Laboratory corrosion testing of medical alloys and devices is an integral part of the development and approval process, but questions are frequently raised regarding the interpretation and relevance of the results and their predictive power with respect to clinical performance. These doubts are based mainly on the use of much simpler test media compared with the human body environment, and the variety of corrosion test parameters, which may lead to contradicting conclusions.

In this study the differences between in vivo and in vitro environments are critically analyzed with a focus on the presence of macrophages and proteins in the human body fluids and their role in corrosion. The published reports on the effects of proteins on the corrosion behavior will be reviewed and new evidence will be presented. The main types of corrosion test results, such as corrosion potential, corrosion current density, galvanic current, polarization behavior and critical potentials will be discussed with emphasis on interpretation, effects of test conditions and relevance to clinical performance. It will be shown that while all the laboratory results are affected by the choice of test conditions, albeit in various degrees, passivity breakdown parameters have a good predictive power with respect to clinical performance, while the corrosion current density and repassivation results require a careful interpretation and consideration of the test conditions.