Distal femoral cutting guide

• US 20080275451A1
• Filed: 05/04/2007
• Published: 11/06/2008
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: Evergreen Orthopedic Research Lab LLC
• Original Assignee: Evergreen Orthopedic Research Lab LLC
• Inventors: Jacobson, Steven, McAllister, Craig M.
• Granted Patent: US 7,985,226 B2
• Time in Patent Office: Days
• US Class Current: 606/87
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/1764 for the knee

Abstract

A device and a method for establishing a position and orientation for a preliminary saw cut in a distal end of a femur to prepare the femur for installation of a prosthetic knee joint. A guide block defining a cutting plane is carried on an adjustably positioned locating arm that is supported on an alignment body that can be mounted on a femur either with or without an intramedullary rod in place in the distal end of the femur. Adjustment screws and horizontal slots in the alignment body provide for varus/valgus angular adjustment of the position of the alignment body. An adjustment guide block may have a saw guiding face defining a differently oriented cutting plane.

Claims

1. A distal femoral cutting guide, comprising:

(a) an alignment body defining a laterally oriented slot and a locating pin hole spaced apart from said slot, said slot defining a horizontal plane and both said slot and said pin hole extending through said alignment body from a front face to a rear face thereof;

(b) a varus/valgus adjustment member mated adjustably with and protruding rearwardly an adjustable distance from said alignment body;

(c) a support member connected with and extending upwardly from a lower portion of said alignment body;

(d) a guide block locating arm adjustably attached to said support member and extending rearwardly therefrom; and

(e) a guide block detachably carried on a rear end of said guide block locating arm.

2. The cutting guide of claim 1 wherein said guide block includes a planar saw guiding face.

3. The cutting guide of claim 1 including a pair of said varus/valgus adjustment members spaced laterally apart from each other on said alignment body.

4. The cutting guide of claim 3 wherein said varus/valgus adjustment members are in threaded engagement in respective through-holes defined in said alignment body.

5. The cutting guide of claim 1 wherein said varus/valgus adjustment member has a sharp-pointed engagement end.

6. The cutting guide of claim 1 wherein said alignment body defines a central hole extending therethrough from a front face to a rear face of said alignment body, said central hole being capable of receiving an intramedullary rod passing therethrough into a distal end of a femur when said alignment body is mounted in an operative location on said distal end of said femur.

7. The cutting guide of claim 6, further comprising a fastening screw extending through said central hole and a compression spring mounted on said fastening screw and urging said alignment body rearwardly with respect to said fastening screw.

8. The cutting guide of claim 6 including a swivel located in said central hole, said swivel defining a bore capable of slidably receiving an intramedullary rod and said swivel also defining an adjustment axis about which said alignment body is movable in response to adjustment of said varus/valgus adjustment member.

9. The cutting guide of claim 8 wherein said adjustment axis is normal to said horizontal plane defined by said laterally oriented slot.

10. The cutting guide of claim 1 wherein said support member defines a height adjustment slot and said cutting guide includes a fastener engaged with said support member and extending from said height adjustment slot to attach said locating arm to said support member.

11. The cutting guide of claim 10 wherein said support member has a flat lateral surface establishing an alignment plane orienting said guide block locating arm with respect to said alignment body.

12. The cutting guide of claim 1 including a fastener selectively securing said guide block locating arm to said support member and wherein said locating arm is selectively movable rearwardly and forwardly with respect to said support member.

13. The cutting guide of claim 12 wherein said locating arm includes indicia representative of a distance between a reference part of said alignment body and a saw guiding face of said guide block when said guide block is mounted on said locating arm.

14. The cutting guide of claim 1 wherein said alignment body includes a second said laterally oriented slot, each said laterally oriented slot defining a respective said horizontal plane.

15. The cutting guide of claim 14, wherein said respective horizontal planes defined by said laterally oriented slots coincide as a single said horizontal plane.

