Showing papers by "Nuffield Orthopaedic Centre published in 1993"

The definition and measurement of acetabular orientation.

Abstract: The orientation of an acetabulum or an acetabular prosthesis may be described by its inclination and anteversion. Orientation can be assessed anatomically, radiographically, and by direct observation at operation. The angles of inclination and anteversion determined by these three methods differ because they have different spatial arrangements. There are therefore three distinct definitions of inclination and anteversion. This paper analyses the differences between the definitions and provides nomograms to convert from one to another. It is recommended that the operative definitions be used to describe the orientation of prostheses and that the anatomical definitions be used for dysplastic acetabula.

Coupled Nonlinear Oscillators and the Symmetries of Animal Gaits

Abstract: Animal locomotion typically employs several distinct periodic patterns of leg movements, known as gaits. It has long been observed that most gaits possess a degree of symmetry. Our aim is to draw attention to some remarkable parallels between the generalities of coupled nonlinear oscillators and the observed symmetries of gaits, and to describe how this observation might impose constraints on the general structure of the neural circuits, i.e. central pattern generators, that control locomotion. We compare the symmetries of gaits with the symmetry-breaking oscillation patterns that should be expected in various networks of symmetrically coupled nonlinear oscillators. We discuss the possibility that transitions between gaits may be modeled as symmetry-breaking bifurcations of such oscillator networks. The emphasis is on general model-independent features of such networks, rather than on specific models. Each type of network generates a characteristic set of gait symmetries, so our results may be interpreted as an analysis of the general structure required of a central pattern generator in order to produce the types of gait observed in the natural world. The approach leads to natural hierarchies of gaits, ordered by symmetry, and to natural sequences of gait bifurcations. We briefly discuss how the ideas could be extended to hexapodal gaits.

Survival analysis of joint replacements

Abstract: Survival analysis is a powerful tool for analysing the results of total joint replacement, but it has major drawbacks when the failure rates are very low. We have reviewed 35 recent survival analyses of joint replacements to assess the magnitude of these problems and make recommendations as to how they may be avoided.

Proprioception after rupture of the anterior cruciate ligament. An objective indication of the need for surgery

Abstract: Failure of conservative treatment is the usual indication for the reconstruction of a knee with deficiency of the anterior cruciate ligament (ACL) and this depends on subjective judgement. The ability of muscles to protect the subluxing joint by reflex contraction could provide an objective measurement. We have studied 30 patients with unilateral ACL deficiency by measuring the latency of reflex hamstring contraction. We found that the mean latency in the injured leg was nearly twice that in the unaffected limb (99 ms and 53 ms respectively). There was a significant correlation between the differential latency and the frequency of 'giving way' indicating that functional instability may be due, in part, to loss of proprioception. Measures of proprioception, including reflex hamstring latency, may be useful in providing an objective assessment of the efficacy of conservative treatment and the need for surgery.

Formation of mineralized nodules by bone derived cells in vitro: a model of bone formation?

Abstract: The identification of the factors which regulate the proliferation and differentiation of cells of the osteoblast lineage remains one of the major challenges in the field of bone cell biology. Although considerable progress has been made in the isolation and culture of cells of the osteoblast lineage from both animal and, more recently, human bone, uncertainties have persisted as to the extent to which these cell populations retain the ability to differentiate into functional osteoblasts in vitro. The formation in vitro of mineralized nodules that exhibit the morphological, ultrastructural and biochemical characteristics of embryonic/woven bone formed in vivo, represents the first evidence that the differentiation of functional osteoblasts can occur in cultures of isolated animal bone-derived cell populations. It is clear, however, that the culture conditions employed at present only permit a small number of cells to differentiate to the extent of being capable of organising their extracellular matrix into a structure that resembles that of bone. Moreover, it has generally been found that the reproducible mineralization of this extracellular matrix requires supplementation of the culture medium with mM concentrations of beta-GP, which raises doubts as to the physiological relevance of this process. The formation of nodules has also been observed in cultures of human bone-derived cells. As found in cultures of animal bone-derived cells, reproducible mineralization of these nodules will occur in the presence of beta-GP. We have shown, however, that in the presence of the long acting ascorbate analogue Asc-2-P, the formation and mineralization of nodules can occur in the absence of beta-GP. The nodules formed in human bone-derived cell cultures have yet to be characterized as rigorously as those formed in cultures of animal bone-derived cells and thus it remains to be shown that they resemble bone formed in vivo.

