System and method for pre-operatively determining desired alignment of a knee joint

1. A joint alignment method comprising:

using imaging data of at least a portion of a leg to create a leg model, the leg model including a femur having medial and lateral condyles and a tibia having a tibial plateau configured to engage the medial and lateral condyles at a knee joint, wherein one of the medial and lateral condyles is an arthritic condyle and the other one of the medial and lateral condyles is a non-arthritic condyle;

displaying an image of the leg model for manipulation by a user;

identifying a contact point between a distal end of the non-arthritic condyle and a proximal end of the tibial plateau with the knee joint in extension;

locating a first pivot point within the non-arthritic condyle, the first pivot point being defined by a center of an arc that approximates a first curvature of an outer condylar surface of the non-arthritic condyle, the first curvature extending through the contact point;

identifying a distalmost point of the non-arthritic condyle;

locating a second pivot point within the non-arthritic condyle, the second pivot point being defined by a center of an arc that approximates at least a portion of a second curvature of the outer condylar surface of the non-arthritic condyle, the second curvature extending through the distalmost point; and

rotating, in the displayed image, the tibia with respect to the femur, about one or more of the first pivot point and the second pivot point, to obtain a desired knee joint articulation in one or more of a first plane and a second plane;

wherein the first curvature is a medial-lateral curvature and the second curvature is an anterior-posterior curvature, and wherein the medial-lateral curvature extends along a plane that is parallel to a plane containing an epicondylar axis.

2. The method of claim 1 , wherein the first plane is a varus-valgus plane and the second plane is a flexion-extension plane.

3. The method of claim 1 , wherein the desired knee joint articulation is selected from the group consisting of a varus knee joint alignment, a valgus knee joint alignment, and a neutral knee joint alignment.

4. The method of claim 1 , wherein the desired knee joint articulation is selected from the group consisting of full extension of the knee joint, flexion of the knee joint, and hyperextension of the knee joint.

5. The method of claim 1 , wherein the first pivot point is a varus-valgus pivot point and the second pivot point is a flexion-extension pivot point.

6. The method of claim 1 , further comprising visually displaying a prosthetic implant on the arthritic condyle after the step of rotating the tibia to obtain the desired knee joint articulation.

7. The method of claim 6 , wherein the prosthetic implant indicates an implant size that is suitable for achieving the desired knee joint articulation.

8. The method of claim 1 , further comprising performing the imaging using a magnetic resonance imaging system.

9. A joint alignment method comprising:

obtaining a plurality of two-dimensional images of a leg;

creating a three-dimensional leg model using the two-dimensional images, the leg model including a femur having medial and lateral condyles and a tibia having a tibial plateau configured to engage the medial and lateral condyles at a knee joint, wherein one of the medial and lateral condyles is an arthritic condyle and the other one of the medial and lateral condyles is a non-arthritic condyle;

displaying an image of the three-dimensional leg model for manipulation by a user;

identifying a contact point between a distal end of the non-arthritic condyle and a proximal end of the tibial plateau with the knee joint in extension;

locating a varus-valgus pivot point within the non-arthritic condyle, the varus-valgus pivot point being defined by a center of an arc that approximates a medial-lateral curvature of an outer condylar surface of the non-arthritic condyle, the medial-lateral curvature extending through the contact point and along a plane that is parallel to a plane containing an epicondylar axis;

identifying a distalmost point of the non-arthritic condyle;

locating a flexion-extension pivot point within the non-arthritic condyle, the flexion-extension pivot point being defined by a center of an arc that approximates at least a portion of an anterior-posterior curvature of the outer condylar surface of the non-arthritic condyle, the anterior-posterior curvature extending through the distalmost point; and

rotating, in the displayed image, the tibia with respect to the femur, about one or more of the varus-valgus pivot point and the flexion-extension pivot point, to obtain a desired knee joint articulation in one or more of a varus-valgus plane and a flexion-extension plane.

10. The method of claim 9 , further comprising visually displaying a prosthetic implant on the arthritic condyle after the step of rotating the tibia to obtain the desired knee joint articulation.

11. The method of claim 10 , wherein the prosthetic implant indicates an implant size that is suitable for achieving the desired knee joint articulation.

12. A pre-operative method for visualizing alignment of a joint comprising:

displaying a three-dimensional model of a knee joint, the three-dimensional model including a distal end of a femur having an arthritic condyle and a non-arthritic condyle and a proximal end of a tibia having a tibial plateau;

locating first and second pivot points within the non-arthritic condyle, wherein the first pivot point is located at a center of a medial-lateral arc that approximates a curvature of an articulation surface of the non-arthritic condyle in a first plane that is parallel to a plane containing an epicondylar axis, and wherein the second pivot point is located at a center of an anterior-posterior arc that approximates a curvature of at least a portion of the articulation surface of the non-arthritic condyle in a second plane, wherein the first plane is transverse to the second plane; and

manipulating a displayed position of the arthritic condyle by rotating the tibia about the first pivot point and the second pivot point to determine a desired pre-operative alignment of the joint.

13. The method of claim 12 , wherein the medial-lateral arc passes through a contact point between a distal end of the articulation surface and a proximal end of the tibial plateau.

14. The method of claim 13 , wherein the anterior-posterior arc passes through a distal point on the articulation surface.