Method and apparatus for achieving correct limb alignment in unicondylar knee arthroplasty

• US 20040102785A1
• Filed: 11/27/2002
• Published: 05/27/2004
• Est. Priority Date: 11/27/2002
• Status: Active Grant

• Current Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Hodorek, Robert A., Sanford, Adam H., Farling, Toby N., Williamson, Richard V., Saenger, Paul L.
• Granted Patent: US 7,094,241 B2
• Time in Patent Office: Days
• US Class Current: 606/87
• CPC Class Codes: A61B 17/154 for preparing bone for knee prosthesis
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/157 Cutting tibia

Abstract

A method and apparatus for correcting limb alignment in a unicondylar knee arthroplasty and linking the distal femoral cut and the proximal tibial cut. Alignment rods are connected to a spacing apparatus to facilitate correction of limb alignment. The alignment rods are positioned along the mechanical axis of the femur and the tibia and the knee joint is positioned to correct alignment. A spacing apparatus is positioned in the relevant knee compartment and utilized to hold the knee in position to correct limb alignment. The spacing apparatus includes a femoral cut slot through which the distal femoral cut is made and further includes tibial affixment apertures through which a headless securing device can be positioned to secure the spacing apparatus to the tibia. After the distal femoral resection is complete, the spacing apparatus is removed, with the headless securing devices remaining positioned in the tibia. The headless securing devices are used as a reference for securing a tibial cut block to the tibia for making the proximal tibial resection. With the mechanism of the present invention, the knee can be placed in flexion when making the proximal tibial cut and the distal femoral cut is linked to the proximal tibial cut.

Claims

1. A method of creating a desired alignment between a tibia and a femur that form a knee joint having an alignment deformity, comprising:

inserting a spacer into the knee joint;

connecting a femoral alignment rod having a first end, a second end, and a longitudinal axis to said spacer, the first end of the femoral alignment rod positioned between a pair of condyles positioned at a distal end of the femur and the second end of the femoral alignment rod extending proximally toward a femoral head of the femur;

connecting a tibial alignment rod having a first end and a second end to said spacer, the first end of the tibial alignment rod positioned between the pair of condyles, the second end of the tibial alignment rod extending distally, said tibial alignment rod one of substantially parallel to and colinear with said femoral alignment rod;

connecting a targeting guide to said second end of said femoral alignment rod, said targeting guide having a reference offset from said longitudinal axis of said femoral alignment rod;

aligning said reference of said targeting guide with a femoral head;

aligning the tibial alignment rod with a tibial mechanical axis; and

adjusting the spacer to maintain the knee in a position whereby said reference of said targeting guide remains aligned with the femoral head and said tibial alignment rod remains aligned with the tibial mechanical axis.

2. The method of claim 1, wherein said spacer comprises:

an adjustable alignment block comprising;

a body;

a femoral paddle connected to said body; and

a tibial paddle connected to said body, one of said femoral paddle

and said tibial paddle moveably connected to said body; and

wherein said step of inserting a spacer into the knee joint comprises the step of;

inserting the femoral paddle and the tibial paddle of said adjustable alignment block into a compartment of the knee joint.

3. The method of claim 2, wherein said step of adjusting the spacer to maintain the knee in a position whereby said femoral alignment rod remains aligned with the femoral mechanical axis and said tibial alignment rod remains aligned with the tibial mechanical axis comprises the step of:

moving one of the femoral paddle and the tibial paddle until the femoral paddle contacts the distal end of the femur and the tibial paddle contacts the proximal end of the tibia.

4. The method of claim 2, wherein said step of connecting a femoral alignment rod to said spacer comprises:

connecting an alignment tower to said adjustable alignment block, with an alignment rod receiving end of said alignment tower positioned between the pair of condyles positioned at the distal end of the femur; and

connecting said femoral alignment rod to said alignment rod receiving end of said alignment tower.

