Cadaver knee joints were mounted so that life-like forces of weight-bearing were simulated. The patello-femoral contact areas were defined under load throughout the range of movement by the dye method. During movement from extension to 90 degrees of flexion a band of contact sweeps across the patella from inferior to superior pole, but the odd facet makes no contact. At about 135 degrees of flexion separate medial and lateral contact areas form, the medial one limited to the odd facet. From extension to 90 degrees of flexion the patella holds the quadriceps tendon away from the femur, but in further degrees of flexion an extensive "tendo-femoral" contact area forms. Between 90 degrees and 135 degrees of flexion the patella rotates and the ridge between the medial and odd facets engages the femoral condyle. The odd facet is shown to be a habitual non-contact area and the ridge to be subject to high load, observations which correlate with cartilage lesions described in Part 2 of the paper

1. The uptake of S. 35. labelled sodium sulphate has been studied autoradiographically in the intervertebral disc of the young rabbit. 2. The sojourn of the isotope in the tissues includes an intracellular phase of approximately twenty-four hours, followed by an extracellular phase. 3. The cells exhibiting by far the greatest affinity for the sulphate ion are the peripheral groups of cells of the nucleus pulposus, while the chondrocyte-like cells of the cartilaginous segment of the annulus fibrosus are also fairly active. The central cells of the nucleus and the fibroblasts of the outer one-third of the annulus have a much lower uptake. 4. By analogy with similar studies on hyaline cartilage, and on the basis of correlation between the alcinophilia of the tissues and the concentration of the label, both before and after hyalase digestion of the tissue, it is considered that in the young rabbit disc, as in articular cartilage, the sulphate is incorporated primarily into chondroitin sulphate. 5. The elimination of the isotope from the nucleus at twenty-four days and the persistence of the label in the annulus fibrosus at thirty-two days tends to suggest that the metabolic turnover of acid mucopolysaccharide is considerably slower in the annulus than in the nucleus

Objectives

The primary objective of this study was to compare accuracy in restoring the native centre of hip rotation in patients undergoing conventional manual total hip arthroplasty (THA) versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, component inclination, component version, and leg-length correction.

In ten patients with sickle-cell disease, we used a new technique of cement injection for the treatment of 16 painful hips with a radiographic crescent line or flattening of the articular surface due to avascular necrosis. The necrotic bone and overlying cartilage are elevated by the injection to restore the sphericity of the femoral head. Five days after the operation, full weight-bearing was allowed with the help of crutches for three weeks. The time in hospital averaged eight days; the average blood loss was 100 ml. There was early pain relief and postoperative radiographs showed improvement in the shape of the femoral head. At a mean follow-up of 5 years (3 to 7), 14 of the 16 hips were still improved although some gave slight pain. Only two hips had required revision to total hip arthroplasty, at one year and two years respectively. The increasing longevity of patients with sickle-cell disease means that avascular necrosis will be an increasing problem. Total hip replacement has a poor prognosis because of the risks of infection, high blood loss, and early loosening. Cement injection does not have these problems and allows for earlier, more conservative surgery

We compared the effects of continuous passive motion with those of intermittent active motion on the results of the resurfacing with autogenous periosteal grafts of full-thickness defects on the articular surface of rabbit patellae. Of 45 rabbits with defects, 30 received grafts. Fifteen of these had continuous passive motion for two weeks and intermittent active motion for four weeks; the other 15 had intermittent active motion for six weeks. In 15 the defects were not grafted (control group) and they had intermittent active motion for six weeks. Ten more rabbits had a sham operation. Six weeks after surgery, the results were assessed by the gross appearance, histology, histochemistry, immunohistochemistry and electron microscopy. By all assessments the quality of neochondrogenesis produced by periosteal grafts was superior to that in ungrafted defects (p less than 0.05) and the results in continuous passive motion treated animals were superior to those in intermittent active motion treated animals (p less than 0.05). The periosteal grafts produced hyaline cartilage containing type II collagen but the organisation of its fibres was irregular

1. Fifty cases of fibrosarcoma from the records of the Bristol Bone Tumour Registry are reviewed. They present further clinical and radiological evidence supporting the concept of fibrosarcoma as a distinctive type of bone tumour. 2. The radiographic appearances have often been those ofan osteolytic lesion totally enclosed by reactive subperiosteal new bone. 3. Included in the group are eleven cases with Paget's osteitis deformans, three cases in which the sarcoma was associated with calcified cartilage and one case that is regarded as a post-irradiation sarcoma. 4. Several clinically differing modes of presentation are described. 5. Fibrosarcoma in bone has often been said to be "central" or "medullary" but because the present series includes tumours with eccentric origin and unilateral cortical destruction this description is inappropriate. 6. The histological differentiation from other fibroblastic lesions is briefly discussed. 7. The five-year and ten-year survival rates were respectively 28 per cent and 1 2 per cent, with an average survival oftwenty-four months in the thirty-six patients who died. Among the long survivors were two patients with Paget's disease

Aims

The Ponseti method is an effective evidence-based treatment for clubfoot. It uses gentle manipulation to adjust the position of the foot in serial treatments towards a more physiological position. Casting is used to hold the newly achieved position. At first, the foot resists the new position imposed by the plaster cast, pressing against the cast, but over time the tissues are expected to adapt to the new position and the force decreases. The aim of this study was to test this hypothesis by measuring the forces between a clubfoot and the cast during treatment with the Ponseti method.

