| CPC A61F 2/30942 (2013.01) [A61F 2/3859 (2013.01); A61F 2/3877 (2013.01); A61F 2/389 (2013.01); G06T 7/13 (2017.01); G06T 7/174 (2017.01); G06T 7/60 (2013.01); G06T 7/73 (2017.01); G16H 30/40 (2018.01); A61F 2002/30952 (2013.01); A61F 2002/4668 (2013.01); G06T 2207/10081 (2013.01); G06T 2207/10088 (2013.01)] | 9 Claims |
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1. A computer-aided method using an interactive pre-operative planning software analysis tool for establishing, from patient-specific images, implant parameters and customizing selection of a total knee replacement prosthesis to a patient, the method comprising:
obtaining, and inputting as image data into a computer system, a series of images of a leg of a patient, including at least a set of coronal, axial and sagittal image slices of a knee joint representing a current anatomical condition of a patient;
determining by the computer system a neutral boundary axis, a set of epicondylar and trochlear features that define an elliptical cam, and a medial-lateral tibial slope, from the image data;
defining, by the computer system from the determined epicondylar features, a sagittal plane containing a most posterior point of a medial condyle and identifying in that sagittal plane a most distal point P1 of the medial condyle, the most posterior point P2 of the medial condyle, and an end point P3 of the medial condyle at deepest flexion, the three points P1, P2 and P3 defining a first circle with a center point Fc and a radius R;
defining, by the computer system from the determined trochlear features, a sagittal plane containing a deepest aspect of a trochlear groove and identifying in that sagittal plane a distal trochlear groove point Q1, a mid-trochlear groove point, and an anterior trochlear groove point Q3, the three points Q1, Q2 and Q3 defining a second circle with a center Ft with a radius R, the first and second circles overlapping;
defining an ellipse with eccentricity 0.25 and focal points Fc and Ft; and
constructing knee prosthesis components with dimensions determined from the image data, the knee prosthesis having a femoral component as an elliptical cam with dimensions defined by the ellipse, and having tibial and patellar components interacting with the femoral component as cam followers under knee flexion.
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