Expectations and outcome of a scientifically developed hip prosthesis in 170 hips with a follow-up of 5-12 years.

Roentgen stereophotogrammetric analysis (RSA) is commonly used to assess prosthetic stability as a predictor of the long-term clinical outcome of new total hip systems. Although the RSA technique is very accurate, it may not be trivial to interpret migration rates into clinical outcome, as critical migration rates depend heavily on the design of the prosthesis. In the present study we describe the clinical results of the Scientific Hip Prosthesis (SHP), which had unexpectedly high migration values in a clinical RSA study. We evaluated the clinical results of a single surgeon study consisting of 170 hips with a follow-up of 5-12 years (mean: 83 years). The survival rate was 98.8% at ten years for aseptic loosening of the stem. This study therefore indicates that a prosthetic design may function clinically rather well although relatively high migration rates have been reported. The prediction of clinical survival of new prosthetic components remains a challenging task and the interpretation of migration rates with new designs should be considered with much caution.