Normalized and proportionalized cemented femoral stem designs. A 10-year clinical study

Two hundred fifteen cemented total hip arthroplasties were performed in 184 patients using normalized and proportionalized femoral stems. Normalization or stepped tapering of the stem minimizes development of tensile hoop stresses by altering force transmission from the femoral stem to the cement mantle. The proportionality of the stem was based on an anatomic study that resulted in the development of a series of prostheses achieving a more complete femoral canal fill. Patients were followed clinically and radiographically from 8 to 12 years or until revision. Average hip scores (d'Aubigne and Postel) improved for pain (3.0-5.9), function (2.9-5.5), and motion (3.3-5.5). Radiographic results demonstrated a 4% incidence of loosening, a 16% incidence of cortical hypertrophy, and no femoral stem fractures. Revision rate was 3%. These results support use of this device.