The pathogenesis of aseptic loosening of total joint prostheses is not clearly understood. Two features are associated with loosened prostheses, namely, particulate debris and movement of the implant. While numerous studies have evaluated the cellular response to particulate biomaterials, few have investigated the influence of movement of the implant on the biological response to particles. Our aim was therefore to test the hypothesis that excessive mechanical stimulation of the periprosthetic tissues induces an inflammatory response and that the addition of particulate biomaterials intensifies this.

We allocated 66 adult Beagle dogs to four groups as follows: stable implants with (I) and without (II) particulate polymethylmethacrylate (PMMA) and moving implants with (III) and without (IV) particulate PMMA. They were then evaluated at 2, 4, 6, 12 and 24 weeks.

The stable implants were well tolerated and a thin, fibrous membrane of connective tissue was observed. There was evidence of positive staining in some cells for interleukin-6 (IL-6). Addition of particulate PMMA around the stable implants resulted in an increase in the fibroblastic response and positive staining for IL-6 and tumour necrosis factor-alpha (TNF-α). By contrast, movement of the implant resulted in an immediate inflammatory response characterised by large numbers of histiocytes and cytokine staining for IL-1ß, TNF-α and IL-6. Introduction of particulate PMMA aggravated this response. Animals with particulate PMMA and movement of the implant have an intense inflammatory response associated with accelerated bone loss.

Our results indicate that the initiation of the inflammatory response to biomaterial particles was much slower than that to gross mechanical instability. Furthermore, when there was both particulate debris and movement, there was an amplification of the adverse tissue response as evidenced by the presence of osteolysis and increases in the presence of inflammatory cells and their associated cytokines.

There is a need for the accurate measurement of the outcome after knee surgery. The Oxford Knee Score is being increasingly used since it is reported to be short, simple, inexpensive and validated.

We sent the questionnaire to 346 patients awaiting surgery to the hip or lumbar spine. Only 11% of 141 patients with proximal pathology who denied knee problems gave a maximum score. Their mean score was substantially lower than expected at 28.7 (maximum 48), and was significantly lower than the score of 36.5 obtained from patients after total knee replacement.

We therefore suggest that the frequent coexistence of hip or spinal pathology will significantly alter both the absolute score and any improvement to be expected after knee surgery. Although sensitive to disability originating from the knee the Oxford Knee Score is not sufficiently specific since it is heavily influenced by more proximal pathology.

Discitis is uncommon in children and presents in different ways at different ages. It is most difficult to diagnose in the uncommunicative toddler of one to three years of age. We present 11 consecutive cases. The non-specific clinical features included refusal to walk (63%), back pain (27%), inability to flex the lower back (50%) and a loss of lumbar lordosis (40%). Laboratory tests were unhelpful and cultures of blood and disc tissue were negative.

MRI reduces the diagnostic delay and may help to avoid the requirement for a biopsy. In 75% of cases it demonstrated a paravertebral inflammatory mass, which helped to determine the duration of the oral therapy given after initial intravenous antibiotics.

At a mean follow-up of 21 months (10 to 40), all the spines were mobile and the patients free from pain. Radiological fusion occurred in 20% and was predictable after two years. At follow-up, MRI showed variable appearances: changes in the vertebral body usually resolved at 24 months and recovery of the disc was seen after 34 months.

Thirty cruciate ligaments were retrieved from either cadavers or limbs which had been amputated. Each specimen was sectioned and stained to demonstrate the presence of collagen, nerves and vessels.

All 30 specimens contained an interconnecting band of collagen fibres between the anterior and posterior cruciate ligaments. Vascular structures were present in all specimens and nerve fibres were identified in 26 (86%). We have called this structure the ‘intercruciate band’. The anterior and posterior cruciate ligaments should no longer be thought of in isolation, but together as a ‘cruciate complex’.

Between January 1987 and December 1988 there were 7575 births in the Swansea maternity unit. Of these 823 (10.9%) were considered to be at ‘high risk’ for developmental dysplasia of the hip (DDH). Static ultrasound examination was performed in each case and the results classified on the basis of the method of Graf. A total of 117 type III–IV hips in 83 infants was splinted using the Aberdeen splint.

