Failure of reconstructions as a result of infective or aseptic loosening and massive bone loss may make amputation necessary. If neurovascular structures can be preserved to keep a functional foot, rotationplasty may be considered an option. Four patients treated for malignant bone tumours (two osteosarcomas, one Ewing sarcoma, and one malignant fibrous histiocytoma) of the proximal tibia and distal femur (n=2 each) at the ages of 13 to 21 years had reconstructions that failed 3, 4, 5, and 15 years later. In three patients the cause was intractable infection, and in one loosening with shortening and deficiency of the extensor mechanism. The patients had the option to contact patients who had had rotationplasty as the primary procedure for tumours or severe femoral deficiencies. In two patients an AI-type rotationplasty was done, in one a type AII rotationplasty, and in the fourth a modification with shortening of the lower leg but retention of the knee joint. There were no postoperative complications such as persisting infections, fractures, or pseudarthrosis. All patients are active and are able to go alpine skiing or snowboarding. The main advantage of procedures in which a sensory-motor functional foot is retained is to avoid neuroma pain or phantom sensations. The foot allows for active knee movement of the orthoprosthesis and full weight bearing. It is of great psychological help for the patients to have contact during the decision-making with patients who have had similar procedures. It should be considered as an alternative to amputation.