1. A thousand arthritic hips have been replaced by an uncemented metal-on-metal prosthesis, and 942 followed by annual review. The mortality of the operation has been 1·1 per cent, the rate of deep-seated infection 0·7 per cent and the incidence of dislocation 0·3 per cent.

2. Of 169 hips replaced by an earlier type of the prosthesis and followed for five to eight years, 45 per cent have remained excellent and 29 per cent good, but 14 per cent have required revision, mainly for loosening of the femoral component.

3. The current types of prosthesis, now used for five years, have given excellent results in 69 per cent and good results in 21 per cent of 535 patients followed for one to five years. Revision for loosening has been necessary in 2 per cent.

4. The improvement in results has been obtained by the introduction of a tapered screw thread on the pelvic component, and by a range of femoral components that ensures a good cortical fit.

1. A complete replacement arthroplasty of the hip is described in which both components are inherently stable.

2. The arthroplasty does not require the use of acrylic cement.

3. It is appropriate for the treatment of the severely arthritic hip in which arthrodesis is not indicated, and for the mobilisation of two stiff and painful hips at any age.

4. It can be performed on both sides at the same time.

5. It produces a stable, pain-free and mobile joint in a high proportion of cases, and has appeared not to deteriorate over periods of up to four years.

1. An experimental study of the effects of nerve and muscle lesions upon the growth of bone has been made. In each case animals were subjected to unilateral lesions in the hind limb, the other limb serving as a control. The growth of the tibia was measured by calculating the difference between the length of the bone on a radiograph at the beginning of the experiment and the length of the dried bone after necropsy. The weights of the dried bones were compared.

2. In the young rabbit simple exposure of the common peroneal nerve, or division of the sural nerve, produced no change in the growth rate of the tibia. Division of both peroneal nerves, producing paralysis of the muscles below the knee, led to lengthening of the affected tibia, and this lengthening persisted until maturity several months later. A similar lengthening was seen after division of the tendons around the ankle. In spite of this lengthening the tibia on the side of the operation was almost always lighter than its fellow.

3. In the puppy division of the anterior nerve roots supplying the hind limb produced a significant lengthening of the tibia of the affected limb three months after operation. No significant changes in limb length occurred after lumbar sympathectomy in the puppy.

4. The significance of these experimental nerve lesions has been considered together with recent observations upon the growth of bone in the presence of lower motor neurone lesions in the child. From this analysis it is suggested that the initial effect of paralysis is to produce lengthening of the affected bone. This lengthening is probably due to the hyperaemia of disuse. In the presence of persistent paralysis the growth of the limb is ultimately depressed. This depression is rarely seen in the experimental animal because the growing period is relatively short. The possible causes of this secondary depression of bone growth have been considered.

1. The results of fifty-three operations in forty adults with a persistent congenital dislocation of the hip have been reviewed.

2. Arthrodesis as a primary operation was successful in five of six patients, giving a pain-free hip and good function. After an arthroplasty or an osteotomy that had failed to relieve symptoms it was successful in only one patient.

3. Cup arthroplasty on one hip relieved pain in five of nine patients, giving an increase in functional activity, although the range of hip movement was often disappointing. Bilateral cup arthroplasty, performed in four patients, gave partial relief in three, but did not permit an increase in activity.

4. High osteotomy of the femur was undertaken in eleven patients with a unilateral dislocation; pain was rarely relieved, and a stiff hip resulted in seven.

5. Low osteotomy in nine patients gave some relief from pain with a good range of hip movement.

6. In unilateral dislocation arthrodesis appeared to be the operation of choice, although cup arthroplasty was capable of giving a good functional result.

7. In bilateral dislocation, when only one hip was painful, the results of both these operations were on the whole good. When both hips were painful the operations that had been performed seldom gave clinical improvement.

8. High osteotomy of the femur appeared to have little place in the treatment of the painful dislocated hip. Low osteotomy, either of the Schanz or Batchelor type, appeared to be of value mainly as a salvage procedure when other measures had failed to give relief.

1. Nineteen patients with congenital shortening of the femur without associated coxa vara have been examined and discussed.

2. The diagnosis is made on finding a short, bulky thigh, held in lateral rotation. The radiographs commonly show no abnormality apart from shortening, but delay in ossification of the head of the femur, with lateral bowing and cortical sclerosis of the shaft, are occasionally present. The overall shortening of the limb seldom exceeds three inches.

3. The place of various surgical procedures to control limb length is briefly discussed.

1. An experimental technique for the transplantation of epiphysial cartilage in the rabbit is described.

2. Autogenous transposition of the distal epiphysial cartilage of the ulna was followed by normal growth in five of eighteen animals.

3. Homogenous transplantation was unsuccessful in all the animals studied.

4. Homogenous grafting gives rise to an immunity reaction confined to the reserve Zone of the cartilage.

5. It is suggested that the difference between the fate of homogenous grafts of epiphysial and non-epiphysial cartilage lies in the vascularity of the former.