Up to 100,000 total knee arthroplasties are performed annually in Germany resulting in an increasing number of revision operations. Different underlying causes might preclude the reimplantation of an endoprosthesis, and knee arthrodesis represents the alternative of first choice to above-knee amputation. The most common indications for arthrodesis are the infected knee arthroplasty with defects of the extensor mechanism, soft tissue and bone defects, and persisting infection. Several procedures of arthrodesis have been introduced and should be well adapted to the individual situation of the patient. The results--especially related to quality of life--are encouraging and should facilitate the demanding decision if a total joint reimplantation is not reasonable.