Quantifying the cosmetic defect of adolescent idiopathic scoliosis

Abstract: Cosmesis is important in the treatment of adolescent idiopathic scoliosis patients. The aim of this study was to quantify the cosmetic defect using parameters of the ISIS (Oxford Metrics Ltd., Oxford, England) scan. Ten nonmedical judges scored photographs of 100 adolescent idiopathic scoliosis patients based on cosmetic criteria. This Cosmetic Spinal Score proved to be a reliable figure. The Cosmetic Spinal Score was then compared with ISIS parameters and the Cobb angle. An equation based on ISIS parameters was developed, which could predict Cosmetic Spinal Score with sufficient reproducibility to have a useful clinical application. Bracing reduced the rib hump but not enough to improve the cosmetic appearance. Spinal fusion and Harrington instrumentation improved all measured parameters influencing physical appearance.

Medial unicompartmental arthroplasty. A survival study of the Oxford meniscal knee.

Abstract: One hundred twenty-one knees with medial compartment osteoarthrosis were treated by unicompartmental arthroplasty with the Oxford Knee. The strict selection criteria were (1) the presence of a functioning anterior cruciate ligament, (2) fully correctable deformity, and (3) full thickness of articular cartilage in the lateral compartment. The mean elapsed time from surgery was 44.4 months. One knee has required revision for a loose tibial component. The results at this stage are as acceptable as those of tricompartmental knee arthroplasty and better than those of high tibial osteotomy.

Can MRI of the knee affect arthroscopic practice? A prospective study of 58 patients

Abstract: We made a prospective study of 58 patients with suspected internal derangement of the knee. They were examined by magnetic resonance imaging using 3-D gradient echo intermediate-weighted studies before having an arthroscopy. The preoperative clinical assessment was found to have a diagnostic sensitivity of 77% and a specificity of 43%, compared with 100% and 63% respectively for magnetic resonance imaging. Comparison of magnetic resonance imaging and arthroscopy confirmed the accuracy of magnetic resonance imaging in the diagnosis of internal derangement but the results for articular cartilage lesions were much less good, with a sensitivity of only 18% but a specificity of 100%. Acceptance of the magnetic resonance imaging findings could have resulted in a 29% reduction in the number of arthroscopies without missing any significant meniscal lesion.

Investigation into the formation and mechanical properties of a bioactive material based on collagen and calcium phosphate

Abstract: A biomaterial composite was formed by the room-temperature precipitation of calcium phosphate (in the form of brushite) on to collagen. It was found that the addition of 1 mM O-phosphoserine (Ser P) causes the morphology of the brushite crystals to change from large plates to small needles. An increase in the surface coverage and weight fraction of brushite incorporated into the collagen was observed. The mechanical properties of this composite were tested in the wet state. The ultimate tensile strength (UTS) was 45 MPa compared with 34 MPa for the wet collagen. Osteoblastic differentiation was promoted on the surface of the material and new bone formed.

A comparison of the sensitivity to change of several health status instruments in rheumatoid arthritis.

Abstract: We carried out a study to compare the sensitivity to change of disease specific compared with more generic health status instruments in relation to rheumatoid arthritis (RA). A sample of 102 patients was recruited and assessed by means of 4 health status instruments and standard rheumatological measures on 3 occasions separated by 3 monthly intervals. Sensitivity to change for mobility, activities of daily living, household, pain, emotions and social dimensions were calculated. For some dimensions disease specific health status instruments performed less well. However overall there was no evidence of consistent differences between the 2 approaches. We conclude that generic instruments have a role in the assessment of RA.

Haemostasis during carpal tunnel release under local anaesthesia: a controlled comparison of a tourniquet and adrenaline infiltration.

