In Vivo Determination of 3D Patellofemoral Mechanics

Patella Flexion With Respect to Femur

Full extension to maximum flexion. Degrees of flexion analyzed for participants with and without implants.

Time frame: Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months.

Patella Rotation With Respect to Femur

Patellar rotation from full extension to maximum flexion for subjects with and without implants. A positive measurement of patellar rotation refers to positive flexion of the patella about the medial-lateral axis, where the patella component rotates so that the top of the patella rotates toward the femur and the bottom rotates away. Conversely, a negative measurement refers to negative flexion of the patella about this axis, where the patellar component rotates so that the top of the patella moves away from the femur and the bottom moves towards.

Time frame: Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months.

Patella Tilt With Respect to Femur

full extension to maximum flexion for participants with and without implants.

Time frame: Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months.

Normalized Medial Patella Contact Point Translation

full extension to maximum flexion for participants with and without implants. Position of the patellar contact point was determined by locating the closest point to the femur on the patella throughout flexion. There are 2 patello-femoral contact points: a point on the medial aspect of the patella and a point on the lateral aspect of the patella. Throughout flexion, the medial contact point generally moves closer to the top of the patella (hence the positive value for the results). The translation of this contact point is normalized to report a ratio between -1 and 1. In other words, the distance the point has traveled compared to the total height of the patella. For example, if the patella is 8 cm in height and the point travels approximately 2 cm upwards during flexion, the value would be reported as +2/8 = +0.25. Definition of normalized: "multiply (a series, function, or item of data) by a factor that makes the norm or some associated quantity such as an integral equal

Time frame: Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months.

Normalized Lateral Patella Contact Point Translation

full extension to maximum flexion for participants with and without implants. Position of patellar contact point was determined by locating closest point to femur on patella throughout flexion. There are 2 patello-femoral contact points: 1 point on the medial aspect of the patella and 1 point on the lateral aspect of the patella. Throughout flexion, lateral contact point generally moves closer to the top of the patella (hence, the positive value for the results). The translation of this contact point is normalized to report a ratio between -1 and 1. The distance the point has traveled compared to the total height of the patella. For example, if the patella is 8 cm in height and the point travels approximately 2 cm upwards during flexion, the value would be reported as +2/8 = +0.25. Definition of normalized: "multiply (a series, function, or item of data) by a factor that makes the norm or some associated quantity such as an integral equal to a desired value (usually 1)."

Time frame: Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months.