[Technical development and radiological surveillance of the Schmitt minimadreporic uncemented total hip prosthesis. Evaluation of 275 arthroplasties with a follow-up of more than 6 years for the oldest cases].

The authors describe a porous-coated uncemented total hip prosthesis which has been used for more than six years: the Schmitt minimadreporic prosthesis. A homogenous series of 275 arthroplasties has been reviewed with a mean follow-up of three years and five months. The method of radiological assessment of the position of the femoral and acetabular components and their possible loosening is described in detail. Infection (0.72%) and aseptic loosening (1.8%) specific to this type of prosthesis was rare. For the series as a whole there were 92% of good, very good and excellent results and for 81 arthroplasties with a follow-up greater than four years the figure was 90%. The frequency of secondary displacement of the femoral component is emphasised, with 15 prostheses sinking downwards and 96 displacing into varus. Statistical analysis has shown the principal factors affecting the clinical result and has demonstrated the effect of resorption of the calcar in causing downward displacement of the femoral stem and insufficient filling of the medullary cavity on the development of varus angulation of the prosthesis.