In a post-mortem study, we compared subjects with metal implants with and without visible wear with an age-matched control group to determine the extent and effects of dissemination of wear debris. In subjects with stainless-steel and cobalt-chrome prostheses metal was found in local and distant lymph nodes, bone marrow, liver and spleen. The levels were highest in subjects with loose, worn joint prostheses and the main source of the debris was the matt coating. Metal levels were also raised in subjects with implants without visible wear and, to a less extent, in those with dynamic hip screws. Necrosis of lymph nodes was seen in those cases with the most wear, and potential damage to more distant organs such as the bone marrow, liver and spleen in the long term cannot be discounted. The consequences for the immune system and the role of metal dissemination in the possible induction of neoplasia are discussed.

We used MRI to examine the hips of 32 asymptomatic patients at 9 to 21 months after renal transplantation covered by high-dose corticosteroids. Five hips in three patients showed changes which indicate avascular necrosis, although radiographs, CT scans and isotope scans were normal. These patients had repeat MRI scans after another two years and three years. One patient with bilateral MRI changes developed symptoms and abnormal radiographs and CT and isotope scans in one hip nine months after the abnormal MRI. Intraosseous pressure was found to be raised in both hips, and core biopsies revealed necrotic bone on both sides. The other three hips have remained asymptomatic with unchanged MRI appearances three years after the initial MRI. It seems that idiopathic avascular necrosis does not always progress to bone collapse in the medium term.

We describe the use of intramedullary reconstruction nails in the treatment of 14 patients with pathological subtrochanteric fractures and coexisting metastases in the femoral shaft. After nailing, all patients were free from pain and regained mobility. They were followed up clinically and radiologically until death from the primary disease. There were no mechanical failures even when a less than ideal reduction had been achieved.

The production of particulate wear debris is a recognised complication of joint arthroplasty, but interest has concentrated on local tissue reactions and a possible association with implant loosening. The fate of wear products in the body remains unknown, although some of the metals used in the construction of orthopaedic implants are known to have toxic and oncogenic properties. We report histological and electron-microscopic evidence from two cases which shows that metallic debris can be identified in the lymphoreticular tissues of the body distant from the hip some years after joint replacement. The increase in the use of total arthroplasty in younger patients, the development of new alloys and the use of porous coatings must raise concern for the long-term effects of the accumulation of wear debris in the body.

A method for direct measurement of the local pressures in the acetabular cartilage is described. Pressure transducers were introduced into the subchondral bone and positioned there in contrast with the cartilage: the transducers were calibrated in situ. Twelve cadaveric hips were prepared in this way and the pressures were measured with the joint loaded in flexion, extension, abduction, adduction, and in lateral and medial rotation. The highest pressures were recorded in the anterior and posterior segments of the acetabulum; the lowest pressures were constantly found at the zenith of the joint. The relationship of these findings to the pathogenesis of osteoarthritis is considered.

The division of osteoarthritis into primary and secondary varieties implies that these are aetiologically distinct entities, the former being due to some intrinsic defect of cartilage and the latter resulting from previous articular damage. This traditional concept is questioned and the hypothesis is advanced that osteoarthritis is always secondary to some underlying abnormality of the joint. A detailed clinical, radiographic and morbid anatomical study of 327 cases of osteoarthritis of the hip is presented. In all but twenty-seven some predisposing abnormality of the joint was diagnosed: 107 (33%) were associated with major pathology such as Perthes' disease or epiphysiolysis; minor acetabular dysplasia was present in sixty-seven (20%), with a male: female ratio of 1:10; minimal femoral head tilt was demonstrated in fifty-nine (18%), the male: female ratio being 14:1; and in forty-three (13%) there were features suggesting an underlying inflammatory arthritis. On the basis of this study a new classification is proposed and osteoarthritis of the hip is divided into three pathogenetic groups: 1) failure of essentially normal cartilage subjected to abnormal or incongruous loading for long periods; 2) damaged or defective cartilage failing under normal conditions of loading; 3) break-up of articular cartilage due to defective subchondral bone.

1. It is well known that the administration of corticosteroids may result in necrosis and progressive destruction of the femoral head. Identical changes have been found in chronic alcoholics, in South African negroes suffering from iron-overload osteoporosis and in patients with arthritis of the hip treated with non-steroid anti-inflammatory and analgesic preparations. The term "drug-induced arthropathy" is used to describe the common pathological lesion.

2. Seventy-two patients with this complication have been investigated and forty-two femoral heads were available for detailed study. The characteristic change is subchondral fragmentation and osteonecrosis, followed later by reactive bone formation and the typical increased radiographic density.

3. The frequent occurrence of fat occupying the Haversian canals in the affected femoral heads has not been adequately explained and its relationship to the destructive arthropathy remains obscure. The findings presented here do not support the theory that fat emboli are responsible for the subchondral bone changes.

4. More credence is given to the theory of subchondral microfracture in osteoporotic bone. The destructive arthropathy invariably follows the administration of some anti-inflammatory or analgesic preparation. It is postulated that a state of diminished sensibility predisposes to microtrauma in osteoporotic bone resulting in subarticular collapse of the femoral head.

