CURRENT CONCEPTS REVIEW The author surveys important landmarks in the

development of total hip arthroplasty, with an accent on implant fixation using acrylic cement. He explains why he personally opted for hybrid prostheses, com-bining a cemented stem and a cementless socket, in patients over sixty years. Excellent cementless, sockets have been available for a long time; on the femoral side, the first steps were difficult, but several cementless, stems were subsequently developed, which provided excellent long term results. This his-torical evolution resulted in a very uneven use of cemented versus cementless stems from one country to another in Europe. Cemented implants have enjoyed a renewed popularity over the past few years as a result of several factors, including economical factors. The author discusses the conditions for opti-mal fixation of a cemented stem; these conditions are not always met satisfactorily, as a number of sur-geons obviously stick to a crude cementing tech-nique. The author describes the role of the stem geometry and surface finish, as well as the possible influence of a centralizer; he explains why, based on a correct analysis of the available data, discredit has been unduly cast on cemented stems made of titani-um alloy. He insists on one important although often disregarded factor: the specific type of cement used, as better results have clearly been achieved with cer-tain cements than with others. He insists on the necessity to take into account all the elements involved, in order to avoid making erroneous conclu-sions. He also insists on one very important variable, the quality of the surgical technique. Total hip arthroplasty is likely to make further progress in the future, although we are likely now in the asymptotic portion of an ascending curve. Further improvement in clinical results will result from improvement of currently existing systems and optimization of surgi-cal technique, rather than from the continuous designing of new implants