Abstract: A randomized controlled comparison of tourniquet and local adrenaline infiltration for control of bleeding was performed in patients undergoing bilateral carpal tunnel release under local anaesthesia. Visual analogue scores for intra-operative pain were substantially greater for tourniquet (mean score 4.7) than for adrenaline (2.2). Incomplete control of bleeding was responsible for longer operating time and for the surgeons' perception of slightly greater operative difficulty with the use of adrenaline. There were no complications attributable to the use of adrenaline. The use of adrenaline-containing local anaesthesia for carpal tunnel release avoids tourniquet pain and is preferred by patients.

Septic arthritis in haemophilia

Abstract: Septic arthritis has been regarded as rare in haemophiliacs, but its incidence may have increased since HIV infection has become widespread in these patients. We describe six cases treated at one haemophilia unit over a two-year period and discuss their investigation, diagnosis and treatment. Four of the patients were seropositive to anti-HIV.

Bilateral knee replacements: simultaneous or staged?

Abstract: Approximately one-third of primary knee replacements are performed on patients with bilateral symptomatic disease. This retrospective study compared the complication rate, functional outcome and cost implications of performing bilateral total knee replacements under a single anaesthetic or as staged procedures with a control group of unilateral cases. There was no significant difference in the complications or outcome. There was a significant reduction in the mean hospital admission time of 7 days per knee replacement (P < 0.001, Student's t test) by performing bilateral knee replacements for osteoarthritis under the same anaesthetic. However, a survey of practising knee surgeons in three health regions in the United Kingdom shows that only 24% would regularly perform bilateral knee replacements under one anaesthetic.

One-stage lengthening for femoral shortening with associated deformity.

Abstract: One-stage femoral lengthening is thought to have an unacceptably high complication rate and is not widely practised. We reviewed 17 patients after one-stage lengthening for femoral shortening with associated angular or rotational deformities. Minimal dissection of the bone ends was undertaken. The mean length gain was 4 cm (2 to 7), and the average time to union was 6 months (3 to 10). There were no neurovascular complications. Four patients had delayed or nonunion, but union was achieved after bone grafting. We conclude that with minimal dissection, and with iliac crest cancellous bone grafting, one-stage leg lengthening for correction of deformity and leg-length inequality of up to 7 cm, in selected patients, can be effected safely with a relatively short rehabilitation.

Erdheim-Chester disease with epiphyseal and systemic disease

Abstract: A case of Erdheim-Chester disease which affected the epiphysis and showed evidence of systemic disease is presented. Clinical and histopathological similarities with other forms of disseminated Langerhans' cell histiocytosis are noted, particularly reaction of infiltrating histiocytes for S100 and HLA-DR.

Joint laxity and hip rotation in normal children and in those with congenital dislocation of the hip.

Abstract: We measured the range of rotation in both hips of 397 normal children and in the unaffected hip of 135 children with unilateral congenital dislocation of the hip. Both groups were assessed for generalised joint laxity. Joint laxity was more common in normal children with an internally centred arc of hip rotation than in normal children with a neutral or an externally rotated arc. The children with congenitally dislocated hips had significantly more joint laxity than did the control group and significantly more of them had an internally centred arc of hip rotation. We suggest that the lax joint capsule fails to mould away the neonatal anteversion of the femoral neck during the first few months of life.

Improvement in acetabular index after reduction of hips with developmental dysplasia

Abstract: After late reduction of the hip in children with developmental dysplasia the acetabular contour slowly improves and it is difficult to know if and when acetabular reconstruction is required. We studied the radiographs of 19 patients with unilateral dislocated or subluxated hips which had been reduced between the ages of one and two years. Preoperatively, all the affected hips showed acetabular dysplasia. After reduction they steadily improved for three years by which time none was dysplastic as measured by the acetabular index. After the age of ten years, when assessed by the more sensitive centre-edge angle, two were found to be dysplastic. It was not possible to predict these from early radiographs. We conclude that the decision to reconstruct an acetabulum should not be taken until three years after reduction, and that a few hips which appear to be developing satisfactorily at that time will, nevertheless, become dysplastic.

