations to a surgical plan, taken in connection with surgical planning as described herein. The planning systems can store data related to this user input, which can later be accessed to improve the planning system&#39;s algorithm. For example, in the exemplary embodiment of  FIGS. 1A-1F , a certain placement of femoral component  4  is suggested by the planning system to achieve the initial surgical plan illustrated in  FIG. 1F . However, if it is found that users typically modify the suggested femoral placement for patients with a certain type of bone structure, the algorithm might be altered to arrive automatically at the modified femoral placement when creating initial surgical plans in the future. In this manner, data obtained by evaluating user customizations can be applied to improve the planning system&#39;s algorithm. 
     The methods of guiding a user during surgical planning described herein may be implemented using a treatment planning computing system, such as the computing system associated with a RIO® Robotic Arm Interactive Orthopedic System available from MAKO Surgical Corp., Ft. Lauderdale, Fla.  FIG. 5  shows an embodiment of an exemplary surgical system  50  in which and for which the techniques described above can be implemented. The surgical system  50  includes a computing system  52 , a haptic device  54 , and a tracking system  56 . In operation, the surgical system  50  enables comprehensive, intraoperative surgical planning. The surgical system  50  may also provide haptic guidance to a user (e.g., a surgeon) and/or limits the user&#39;s manipulation of the haptic device  54  as the user performs a surgical procedure. 
     Embodiments of the subject matter, the methods, and the operations described in this specification can be implemented in digital electronic circuitry, or in computer software embodied on a tangible medium, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. In the embodiment of  FIG. 5 , the computing system  52  may include hardware and software for operation and control of the surgical system  50 . Such hardware and/or software is configured to enable the system  50  to perform the techniques described herein. The computing system  52  includes a surgical controller  62 , a display device  64 , and an input device  66 . 
     The surgical controller  62  may be any known computing system but is preferably a programmable, processor-based system. For example, the surgical controller  62  may include a microprocessor, a hard drive, random access memory (RAM), read only memory (ROM), input/output (I/O) circuitry, and any other known computer component. The surgical controller  62  is preferably adapted for use with various types of storage devices (persistent and removable), such as, for example, a portable drive, magnetic storage, solid state storage (e.g., a flash memory card), optical storage, and/or network/Internet storage. The surgical controller  62  may comprise one or more computers, including, for example, a personal computer or a workstation operating under a suitable operating system and preferably includes a graphical user interface (GUI). 
     Referring to  FIG. 6 , in an exemplary embodiment, the surgical controller  62  includes a processing circuit  70  having a processor  72  and memory  74 . Processor  72  can be implemented as a general purpose processor executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit), a group of processing components, or other suitable electronic processing components. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. Memory  74  (e.g., memory, memory unit, storage device, etc.) comprises one or more devices (e.g., RAM, ROM, Flash-memory, hard disk storage, etc.) for storing data and/or computer code for completing or facilitating the various processes described in the present application. Memory  74  may be or include volatile memory or non-volatile memory. Memory  74  may include database components, object code components, script components, or any other type of information structure for supporting the various activities described in the present application. According to an exemplary embodiment, memory  74  is communicably connected to processor  72  and includes computer code for executing one or more processes described herein. The memory  74  may contain a variety of modules, each capable of storing data and/or computer code related to specific types of functions. In one embodiment, memory  74  contains several modules related to surgical procedures, such as a planning module  740 , a navigation module  742 , a registration module  744 , and a robotic control module  746 . 
     Alternatively or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate components or media (e.g., multiple CDs, disks, or other storage devices). Accordingly, the computer storage medium may be tangible and non-transitory. 
     A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. 
     Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few. Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. 
     Embodiments of the subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an embodiment of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks). 
     Referring to the embodiment of surgical system  50  depicted in  FIG. 6 , the surgical controller  62  further includes a communication interface  76 . The communication interface  76  of the computing system  52  is coupled to a computing device (not shown) of the haptic device  54  via an interface and to the tracking system  56  via an interface. The interfaces can include a physical interface and a software interface. The physical interface of the communication interface  76  can be or include wired or wireless interfaces (e.g., jacks, antennas, transmitters, receivers, transceivers, wire terminals, etc.) for conducting data communications with external sources via a direct connection or a network connection (e.g., an Internet connection, a LAN, WAN, or WLAN connection, etc.). The software interface may be resident on the surgical controller  62 , the computing device (not shown) of the haptic device  54 , and/or the tracking system  56 . In some embodiments, the surgical controller  62  and the computing device (not shown) are the same computing device. The software may also operate on a remote server, housed in the same building as the surgical system  50 , or at an external server site. 
