Published: Jan 2003
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Three types of hip stems, MS-30™ high-nitrogen stainless steel, Natural Hip™ cobalt-chromium, and APR® II porous titanium were interfaced with cobalt-chromium femoral heads. They were tested according to ASTM F 1875-98. In the initial 1 Hz cyclic loading up to 480 cycles, the average fretting current generated from the taper interface was 0.4, 0.6, and 1 μA, respectively for the stainless steel, cobalt-chromium, and titanium stems. In the following 2 Hz cyclic loading up to 3600 cycles, the average fretting current was 1.3, 0.6, and 2.25 μA, accordingly. In the potentiodynamic polarization, the titanium stems showed relatively high anodic current in the range of -100 to 500 mV. The cobalt-chromium stems had the highest anodic current in the range of 500 to 1200 mV. The stainless steel stems exhibited the best corrosion resistance in the whole potential range of polarization.
stainless steel, cobalt-chromium, titanium, fretting corrosion, orthopedic hip stems, femoral head, taper interface
Senior Research Engineer, Sulzer Orthopedics Inc., Austin, TX
Manager of Materials, Sulzer Orthopedics Ltd., Winterthur,