Wear and friction of thin, large-diameter acetabular liners made from highly cross-linked, vitamin-E-stabilized UHMWPE against CoCr femoral heads

摘要

The experience of hip resurfacing with an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup in the 1970s and 1980s was disappointing, partly because of the inadequate material properties of UHMWPE at the time. The use of state-of-the-art, vitamin-E-stabilized, highly cross-linked polyethylene, VEXLPE, should improve implant survivorship due to its advanced wear and oxidation resistance. Experimental, metal-backed VEXLPE liners of 4.0 mm thickness were wear and friction tested against 54 mm diameter CoCr femoral heads. The tests were conducted in a multidirectional hip joint simulator with an optimal (45 degrees) and a high (65 degrees) abduction angle of the acetabular component. Calf serum was used as the lubricant. The VEXLPE liners showed reasonable wear and friction behavior. The wear was linear with wear rates of 8.5 +/- 0.6 mg/10(6) cycles and 12.9 +/- 0.3 mg/10(6) cycles at 45 degrees and 65 degrees abduction, respectively. Before the wear test, the frictional torque with both positions was 3.6 +/- 0.3 Nm, and after the wear test, the frictional torques with 45 degrees and 65 degrees abduction were 2.6 +/- 0.3 Nm and 2.4 +/- 0.6 Nm, respectively. The mean wear rate was 1.9-fold lower than that of a conventional total hip prosthesis, whereas the mean frictional torque was 1.7-fold higher.