The isoelastic, noncemented total hip arthroplasty. Preliminary experience with 400 cases.

The first 400 patients having cementless isoelastic total hip arthroplasties with a polyacetyl femoral component stem were assessed by independent observers with a minimum review time of two years. Six percent of the patients had died at the time of review; these were mainly elderly patients with subcapital fractures. Ninety-seven percent of the surviving patients appeared for a complete clinical and radiological review. Ninety-two percent of these patients considered that they had a good result following surgery. Six patients (1.6%) developed infection, and three patients (0.8%) required revision procedures, two for femoral loosening and one for recurrent dislocation. Two (0.5%) acetabular components were loose, one of which was associated with infection. In the initial part of the series with narrow-diameter, second-generation femoral components, some had subsided and tilted into varus, but with improved instrumentation and availability of wider diameter femoral components, this problem has been overcome. In order to obtain a more secure mechanical fixation of the femoral component in the medullary canal and to increase implant-bone interface, the third-generation femoral components were used in the latter 48 cases of the series, and clinical and radiological results were excellent with corresponding reduction in the recommended period of gait support. No component had broken. Femoral fractures incurred during surgery by dislocation or impaction had all healed with routine management. These early results are encouraging, but the effectiveness of this prosthesis must be determined by longer follow-up data.