[Freeman's double-cup total hip endoprosthesis. Clinical results and biomechanical studies].

From July 1976 up to the end of 1979 forty-three Double Cup hip replacements of the Freeman type were implanted in thirty-seven patients at the Department of Orthopaedic Surgery, Balgrist, of the University of Zurich. Now, four to seven years after implantation, 15% of early complications have developed and only 25% of all the hips are free of pain. Radiographically, every second femoral cup shows migration of about 2 mm. pro year at an average. Clinical and radiographical investigations, as well as biomechanical experiments and calculations show the possible reasons for the unsatisfactory results. Subsequently, we are now very cautious when considering the indications for the implantation of Double Cups.