Special problems of cementless fixation of total hip-joint endoprostheses with reference to the PM type.

The success of cement-free hip endoprosthetics is largely dependent on precise surgical techniques and primary stability of the anchorage, in which favorable biomechanical conditions as well as the quality of the stabilizing bone are of considerable importance. Information gathered from more than 1500 cementless hip-joint endoprosthesis implantations is presented with biomechanical solutions and indications regarding operating techniques, and a correlation between clinical symptoms and radiological signs of complications is discussed. In close coordination with material-specific factors, design and surface characteristics are decisive in the function and quality of anchorage of the endoprosthetic replacement. In the case of the PM total hip endoprosthesis, these widely variable values were governed strictly by biomechanical considerations, with particular reference to the resulting bone reactions. Results so far, including those relating to stable integration of the implant, must be regarded as absolutely positive and confirm the design characteristics on which this model was based. Avoiding the disadvantages of bone cement, cementless hip-joint replacement, particularly in operations for the exchange of cemented prostheses after loosening, can be regarded as a step forward in hip-joint surgery.