Mechanical axis alignment using MRI imaging

Patent metadata

Field	Value
Publication number	US-9730616-B2
Application number	US-25594508-A
Country	US
Kind code	B2
Filing date	Oct 22, 2008
Priority date	Oct 22, 2008
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A method of imaging a body part includes locating a first, second and third anatomical reference area. The third anatomical reference area is disposed generally between the first and second anatomical reference areas. Furthermore, the method includes positioning a first member of a reference tool relative to the first anatomical reference area, positioning a second member of the reference tool relative to the second anatomical reference area, and a pivotal coupling member relative to the third anatomical reference area. The pivotal coupling member pivotally couples the first and second members of the reference tool. In addition, the method includes imaging a target area of the body part to produce an image. The image includes the target area of the body part and the first and second members. The first member indicates a first axis of the body part, and the second member indicates a second axis of the body part.

First claim

What is claimed is:

1. A method of imaging a knee joint of a leg before surgery comprising:
locating an approximate center of a femoral head of the leg;
locating an approximate center of an ankle joint of the leg;
locating an approximate center of a knee joint of the leg;
positioning a pivotal coupling member over the approximate center of the knee joint of the leg, the pivotal coupling member pivotally coupling a first and a second member of a reference tool;
pivoting the first member of the reference tool relative to the second member to position the first member over the approximate center of the femoral head;
pivoting the second member of the reference tool relative to the first member to position the second member over the approximate center of the ankle joint; and
imaging the knee joint to produce an image of the knee joint and at least a portion of the first and second members, the at least a portion of the first member indicating a mechanical axis of the leg in the image, and the at least a portion of the second member indicating a tibial axis of the leg in the image, and wherein the image includes the knee joint and excludes the femoral head and the ankle joint.

2. The method of claim 1 , further comprising identifying a joint line of the leg.

3. The method of claim 1 , further comprising positioning a distal end of the first member of the reference tool over the approximate center of the femoral head.

4. The method of claim 1 , further comprising positioning a distal end of the second member over the approximate center of the ankle joint.

5. The method of claim 1 , further comprising extending a length of at least one of the first and second members to at least one of position the first member over the approximate center of the femoral head and position the second member over the approximate center of the ankle joint.

6. The method of claim 5 , wherein extending the length of the at least one of the first and second members includes moving an indicator of the reference tool relative to a plurality of demarcations on the reference tool, and further comprising determining which of the plurality of demarcations that the indicator is indicating to at least one of measure an approximate distance between the center of the knee joint and the center of the ankle joint and measure an approximate distance between the center of the knee joint and the center of the femoral head.

7. The method of claim 1 , wherein the pivotal coupling member includes a ball joint.

8. The method of claim 1 , wherein locating an approximate center of the femoral head includes positioning an external jig over a pelvis, imaging the pelvis and the external jig to produce an image that shows at least a portion of the pelvis and at least a portion of the external jig, and determining the approximate center of the femoral head from the image.

9. The method of claim 1 , further comprising removably attaching the reference tool to a section of skin of the leg with the pivotal coupling member positioned over the approximate center of the knee joint, the first member over the approximate center of the femoral head, and the second member over the approximate center of the ankle joint.

10. The method of claim 1 , further comprising marking a section of skin of the leg to indicate at least one of the approximate center of the ankle joint and the approximate center of the knee joint.

11. The method of claim 1 , wherein the reference tool is made of a non-metallic material.

12. The method of claim 1 , further comprising generating a cutting guide that is customized according to the mechanical axis of the leg in the image, the cutting guide operable to guide cutting of the knee joint.

13. The method of claim 12 , wherein generating the cutting guide includes generating a cutting guide that is operable to guide cutting of the knee joint substantially perpendicular to the mechanical axis of the leg.

14. A method of imaging a knee joint of a leg before surgery comprising:
positioning a reference tool detectable by imaging over a knee joint of a leg of a patient;
positioning a pivotal coupling member of the reference tool about a center of the knee joint;
pivoting a first member of the reference tool about the pivotal coupling member relative to a second member to position a distal end of the first member over a center of a femoral head of the leg;
pivoting the second member of the reference tool about the pivotal coupling member relative to the first member to position the second member over a center of an ankle joint of the leg;
obtaining an image of the knee joint with a portion of the reference tool, wherein the image includes the knee joint and excludes the femoral head and the ankle joint; and
determining a mechanical axis of the leg from the image.

15. The method of claim 14 , further comprising telescoping the first member toward the femoral head to position the distal end of the first member over the center of the femoral head of the leg.

16. The method of claim 14 , further comprising telescoping the second member toward the ankle joint to position the second member over the center of the ankle joint of the leg.

17. The method of claim 14 , further comprising measuring a distance between the center of the ankle joint and the center of the knee joint using a scale extending from the second member.

18. The method of claim 14 , further comprising determining a tibial axis of the leg from the image of the knee joint.

19. The method of claim 14 , further comprising determining the center of the femoral head using an external jig by positioning the external jig across a pelvis, obtaining at least one measurement of the pelvis using the jig, and calculating the center of the femoral head based on the at least one measurement of the pelvis and a known ratio.

20. A method of imaging a knee joint of a leg before surgery comprising:
determining a center of a femoral head of a leg of a patient;
determining a center of the ankle joint of the leg;
determining a center of the knee joint of the leg;
positioning a pivotal coupling member of a reference tool about the center of the knee joint, the pivotal coupling member pivotally coupling a first member and a second member of the reference tool;
pivoting the first member relative to the second member to position a distal end of the first member over the center of the femoral head and to position a distal end of the second member over the center of the ankle joint;
obtaining an image of the knee joint showing the pivotal coupling member and at least portions of the first and second members extending from the pivotal coupling member;
determining a mechanical axis of the leg from the image of first member; and
determining a tibial axis from the image of the second member.

21. The method of claim 20 , wherein the image includes the knee joint and excludes the femoral head and the ankle joint.

22. The method of claim 20 , further comprising telescopically extending the second member to position the distal end of the second member over the center of the ankle joint.

23. The method of claim 20 , further comprising telescopically extending the first member to position the distal end of the first member over the center of the femoral head.

Assignees

• Hershberger Troy W
• Biomet Mfg Llc

Inventors

• Hershberger Troy W

Classifications

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• A61B17/151

  for corrective osteotomy · CPC title

• A61B2017/22001

  Angioplasty, e.g. PCTA · CPC title

• A61B5/4528

  Joints (A61B5/4533, A61B5/4538 take precedence) · CPC title

• A61B6/12

  Arrangements for detecting or locating foreign bodies · CPC title