Abstract

The present study analyses the long-term outcome of isoelastic hip prostheses and their influence on the extent of periprosthetic bone remodeling. Ninety-two patients (102 hips) with Isoelastic/Isotitan uncemented total hip arthroplasty were evaluated after an average of 13.4 years. The average age of patients at surgery was 42.5 years. The clinical outcome was assessed based on the Harris hip score, complications and thigh pain. Bone mineral density (BMD) of the proximal femur in the seven Gruen zones was evaluated by dual-energy X-ray absorptiometry (DEXA) scans with the contralateral hip serving as a control. The average Harris hip score at the most recent follow-up was 72 points, with 72 hips (70%) rating completely pain free. Eight stems required revision whereas none of the cups showed any evidence of loosening. The change in the mean BMD values between the femora on the operated side and the contralateral femora averaged 15% for all zones Although the isoelastic stems are no longer used owing to their high loosening rate, it appears that this prosthesis preserved periprosthetic bone better than reported for cemented or uncemented metallic implants. Besides, the provision of a titanium coating on the isoelastic stem, comparable to that on the RM cup, would presumably have improved its long-term fixation by encouraging bony ongrowth.