Fifty-four hips converted to low friction arthroplasty between 1965 and 1975 have been reviewed one to eleven years after operation. In many cases malposition had led to degenerative changes in the opposite hip, the lumbar spine or the knee, often with severe loss of function due to pain. It was found that total replacement could give useful relief of pain and improved function, though the range of movement obtained was not as good as in primary replacement. An outstanding feature was the correction of inequality of leg length. In general, the results were much better in cases of ankylosis acquired in adult life than in cases of spontaneous fusion after sepsis in childhood. The most important complication was a single case of sciatic palsy.

In fifty-six patients with ankylosing spondylitis three types of arthroplasty had been performed in ninety-nine hips. Forty-one of the patients were men and fifteen were women, their average age at operation being forty-two years. Primary pseudarthrosis produced well-satisfied patients, but only a fair result in five hips, whereas cup arthroplasty resulted in a poor outcome for eight hips, all of which needed revision. Total replacement of eighty-six hips, however, led to 73 per cent being graded as good or excellent up to ten years later. The main complications were deep infection of five hips, para-articular ossification around nine hips (six leading to bony ankylosis), and fibrous ankylosis of six hips.

The records of 107 patients with displaced subcaptial hip fractures treated by Thompson's femoral head replacements have been reviewed to determine the mortality and certain aspects of systemic morbidity. Comparison was made with a group, matched exactly for age and sex, in which intertrochanteric fractures were treated by nail-plate fixation. The patients treated by Thompson's arthroplasty were further subdivided into two groups: one in which methylacrylic cement was used, and one in which it was not used. We found no difference in the mortality of the patients undergoing replacement arthroplasty and nail-plate fixation. Similarly there was no difference in the incidence of cerebrovascular incidents and myocardial infarction after operation. There was a higher incidence of transient cardiac failure following Thompson's arthroplasty. Hypotension during the operation occurred irrespective of whether cement was used; nor was the use of cement associated with increased mortality. However, it seems that methylacrylic cement does contribute to the cardiac failure that may occur after Thompson's arthroplasty.

The results of operation for traumatic anterior dislocation of the head of the radius in eight children have been reviewed. We are satisfied on the basis of the results obtained and the outcome in one untreated patient that operative reduction is fully justified, provided that the annular ligament is reconstructed and internal fixation employed. We have not seen unilateral congenital dislocation and doubt its existence. Secondary subluxation of the distal radio-ulnar joint has been noted in an untreated patient.

Traumatic tenosynovitis of the wrist extensors is a common and disabling condition associated with overuse. It has been found to be associated with hypertrophy of the bellies of abductor pollicis longus and extensor pollicis brevis where they overlie the radial extensor tendons in the forearm, compressing these tendons and their enveloping paratenons against the deep structures beneath. Simple surgical decompression of the sheath of these overlying muscles has been found to give quick relief of symptoms and to allow a more rapid return to strenuous work than the conservative treatments usually employed.

Ninety-eight fractures of the shaft of the femur were seen in one unit over the two years 1974 and 1975, and the results have been assessed in sixty-nine. Of these, thirty-eight were treated by skeletal traction in a Thomas's splint followed by skin traction, and thirty-one by skeletal traction followed by a cast-brace. The technique of application is described in some detail. The average time for application of the cast-brace was six weeks after the injury, the time in hospital eight weeks and the time till removal fifteen weeks. The patients selected for a cast-brace were in hospital for just over half the time of the others and their fractures on average united more quickly, though with some trouble from angulation of fractures of the uppermost third of the shaft. It is concluded that when used with all the judgment and skill it demands, the cast-brace method is a great advance in conservative treatment.

Twenty patients with complete brachial plexus lesions were reviewed approximately nine and a half years after injury. Thirteen were amputees and seven had received no surgical treatment. Amputation did not alleviate pain and a prosthesis was frequently of no greater use of the patient than the useless limb it replaced: only two of the thirteen amputees were true prosthetic users and they both had dominant limb involvement, the rest adapting easily to being one-handed. Initial treatment should therefore be conservative, with intensive rehabilitation and retraining. It is recommended that amputation should not be considered until a year after injury and only if the flail limb causes repulsion, prevents sporting activities or if the patient has difficulty in converting to the non-dominant limb. In no instance should smputation be done for relief of pain.