5. The method of claim 2, wherein said step of connecting a tibial alignment rod to said adjustable alignment block comprises:

connecting an alignment tower to said adjustable alignment block, with an alignment rod receiving end of said alignment tower positioned between the pair of condyles positioned at the distal end of the femur; and

connecting said tibial alignment rod to said alignment rod receiving end of said alignment tower.

6. The method of claim 1, further comprising:

resecting an anterior tibial boss prior to said inserting step.

7. A method of creating a desired alignment between a tibia and a femur that form a knee joint having alignment deformity, comprising:

inserting a spacer into the knee joint;

connecting a femoral alignment rod having a first end, a second end, and a longitudinal axis to said spacer, the first end of the femoral alignment rod positioned between a pair of condyles positioned at a distal end of the femur and the second end of the femoral alignment rod extending proximally toward a femoral head of the femur;

connecting a tibial alignment rod having a first end and a second end to said spacer, the first end of the tibial alignment rod positioned between the pair of condyles, the second end of the tibial alignment rod extending distally, said tibial alignment rod one of substantially parallel to and colinear with said femoral alignment rod;

aligning the tibial alignment rod with a tibial mechanical axis;

substantially aligning the femoral alignment rod with a femoral mechanical axis; and

adjusting the spacer to maintain the knee in a position whereby said tibial alignment rod remains aligned with the tibial mechanical axis and said femoral alignment rod remains substantially aligned with the femoral mechanical axis.

8. The method of claim 7, wherein said step of substantially aligning the femoral alignment rod with a femoral mechanical axis comprises:

connecting a targeting guide to said second end of said femoral alignment rod, said targeting guide having a reference offset from said longitudinal axis of said femoral alignment rod; and

aligning said reference of said targeting guide with a femoral head.

9. A method of linking a proximal tibial cut made with a tibial cut guide and a distal femoral cut made with a femoral cut guide, comprising:

aligning a femur and a tibia to create a desired alignment

securing the femoral cut guide to the femur, the femoral cut guide including a femoral cut slot through which the distal femoral cut can be made;

securing a reference to the tibia, said reference linked to said femoral cut slot;

removing said femoral cut guide; and

connecting the tibial cut guide to said reference, the tibial cut guide including a tibial cut slot through which the proximal tibial cut can be made, wherein said reference links the proximal tibial cut to the distal femoral cut.

10. The method of claim 9, wherein said femoral cut guide includes a pair of tibial reference apertures, wherein said reference comprises a pair of reference posts and wherein said step of securing a reference to the tibia comprises the step of securing said reference posts to the tibia through said reference apertures.

11. The method of claim 10, wherein said reference posts comprise headless screws.

12. The method of claim 10, wherein said reference posts comprise headless pins.

14. The apparatus of claim 12, wherein said headless fixing means comprises a pair of headless screws, and wherein said tibial cut block body includes a pair of tibial securement apertures.

15. The apparatus of claim 12, wherein said headless fixing means comprises a pair of headless pins, and wherein said tibial cut block body includes a pair of tibial securement apertures.

16. The apparatus of claim 12, wherein said tibial cut block includes a plurality of tibial securement apertures spaced differing distances from said tibial cut slot.

17. The apparatus of claim 12, wherein said femoral cut block includes spacing means for maintaining a spacing in a compartment of a knee to correct limb alignment.

18. The apparatus of claim 17, wherein said spacing means comprises:

a femoral paddle extending from said body of said femoral cut block; and

a tibial paddle moveably connected to said body of said femoral cut block, whereby said tibial paddle is moved to abut a proximal tibia, with said femoral paddle abutting a distal femur when said knee is positioned to correct limb alignment.

19. The apparatus of claim 18, further comprising:

a femoral spacer secured to said femoral paddle of said spacing means, said femoral spacer having a thickness extending toward the distal femur.

