The association between rates of wear in retrieved acetabular components and the radius of the femoral head

摘要

Current evidence suggests that loosening of the acetabular socket is related to the volume of ultra-high molecular weight polyethylene wear debris generated at the articulating surfaces, through aprocess of bone resorption. Therefore it is important that the rate of volumetric wear is minimized inan attempt to extend the useful life of the procedure. Laboratory evidence indicates that a reduction insliding distance would be beneficial in achieving this target and may be attained by a reduction infemoral head radius. To investigate the relationship between femoral head size and the rates of bothvolumetric wear and penetration, 200 acetabular components were retrieved at the time of revisionsurgery. The joints had femoral heads ranging in size from 11.1 to 19.8 mm radius. For those socketsthat were loose at revision surgery, a significant correlation was observed between the rate ofvolumetric wear and the radius of the femoral head. For this cohort an increase in radius of 1 mmresulted in an increased rate of volumetric wear of 5.1 (SF 1.4) mm{sup}3/yr. However, theexplained variance in the regression was low and exemplifies the multifactorial nature of the wearprocess In particular, it is anticipated that the activity of the patient will have a significant effect on therate at which the debris is produced. No significant correlation was observed between the rate oflinear wear and femoral head radius. These results would indicate a benefit in using head sizes of asmaller radius, which generate debris at a reduced rate, and therefore require more time toaccumulate large volumes of wear products.