16. The cutting guide of claim 15, said alignment body defining a locating pin hole extending therethrough from said front face to said rear face and oriented parallel with said horizontal plane.

17. The cutting guide of claim 16, wherein said alignment body defines a plurality of said locating pin holes.

18. The cutting guide of claim 17 wherein a pair of said locating pin holes are parallel with each other.

19. The cutting guide of claim 18 including at least one said locating pin hole oriented parallel with said horizontal plane and at an oblique angle with respect to said pair of locating pin holes that are parallel with each other.

20. The cutting guide of claim 1 wherein said horizontal plane is perpendicular to said rear face of said alignment body.

21. The cutting guide of claim 1 wherein said guide block includes a saw guiding face and defines a pair of mounting pin holes that are oriented parallel with said saw guiding face and each other.

22. The cutting guide of claim 21 wherein the ones of said pair of parallel mounting pin holes are spaced apart from each other by at least about 3 centimeters.

23. The cutting guide of claim 1 wherein said guide block defines a receptacle and a rear end of said locating arm fits stably in said receptacle yet is easily removable from said receptacle.

24. The cutting guide of claim 1 including a pair of mounting bars each defining a mounting pin hole extending therethrough and wherein said guide block includes a saw guiding face and defines a pair of parallel mounting bar holes, each shaped and of a size to receive slidingly a respective one of said mounting bars.

25. The cutting guide of claim 24 wherein each of said mounting bars and mounting bar holes is shaped and of a size to permit each said mounting bar to fit in a respective one of said mounting bar holes in each of a plurality of orientations with said mounting pin holes located at a predetermined distance from each other when said mounting bars are both oriented similarly with respect to said guide block.

26. The cutting guide of claim 25 wherein each of said mounting bars is a regular prism and said mounting pin bore is located similarly eccentrically therein.

27. The cutting guide of claim 24 wherein said saw guiding face of said guide block is parallel with a plane defined by respective correspondingly located longitudinal axes of said mounting bar holes.

28. The cutting guide of claim 24 wherein said saw guiding face of said guide block is planar and is oriented at a predetermined angle to a plane defined by respective correspondingly located longitudinal axes of the parallel mounting bar holes.

29. The cutting guide of claim 24 wherein said saw guiding face of said guide block has a predetermined basic orientation with respect to said parallel mounting bar holes, said cutting guide further including an adjustment guide block having an adjustment saw guiding face oriented at a predetermined adjustment angle with respect to said basic orientation.

30. The cutting guide of claim 29 wherein the adjustment guide block includes readily discernable indicia showing a direction and magnitude of said predetermined adjustment angle.

31. The cutting guide of claim 1 wherein the support member is adjustable with respect to the lower portion of the alignment body about a pivot axis extending laterally with respect to the lower portion of the alignment body.

32. The cutting guide of claim 1 including a slide holding said guide block locating arm at a predetermined angle with respect to said support member.

33. The cutting guide of claim 32 wherein said predetermined angle with respect to said support member is a right angle.

34. The cutting guide of claim 32 including a clamp associated with said slide that can be tightened to prevent movement of the guide block locating arm with respect to the support member.

35. The cutting guide of claim 32 wherein the slide is moveable along the support member to adjust the height of the guide block locating arm, and wherein the guide block locating arm is moveable forward and rearward with respect to the slide.

36. The cutting guide of claim 1 wherein said guide block locating arm includes an adjustment screw arranged to move said guide block to a location at a selected distance rearward from said support member.

37. The cutting guide of claim 36 including a slide body engaged with said support member and holding said guide block locating arm at a selected position along said support member and wherein said adjustment screw is mated with a threaded bore defined in said slide body.

38. The cutting guide of claim 36 wherein said guide block locating arm includes indicia representative of said location of said cutting guide block rearward from said support member.

39. The cutting guide of claim 1 including a detent keeping said guide block removably attached to said rear end of said guide block locating arm.

