Multiple-cam, posterior-stabilized knee prosthesis
OwnerMichael A. Masiniinventor
Life of this patent
Estimating the term…
Abstract
A distal femoral knee-replacement component provides additional points of cam action by either distinct bars or interconnected structural elements such as cam extensions to prevent early translation of the knee or dislocation of the femoral component over the tibial post which can occur in cruciate-substituting designs.
Claims17
In a total knee-replacement system including a tibial component having medial and lateral bearing surfaces and a superior post with a posterior surface, and a distal femoral component having medial and lateral condylar protrusions that articulate with the bearing surfaces and an intercondylar region with a central cam that engages with the posterior surface of the superior post, the improvement comprising:
- a distal femoral component having a central cam with a first, convex cam action surface in the intercondylar region that engages the posterior aspect of a tibial post before 90 degrees of flexion;
- a cam extension that terminates in a second cam action surface that makes initial contact with the posterior aspect of the post after 90 degrees of flexion to facilitate enhanced knee flexion without dislocation over the tibial post;
- and
- an intermediate surface portion between the first and second cam action surfaces that does not make contact with the tibial post.
A total knee replacement system, comprising:
- a tibial component having medial and lateral bearing surfaces and a tibial post with a posterior surface;
- a distal femoral component having an intercondylar region configured to receive the tibial post and medial and lateral condylar surfaces that articulate with the bearing surfaces of the tibial component over a range of motion from extension through flexion;
- and
- a member on the distal femoral component bridging the intercondylar region, the member including:
- a first, convex cam surface that engages with the posterior surface of the tibial post following the onset of flexion, and
- a cam extension with a second cam action surface that initially engages with the posterior surface of the tibial post beyond 90 degrees of flexion, to minimize dislocation over the tibial post;
- and
- an intermediate surface portion between the first and second cam action surfaces that does not make contact with the tibial post.
A knee implant for use in posterior cruciate sacrificing procedures, comprising:
- a tibial component having a superior post with a posterior surface;
- a femoral component having medial and lateral condylar protrusions which form separated bearing surfaces configured to articulate with the tibial component and an intercondylar femoral cam mechanism;
- the cam mechanism including an intercondylar bridging structure having a convex surface which engages with the posterior surface of the superior post;
- a cam extension with a separate surface positioned to engage with the posterior surface of the superior post to reduce the risk of dislocation, but only at flexion greater than 90 degrees;
- and
- an intermediate surface portion between the first and second cam action surfaces that does not make contact with the tibial post.
A total knee replacement system, comprising:
- a tibial component having medial and lateral bearing surfaces and a tibial post with a posterior surface;
- a distal femoral component having an intercondylar region configured to receive the tibial post and medial and lateral condylar surfaces that articulate with the bearing surfaces of the tibial component over a range of motion from extension through flexion;
- and
- a member on the distal femoral component bridging the intercondylar region, the member including:
- a convex cam surface that engages with the posterior surface of the tibial post following the onset of flexion, and
- a cam extension with a cam action surface that initially engages with the posterior surface of the tibial post beyond 90 degrees of flexion to minimize dislocation over the tibial post, and
- wherein the cam extension projects proximally away from the tibial articulating surface when the knee is in extension.
Dependencies are inferred from the claim text.