Aims

The aim of this study was to investigate the changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children.

1. The use of a protein-free synthetic medium has provided a new technical approach to the study of fracture healing in vitro. 2. The tibiae of fourteen-day embryonic chicks were cut in half in the middle of the shaft, the fragments were placed in apposition and the explants grown in vitro for up to sixteen days. The process of bone repair was studied by means of histology and biochemical estimations. 3. The rate of growth in length of fractured bones was greater in an atmosphere containing 50 per cent of oxygen than in one with 20 per cent oxygen, thus emphasising the importance of an adequate oxygen supply for the regeneration of osteogenic cells. 4. The effect of varying the concentration of glucose in the medium was investigated. Two milligrams of glucose per millilitre was the most favourable for healing; higher levels caused fibroblastic changes in the cartilage cells and inhibited the proliferation of osteogenic cells at the fracture site. 5. Histological examination showed that many of the phenomena that occur in the repair of fractures in vivo can be reproduced in vitro in synthetic medium. Similar results were obtained whether the fracture was made in whole bones or in isolated shafts from which the cartilaginous ends had been removed; the latter are more favourable for biochemical study

Two groups of intervertebral discs, one normal, as obtained from the post-mortem room, the other prolapsed, as removed at operation, have been compared by chemical analysis of their principal constituents. There is a progression of chemical changes associated with the ageing of the normal disc. This shows not only the expected slight increase in collagen as age advances, but also, surprisingly, that the polysaccharide content rises to a maximum in the fourth decade, in the same way as does polysaccharide in costal cartilage. In prolapsed discs the ageing process is superseded by a different and distinctive progression, which advances, not according to age, but according to the duration of the prolapse. There is a critical level to which the polysaccharide content must apparently fall, irrespective of the normal level for the patient's age, before a prolapse occurs. Normal ageing probably consists in the breakdown of a particular polysaccharide/protein linkage, with coincident "maturation" of collagen. In the prolapsing disc multiple, and possibly different, linkages are rapidly broken down. This depolymerisation of a gel structure must be presumed to be the basis of the decreased imbibition capacity of the nucleus pulposus, and to be the source of the hydrostatic abnormalities which result in disc prolapse. In both normal and prolapsing discs the products of mucopolysaccharide breakdown appear to participate in the metabolism of collagen

1. Clinically, hallux rigidus is a painful condition of the joints of the great toe associated with loss of dorsiflexion of the first phalanx. 2. Pathologically, the morbid changes are those of a traumatic synovitis followed by an early development of osteoarthritis, the initial lesions of which are erosions of the cartilage at the centre and near the dorsal margin of the base of the proximal phalanx. There is no fundamental pathological difference between the adult and adolescent varieties of hallux ngidus. Both represent stages in the developmental cycle of osteoarthritis in the proximal joint of the great toe. 3. The radiographic density and apparent fragmentation of the phalangeal epiphysis do not represent an abnormality of the bone and have no significance in the etiology of hallux rigidus. 4. The cause of hallux rigidus is an abnormal gait developed either to protect an injured or inflamed metatarso-phalangeal joint from the pressure of weight-bearing, or to stabilise a hypermobile first metatarsal. The effects of this gait are to transfer most of the pressure from the flexor brevis tendon and the two sesamoids to the base of the first phalanx. Excessive pressure on this joint predisposes to osteoarthritis. 5. Evidence of this abnormal gait is found in the peculiarities of wear seen in old shoes. 6. There is a high correlation between unilateral hallux rigidus and the patient's footedness

Objectives

This study looked to analyse the expression levels of microRNA-140-3p and microRNA-140-5p in synovial fluid, and their correlations to the severity of disease regarding knee osteoarthritis (OA).

