Inaccuracy of acetabular reaming under surgical conditions

Press-fit uncemented acetabular components require accurate implant-bone ca vity fit. Ten cavities produced during actual hip arthroplasty using debris -retaining reamers were replicated in dental alginate. An experimental ream er with better cutting prepared 12 acetabulae in mortua under similar condi tions. Positives in dental stone were measured on a coordinate measuring ce nter. Spheres of best-fit and variation of each point from these spheres we re calculated. Control cavities in polyurethane foam were measured to estim ate casting errors. Diametral errors of conventionally reamed cavities aver aged 2.1%, whereas experimental reamers' cavities varied by 0.5% (P < .005) . Overall surface variation from hemispheric form in conventionally reamed cavities exceeded the experimental reamer's results (P < .005). Conventiona l acetabular reamers cut bone inaccurately. Reamers designed for improved b one cutting reduce cavity errors.