1. Twenty-two cases of synovial rupture of the knee have been studied. This condition may complicate any chronic synovitis of the knee in which a tense intra-articular effusion is subjected to increased tension during flexion and extension of the joint.

2. Two types of rupture have been seen; a herniation of the synovial membrane into the popliteal fossa and down the leg, and an acute synovial tear with extravasation of joint contents between the muscle planes of the calf.

3. The diagnosis of this condition, the differentiation of the types of rupture and their treatment are discussed.

4. The acute rupture usually responds to simple bed-rest; the large synovial herniations often need removal and repair of the posterior capsule.

1. The hyaluronate of synovial fluid is an acidic linear polymer which can effectively resist the diffusion of other macromolecules into its domain. Gelatin was used as an experimental model for hyaluronate, to investigate its effect upon the diffusion of protein-polysaccharides from cartilage slices.

2. The concentration of protein-polysaccilaride in the extracting medium was quantitated by uronic acid estimation and liquid scintillation spectrometry of ³⁵sulphate-labelled proteinpolysaccharide.

3. Concentrations of gelatin in excess of 20 per cent (W/v) significantly retarded diffusion of protein-polysaccharides out of cartilage slices, but evidently not the movement of these molecules within cartilage.

4. It is suggested that disaggregation of both the protein-polysaecharide molecules of cartilage and the hyaluronate of synovial fluid contribute to cartilage breakdown.

1. Senile osteoporosis is one of the common causes of morbidity in old people. Its distribution in European and American populations has been deduced from epidemiological studies of its major complications, such as fractures of the vertebrae and the femoral neck. Although there has been some evidence that different population groups differ in their susceptibility to this condition, no demographic study of its prevalence in the white and Bantu races has previously been made.

2. The present paper describes an epidemiological study of femoral neck fractures in the Bantu population of Johannesburg, covering the years 1957-63. The cases were analysed by age and sex, the type of trauma and the level of the fracture. The number of fractures was related to the population at risk; the fracture incidence was expressed both as an age-specific rate and as a standardised rate and compared with fracture rates in European populations. It was found that the fracture rate in the elderly Bantu is less than one-tenth of that in Western European populations, and that males and females are affected equally. It was concluded that senile or post-menopausal osteoporosis is much less pronounced in the Bantu than in white populations.

3. The relationship of these findings to endocrine changes, calcium balance and racial factors is discussed. It is suggested that senile osteoporosis is not caused by a simple calcium deficiency but may be related to an imbalance between calcium intake, absorption and excretion, or a failure of the complex mechanism which normally controls this balance. Whatever the immediate cause, however, race plays an important part in determining the onset and distribution of the condition.

1. Diametric growth and organisation of the epiphysial cartilage plate have been studied by microradiography of human bone and autoradiography of the epiphysial plate in growing rabbits, using sulphur³⁵. These investigations were supplemented by a radiographic study of four patients with dyschondroplasia in whom the progress of the characteristic epiphysial defects were traced during several years' growth.

2. A perichondrial sheath of bone, at the junction of the epiphysial plate with the metaphysis, was demonstrated by microradiography of the distal end of the human femur. Its relationship to epiphysial growth is discussed.

3. Autoradiography, to determine the direction of the cellular proliferation between the epiphysial plate and the overlying perichondrium, demonstrated the appearance of new cartilage cells at the periphery of the plate over a period of six days.

4. The evidence presented strongly favours the postulate that the transverse diameter of the epiphysial cartilage plate increases by appositional growth from the overlying perichondrium and that the same source is responsible for lateral extension of the articular cartilage during growth.

1. Hereditary multiple exostosis has been studied in fifty-six patients and their relatives. In most cases previous records were available and the progress of the disease could be traced over many years.

2. The characteristic lesions are described and the complications encountered in the present series of cases are noted. The disease is inherited in approximately two-thirds of the cases and invariably produces detectable lesions in the heterozygote.

3. The cartilage-capped exostoses are confined to the endochondral skeleton where their incidence is closely related to the growth potential of the sites involved.

4. An attempt has been made to explain the curious distribution of the exostoses, and the likely theories of the pathogenesis of the disease are discussed.

1. The widespread deformities commonly associated with diaphysial aclasis have been studied in seventy-six patients. Apart from the adaptations of growth due to pressure by neighbouring exostoses, all the deformities of the tubular bones can be explained in terms of the same underlying factor–diminished length of the bones affected by the disease.

2. When the condition first manifests itself the future pattern of bone growth is completely unpredictable except in so far as it is known that the more actively growing ends of the long bones are the more severely affected in each case. It has also been shown in this series that, in general, the bones with the smallest cross-sectional area at the epiphysial plates (such as the ulna and the fibula) are the most severely shortened of all.

3. The cause of this disturbance of growth is still unknown, but there is an undoubted relationship between the presence of exostoses or thickening of the metaphysial region and shortening of the bone involved.

4. The phenomena of migrating exostoses and disappearing exostoses are also described and are shown to be examples of the normal process of bone modelling applied in special circumstances.

5. Although the importance of the cartilage-capped exostoses is not underestimated, it is hoped that this study will stimulate further work on what is probably the basic defect in this disease–namely, the disturbance of bone growth.