A comparison between gravimetric and volumetric techniques of wear measurement of UHMWPE acetabular cups against zirconia and cobalt-chromium-molybdenum femoral heads in a hip simulator

Five cobalt-chromium-molybdenum (CoCrMo) and five zirconia femoral head com ponents have been wear tested against 28 mm diameter ultra high molecular w eight polyethylene (UHMWPE) acetabular cups for 5 million cycles in the Dur ham hip joint wear simulator using bovine serum as a lubricant. Wear measur ements used gravimetric and volumetric techniques and no statistically sign ificant difference was found between the measurement methods. The wear rate s of the acetabular cups against both femoral heads are presented for both measurement methods. The UHMWPE acetabular cups showed a statistically sign ificant higher linear wear rate for the first 2 million cycles than the low er linear wear rate from 2 million cycles to the end of the test, against b oth femoral head materials. Over the full duration of the wear test, the we ar rates of acetabular cups articulating against zirconia femoral heads wer e lower than against CoCrMo femoral heads. The wear rates up to 2 million c ycles and from 2 to 5 million cycles for both femoral head materials were c onsistent with other studies.