Radiographs of these hips were taken at six and 12 months. Hilgenreiner’s measurements of the acetabular angle were made in all cases and the development of the femoral capital epiphysis was assessed by measuring the epiphyseal area. The effect of splintage on the acetabular angle and the epiphyseal area between the normal and abnormal splinted hips was compared. Radiographs of 16 normal infants (32 normal unsplinted hips) were used as a control group.

This cohort has now been followed up for a minimum of nine years. There have been no complications as a result of splintage. The failure rate was 1.7% or 0.25 per 1000 live births. No statistical difference was found when comparing the effect of splintage on the acetabular angle and epiphyseal area between normal and abnormal splinted hips and normal unsplinted hips.

Our study has shown that while the Aberdeen splint had a definite but small failure rate, it was safe in that it did not produce avascular necrosis. The current conventional view that a low rate of splintage is always best is therefore brought into question if the Aberdeen splint is chosen for the management of neonatal DDH.

Children with a mucopolysaccharidosis or mucolipidosis suffer progressive disability of the hands, particularly in relation to dysfunction of the median nerve. This is an increasing problem because bone-marrow transplantation has dramatically improved survival without apparently changing the musculoskeletal manifestations. We have reviewed 48 children with these syndromes who required carpal tunnel decompression, recording symptoms, signs, radiological, electrophysiological and operative findings, histology and upper-limb function. In these children the carpal tunnel syndrome differs from that seen in adults. Symptoms are rare but signs such as decreased sweating, pulp atrophy, thenar wasting and manual clumsiness are much more common. At operation, the flexor retinaculum was thickened and a mass of white tenosynovium engulfed the flexor tendons. Most patients had some definite nerve constriction with a thickened epineurium.

Functional improvement was seen after early decompression, with some benefit from simultaneous tendon release. Regular physiotherapy helped to maintain increased hand movement.

We describe our assessment protocol, the physiotherapy and operative regime and the standard functional review which helps to maximise function in the hands and upper limbs of these children.

We have studied retrospectively 37 hips in 36 children at an average of 91 months after simultaneous open reduction and Salter innominate osteotomy for developmental hip dysplasia. At the latest review 97.3% were clinically and 83.8% radiologically good or excellent. In three hips (8%) there were signs of avascular necrosis, but only one had been symptomatic. There were no cases of recurrent posterior displacement.

The early diagnosis of aseptic loosening of a total hip replacement by plain radiography, scintigraphy and arthrography has been shown to be unreliable. It has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. We have assessed the use of this technique in vitro using models of early and late loosening. Late loosening with an unstable prosthesis can be reliably detected by vibration analysis, but this method was shown to have a very poor diagnostic sensitivity in early loosening when there is no obvious prosthetic instability.

We performed a retrospective study of the factors affecting the outcome of Weber type-C ankle fractures in 43 patients reviewed at two to nine years after injury. We determined the functional result in relation to the use of a diastasis screw, the accuracy of reduction, the presence of tibiotalar dislocation, and of injury to the medial side of the ankle by medial malleolar fracture or deltoid ligament rupture. We assessed the use of a diastasis screw as appropriate or inappropriate on the basis of an anatomical study performed by Boden et al (1989). The diastasis screw was used unnecessarily in 19 of the 31 patients so treated, but this did not appear to affect the final functional result. The worse functional results were in ankles dislocated at the initial injury, and in those with medial malleolar fractures as opposed to those with deltoid ligament ruptures. The best results were after accurate reduction of the fibula and the syndesmosis, and greater increase in the width of the syndesmosis was associated with a worse result. Our results suggest that an increase of more than 1.5 mm in syndesmosis width is unacceptable. We recommend that when the deltoid ligament is ruptured, a diastasis screw should be used if the fibular fracture is more than 3.5 cm above the top of the syndesmosis. When a medial malleolar fracture has been rigidly repaired a diastasis screw is required if the fibular fracture is more than 15 cm above the syndesmosis.

Isolated wear of the polyethylene tibial component led to failure in five of a series of 108 uncemented porous-coated knee replacements. The clinical features included pain, effusion and instability with progressive varus deformity. In all cases there was extensive wear on the medial side of the polyethylene surface of the prosthesis. The mechanism of such wear is complex, being due in part to the unconstrained nature of the joint and the incongruity of its surfaces. Other design characteristics may have contributed.