13. An apparatus for linking a distal femoral cut and a proximal tibial cut, comprising:

a femoral cut block comprising;

a body having a femoral cut slot, a femoral securement aperture and a tibial securement aperture formed therein;

headless fixing means for securing said femoral cut block to a tibia, said headless fixing means traversing said tibial securement aperture in said femoral cut block to secure said femoral cut block to said tibia; and

a tibial cut block comprising;

a body having a tibial cut slot, and a tibial securement aperture formed therein, said tibial securement aperture sized to accommodate passage of said headless fixing means there through, whereby said tibial securement aperture of said femoral cut block is spaced a predetermined distance from said femoral cut slot, and said tibial securement aperture of said tibial cut block is spaced a predetermined distance from said tibial cut slot, whereby said femoral cut slot is linked to said tibial cut slot by said headless fixing means.

20. An apparatus for preparing a knee for receiving a knee prosthesis, comprising:

a femoral cut block having a femoral cut slot;

a tibial cut block having a tibial cut slot; and

means for linking said femoral cut slot and said tibial cut slot and allowing a proximal tibial cut to be made through said tibial cut slot with the knee in flexion.

21. The apparatus of claim 20, wherein said means for linking said femoral cut slot and said tibial cut slot comprises:

a tibial securement aperture formed in said femoral cut block;

headless fixing means for securing said femoral cut block to a tibia, said headless fixing means traversing said tibial securement aperture in said femoral cut block to secure said femoral cut block to said tibia; and

a tibial securement aperture formed in said tibial cut block.

22. The apparatus of claim 21, wherein said headless fixing means comprises a pair of headless screws, and wherein said tibial cut block body includes a pair of tibial securement apertures.

23. The apparatus of claim 21, wherein said headless fixing means comprises a pair of headless pins, and wherein said tibial cut block body includes a pair of tibial securement apertures.

24. An apparatus for maintaining a spacing in a compartment of a knee to correct limb alignment, comprising:

a body;

a femoral paddle extending from said body;

a tibial paddle moveably connected to said body, whereby said tibial paddle is moved to abut a proximal tibia, with said femoral paddle abutting a distal femur when said knee is positioned to correct limb alignment; and

a femoral spacer releasably secured to said femoral paddle, said femoral spacer having a thickness extending toward the distal femur when said femoral spacer is secured to said femoral paddle and said apparatus is operably positioned to maintain the spacing in a knee compartment to correct limb alignment.

25. The apparatus of claim 24, wherein said femoral spacer includes a pair of opposing dovetails extending from a lower surface thereof to releasably secure said femoral spacer to said femoral paddle, said femoral spacer further includes an expansion channel extending the thickness of the femoral spacer and positioned intermediate said dovetails.

26. An alignment apparatus for correcting alignment of a leg, comprising:

a spacer for insertion into a compartment of a knee;

a tibial alignment rod connected to said spacer, said tibial alignment rod having a longitudinal axis;

an ankle clamp releasably connected to said tibial alignment rod; and

a femoral alignment rod connected to said spacer, said femoral alignment rod having a longitudinal axis, said longitudinal axis of said tibial alignment rod and said longitudinal axis of femoral alignment rod being one of collinear and parallel.

27. The alignment apparatus of claim 26, further comprising:

a targeting guide releasably secured to said femoral alignment rod, said targeting guide having a reference offset from said longitudinal axis of said femoral alignment rod.

28. An alignment apparatus for correcting alignment of a leg, comprising:

a spacer for insertion into a compartment of a knee;

a tibial alignment rod connected to said spacer, said tibial alignment rod having a longitudinal axis;

a femoral alignment rod connected to said spacer, said femoral alignment rod having a longitudinal axis, said longitudinal axis of said tibial alignment rod and said longitudinal axis of femoral alignment rod being one of collinear and parallel; and

a targeting guide releasably secured to said femoral alignment rod, said targeting guide having a reference offset from said longitudinal axis of said femoral alignment rod.