A PROSPECTIVE STUDY COMPARING ACETABULAR BONE REMOVAL IN HIP RESURFACING AND UNCEMENTED TOTAL HIP ARTHROPLASTY

Abstract

Aim: To prospectively compare the quantity of bone removed from the acetabulum in hip resurfacing arthroplasty and uncemented total hip replacements.

Methods: Sixty four patients were prospectively enrolled in the study. We compared 32 birmingham hip resurfacing acetabular components with 32 trident uncemented acetabular cups. To assess the pre-reaming size of the acetabulum, and to allow comparison between acetabular sizes, the size of the femoral head was assessed to the nearest millimetre intraoperatively with the use of a measuring calliper. The reamings from the acetabulum were collected. This bone was then dehydrated and defatted with five washes of acetone followed by five washes of diethyl ether. The bone was then placed in a furnace at 200 degrees Celsius until a consistent dry weight was achieved. The size of acetabular component used was recorded in all cases.

Results: The mean weight of bone removed from the acetubulum of the resurfacing group was 13.79 g. The corresponding mean weight of bone removed from the acetabulum of the total hip replacement group was 11.71g. Using a non-parametric analysis of covariance (ANCOVA) to account for the covariate of acetabular size, regression analysis indicated no evidence of a difference between the mean bone weight removed in the two groups (p-value of 0.57).

Conclusions: Close attention to surgical technique in preparing the femoral head during resurfacing will allow the use of an appropriately small femoral component. If performed accurately this will avoid oversizing the acetabular component and removal of excess bone stock.