US 7,081,137 B1Granted

Knee prosthesis with extended range of motion

AssigneeHowmedica Osteonics Corp.

InventorDamon J. Servidio

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Abstract

In a knee prosthesis, the condylar surfaces of a femoral component engage corresponding articular surfaces of a tibial component along prescribed tracks of predetermined curvature which enable relative rotation between the femoral component and the tibial component about a longitudinal axis during articulation of the knee prosthesis, and at least the condylar surfaces or the articular surfaces are flared in a direction away from corresponding articular surfaces or condylar surfaces along engaged posterior and anterior portions of the condylar surfaces and articular surfaces to provide an increased area of contact in deep flexion and in extended hyperextension for reducing contact stresses and concomitant wear while militating against unwanted distraction of the knee prosthesis. In addition, the radius of curvature of the condylar surfaces is reduced along posterior portions of the condylar surfaces to further avoid distraction of the knee prosthesis in deep flexion, thereby enabling deep flexion with greater ease and without excessive contact forces between the femoral component and the tibial component in deep flexion.

Claims44

Dependent claims

In a knee prosthesis for implantation to replace a natural knee joint, the knee prosthesis having a femoral component including at least one condylar element with a condylar surface having a transverse axis of rotation, and a tibial component including at least one articular surface configured for engagement with the condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surface and the articular surface engaged along corresponding posterior aspects during deep flexion, and along corresponding anterior aspects during hyperextension, the condylar surface and the articular surface being configured for enabling engagement between the condylar surface and the articular surface along a prescribed track having a predetermined curvature which enables relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surface and the articular surface including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surface having an inner surface portion confronting the longitudinal axis of rotation, and the articular surface having an outer surface portion for engagement with the inner surface portion during articulation:

an improvement wherein at least one of the inner surface portion and the outer surface portion is flared in a direction away from a corresponding other of the inner surface portion and the outer surface portion, along the posterior aspect of a corresponding one of the condylar surface and the articular surface so as to maintain essential congruency between the profile contour configurations and thereby enable an increased area of contact and decreased stress between the condylar surface and the articular surface while militating against distraction of the knee prosthesis during articulation through deep flexion.

In a knee prosthesis for implantation to replace a natural knee joint, the knee prosthesis having a femoral component including at least one condylar element with a condylar surface having a transverse axis of rotation, and a tibial component including at least one articular surface configured for engagement with the condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surface and the articular surface engaged along corresponding posterior aspects during flexion, and along corresponding anterior aspects during hyperextension, the condylar surface and the articular surface being configured for enabling engagement between the condylar surface and the articular surface along a prescribed track having a predetermined curvature which enables relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surface and the articular surface including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surface having an inner surface portion confronting the longitudinal axis of rotation, and the articular surface having an outer surface portion for engagement with the inner surface portion during articulation:

an improvement wherein at least one of the inner surface portion and the outer surface portion is flared in a direction away from a corresponding other of the inner surface portion and the outer surface portion, along the anterior aspect of at least a corresponding one of the condylar surface and the articular surface so as to maintain essential congruency between the profile contour configurations and thereby enable an increased area of contact and decreased stress between the condylar surface and the articular surface while militating against distraction of the knee prosthesis during articulation through hyperextension.

In a knee prosthesis for implantation to replace a natural kneejoint, the knee prosthesis having a femoral component including a lateral condylar element and a medial condylar element, each condylar element including a condylar surface having a transverse axis of rotation, and a tibial component including a lateral articular surface and a medial articular surface, each articular surface being configured for engagement with a corresponding condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surfaces and the articular surfaces engaged along corresponding posterior aspects during deep flexion, and along corresponding anterior aspects during hyperextension, each condylar surface and each articular surface being configured for enabling engagement between the condylar surfaces and corresponding articular surfaces along respective prescribed tracks each having a predetermined curvature which enable relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surfaces and the articular surfaces including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surfaces each having an inner surface portion confronting the longitudinal axis of rotation and the articular surfaces each having an outer surface portion for engagement with a corresponding inner surface portion during articulation:

an improvement wherein at least one of the inner surface portions and the outer surface portions is flared in a direction away from a corresponding other of the inner surface portions and the outer surface portions, along the posterior aspect of at least a corresponding one of the condylar surfaces and articular surfaces so as to maintain essential congruency between the profile contour configurations and thereby enable an increased area of contact and decreased stress between the condylar surfaces and the articular surfaces while militating against distraction of the knee prosthesis during articulation through deep flexion.

In a knee prosthesis for implantation to replace a natural knee joint, the knee prosthesis having a femoral component including a lateral condylar element and a medial condylar element, each condylar element including a condylar surface having a transverse axis of rotation, and a tibial component including a lateral articular surface and a medial articular surface, each articular surface being configured for engagement with a corresponding condylar surface of the femoral component during articulation of the knee prosthesis about the transverse axis of rotation, with the condylar surfaces and the articular surfaces engaged along corresponding posterior aspects during flexion, and along corresponding anterior aspects during hyperextension, each condylar surface and each articular surface being configured for enabling engagement between the condylar surfaces and corresponding articular surfaces along respective prescribed tracks each having a predetermined curvature which enables relative rotational movement between the femoral component and the tibial component about a longitudinal axis of rotation during articulation about the transverse axis of rotation, the condylar surfaces and the articular surfaces including profile contour configurations in generally medial-lateral longitudinal planes, the condylar surfaces each having an inner surface portion confronting the longitudinal axis of rotation and the articular surfaces each having an outer surface portion for engagement with a corresponding inner surface portion during articulation:

an improvement wherein at least one of the inner surface portions and the outer surface portions is flared, in a direction away from a corresponding other of the inner surface portions and the outer surface portions, along the anterior aspect of at least a corresponding one of the condylar surfaces and articular surfaces so as to maintain essential congruency between the profile contour configurations and thereby enable an increased area of contact and decreased stress between the condylar surfaces and the articular surfaces while militating against distraction of the knee prosthesis during articulation through hyperextension.

Dependencies are inferred from the claim text.