Zimmer Gmbh

Matthias Schäpper

Roger Scherrer

Marco A H Heggendorn

Marco Heggendorn

A knee prosthesis has a femoral component with a medial condyle defining a constant bearing spacing relative to a central sagittal component plane SP, and a lateral condyle defining divergent bearing spacing from the central sagittal component plane along an extension-to-flexion path. High congruence between the medial articulation surfaces creates a pivot point for external rotation at the medial contact area, while lower congruence in the lateral articulation surfaces allows the lateral femoral condyle to track anteriorly and posteriorly during flexion. The amount of lateral condyle bearing spacing divergence is calculated to produce a substantially linear anteroposterior motion profile of the lateral femoral condyle upon the lateral tibia articular surface throughout a wide range of flexion.

Femoral knee prosthesis with diverging lateral condyle

An orthopaedic knee joint prosthesis () provides guided motion in a wide range of motion, and in both extension and flexion. In flexion, a tibial bearing component () shifts to a first position in which a posterior cam () formed in a femoral component () engages a tibial spine () coupled to a tibial component (). Contact between the posterior cam and the spine guides the motion profile of the knee joint prosthesis throughout a wide range of flexion movement. In extension, the bearing component shifts to a second position in which an anterior cam () formed in the femoral component engages the spine. Contact between the anterior cam and spine guides the motion profile of the knee joint prosthesis throughout a wide range of extension. The anterior and posterior cams, mobile bearing component, and tibial component-mounted spine cooperate to facilitate guided flexion and extension of the knee joint prosthesis throughout a wide range of motion.

Knee prosthesis with guided extension and flexion

One or both of the condyles in a femoral component for a partial or total knee prosthesis includes a J-curve with a plurality of distinct radii, such as 5 or more radii. The centers of the radii are arranged along an arcuate path extending anteroposteriorly so that successively larger radii are serially arranged along the arcuate path from the posterior side of the femoral component to the anterior side. The femoral component provides a high degree of stability throughout the range of motion of the knee prosthesis, and facilitates a close approximation to the motion of a natural knee.

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Winterthur, Switzerland

Matthias Schäpper