System and Method for Fabricating a Customized Patient-Specific Surgical Instrument

• US 20090093816A1
• Filed: 09/29/2008
• Published: 04/09/2009
• Est. Priority Date: 09/30/2007
• Status: Active Grant

• Current Assignee: DePuy Synthes Products LLC (Johnson & Johnson)
• Original Assignee: DePuy Synthes Products LLC (Johnson & Johnson)
• Inventors: Sokolov, Dimitri, Rose, Bryan, Roose, Jeffrey R., Aram, Luke J.
• Granted Patent: US 8,594,395 B2
• Time in Patent Office: Days
• US Class Current: 606/87
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/157 Cutting tibia
• CPC Class Codes: A61B 17/1764 for the knee
• CPC Class Codes: A61B 2017/00526 Methods of manufacturing
• CPC Class Codes: A61B 2017/568 produced with shape and dimensions specific for an individual patient
• CPC Class Codes: A61B 2034/108 Computer aided selection or customisation of medical implants or cutting guides
• CPC Class Codes: Y10T 409/30084 with regulation of operation by templet, card, or other replaceable information supply

Abstract

A number of orthopaedic surgical instruments are also disclosed. A method, apparatus, and system for fabricating such instruments are also disclosed.

Claims

1. A method for designing a customized patient-specific bone cutting block for use in an orthopaedic surgical procedure to perform a bone cut on a patient'"'"'s bone, the method comprising:

determining a cartilage thickness value indicative of the average thickness of the cartilage present on a relevant end of the patient'"'"'s bone;

determining a reference contour based on a surface contour of the relevant end of the patient'"'"'s bone;

generating a scaled reference contour by scaling the reference contour based on the cartilage thickness value; and

defining a customized patient-specific negative contour of the customized patient-specific bone cutting block using the scaled reference contour.

2. The method of claim 1, wherein determining the cartilage thickness value comprises determining the cartilage thickness value based on the gender of the patient.

3. The method of claim 1, wherein determining a reference contour comprises determining a reference contour based on a surface contour of a three-dimensional model of the patient'"'"'s bone.

4. The method of claim 3, wherein generating a scaled contour comprises:

determining a reference point in the three-dimensional model of the patient'"'"'s bone, and

increasing the distance between the reference point and a point on the reference contour.

5. The method of claim 4, wherein determining the reference point comprises:

generating a first line segment extending from a first point defined on the surface contour of a medial side of the three-dimensional model to a second point defined on the surface contour of a lateral side of the three-dimensional model;

generating a second line segment extending from a third point defined on the surface contour of an anterior side of the three-dimensional model to a fourth point defined on the surface contour of a posterior side of the three-dimensional model, wherein the first, second, third, and forth points are coplanar; and

determining a point of intersection between the first line segment and the second line segment, the point of intersection corresponding to the reference point.

6. The method of claim 5, wherein determining the reference point further comprises moving the reference point away from the point of intersection a distance approximately equal to half the length of the second line segment.

7. The method of claim 4, wherein increasing the distance between the reference point and the point on the reference contour comprises:

determining a length value equal to a percentage of the distance between the reference point and the point on the reference contour, and

increasing the distance between the reference point and the point on the reference contour by the length value.

8. The method of claim 4, further comprising:

determining areas of the relevant end of the patient'"'"'s bone having a reduced thickness of cartilage; and

adjusting the scaled reference contour to compensate for the areas of reduced thickness of cartilage of the relevant end of the patient'"'"'s bone.

9. The method of claim 8, wherein determining areas of the relevant end of the patient'"'"'s bone having the reduced thickness of cartilage comprises identifying points of bone-on-bone contact between the patient'"'"'s femur and the patient'"'"'s tibia based on a medical image of the femur and tibia.

10. The method of claim 8, wherein adjusting the scaled reference contour comprises decreasing the distance between the reference point and a point on the reference contour corresponding to the areas of reduced thickness of cartilage.

11. The method of claim 1, wherein:

the reference contour includes an anterior side, a medial side, and a lateral side, and

generating the scaled reference contour comprises increasing the distance between the reference point and the anterior side and subsequently reducing the distance (i) between the reference point and the medial side and (ii) between the reference point and the lateral side.

