Mucormycosis is an opportunistic infection that very occasionally causes osteomyelitis and avascular necrosis of bone. The infection may prove fatal if not diagnosed promptly. If early treatment is instituted the prognosis is good.

We perfused 16 human femora with a 50% barium sulphate suspension and studied the intra-osseous vessels by microfocal radiography and histology. There were few anastomoses between the vessels of the greater trochanter and those of the adjacent cancellous bone of the shaft. Ischaemia of the trochanter may contribute to nonunion after trochanteric osteotomy.

We report the results of conservative treatment of stage III and stage IV avascular necrosis of bone (AVN) affecting the hip or knee in renal transplant patients. Twenty-nine patients were followed for a mean period of five years. Conservative management was successful in controlling symptoms in 40% of those with AVN of the hip and in 70% of those with AVN of the knee. Knowledge of the natural history of AVN is important because of the long survival times after renal transplantation.

An eight-year-old boy presented with massive pseudomalignant heterotopic ossification around the upper femur. The mass was completely excised because of severe pain, systemic illness and a flexion contracture at the hip. Symptomatic improvement was swift, but two weeks later the mass had recurred and was even more extensive. During the subsequent 18 months of conservative management he has been free of pain and there has been progressive resorption and remodelling of the heterotopic bone. There is now no limitation of physical activity and movement at the hip is full.

The occurrence of osteonecrosis following renal transplantation is well recognised but its pathogenesis remains unknown. We have quantified the number of empty osteocytic lacunae in the subchondral bone of femoral heads from a control group of patients, and compared these with femoral heads from a group of renal transplant recipients without evidence of overt osteonecrosis. There is a significant increase in empty osteocytic lacunae in renal transplant patients. We conclude that loss of osteocytes precedes other manifestations of osteonecrosis.

The clinical and pathological findings in a case of early avascular necrosis of the femoral head following renal transplantation are described. Regions of subchondral bone distant from the principal lesions showed increased numbers of empty osteocytic lacunae. This has been quantified and it is suggested that a loss of osteocytes is perhaps one of the earliest lesions leading to established avascular necrosis.

Between 1980 and 1984 nine adult patients in the renal unit of Guy's Hospital developed bone and joint infection. The commonest site of infection was the spine. In this series two patients died, a mortality of 22%. The purpose of this paper is to illustrate the pitfalls in the diagnosis and management of bone and joint infection in patients with renal failure and renal transplants.