The number of knee arthroplasties in Germany increases about 6.8% annually. Parallel to the increasing number of primary total knee arthroplasties (TKA) the frequency of TKA revision surgery also goes up and is a growing challenge for orthopedic surgeons. The main reason for revision arthroplasty is aseptic or septic mechanical loosening of the implant. Other reasons are persisting pain, instability or limited range of motion. The aim of preoperative evaluation by examination, x-ray control and serum tests is to understand the mechanism of implant failure. Besides the stable mechanical fixation of the new implant, reconstruction of limb alignment, joint line and balanced extension and flexion gaps must be achieved. Bone defects also need to be reconstructed. Modular revision implants and bone grafts support the surgeon in restoring a pain-free knee function.