Transverse fractures of the sacrum with neurological complications have been studied in four patients illustrating the following features: diagnosis is often delayed, there are radiological difficulties in making the diagnosis, and the indications for surgery are not well defined. Specific radiographic views are recommended. All the cases presented in this report responded well to conservative management.

We used ultrasonography to study 26 hips with slipped capital femoral epiphyses. In recently slipped epiphyses the ultrasound image revealed a step at the anterior physeal outline (mean 6.4 mm), diminished distance between the anterior acetabular rim and the femoral metaphysis (mean 4.3 mm) and an effusion. As metaphyseal remodelling progressed the physeal step decreased. The femoral neck appeared straighter in hips which had been symptomatic for longer than three weeks. It was possible to measure posterior epiphyseal displacement without projectional errors and the method was accurate in diagnosing minimal slip and in staging displacement. The suggested criteria are, less than 7 mm for a mild slip, 7 to 11 mm for a moderate slip and more than 11 mm for a severe slip. We recommend ultrasonography for the diagnosis, staging and follow-up management of slipped upper femoral epiphysis.

A computer-based image analysis system has been developed as a research tool in total hip replacement. The system has been programmed to take multiple measurements from coronal plane radiographs. Poor quality radiographic images can be enhanced and standardised. The measurements which can be obtained include stem subsidence, cup migration, cup wear, and stem loosening. Reproducibility and accuracy were +/- 0.01 mm and +/- 0.5 mm respectively. The present application is in retrospective research, but prospective monitoring of radiographs is planned.

Since 1981, during operations for spinal deformity, we have routinely used electrophysiological monitoring of the spinal cord by the epidural measurement of somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial nerve. We present the results in 1168 consecutive cases. Decreases in SEP amplitude of more than 50% occurred in 119 patients, of whom 32 had clinically detectable neurological changes postoperatively. In 35 cases the SEP amplitude was rapidly restored, either spontaneously or by repositioning of the recording electrode; they had no postoperative neurological changes. One patient had delayed onset of postoperative symptoms referrable to nerve root lesions without evidence of spinal cord involvement, but there were no false negative cases of intra-operative spinal cord damage. In 52 patients persistent, significant, SEP changes were noted without clinically detectable neurological sequelae. None of the many cases which showed falls in SEP amplitude of less than 50% experienced neurological problems. Neuromuscular scoliosis, the use of sublaminar wires, the magnitude of SEP decrement, and a limited or absent intra-operative recovery of SEP amplitude were identified as factors which increased the risk of postoperative neurological deficit.

Ten normal neonatal hips were examined in stillborn babies. At first, forcible Barlow manoeuvres did not produce subluxation or dislocation, but by repeated examination a previously stable joint could be rendered unstable. Dissection of the hips showed that the vacuum fit between the femur and the acetabulum was an important factor in neonatal hip stability. The posterior capsule was not a strong or, in itself, an important structure. It is postulated that the capsule and the labrum act together as 'O' rings to maintain the vacuum fit; it is possible that repeated examinations, by producing an effusion, could break the seal and allow instability.

We compared the mechanical properties of carbon fibre composite bone plates with those of stainless steel and titanium. The composite plates have less stiffness with good fatigue properties. Tissue culture and small animal implantation confirmed the biocompatibility of the material. We also present a preliminary report on the use of the carbon fibre composite plates in 40 forearm fractures. All fractures united, 67% of them showing radiological remodelling within six months. There were no refractures or mechanical failures, but five fractures showed an unexpected reaction; this is discussed.

We assessed 70 hips at an average of 7.1 years after pinning for slipped upper femoral epiphysis to determine the frequency of remodelling, what factors influence it and its effect on the clinical outcome. Remodelling was defined by a new classification of the anterior femoral head-neck profile as seen on the lateral radiograph. Remodelling occurred in 50% of hips with a head-shaft angle of 30 degrees or more; the probability of remodelling was significantly less the greater the degree of slip, but was significantly increased if the triradiate cartilage was open at the time of presentation. We found no significant effect for age, sex, weight or length of symptoms. The range of internal rotation was significantly greater in those hips that remodelled. We support the treatment of moderate slips in skeletally immature patients by pinning in situ, since the probability of satisfactory remodelling was 75% for slips of 40 degrees or less.

