Long-term evaluation of a compliant cushion form acetabular bearing for hip joint replacement: a 20 million cycles wear simulation.

Soft bearing materials that aim to reproduce the tribological function of the natural joint are gaining popularity as an alternative concept to conventional hard bearing materials in the hip and knee. However, it has not been proven so far that an elastic cushion bearing can be sufficiently durable as a long term (∼20 years) articulating joint prosthesis. The use of new bearing materials should be supported by accurate descriptions of the implant following usage and of the number, volume, and type of wear particles generated.

MRI-based characterization of bone anatomy in the human knee for size matching of a medial meniscal implant.

Allograft or synthetic menisci have been suggested as a means to restore contact pressures following meniscectomy. However, when the natural meniscus is severely damaged/absent, the necessary size cannot be determined according to the recipient size and there is a need to estimate it from magnetic resonance imaging (MRI) of the contralateral knee or the injured knee bones. The use of the contralateral-knee for size matching is problematic due to economic and practical reasons.

Design of a free-floating polycarbonate-urethane meniscal implant using finite element modeling and experimental validation.

The development of a synthetic meniscal implant that does not require surgical attachment but still provides the biomechanical function necessary for joint preservation would have important advantages. We present a computational-experimental approach for the design optimization of a free-floating polycarbonate-urethane (PCU) meniscal implant. Validated 3D finite element (FE) models of the knee and PCU-based implant were analyzed under physiological loads.

Chondroprotective effects of a polycarbonate-urethane meniscal implant: histopathological results in a sheep model.

Purpose: injury or loss of the meniscus generally leads to degenerative osteoarthritic changes in the knee joint. However, few surgical options exist for meniscal replacement. The goal of this study was to examine the ability of a non-degradable, anatomically shaped artificial meniscal implant, composed of Kevlar-reinforced polycarbonate-urethane (PCU), to prevent progressive cartilage degeneration following complete meniscectomy.

Wear rate evaluation of a novel polycarbonate-urethane cushion form bearing for artificial hip joints.

There is growing interest in the use of compliant materials as an alternative to hard bearing materials such as polyethylene, metal and ceramics in artificial joints. Cushion form bearings based on polycarbonate-urethane (PCU) mimic the natural synovial joint more closely by promoting fluid-film lubrication. In the current study, we used a physiological simulator to evaluate the wear characteristics of a compliant PCU acetabular buffer, coupled against a cobalt-chrome femoral head.