Rationale, Experience, and Results of Long-Stem Femoral Prosthesis

Abstract

A long, curved-stem, uncemented femoral component was evaluated for use in primary and revision hip arthroplasty in young patients aged 43.5 years (range, 16-60 years). The femoral component has a proximal wedge shape and a medial collar for proximal press fit and load transfer; anterior and posterior ingrowth pads; anteverted head and neck; and a long, anatomically curved intramedullary stem for distal stability. In testing the contribution of the long, curved stem to the torsional stability of uncemented prostheses by comparing it with other stems, the long, curved stem was the most stable, followed by a shorter straight stem, and a short, proximally curved stem. If the long, and a short, proximally curved stem. If the long, curved stem is incrementally shortened by 1.5-7.5 cm, the initial torsional stability is reduced in proportion to the amount of shortening. Geometrically, for a given patient, the stem-bone contact (and thus the distal stability) is increased when a larger stem is inserted. Clinically, Harris hip scores in 69 hips followed for five to seven years (average patient age, 43.5 years) improved from 52.6 to 92.0 at last follow-up evaluation. The femoral component revision rate was 2.9%, the acetabular rate was 8.9%, and bipolar revision rate was 3.1%, for a combined rate of 12%.