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

Abstract

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.

The Cementless Pm Hip Arthroplasty

“…It is also doubtful whether long-term press-fit fixation is achievable. In 1988 a new design of stem was introduced with a porous coating on the proximal third of the shaft (Refior et al 1988). No results have yet been published for this modification.…”

“…The stem has a drop-shaped macrostructure on its anterior and posterior surfaces. A good press-fit fixation of the distal two-thirds of the stem should be achieved after reaming the medullary canal (Refior et al 1988). We used a modular head of aluminium oxide ceramic (Biolox, Feldmühle Corporation); 83% of the stems had a collar (Fig.…”

“…The value of any follow-up study depends on reducing the number of cases lost to a minimum; this is often difficult to achieve (Dobbs 1980). The cementless PM hip replacement (Aesculap Corporation, Tuttlingen, Germany) has been used throughout Europe (Refior et al 1988;Havelin et al 1993) but only the results of short-term studies have been published (Parhofer and Ungethüm 1984;Trepte and Gauer 1986;Wolf, Reichelt and Schlepckow 1988).…”

Biological fixation of total hip arthroplasty: Facts and factors

“…The success of biological fixation is mainly dependent on meticulous surgical techniques and primary stability of the implant anchorage. 3 Biological fixation in which the prosthesis is directly fixed to the bone is considered as the best and ultimate fixation method. Absence of cement at the implant bone interface reduces the mechanically unstable interface.…”