Recurrent patella dislocation treated by closed lateral retinacular release.

Abstract: This study describes the results of treating selected patients suffering from recurrent dislocation of the patella, with closed lateral retinacular release. Thirty-nine patients were reviewed after a mean follow-up time of 28 months. Thirty patients were substantially improved by the procedure, two patients had sustained a further dislocation. The major complication--haemarthrosis--occurred in four patients. These results compare favourably with those achieved by major realignment procedures. So lateral retinacular release is an effective treatment for selected patients with recurrent patella dislocation, and it offers distinct advantages over other procedures.

Epiphyseal distraction for bony bridges: a biomechanical and morphologic study.

Abstract: Partial physeal bridges were produced by resecting part of the lower femoral physis in 8-week-old rabbits. After 4 weeks, an external fixator, strain-gauged to measure distraction forces, was applied across the physis. Distraction was performed for 15 days: 1.0 mm/day medially and 0.5 mm/day laterally. Weekly radiographs were obtained. Animals were killed at 0, 3, and 6 weeks after distraction. Characteristic force patterns were evident if the bridge fractured. Medial fixator forces just before bridge fracture were very high (mean 89 N, SD 28 N), although forces in the lateral fixator were low (mean 25 N, SD 15 N). All animals killed 3 and 6 weeks after distraction ceased showed complete physeal closure. Results suggest that distraction epiphysiolysis may have high potential for producing premature physeal fusion.

The Oxford knee. Survival analysis of joint replacement.

Abstract: To evaluate the success of a knee prosthesis, long-term follow-up studies are needed. The best means for this is survival analysis. It would be desirable for a contribution towards the costs of these essential follow-up studies to be included in the sale price of the prosthesis.

Immunophenotypic Analysis of Mononuclear Phagocyte Antigens in the Arthritic Synovium of the Hip Joint

Abstract: The antigenic phenotype of lining and subintimal mononuclear phagocytes (MPs) of the synovium in osteoarthritis (OA) and rheumatoid arthritis (RA) was characterised, using monoclonal antibodies directed against a range of monocyte/macroph-ageassociated antigens, in order to determine the role of MPs in the pathobiology of OA and RA of the hip. A major proportion of synovial lining cells (SLCs) and subintimal cells in RA and OA consisted of CD68 positive MPs which expressed a wide range of macrophage-associated antigens. The monocyte marker, CD14, was downregulated on SLCs in RA while OA and early markers of MP activation predominated in the OA synovium which was independent of the level of inflammation. In contrast, synovial MPs in RA showed increased expression of activation, maturation and functional antigens such as CD11a, CD11b, CD11c, CD16, CD32, CD54, CD64. Moreover, MP recruitment did not correlate with the degree of lymphocytic infiltration in RA. Thus, synovial MPs in RA are rapidly and fully act...

Ultrasound of Soft Tissue Injury

Abstract: Introduction High resolution ultrasound is an ideal method of examining the injured extremity. Examinations can be performed quickly, painlessly and cheaply to provide accurate diagnosis following tendon, ligament and muscle injury. This paper will be divided into two parts. The first will describe the generic appearances of injury to tendons, ligaments and muscles, regardless of site. The second will briefly describe the ultrasound appearances of common injuries at various anatomical sites. Technical factors including probe frequency and configuration have been well described elsewhere'.

Rupture of the ulnar collateral ligament of the thumb in a 5-year-old girl.

Abstract: Injuries to the metacarpophalangeal joint of the thumb are rare in children and usually involve avulsion of the bone or cartilage. We describe a tear of the ulnar collateral ligament of the thumb with minimal symptoms in a 5-year-old girl.

Anaplastic large cell Ki-1 lymphoma arising in bone.

Abstract: Anaplastic large cell Ki-1 lymphoma is a very rare tumour that involves predominantly lymph nodes, the skin and the gastrointestinal tract. This report describes the diagnosis and treatment of a case of anoplastic large cell Ki-1 lymphoma arising in two thoracic vertebrae in a 14-year-old boy.