Femoral component geometry. A factor in total hip arthroplasty durability.

The theoretically conceived geometric design for femoral components, including a longer length, an extended width, and a stiffer modulus, is expressed in the clinical design of the Buck-32 prosthesis. This prosthesis was used in 110 patients with 122 hip arthroplasties between 1975 and 1979, giving a follow-up period of five to nine years (average, 7 years). Femoral loosening requiring revision surgery occurred in 2.3% of the patient population. Radiolucencies were noted in 24% of the cases but were progressive in only 17%. Complications were minimal, as were bone changes about the prosthetic units. There is clinical evidence in the literature, substantiated by this study, that geometric design does influence the durability of a cemented femoral component.