We describe a simple, quick ultrasound screening test for CDH, and its use in a prospective study of babies with a 'high risk' factor, over one year from January 1987. From a birth population of 3,879, 812 hip scans were performed on 406 babies and 98 babies were abnormal. So far, there have been no late cases of CDH. Family history, breech malposition, and postural foot deformities were confirmed to be important risk factors, but babies with a simple click were equally at risk. Our early results indicate that a large proportion of the potential late cases are contained within our extended high-risk group.

Condensing osteitis of the clavicle was first described as a disease entity in 1974. There is painful localised swelling of the clavicle of undetermined origin, with increased radio-density, but an infective aetiology has not been excluded by previous authors. We report three children with the clinical and radiological findings of 'condensing osteitis'. Two of them had raised levels of antistaphylolysin titres and all responded to antibiotic therapy. We conclude that condensing osteitis is due to low-grade staphylococcal osteomyelitis; biopsy and treatment by antibiotics is recommended.

We have reviewed 82 children with congenital dislocation of the hip, after treatment by anterior open reduction followed by derotation femoral osteotomy. The clinical and radiological results were significantly better in the group that had open reduction before the appearance of the capital femoral epiphysis; this group also had a lower incidence of avascular necrosis. We conclude that, when it is clearly indicated, the earlier an open reduction is carried out the better the results.

Ten epiphyses in seven children underwent fixed-rate distraction of 0.25 mm twice daily in an attempt to achieve percutaneous leg lengthening by chondrodiatasis. The forces generated across the growth plate were recorded by means of strain gauges incorporated into the distractors. All epiphyses fractured before 33 days of lengthening. An average gain of 6.75 cm was achieved. Epiphyseal distraction at the lower femur produced many complications, but at the upper tibial epiphysis planned lengthening was achieved, with excellent bone production and few complications.

There is a high incidence of spinal deformity in children with the Prader-Willi syndrome. We have encountered major complications following spinal surgery in this condition. We report our experience and conclude that spinal surgery is a formidable undertaking and the risks should be appreciated by the surgeon and the parents.

Three cases are reported which presented as "irritable" or "observation" hips and failed to respond to rest at home and in hospital. In each case a campylobacter organism was grown from the faeces; none were found in a group of 20 patients in the paediatric ward for other reasons. The patients responded to a course of erythromycin. It is postulated that they may have had a reactive arthropathy of the hip and suggested that cultures for Campylobacter be made as part of the investigation of irritable hip.

We report a case of neonatal separation of the distal humeral epiphysis in which non-invasive ultrasonic examination provided clear definition of the injury.

The results of primary total hip arthroplasty for sub-capital femoral neck fracture in previously normal hips are reported. Thirty-seven patients aged 70 or less at the time of surgery were reviewed at an average follow-up of 56 months. Eighteen (49%) had undergone or were awaiting revision surgery. A further four (11%) had definite radiological signs of loosening. Harris hip scores were calculated and correlated well with the results of gait analysis; these suggested that it was the more vigorous patients that were more liable to early failure. Consequently, primary total hip replacement is not recommended for subcapital fractures in the younger patient without pre-existing hip pathology.

We examined the structure of the digital flexor sheath by dissection and histology. The inner aspect of the sheath was found not to be a continuous smooth surface, as depicted in anatomical and surgical texts. The thin parts of the sheath often overlapped the pulleys before attaching to their superficial aspects, so that the pulleys possessed free edges within the sheath. The frequency of occurrence and sizes of these overlaps were studied in 48 cadaveric fingers; the largest and most frequent overlap was at the distal end of the A2 pulley. Functional studies showed an intricate mechanism of pulley approximation and sheath bulging during flexion. Sutured or partly cut tendons triggered on the free edges; this could be a major contributor to the failures of tendon repairs in "no man's land".

A consecutive series of 100 cases of wrist injury, other than those referred with a radial fracture, have been reviewed to determine the incidence of acute scapholunate instability; a "clenched fist" radiograph was used in addition to the routine scaphoid views. Of 19 patients with an increase in the scapholunate gap, five were eventually considered to have significant scapholunate instability, two in association with Colles' fractures. Injuries producing significant ligamentous damage and carpal instability may be as common as scaphoid fractures. They require special consideration in diagnosis and management.