40. A method of preparing a femur for receiving a distal femoral part of a prosthetic knee joint, comprising:

(a) providing an alignment body defining a horizontal slot and a locating pin hole extending therethrough;

(b) placing said alignment body in a selected location adjacent a distal end portion of said femur;

(c) forming a hole extending into said femur and aligned with said horizontal slot;

(d) placing a first locating pin through said horizontal slot and so that it extends into said hole extending into said femur;

(e) establishing a varus/valgus alignment of said alignment body by placing an end of at least one varus/valgus adjustment pin located in said alignment body into contact against said femur so as to support said alignment body in an aligned position with respect to said distal end of said femur;

(f) forming a second hole extending into said femur and aligned with said locating pin hole;

(g) placing a second locating pin through said locating pin hole so as to extend into said second hole in said femur;

(h) thereafter, securing said alignment body to said femur in a said aligned position by forming a third hole extending into said femur in a location aligned with a corresponding locating pin hole oriented at an oblique angle with respect to said second alignment pin and placing a third locating pin so as to extend through said corresponding locating pin hole in said alignment body and into said third hole in said femur;

(i) supporting a cutting guide block on a locating arm adjustably attached to said alignment body;

(j) positioning said cutting guide block relative to said alignment body, to bring a guiding face of said cutting guide block into a predetermined orientation and position with respect to said alignment body;

(k) connecting said cutting guide block to an anterior face of said distal end portion of said femur so as to hold said guiding face in said predetermined orientation;

(l) removing said alignment body and said locating arm from said femur and said cutting guide block, leaving said cutting guide block adjacent said anterior face of said distal end of said femur with said guiding face in said predetermined orientation and leaving an unobstructed cutting plane through said distal end of said femur defined by said guiding face of said cutting guide block; and

(m) thereafter, using said guiding face to guide a cutting tool to remove a part of said distal end portion.

41. The method of claim 40 wherein said alignment body defines a central through-hole extending therethrough from a front face to a rear face of said alignment body, wherein the step of placing said alignment body in a selected location includes placing said alignment body where an intramedullary rod fitted in an intramedullary canal of said femur extends through said central through-hole when said alignment body is in said selected location.

42. The method of claim 41 wherein said alignment body includes a swivel located in said central through-hole, said swivel defining a bore extending through said central through-hole and said swivel establishing a vertical axis parallel with said rear face of said alignment body and intersecting said bore, and wherein said step of placing said alignment body in a selected location includes locating said alignment body where said intramedullary rod extends through said bore defined by said swivel.

43. The method of claim 40 wherein said alignment body includes an upwardly extending support member defining a height adjustment slot, and including the step of using a fastener extending from said height adjustment slot to hold said locating arm in a position at a selected height with respect to said support member.

44. The method of claim 40 wherein said support member has a flat lateral surface establishing an alignment plane orienting said locating arm in a predetermined plane with respect to said rear face of said alignment body.

45. The method of claim 40 including the step of adjusting a position of said locating arm in a direction parallel with a longitudinal axis of said femur.

46. The method of claim 45 including providing indicia on said locating arm and using said indicia to locate a planar saw guiding face of said guide block at a desired distance from said alignment body when said guide block is mounted on said locating arm.

47. The method of claim 40 wherein said alignment body includes a second said slot establishing a respective horizontal plane, and including the steps of forming a hole in said femur aligned with said second slot and placing a locating pin through said second slot into said femur.

48. The method of claim 40, including inserting a locating pin into said femur through a second slot extending from a front face to a rear face of said alignment body and oriented parallel with said horizontal plane prior to said step of performing a varus/valgus adjustment.

49. The method of claim 48 including the further step of thereafter inserting at least one said locating pin into said femur through a locating pin hole oriented parallel with said horizontal plane and at an oblique angle with respect to said rear face of said alignment body.

50. The method of claim 40 including the step of providing a plurality of pairs of mounting pin holes in said cutting guide block, the holes of each said pair being spaced apart from each other by an equal distance and the mounting pin holes all being aligned parallel with said guiding face, and performing said step of connecting by inserting respective mounting pins through both of a pair of said mounting pin holes so as to extend into said anterior face.