12. The method of claim 1, wherein determining a reference contour comprises determining a reference contour based on a surface contour of an osteophite of the patient'"'"'s bone.

13. The method of claim 1, wherein generating a scaled reference contour comprises generating a scaled reference contour having a superior end defining a negative contour corresponding to a surface contour of the patient'"'"'s femur located superiorly to a cartilage demarcation line of the patient'"'"'s femur.

14. The method of claim 1, wherein generating a scaled reference contour comprises generating a scaled reference contour having an inferior end defining a negative contour corresponding to a surface contour of the patient'"'"'s tibia located inferiorly to a cartilage demarcation line of the patient'"'"'s tibia.

15. The method of claim 1, further comprising determining a position of a cutting guide of the customized patient-specific cutting block.

16. The method of claim 15, wherein the position of the cutting guide is determined based on an angle defined between a mechanical axis of the patient'"'"'s femur and a mechanical axis of the patient'"'"'s tibia.

17. A method for generating a customized patient-specific negative contour of a customized patient-specific bone cutting block, the method comprising:

determining a cartilage thickness value indicative of the average thickness of the cartilage present on a relevant end of a patient'"'"'s bone;

determining a reference contour corresponding to a surface contour of a three-dimensional model of the relevant end of the patient'"'"'s bone;

determining a reference point in the three-dimensional model of the patient'"'"'s bone;

increasing the distance between the reference point and a point on the reference contour; and

defining a customized patient-specific negative contour of the customized patient-specific bone cutting block using the scaled reference contour.

18. The method of claim 17, wherein determining the reference point comprises:

generating a first line segment extending from a first point defined on the surface contour of a medial side of the three-dimensional model to a second point defined on the surface contour of a lateral side of the three-dimensional model;

generating a second line segment extending from a third point defined on the surface contour of an anterior side of the three-dimensional model to a fourth point defined on the surface contour of a posterior side of the three-dimensional model, wherein the first, second, third, and forth points are coplanar; and

determining a point of intersection between the first line segment and the second line segment, the point of intersection corresponding to the reference point.

19. The method of claim 17, wherein determining the reference point further comprises moving the reference point away from the point of intersection a distance approximately equal to half the length of the second line segment.

20. The method of claim 17, wherein increasing the distance between the reference point and the point on the reference contour comprises:

determining a length value equal to a percentage of the distance between the reference point and the point on the reference contour, and

increasing the distance between the reference point and the point on the reference contour by the length value.

21. The method of claim 20, wherein the percentage is about ten percent.

22. The method of claim 17, further comprising:

determining areas of the relevant end of the patient'"'"'s bone having a reduced thickness of cartilage; and

adjusting the scaled reference contour to compensate for the areas of reduced thickness of cartilage of the relevant end of the patient'"'"'s bone.

23. The method of claim 22, wherein adjusting the scaled reference contour comprises decreasing the distance between the reference point and a point on the reference contour corresponding to the areas of reduced thickness of cartilage.

24. The method of claim 17, wherein:

the reference contour includes an anterior side, a medial side, and a lateral side, and

scaling the reference contour comprises increasing the distance between the reference point and the anterior side and subsequently reducing the distance (i) between the reference point and the medial side and (ii) between the reference point and the lateral side.

25. The method of claim 17, wherein determining a reference contour comprises determining a reference contour based on a surface contour of an osteophite of the patient'"'"'s bone.

26. A method for fabricating a customized patient-specific bone cutting block, the method comprising:

determining a cartilage thickness value indicative of the average thickness of the cartilage present on a relevant end of a patient'"'"'s bone;

determining a reference contour corresponding to a surface contour of the relevant end of a three-dimensional image of the patient'"'"'s bone;

generating a scaled reference contour by scaling the reference contour based on the cartilage thickness value; and

establishing a customized patient-specific negative contour on a bone cutting block blank based on the scaled reference contour.

27. The method of claim 26, further comprising:

determining areas of the relevant end of the patient'"'"'s bone having a reduced thickness of cartilage, and

adjusting the scaled reference contour to compensate for the areas of reduced thickness of cartilage of the relevant end of the patient'"'"'s bone.