DESIGN-RELATED FRETTING WEAR IN MODULAR NECK HIP-PROSTHESIS

An accelerated cyclic loading corrosion test was used to determine the corrosion behavior of a commercial (GSP) and a prototype titanium hip prosthesis each with a modular neck. Four GSP and four prototype stem s were subjected to a 2-Hz cyclic load ranging between 200 and 2,100 N for 1,000,000 cycles. Three stems were tested in an environment of Fe Cl3 solution, three stems were tested in Ringer's solution, and two st ems were tested in air. After cyclic loading, the specimens were caref ully examined with optical and scanning electron microscopy (SEM). Non e of them showed macroscopic or microscopic signs of corrosion, regard less of the environment to which the specimens were subjected. However , macroscopic evidence of mechanical fretting was present at the neck- stem modular junction, primarily concentrated at the medial contact po int between stem and neck, especially for the prototype stems. SEM ana lysis confirmed these observations. The appreciable differences observ ed between the two designs suggest that the problem can be minimized o r eliminated with an accurately designed taper fitting. (C) 1996 John Wiley & Sons, Inc.