We have made a retrospective study of 1001 custom-made prostheses used as replacements after surgery for bone tumours. There were 493 distal femoral, 263 proximal femoral and 245 proximal tibial prostheses. Aseptic loosening was shown to be the principal mode of failure of the implants, and 71 patients had revision for aseptic loosening of a cemented intramedullary stem.

The probability of a patient surviving aseptic loosening for 120 months was 93.8% for a proximal femoral replacement, 67.4% for a distal femoral prosthesis and 58% for a proximal tibial implant. In patients with distal femoral replacements the age of the patient at the time of operation and the percentage of bone resected were related to the risk of aseptic loosening. Young patients with distal femoral prostheses in whom a high percentage of the femur had been replaced had the poorest prognosis for survival without aseptic loosening. The percentage of bone removed had a significant effect in the proximal tibial replacement group, but the age of the patient did not. By contrast, neither the age nor the percentage of bone removed was a factor after proximal femoral replacement.

The significance of these findings is discussed in relation to mechanical factors.

1. Attention is drawn to the danger of avascular necrosis developing in the capital femoral epiphysis as a complication of osteomyelitis in the intertrochanteric region.

2. This necrosis is commonly aseptic. It is believed to be caused by compression or thrombosis of the epiphysial vessels.

3. The situation will be aggravated if infection spreads to involve the joint.

4. We believe that prompt decompression of both the joint and the bone is indicated in order to reduce the incidence and severity of these complications.

1. The results of treatment of 117 tuberculous and fourteen other types of infection of the spine in adults by anterior fusion and chemotherapy have been reviewed.

2. It is suggested that anterior fusion is justified because: a) it permits isolation of the organism, and hence the determination of drug sensitivities and appropriate chemotherapy; b) removal of the diseased tissue and the stabilisation of the affected segment by iliac bone grafts can be effected, leading to rapid healing by bony fusion with little further collapse; c) rehabilitation of the patient is hastened; and d) the incidence of reactivation is probably diminished.

1. Pyogenic infection of the intervertebral disc in fifteen patients is described.

2. The importance of certain radiological signs in establishing the diagnosis is discussed.

3. Delayed diagnosis is believed to be responsible for the high incidence of paraplegia in this condition.

4. The place of operation in the management of this lesion is considered.

1. The case is described of a twenty-nine-year-old man with back pain due to an extensive vascular malformation replacing the major part of a vertebral body.

2. Treatment was by transthoracic ligation of the segmental vessels, with irradiation and spinal fusion later.

3. The importance of demonstrating the origin of the thoraco-lumbar supply to the anterior spinal artery is emphasised.

1. An ancillary diagnostic technique using Fluorine-l8 or Strontium-87m is described, and has assisted in the correct diagnosis of fifty-two patients admitted with the provisional diagnosis of infective spondylitis.

2. The technique is of particular value in the assessment of reactivation of chronic spinal infections and in the differential diagnosis of atypical lesions.