High flexion articular insert

Abstract

A knee prosthesis is provided that allows for increased flexion. The knee prosthesis includes (a) a femoral component adapted to fit on a distal end of the femur which includes a lateral condylar structure and a medial condylar structure and (b) an intermediate structure configured to cooperate with a femoral component of a knee prosthesis. The intermediate structure includes at least one surface for contacting the femoral component and a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface at the contact interface of the femoral component and the intermediate structure when the knee is flexed at approximately 120° to 140°. The knee prosthesis minimizes impingement on the femoral posterior cortex in deep flexion, increases the dislocation safety factor and allows for easier reengagement of the articular surface should the femoral component externally rotate off of the tibial plateau.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Application Ser. No. 60 / 512,457, filed on Oct. 17, 2003.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates generally to knee prostheses and, more specifically, to knee prostheses which include the use of posterior stabilized inserts and have an extended range of flexion. [0004] 2. General Background of the Invention [0005] Arthritis of the knee is a disease in which the surfaces of the knee gradually “wear out.” Osteoarthritis, characterized by chronic degeneration of the cartilage of the joints, is the most common form of arthritis. This may be due to either old age, congenital deformity, or damage due to trauma. Osteoarthritis, characterized by chronic degeneration of the cartilage of the joints, is the most common form of arthritis. Systemic arthritis, such as rheumatoid arthritis, or gout affects the synovium (the membrane tissue in the joint that normal...

AI Technical Summary

Benefits of technology

"The invention provides improved knee prostheses that can replace a portion of a knee joint between the femur and the tibia. The prostheses have a femoral component that includes a lateral and medial condylar structure and an intermediate structure that cooperates with the femoral component. The intermediate structure has a proximal surface that can flex the knee greater than 130 degrees. The prostheses also have a curved surface that contacts the femoral component and provides support to the femoral component when the knee is flexed at approximately 120 degrees to 140 degrees. The technical effects of the invention include improved flexion and reduced impingement on the patellar component."

Problems solved by technology

This may be due to either old age, congenital deformity, or damage due to trauma.

In either case, when the surface of the joint is worn away, the activities of daily living can become very difficult.

In many cases, however, despite the above non-surgical treatments, functional limitations persist.

Another problem encountered by TKR patients is unwanted movement of the femoral component on the tibial component.

A tight posterior cruciate ligament may cause the knee to move in an unnatural motion.

This can lead to excessive polyethylene wear.

In conforming knee designs, this can limit range of motion because more implant material is located on the posterior edge of the insert.

Thus, there is a need for an insert that provides sufficient posterior support and reduces posterior conformity.

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