Given the complex biomechanical situation of the knee joint, and the peculiarities of the individual patient, implantation of a knee joint endoprosthesis makes great demands on both the implant and the surgeon. The correct choice of implant from among unconstrained, semiconstrained and constrained types of endoprosthesis, as well as from among cemented, hybrid and uncemented anchorage, is essential. In addition, a meticulous preoperative analysis of knee and leg axes, and appropriate detailed presurgical planning is a must, as is uncompromisingly intensive postoperative physiotherapy. Clinical experience identifies the patella, instability and axis deviations as the major problems of knee arthroplasty.