51. The method of claim 50 wherein said pairs of mounting pin holes are located at different distances from said guiding face, including the further step of thereafter moving said cutting guide block to a selected location with respect to said distal end portion of said femur by sliding said cutting guide block off said mounting pins and placing said cutting guide block adjacent said anterior face with said mounting pins extending through the holes of another one of said pairs.

52. The method of claim 40 wherein the step of connecting said cutting guide block to said anterior face includes inserting a pair of mounting pins into respective mounting pin holes in said distal end portion through respective mounting pin holes defined in a pair of mounting bars fitted in respective mounting bar holes in said cutting guide block, including the additional step of adjusting the position of said cutting guide block with respect to said distal end portion by similarly reorienting each of said pair of mounting bars in said respective mounting bar holes in said cutting guide block, so as to move said cutting guide block with respect to said pair of mounting pins with said pair of mounting pins left extending through respective mounting pin holes defined in said mounting bars and thence extending further into said respective mounting pin holes in said anterior face of said distal end portion of said femur.

53. The method of claim 52 including the additional step of removing the cutting guide block from said mounting bars and mounting on said mounting bars an adjustment cutting guide block having an adjustment guiding face, with said adjustment guiding face oriented at a selected acute angle with respect to an orientation of said guiding face of said cutting guide block when said cutting guide block is mounted on said mounting bars.

54. The method of claim 40 wherein said step of connecting said cutting guide block to an anterior face includes inserting a pair of mounting pins through respective mounting pin holes in said cutting guide block into respective mounting pin holes in said anterior face of said distal end portion of said femur, and including the additional step of thereafter removing the cutting guide block from said mounting pins and mounting on said mounting pins an adjustment guide block having an adjustment guiding face with said adjustment guiding face oriented at a selected acute angle with respect to said predetermined orientation of said guiding face of said cutting guide block when said cutting guide block is connected to said anterior face by said mounting pins.

55. The method of claim 40 including the step of inserting a spring-loaded attachment screw through an aperture in the alignment body and into said femur, thereby fastening the alignment body to the distal end of the femur in an initial position, prior to adjusting varus/valgus.

56. The method of claim 40 wherein the step of positioning said cutting guide block relative to said alignment body includes turning an adjustment screw to move said cutting guide block to a location at a selected distance rearward from a support member to which said locating arm is attached.

57. A method of preparing a femur for receiving a distal femoral part of a prosthetic knee jointing, comprising:

(a) providing an alignment body defining a fastener hole extending therethrough;

(b) forming a hole extending into a distal end portion of said femur;

(c) placing said alignment body in a selected location adjacent said femur and aligned with said fastener hole;

(d) placing a fastener through said fastener hole so that it extends into said hole extending into said femur and causes a spring to urge said alignment body toward said femur;

(e) establishing a varus/valgus alignment of said alignment body by placing an end of at least one varus/valgus adjustment member located in said alignment body into contact against said femur so as to support said alignment body in an aligned position with respect to said distal end of said femur;

(f) supporting a cutting guide block on a locating arm adjustably attached to said alignment body;

(g) positioning said cutting guide block relative to said alignment body, to bring a guiding face of said cutting guide block into a predetermined orientation and position with respect to said alignment body;

(h) connecting said cutting guide block to an anterior face of said distal end portion of said femur so as to hold said guiding face in said predetermined orientation;

(i) removing said alignment body and said locating arm from said femur and said cutting guide block, leaving said cutting guide block adjacent said anterior face of said distal end of said femur with said guiding face in said predetermined orientation and leaving an unobstructed cutting plane through said distal end of said femur defined by said guiding face of said cutting guide block; and

(j) thereafter, using said guiding face to guide a cutting tool while using said cutting tool to remove a part of said distal end portion from said femur.