A study of two siblings with a severe infantile form of familial idiopathic hyperphosphatasia is reported. A girl aged one year was followed for two years while receiving intermittent treatment with porcine calcitonin. This induced a clinical remission, a reduction of both the high serum level of alkaline phosphatase and the raised urinary excretion of hydroxyproline, and a remarkable improvement in bone structure as seen radiologically. Her sister aged two months received porcine calcitonin for three weeks, during which clinical improvement, no change in the serum level of alkaline phosphatase and a marked decrease of the excretion of hydroxyproline were recorded.

Two hundred and twenty-two adult crawling poliomyelitic cripples were investigated. Analysis showed that bilateral lower limb paralysis with or without trunk involvement was the most common residual lesion. Remarkably paralysis was confined to a single lower limb in six cases. The various crawling patterns can be classified into six broad groups which are described and illustrated. It is suggested that in a developing country this classification has a practical application in the assessment of patients for rehabilitation to crutch walking. Subjects in the "true quandruped progression" and "squatting gait" categories generally have an excellent potential for rehabilitation, as often do those in the "infant-like crawl" group. Caution should be exercised in attempting crutch walking for those in the "body-dragging" group, and there seems little indication for attempting to establish upright walking for those in the "buttock pivoting" and "minimal movement" groups.

A follow-up study, on average four years after operation, of seventy-six cildren with myelomeningocele who had surgical treatment for flexion contracture of the knee, is reported. After a single operation sixty-eight knees (55 per cent) had a contracture of less than 20 degrees, which was the main criterion of success. About half of the cases of transplantation of the hamstrings to the femur, division or elongation of the hamstrings, or supracondylar osteotomy had successful results. Transfer of the hamstring tendons to the patella was successful in nine of twelve instances, so giving the lowest rate of failure. Forty-five patients were active walkers at follow-up as compared to eighteen before operation. However, only one of the eleven patients over twelve years of age with a motor level above T.12 was an active walker at review. Several conclusions are drawn. A flexion contracture of the hip greater than 30 degress should be corrected before operation of the knee. Supracondylar osteotomy as a primary procedure should only be used to correct flexion contracture of the knee secondary to malunited fractures. Faradic stimulation is useful in the evaluation of muslce function before operation. An intelligence quotient below 65 and weakness of the arms are relative contraindications for correction of the deformity of the knee.

A new cosmetic weight-relieving brace which utilises stainless steel and light alloy in its structure is described. A clinical assessment of thirty-six patients (four bilateral cases) has shown the Salford Cosmetic brace to be suitable for over 80 per cent of patients attending for assessment. Five patients rejected the brace, and the reasons are discussed. Contra-indications which emerged during the assessment included limb shortening of more than 5 centimetres; fixed equinus of more than 10 degrees; and fixed deformity of the knee of more than 10 degrees. The safety and durability of the brace, first demonstrated in laboratory tests, are confirmed. Further possible development is outlined.

The paper reports an experimental investigation into the mechanisms whereby the joints of living animals maintain their precise contours. The normal patter of joint incongruity in the rabbit's hip having first been established, three groups of experimental animals underwent operative procedures designed to reduce the joint pressure to a level unrealistic in normal life. In one group the hip was dislocated by manipulation; in a second group the muscles around the hip joint were divided; and in a third group the hind limb was disarticulated through the knee. When the animals were killed at intervals of a few weeks after the operations the experimental hip joint showed increased congruity in all cases. It is concluded that in immature animals there is a mechanism in joints to control the modelling of their shapes towards an ideal incongruity, and that that mechanisms is pressure sensitive.

In thirty-one rat tibiae, plugs of plain acrylic cement were inoculated with Staphylococcus aureus; these all remained contaminated at the end of two weeks when the animals were killed. Inoculation with known strains of Pseudomonas, Proteus and Gp. G Streptococcus resulted in 70 to 93 per cent persisting contamination. Gentamicin, to which the organisms were fully sensitive, was efficacious in controlling the infection (90 per cent plugs proving sterile after two weeks). Fucidin was less successful against Staphylococcus aureus although effective in vitro. Intravenous inoculation with a suspension of Staphylococcus aureus succeeded in contaminanting 70 per cent of sixty plain cement plugs when injected into the tail vein half an hour after closure of the leg wounds. Only 11 per cent of sixty-four plugs were so contaminanted when the injection was delayed for two weeks. This animal model is submitted as a possible future means of testing different antibiotic-cement combinations against infection.

