Endoprosthetic surgery in 1988.

Aseptic loosening remains the main problem of arthroplasty. On one hand, this has led to the development of new cements and improvement in cementing techniques. On the other hand, especially intensive efforts have been made in recent years to anchor the implants directly to bone. The major alternatives available today for endoprosthetic fixation are cement "pressurization" and "bony ingrowth". The differences in implant fixation, with or without cement, must take into consideration the design, surface characteristics, and the material properties of the implants as well as the operative technique. In principle, there are major differences both with regard to the biology and to the mechanics between the acetabulum and the femur. On the acetabular side, the objective of reliable fixation has been achieved at least in the medium term. Gratifying advances are also being increasingly shown in the femur. However, until today hardly any prosthetic femoral model is able to provide reliable primary results with regard to freedom from pain, as is the case with the modern cement techniques. For many orthopaedic surgeons, a "hybrid" is the solution to the problem for patients over 60 years old: i.e. cementless anchoring of the acetabulum socket and cementing of the prosthetic shaft. For young, active patients and for revision arthroplasties, with major loss of bone substance, we require a cementless technique. With this technique and use of bone transplantation, it is today possible to reconstruct even severely damaged joints and to create situations corresponding to those of a primary arthroplasty. In the knee joint aseptic loosening of cemented endoprostheses is less of a problem and the decision in favour of cementless fixation depends even more on the quality of the bone than on the hip joint. For the future it is becoming increasingly apparent that a single method on its own will not exist, but that the surgeon must choose the most suitable method (with or without cement) dependent on the case. Accurate preoperative planning becomes indispensable.