Author(s)

CLAUDIO T. DOS SANTOS, IEDA M. V. CAMINHA, WELLINGTON G. FERNANDES, MAURÍCIO J. MONTEIRO, PATRÍCIA O. CUBILLOS, CARLOS R. M. ROESLER

Abstract

Modular hip prostheses allow better adjustment to the patient’s anatomy. We used a combination of materials to make the prosthesis more resistant to wear and corrosion; however, modular connections are inevitably subjected to fretting corrosion, due to micromotion. Evaluation of this corrosion is generally based on two in vitro test methods: a long-term test method (fatigue-corrosion) for the simultaneous assessment of mechanical stability, particle release and analysis of damage on the surfaces of prosthesis components; and a short-term electrochemical test method, for current and potential generated by fretting and corrosion in the modular connection. In both methods, the prosthesis is mechanically loaded in a saline environment, to simulate human body conditions. Although these methods are complementary, there are still few studies using the electrochemical test method. This study aims to present the methodology used in an electrochemical test and the results obtained in our laboratory for a stainless steel commercial prosthesis. In addition, we discuss the mechanisms involved in the fretting corrosion process. We conclude that the results of the electrochemical test, together with those obtained in the fatigue-corrosion test, contribute to an effective evaluation of the quality of modular prostheses, in terms of their safety and performance.

Keywords

hip prosthesis, fretting corrosion, electrochemical test, modular interface, medical device safety, performance, head-stem combinations