Shelf operations performed on 24 patients (27 hips) for late presentation of congenital hip dysplasia were evaluated. The mean age at operation was 14 years 9 months and the mean follow-up 16 years 8 months. Two-thirds of the hips had good clinical results at follow-up. Patients operated on under the age of 20 years and with little or no radiological evidence of degenerative joint changes had the highest likelihood of success. The shelf operation was found to provide good cover of the femoral head and, should failure occur, also provides adequate superior support for the seating of an acetabular prosthesis.

Patients with myelomeningocele who had had surgery to stabilise the hip were reviewed; the results of the 106 operations in 88 patients were assessed. In the earlier part of the series there were 55 children who had 64 iliopsoas transfers; later in the series 33 children had 42 varus-rotation osteotomies combined with adductor tenotomy, anterior obturator neurectomy and psoas division. The technical results of both operations were satisfactory: following iliopsoas transfer only 19% of the hips were either dislocated or subluxated; the corresponding figure for the osteotomy was 12%. Thus varus-rotation osteotomy with psoas division, adductor tenotomy and anterior obturator neurectomy was at least as effective in stabilising the hip as iliopsoas transfer. Nevertheless 80% of the latter and 61% of the osteotomy patients relied on wheelchairs for mobility.

We have reviewed 60 patients with primary bone infections; 21 of these (35%) had subacute osteomyelitis, a figure which supports other recent observations that this variant of bone infection is becoming more widespread. In this group open culture and biopsy were necessary in order to exclude bony malignancy, and a raised erythrocyte sedimentation rate proved a useful diagnostic aid. All the patients with acute osteomyelitis or with vertebral infection responded to primary treatment, but five of those with subacute osteomyelitis had recurrences.

The uptake of 99mTc-MDP was studied in 73 patients after a tibial fracture. The image obtained five minutes after injection during a period between one and four weeks after fracture was found to be related to the incidence of non-union after six months. A ratio of 1.3 between the uptake at the fracture site and at normal bone adjacent to it predicted non-union in an individual patient with a sensitivity of about 70% and a specificity of 90%.

Unilateral Colles' fractures in 187 patients over the age of 55 years were studied in a randomised prospective trial: 97 fractures were minimally displaced and were treated either conventionally or in a crepe bandage; 90 displaced Colles' fractures were reduced and of these 47 were treated conventionally while 43 were encouraged to mobilise the wrist in a cast which restricted extension. Early wrist movement hastened functional recovery and led to earlier resolution of wrist swelling. Discomfort was no greater than in patients who were treated conventionally. The bony deformity, which recurred irrespective of the method of treatment, was not adversely affected by early mobilisation.

In a prospective, controlled study 58 patients aged under 60 years with Colles' fractures were treated either by a forearm plaster or by the application of an external fixator. In 94% of those treated by a fixator it was possible to insert the distal pins of the frame into the fracture fragment, the fixation obtained being sufficient to forgo additional splintage. The external fixator proved more effective at holding the manipulated position, and the radiological loss of position during fracture union was minimal compared with that seen in patients treated in plaster.

Four types of prosthetic replacement for the anterior cruciate ligament (carbon fibre, carbon fibre and Dacron composite, Dacron alone and bovine xenograft) were assessed at three, six and 12 months after implantation in the knees of New Zealand white rabbits. The synovium and both intra-articular and intra-osseous portions of the ligaments were examined macroscopically, by light microscopy and by scanning electron microscopy. All the knees showed mild synovitis, and there was no significant growth into the intra-articular part of any ligament. Carbon fibre and xenograft did not appear to be suitable materials in this animal model. The composite ligament showed short-term ingrowth of fibrous tissue only into the periphery of the sheath in its intra-osseous portion, whereas the Dacron ligament showed progressive fibrous tissue ingrowth with some bony incorporation of its outer fibres.

Thirty-nine patients with neuralgic amyotrophy were reviewed. In addition to the clinical findings reported in the neurological literature, we commonly found pain throughout the upper limb, and diffuse involvement of the brachial plexus. Five patients had spinal accessory nerve lesions and five had glenohumeral instability. Sixty-four per cent of the patients had had an orthopaedic consultation during their acute illness. It is therefore important that orthopaedic surgeons are aware of this clinical syndrome and its management. The prognosis is excellent with non-invasive treatment.