     Computer system  52  also includes display device  64 . The display device  64  is a visual interface between the computing system  52  and the user. GUI  2  described according to the exemplary embodiments of  FIGS. 1A-4F  may be displayed on display device  64 . The display device  64  is connected to the surgical controller  62  and may be any device suitable for displaying text, images, graphics, and/or other visual output. For example, the display device  64  may include a standard display screen (e.g., LCD, CRT, OLED, TFT, plasma, etc.), a touch screen, a wearable display (e.g., eyewear such as glasses or goggles), a projection display, a head-mounted display, a holographic display, and/or any other visual output device. The display device  64  may be disposed on or near the surgical controller  62  (e.g., on the cart as shown in  FIG. 5 ) or may be remote from the surgical controller  62  (e.g., mounted on a stand with the tracking system  56 ). The display device  64  is preferably adjustable so that the user can position/reposition the display device  64  as needed during a surgical procedure. For example, the display device  64  may be disposed on an adjustable arm (not shown) or to any other location well-suited for ease of viewing by the user. As shown in  FIG. 5  there may be more than one display device  64  in the surgical system  50 . 
     The display device  64  may be used to display any information useful for a medical procedure, such as, for example, images of anatomy generated from an image data set obtained using conventional imaging techniques, graphical models (e.g., CAD models of implants, instruments, anatomy, etc.), graphical representations of a tracked object (e.g., anatomy, tools, implants, etc.), constraint data (e.g., axes, articular surfaces, etc.), representations of implant components, digital or video images, registration information, calibration information, patient data, user data, measurement data, software menus, selection buttons, status information, and the like. 
     In addition to the display device  64 , the computing system  52  may include an acoustic device (not shown) for providing audible feedback to the user. The acoustic device is connected to the surgical controller  62  and may be any known device for producing sound. For example, the acoustic device may comprise speakers and a sound card, a motherboard with integrated audio support, and/or an external sound controller. In operation, the acoustic device may be adapted to convey information to the user. For example, the surgical controller  62  may be programmed to signal the acoustic device to produce a sound, such as a voice synthesized verbal indication “DONE,” to indicate that a step of a surgical procedure is complete. Similarly, the acoustic device may be used to alert the user to a sensitive condition, such as producing a tone to indicate that a surgical cutting tool is nearing a critical portion of soft tissue. 
     To provide for other interaction with a user, embodiments of the subject matter described in this specification can be implemented on a computer having input device  66  that enables the user to communicate with the surgical system  50 . The input device  66  is connected to the surgical controller  62  and may include any device enabling a user to provide input to a computer. For example, the input device  66  can be a known input device, such as a keyboard, a mouse, a trackball, a touch screen, a touch pad, voice recognition hardware, dials, switches, buttons, a trackable probe, a foot pedal, a remote control device, a scanner, a camera, a microphone, and/or a joystick. For example, input device  66  can allow the user to make the selections as described above to adjust the surgical plan. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user&#39;s client device in response to requests received from the web browser. 
     The system  50  also includes a tracking (or localizing) system  56  that is configured to determine a pose (i.e., position and orientation) of one or more objects during a surgical procedure to detect movement of the object(s). For example, the tracking system  56  may include a detection device that obtains a pose of an object with respect to a coordinate frame of reference of the detection device. As the object moves in the coordinate frame of reference, the detection device tracks the pose of the object to detect (or enable the surgical system  50  to determine) movement of the object. As a result, the computing system  52  can capture data in response to movement of the tracked object or objects. Tracked objects may include, for example, tools/instruments, patient anatomy, implants/prosthetic devices, and components of the surgical system  50 . Using pose data from the tracking system  56 , the surgical system  50  is also able to register (or map or associate) coordinates in one space to those in another to achieve spatial alignment or correspondence (e.g., using a coordinate transformation process as is well known). Objects in physical space may be registered to any suitable coordinate system, such as a coordinate system being used by a process running on the surgical controller  62  and/or the computer device of the haptic device  54 . For example, utilizing pose data from the tracking system  56 , the surgical system  50  is able to associate the physical anatomy, such as the patient&#39;s spine, with a representation of the anatomy (such as an image displayed on the display device  64 ). Based on tracked object and registration data, the surgical system  50  may determine, for example, a spatial relationship between the image of the anatomy and the relevant anatomy. 
