Development of a protocol for the performance evaluation of wear machines used in tests of joint prostheses

The growing demand for orthopaedic joint implants and the large number of premature failure rates entails an increase in the number of surgeries; as a consequence, the costs of public and private health systems raise proportionally. The decrease of implants longevity is due to premature wear. Human gait simulation tests and orbital machines have contributed in the prediction of hip and knee joint implants performance. Wear tests in hip prostheses are standardized according to ISO 14242-1 and 14242-3. Lack of consensus on a universal standard for testing machines generates conflicting results and prevents a comparison of wear rates for prostheses evaluated by distinct mechanisms. This paper presents a protocol that was used to verify the performance and compliance of a hip simulation mechanical device designed to mimic the different standards. Tests performed with the above-mentioned apparatus are universal, for the simulator is capable of reproducing actual gait. Thus, commercially available wear testing machines ought to be certified for performance and standard compliance prior to be used as tools for obtaining actual rates of wear in joint prostheses.

► A method for evaluation of joint prostheses wear testing machines is proposed.
► Results of tests under the proposed method are in accordance with standards.
► Calculation of effective wear rates should consider contact areas among tested parts.
► MEV and optical images of wear grooves on tested specimens validate the method.
► Testing devices should be certified for compliance with applicable standards.