The role of three genetically distinct collagen types in the formation of endochondral bone and in calcification and resorption of cartilage has been assessed. Using antibodies specific to types I, II and III collagen we have demonstrated in the embryonic chick tibia that endochondral bone formation began with deposition of type III collagen in lacunae of hypertropic chondrocytes by invading bone-marrow-derived cells. This was followed by the deposition of type I collagen, which is the collagenous constituent of endochondral osteoid. At later stages of development endochondral osteoid was found in the epiphysial growth plate in apparently intact lacunae of hypertrophic chondrocytes; this indicated that the latter might contribute to the synthesis of osteoid type I collagen. Immuno-histological staining for collagen types, and von Kossa staining for calcium phosphate on parallel sections, demonstrated that type I and type II collagen matrices were substrates for calcification. Endochondral bone (with type I collagen) was found on scaffolding of both uncalcified and calcified cartilage (with type II collagen), indicating that calcification of endochondral osteoid and of the underlying cartilage occurred independentyl. Spicules of endochondral cancellous bone of a four-week-old chick contained a core of calcified type II collagen.

In talipes equino-varus the diminished bulk of the calf muscle suggests a neuromuscular defect. Accordingly, biopsies were taken from the postero-medial and peroneal muscle groups, and occasionally from abductor hallucis, in sixty patients mostly under the age of five years; 111 were studied histochemically and histologically, and a further fifty-three by electron-microscopy. Histochemical anomalies were revealed in ninety-two specimens; the muscle fibres in the other nineteen varied in size but were abnormal at the ultramicroscopic level, as were all specimens examined with the electron microscope. Evidence of neurogenic disease was seen in most instances and was more obvious in the older patients. The pattern of abnormality was similar in both muscle groups. It is thought that shortening of the postero-medial muscles may result from a small increase of fibrosis due to minor innervation changes occurring in intra-uterine life. There is evidence that immobilisation, stretching or relaxation of muscles does not account for the anomalies observed. This study of the extrinsic muscles in talipes equino-varus indicates a dominant neurogenic factor in its causation.

The features are described of seven cases of "juxtacortical" chondrosarcoma, the term introduced by Jaffe for a rare but distinct entity and now accepted in the World Health Organisation classification as preferable to the term "periosteal" chondrosarcoma. In all cases the lesion involved the shaft of a long bone, most often the femur, and in two cases two different long bones were affected. Six of the seven patients were male and all were in the second decade. The characteristic appearance was that of a small tumour adjacent to the cortex with areas of spotty calcification often accompanied by radiating bone spicules perpendicular to the bone shaft and a typical Codman's triangle. Histologically all the tumours showed a cartilaginous lobular pattern, well limited on the surface and seldom infiltrating the cortex; areas of spotty calcification and enchondral ossification were often present but tumour osteoid and bone were conspicuously absent. Despite the ominous histological aspect, the prognosis proved to be relatively favourable compared with the usual central chondrosarcoma of a similar grade of malignancy.

Ossification of the posterior longitudinal ligament in the cervical region is generally regarded as a rare disease, though a Japanese series of 185 cases has been reported. The main symptoms arise from a myelopathy, the degree of which varies from moderate to severe, due to stenosis of the spinal canal. In order to clarify the relationship between the severity of symptoms and the cross-sectional area of ossification, axial transverse tomography of the cervical spine has been carried out on twenty-six patients at intervals of 5 millimetres over the full extent of the ossification. In this way the cross-sectional areas of the ossified tissue and of the spinal canal were calculated. The former varied from a minimum of 0.8 to a maximum of 1.8 square centimetres. In cases of severe myelopathy the ossification was mainly at the fourth and fifth cervical levels and the stenosis ration exceeded 30 per cent.

A radiographic method is described for making the diagnosis of talo-navicular subluxation before ossification of the navicular bone occurs. Seven basic combinations of deformities are thought to occur in the club foot. Radiography before operation enables the surgeon to determine which of these combinations exists in a particular foot, and radiography during operation enables him to determine wheter or not all the existing deformities have been corrected, and therefore whether or not the operation must be extended.

A study of spondylolysis and spondylolisthesis in 142 children and adolescents is reported. In twelve of the seventy-nine patients followed for over a year the affected vertebra slipped further by 10 per cent or more. Increasing slip occurred mainly during the adolescent growth spurt, and was greater when spinal bifida or other vertebral anomalies were present. If at presentation the slip is less than 30 per cent then further slip beyond 30 per cent is unlikely. Decompression posteriorly is advised when signs of nerve pressure are present. Indications for spinal fusion are suggested; the intertransverse method of fusion was used in sixty-nine patients.