Arthrodesis of the knee without or with simultaneous lengthening. Severe degenerative osteoarthritis in younger patients. Neuropathic joint with bone loss and/or ligamentous instability. Failed total knee arthroplasty. Absolute: extensive osteomyelitis. Relative: severe bone deficiency. In elderly patients a simultaneous limb lengthening constitutes a relative contraindication. For primary arthrodesis: resection of articular cartilage and subchondral bone. For aseptic loosening: removal of components and alignment of bone ends. For infected total joint: 2-stage procedure. In all instances obtain a slight flexion at the arthrodesis. Temporary fixation with crossed Kirschner wires. Application of Ilizarov frame and compression. For lengthening: Ilizarov distraction method. Between 1993 and 1996, 11 patients underwent an Ilizarov knee arthrodesis with an average follow-up interval of 35 months. Indications included: severe osteoarthritis, 2: ligament instability in spina bifida patient, 1; and failed total knee arthroplasty, 8. Three patients developed a pseudarthrosis, all were noted to have a severe bone loss. Two of these patients were fitted with an orthosis and the 3rd underwent a successful AO double plate fixation. Removal of wires on account of infection was needed twice. Average time to union was 4.5 months.