Method of and system for planning a surgery

• US 20090043556A1
• Filed: 08/06/2008
• Published: 02/12/2009
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker Leibinger GmbH & Co. KG (Stryker Corporation)
• Inventors: Moctezuma de la Barrera, Jose Luis, Rueber, Jens, Zimmerman, Peter, Axelson, Stuart L.
• Granted Patent: US 8,382,765 B2
• Time in Patent Office: Days
• US Class Current: 703/11
• CPC Class Codes: A61B 17/1764 for the knee
• CPC Class Codes: A61B 2017/0268 for the knee
• CPC Class Codes: A61B 2034/101 Computer-aided simulation of surgical operations
• CPC Class Codes: A61B 2034/107 Visualisation of planned trajectories or target regions
• CPC Class Codes: A61B 2034/2068 using pointers, e.g. pointers having reference marks for determining coordinates of body points
• CPC Class Codes: A61B 2034/252 indicating steps of a surgical procedure
• CPC Class Codes: A61B 2034/254 being adapted depending on the stage of the surgical procedure
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 34/25 User interfaces for surgical systems
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

A system for virtually planning a size and position of a prosthetic implant for a bone on a patient includes a database containing pre-defined form factor information for a plurality of different implants and a circuit for obtaining surface shape information of the bone. The system further includes a circuit for defining baseline location parameters for an implant location in relation to a virtual representation of the bone based on the surface shape information and a circuit for assessing a fit calculation of each implant in relation to the virtual representation of the bone based on the form factor in formation and a plurality of fit factors at each of a plurality of incremental positions in relation to the bone. Still further, the system includes a circuit for selecting a best fit implant size and position from all of the fit calculations.

Claims

1. A system for assessing a fit of a femoral implant to a distal end of a femur in a selected orientation prior to resecting the femur, wherein the system comprises:

means for obtaining pre-defined form factor information for plurality of femoral implants;

means for obtaining surface shape information of the distal end of the femur;

means for automatically performing a virtual fit assessment of each possible incremental position of a predefined set of incremental positions for each size implant to be considered prior to resecting the femur; and

means for selecting an optimal implant size and position from the virtual fit assessments.

2. The system of claim 1, wherein a target reconstruction position is defined based on design parameters for matching a selected varus or valgus angle, rotation angle, and surface position of posterior condyle and distal condyle of the femur.

3. The system of claim 1, wherein the means for selecting includes means for calculating maximum run out of an anterior resection of the femur from a proximal end contour of the femoral implant.

4. The system of claim 1, wherein the means for selecting includes means for calculating a percentage of the proximal end contour that lies on cut anterior cortex bone.

5. The system of claim 1, wherein the means for selecting includes means for calculating a percentage of the proximal end contour that lies on or above uncut anterior cortex bone.

6. The system of claim 1, wherein the means for selecting includes means for calculating a maximum gap between the femoral implant and the uncut anterior cortex bone.

7. The system of claim 1, wherein the means for selecting includes means for comparing each assessed fit with a weighted algorithm to identify an optimal implant size and position that minimizes notching of the bone and over sizing of the implant.

8. The system of claim 1, further comprising means for previewing a size of flexion and extension gap for a medial and lateral side.

9. The system of claim 1, further comprising means for detecting medial/lateral overhang.

10. The system of claim 1, further comprising means for cutting a proximal tibia and previewing an insert.

11. The system of claim 1, further comprising means for estimating medial condyle for varus knee.

12. The system of claim 1, further comprising means for using a navigated drill template for anterior/posterior alignment.

13. A system for virtually planning a size and position of a prosthetic implant for a bone on a patient, the system comprising:

a database containing pre-defined form factor information for a plurality of different implants;

a survey system for obtaining surface shape information of the bone;

a circuit for defining baseline location parameters for an implant location in relation to a virtual representation of the bone based on the surface shape information;

a circuit for assessing a fit calculation of each implant in relation to the virtual representation of the bone based on the form factor in formation and a plurality of fit factors at each of a plurality of incremental positions in relation to the bone; and

a circuit for selecting a best fit implant size and position from all of the fit calculations.

14. The system of claim 13, wherein the survey system includes a digitizer and an additional circuit for performing a survey of a surface of the bone.

15. The system of claim 13, wherein the circuits for assessing and selecting are activated prior to activating a system for resecting the bone.

16. The system of claim 15, further including a circuit for manually adjusting the best fit implant size and position.

17. The system of claim 15, wherein the circuit for selecting includes one or more systems for assessing a plurality of fit parameters

18. The system of claim 17, wherein the plurality of fit parameters includes rigid bone shape and implant shape parameters.

19. The system of claim 13, wherein the circuit for assessing includes one or more circuits for calculating parameters for a maximum run out of an anterior resection from a proximal end contour of an anterior portion of the implant, a percentage of the proximal end contour of the anterior portion of the implant that lies on resected bone, a percentage of the proximal end contour that lies on or above uncut surface of an anterior cortex, and a maximum gap between the implant and the uncut surface of the anterior cortex.

20. The system of claim 19, wherein the circuit for selecting includes a circuit for processing the assessed parameters with a weighted algorithm to identify an optimal size and position.

21. The system of claim 13, further including a circuit for determining a resection level for the bone that corresponds to the best fit implant size and position.

22. The system of claim 13, wherein the circuit for defining the baseline location parameters includes a circuit for calculating a maximum gap between the implant and uncut surface of an anterior cortex of the bone.

23. The system of claim 13, wherein the circuit for assessing a fit calculation optionally includes at least one of a circuit for previewing a size of flexion and extension gap for a medial/lateral side of the bone, a circuit for detecting medial and lateral overhang, a circuit for cutting a proximal tibia and previewing an insert, a circuit for estimating medial condyle for varus knee, and a circuit for using a navigated drill template for anterior/posterior alignment.