Foreign-body reaction to polyglycolide (PGA) implants has been described in man. Many animal experiments have verified the mechanical properties of fixation devices made from PGA, but a significant foreign-body reaction has not been described. We studied the effect of PGA rods in 12 sheep with standardized osteochondral fractures of the medial femoral condyle fixed with uncoloured, self-reinforced PGA rods (Biofix). Radiographs were taken at intervals ranging from two weeks to two years, and the sheep were killed at intervals ranging from six to 24 months. All knees were examined histologically. Eleven of the 12 fractures healed radiologically and histologically. Moderate to severe osteolysis was seen at four to six weeks with maximum changes at 12 weeks in ten animals. Six knees showed fistula-like connections between the implant site and the joint space. Three developed synovitis, one with inflammatory changes involving the whole cartilage and one with destruction of the medial condyle. Although in our study osteochondral fractures fixed with PGA rods healed reliably, there were frequent, significant foreign-body reactions. Caution is needed when considering the use of PGA fixation devices in vulnerable regions such as the knee

Aims

Intra-articular ⁹⁰Yttrium (⁹⁰Y) is an adjunct to surgical treatment by synovectomy for patients with diffuse-type tenosynovial giant-cell tumour (dtTGCT) of the knee, with variable success rates. Clinical information is, however, sparse and its value remains unclear. We investigated the long-term outcome of patients who underwent synovectomy with and without adjuvant treatment with ⁹⁰Yttrium.

We have evaluated prospectively the arthroscopic findings in acute fractures of the ankle in 288 consecutive patients (148 men and 140 women) with a mean age of 45.6 years. According to the AO-Danis-Weber classification there were 14 type-A fractures, 198 type B and 76 type C. Lesions of the cartilage were found in 228 ankles (79.2%), more often on the talus (69.4%) than on the distal tibia (45.8%), the fibula (45.1%), or the medial malleolus (41.3%). There were more lesions in men than in women and in general they were more severe in men (p < 0.05). They also tended to be worse in patients under 30 years and in those over 60 years of age. The frequency and severity of the lesions increased from type-B to type-C fractures (p < 0.05). Within each type of fracture the lesions increased from subgroups 1 to 3 (p < 0.05). The anterior tibiofibular ligament was injured with increased frequency from type-B.1 to type-C.3 fractures (p < 0.05), but it was not torn in all cases. While lateral ligamentous injuries were seen more often in type-B than in type-C fractures (p < 0.05), no difference was noted in the frequency of deltoid ligamentous lesions. Our findings show that arthroscopy is useful in identifying associated intra-articular lesions in acute fractures of the ankle

Aims

The aim of this study was to investigate the incidence of knee arthroplasty and arthroscopy following patellar fractures, and to compare this with an age- and gender-matched group without a prior patellar fracture.

Dynamic muscle-tendon substitution for acute anterior cruciate deficiency in the dog was studied using the semimembranosus muscle-tendon. Nineteen mongrel dogs each had a semimembranosus transfer in one knee; as a control, the anterior cruciate ligament and the semimembranosus were released in the opposite knee. No postoperative immobilisation was used. The anterior drawer sign was assessed before and after operation and when the dogs were killed five months later. Dogs were excluded from the study if they developed infections or contractures of the hind legs. At five months, 11 dogs were available for study. The operated knees were examined histologically and evaluated using a reproducible index of arthritis based on: the macroscopic discoloration of the articular cartilage, the cellularity of the cartilage, the microscopic appearance of the articular surface, the loss of proteoglycans, the formation of osteophytes and the degree of subchondral osteosclerosis. There was no significant difference in the anterior drawer sign or the degree of arthritic changes between knees with a semimembranous transfer and the controls. Examination showed that a muscle-tendon transfer into the tibia was equivalent to transferring the muscle into the posterior capsule--the intra-articular tendon being weak but histologically viable. The transfer did not prevent the anterior drawer sign becoming positive nor the development of osteoarthritis. A second control group, in which three dogs had an arthrotomy and semimembranosus release in both their hind legs, showed that a semimembranosus release alone did not cause osteoarthritis

1. A study of late segmental collapse in twelve femoral heads shows that it may not develop until two and a half years after the fracture. 2. Until the articular surfaces had collapsed the patients usually had no symptoms. The fractures were united and there was no obvious radiographic evidence of ischaemic necrosis. 3. There was histological evidence that the whole of the femoral heads had been necrotic at one time. The term late segmental collapse is more appropriate than late segmental necrosis. 4. The blood vessels of the ligamentum teres played little or no part in revascularisation which, when it occurred, was almost entirely across the fracture line. 5. In only one femoral head was revascularisation approaching completion and apparently continuing. In the other eleven much of the head remained necrotic and the process appeared to have halted. 6. An increase in radiological density was caused by new bone laid down on unresorbed necrotic trabeculae and was most prominent behind the line of revascularisation when the process had halted. 7. Trabecular collapse was evident within dead bone. In ten of the femoral heads it occurred in the subchondral region and in four just beyond the junction of reossified and dead bone. 8. Osteoarthritic changes occurred in the cartilage covering revascularised bone at the periphery of the head, especially when collapse was severe