     Registration may include any known registration technique, such as, for example, image-to-image registration (e.g., monomodal registration where images of the same type or modality, such as fluoroscopic images or MR images, are registered and/or multimodal registration where images of different types or modalities, such as MRI and CT, are registered); image-to-physical space registration (e.g., image-to-patient registration where a digital data set of a patient&#39;s anatomy obtained by conventional imaging techniques is registered with the patient&#39;s actual anatomy); and/or combined image-to-image and image-to-physical-space registration (e.g., registration of preoperative CT and MRI images to an intraoperative scene). The computing system  52  may also include a coordinate transform process for mapping (or transforming) coordinates in one space to those in another to achieve spatial alignment or correspondence. For example, the surgical system  50  may use the coordinate transform process to map positions of tracked objects (e.g., patient anatomy, etc.) into a coordinate system used by a process running on the computer of the haptic device and/or the surgical controller  62 . As is well known, the coordinate transform process may include any suitable transformation technique, such as, for example, rigid-body transformation, non-rigid transformation, affine transformation, and the like. 
     The tracking system  56  may be any tracking system that enables the surgical system  50  to continually determine (or track) a pose of the relevant anatomy of the patient. For example, the tracking system  56  may include a non-mechanical tracking system, a mechanical tracking system, or any combination of non-mechanical and mechanical tracking systems suitable for use in a surgical environment. The non-mechanical tracking system may include an optical (or visual), magnetic, radio, or acoustic tracking system. Such systems typically include a detection device adapted to locate in predefined coordinate space specially recognizable trackable elements (or trackers) that are detectable by the detection device and that are either configured to be attached to the object to be tracked or are an inherent part of the object to be tracked. For example, a trackable element may include an array of markers having a unique geometric arrangement and a known geometric relationship to the tracked object when the trackable element is attached to the tracked object. The known geometric relationship may be, for example, a predefined geometric relationship between the trackable element and an endpoint and axis of the tracked object. Thus, the detection device can recognize a particular tracked object, at least in part, from the geometry of the markers (if unique), an orientation of the axis, and a location of the endpoint within a frame of reference deduced from positions of the markers. 
     The markers may include any known marker, such as, for example, extrinsic markers (or fiducials) and/or intrinsic features of the tracked object. Extrinsic markers are artificial objects that are attached to the patient (e.g., markers affixed to skin, markers implanted in bone, stereotactic frames, etc.) and are designed to be visible to and accurately detectable by the detection device. Intrinsic features are salient and accurately locatable portions of the tracked object that are sufficiently defined and identifiable to function as recognizable markers (e.g., landmarks, outlines of anatomical structure, shapes, colors, or any other sufficiently recognizable visual indicator). The markers may be located using any suitable detection method, such as, for example, optical, electromagnetic, radio, or acoustic methods as are well known. For example, an optical tracking system having a stationary stereo camera pair sensitive to infrared radiation may be used to track markers that emit infrared radiation either actively (such as a light emitting diode or LED) or passively (such as a spherical marker with a surface that reflects infrared radiation). Similarly, a magnetic tracking system may include a stationary field generator that emits a spatially varying magnetic field sensed by small coils integrated into the tracked object. 
     The haptic device  54  may be the Tactile Guidance System™ (TGS™ ) manufactured by MAKO Surgical Corp., and used to prepare the surface of the patient&#39;s bone for insertion of the spinal plate  10 . The haptic device  54  provides haptic (or tactile) guidance to guide the surgeon during a surgical procedure. The haptic device is an interactive surgical robotic arm that holds a surgical tool (e.g., a surgical burr) and is manipulated by the surgeon to perform a procedure on the patient, such as cutting a surface of a bone in preparation for spinal plate installation. As the surgeon manipulates the robotic arm to move the tool and sculpt the bone, the haptic device  54  guides the surgeon by providing force feedback that constrains the tool from penetrating a virtual boundary. 
     The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.