Hemiarthroplasty of the hip and some other joints has been used for many years with satisfactory results, but the fate of articular cartilage when weight-bearing against metal has not been reported. Replacement of the head of the femur was carried out in one hip of each of 26 dogs, and the changes in acetabular cartilage studied at intervals of up to 24 weeks. There was early loss of proteoglycan, followed by surface damage to the cartilage, progressive degenerative changes, and growth of pannus from the articular margins. At 24 weeks after operation there was little remaining articular cartilage, while intense subchondral activity suggested that the bony skeleton was being remodelled to conform to the shape of the prosthesis. This study is not intended to suggest that hemiarthroplasty does not help patients.

The proximal fibular epiphysis was transferred in young puppies using microvascular techniques. The study demonstrated, as have previous investigators, that free epiphysial transfer without vascular anastomosis results in death of the chondrocytes of the growth plate. Histologically, the chondrocytes do not take up labelled proline, indicating diminished metabolic activity; do not take up radioactive thymidine, indicating that they are not dividing; and there is eventual disruption of the normal histological picture. In contrast, where the microvascular anastomoses re-established the blood supply to the growth plate, the epiphyses demonstrated normal histological appearance, uptake of radioactive proline and thymidine and continued to grow but at a slightly diminished rate. It is concluded that continued growth can occur after free vascularised epiphysial transfer in the dog.

We have reviewed the results of operations to stabilise the paralytic hip and to correct and stabilise the deformed spine of children with myelomeningocele. Despite a high complication rate the spinal operations were frequently successful. The hip operations were less satisfactory, with stabilisation of the hip eventually achieved in 69 per cent of the patients and improved walking in only 27 per cent. We do not recommend that such operations be undertaken on the hips of children with a level of paralysis at L3 or above. If stabilisation is indicated multiple combined procedures produce the best result.

Experience in the management of fourteen children with melorheostosis has been reviewed. The principal and presenting clinical features were unilateral soft-tissue contractures associated with inequality of limb length. In contrast to the disease in adults, pain occurred infrequently and was never intense. The average interval between the discovery of the clinical features and the correct diagnosis was six years. The distinctive radiographic feature in the child was an endosteal pattern of hyperostosis marked by streakiness of the long bones and spotting of the small. This differs from the usual subperiosteal or extracortical pattern of hyperostosis seen in adults. The surgical treatment of the contractures proved difficult and recurrence of the deformity was the rule. Distal ischaemia occurred when the chronically contracted and flexed joint was rapidly extended.

Sixty-six deformities of the foot and ankle in forty-two patients with arthrogryposis multiplex congenita were reviewd. Pes equinovarus proved particularly difficult to treat as there was a tendency for the deformity to recur because of the thick and rigid capsule. Intracapsular procedures were more successful than those done adjacent to the joint. Wide capsulotomy or talectomy were the best procedures under the age of three years and triple arthordesis was most successful for the older child.

Ninety-five patients with steroid-induced avascular necrosis of bone have been personally treated by the author. Of these, eighteen had a lesion of the head of the humerus, on one or both sides. The conditions for which the steroids were given included post-transplantation, lupus erythematosus, glomerulonephritis and asthma. The characteristic lesion began as a subchondral osteolytic area which frequently progressed to collapse. The articular cartilage divided from the subchondral bone, either becoming detached as a free cap or at a later stage reattaching. In some cases the lesion was minimal and the symptoms were slight. Conservative treatment has consisted of pendulum exercises and avoidance of abduction, particularly against resistance. In fourteen patients this led to satisfactory function with only intermittent symptoms. Four patients required replacement of five humeral heads with Neer's prostheses. After one to seven years the results of all five were classified as excellent in terms of absence of symptoms and a free range of movement.