24. A computer readable medium for automatically virtually calculating an optimum size and position of a prosthetic implant for a bone, wherein the computer readable medium includes programming comprising:

a first routine for obtaining pre-defined form factor information for a plurality of different implant sizes;

a second routine for obtaining surface shape information of the bone;

a third routine for defining baseline location parameters for an implant location in relation to a virtual representation of the bone;

a fourth routine for assessing a fit calculation for each implant in relation to the virtual representation of the bone based on a plurality of fit criteria at each of a plurality of incremental positions in relation to the bone; and

a fifth routine for selecting an optimal implant size and position from each fit assessment based on a weighted comparison of each fit calculation for each of the plurality of fit criteria.

25. The computer readable medium of claim 24, wherein the routine for obtaining the surface shape includes a routine for obtaining survey data points of the bone using a pointer and a routine to aid a user to obtain a desirable set of data points to provide a contour map of the surface shape of the bone sufficient to meet specified design accuracy parameters.

26. The computer readable medium of claim 25, wherein the routine for defining baseline location parameters further includes a routine for matching a selected varus/valgus angle, rotation angle, and surface position of a posterior condyle and a distal condyle of an implant.

27. The computer readable medium of claim 26, wherein the routine for assessing a fit calculation further includes routines for calculating fit criteria including a maximum run out of an anterior resection from a proximal end contour of an anterior portion of the implant, a percentage of the proximal end contour of the anterior portion of the implant that lies on resected bone, a percentage of the proximal end contour that lies on or above uncut portions of anterior cortex, and a maximum gap between the implant and the uncut portions of the anterior cortex.

28. The computer readable medium of claim 27, wherein the routine for selecting the optimal implant size and position further includes a routine for comparing each fit calculation with a weighted algorithm of each fit criteria to identify the optimal implant size and position plant from all assessed sizes and positions, wherein the optimal implant size at least minimizes notching and over sizing of the implant.

29. A method of virtually planning a size and position of a prosthetic implant for a bone on a patient, the method comprising the steps:

obtaining pre-defined form factor information for a plurality of different implants;

obtaining surface shape information of the bone;

defining baseline location parameters for an implant location in relation to a virtual representation of the bone;

assessing a fit calculation of each implant in relation to the virtual representation of the bone based on a plurality of fit factors at each of a plurality of incremental positions in relation to the bone; and

selecting a best fit implant and position from all of the fit calculations.

30. The method of claim 29, wherein the step of obtaining the surface shape of the bone includes a step of performing a survey of the bone surface.

31. The method of claim 29, wherein the steps of assessing and selecting are performed prior to a step of resecting the bone.

32. The method of claim 31, further including the step of manually adjusting the calculated optimal size and position.

33. The method of claim 31, wherein the calculating step includes the step of assessing a plurality of fit parameters

34. The method of claim 33, wherein the plurality of fit parameters include rigid bone shape and implant shape parameters.

35. The method of claim 29, wherein the step of assessing a fit calculation includes assessing the implant based on a maximum run out of an anterior resection from a proximal end contour of an anterior portion of the implant, a percentage of the proximal end contour of the anterior portion of the implant that lies on resected bone, percentage of the proximal end contour that lies on or above uncut portion of an anterior cortex, and the maximum gap between the implant and the uncut surface of the anterior cortex.

36. The method of claim 35, wherein the step of selecting the best fit implant and position includes the step of comparing the assessed fits to a weighted algorithm to identify an optimal size and position.

37. The method of claim 29, further including the step of determining a resection level for the bone.

38. The method of claim 29, wherein the baseline location parameters are used to calculate a maximum gap between the implant and the uncut surface of an anterior cortex bone.

39. The method of claim 29, wherein the step of assessing a fit calculation optionally includes steps of previewing a size of flexion and extension gap for a medial and lateral side, detecting medial/lateral overhang, cutting a proximal tibia and previewing an insert, estimating medial condyle for varus knee, and using a navigated drill template for anterior/posterior alignment.

40. A method of assessing a fit of a femoral implant to a distal end of a femur in a selected orientation prior to resecting the femur, wherein the method comprises the steps:

obtaining pre-defined form factor information for the femoral implant;

obtaining surface shape information of the distal end of the femur; and

performing a virtual fit assessment at each of all possible incremental positions of a predefined set of incremental positions for each size implant to be considered prior to resecting the femur.

41. The method of claim 40, wherein a target reconstruction position is defined based on design parameters for matching a selected varus or valgus angle, rotation angle, and surface position of posterior condyle and distal condyle of the femur.

42. The method of claim 40, wherein the step of performing a fit assessment includes the step of calculating maximum run out of an anterior resection of the femur from a proximal end contour of the femoral implant.

43. The method of claim 42, wherein the step of performing a fit assessment includes the step of calculating a percentage of the proximal end contour that lies on cut anterior cortex bone.

44. The method of claim 43, wherein the step of performing a fit assessment includes the step of calculating a percentage of the proximal end contour that lies on or above uncut anterior cortex bone.

45. The method of claim 44, wherein the step of performing a fit assessment includes the step of calculating a maximum gap between the femoral implant and the uncut anterior cortex bone.

46. The method of claim 40, wherein the step of performing a fit assessment includes the step of comparing the assessed fits to a weighted algorithm to identify an optimal size and position.

47. The method of claim 40, wherein the step of performing a fit assessment optionally includes steps of previewing a size of flexion and extension gap for a medial and lateral side, detecting medial/lateral overhang, cutting a proximal tibia and previewing an insert, estimating medial condyle for varus knee, and using a navigated drill template for anterior/posterior alignment.