Study Design: Retrospective chart review.

Objective: To assess the clinical and radiological outcome of surgery for both dystrophic and non-dystrophic curves resulting from neurofibromatosis Type I.:

Subjects: 10 patients (7 females, 3 males) underwent surgical correction for neurofibromatous kypho-scoliosis between 1997–2003. The mean age at surgery was 16 years (range 8–37 years). Average follow-up 20 months (range 9 months – 4.5 years). Seven patients had MRI proven dystrophic curves (group I). These underwent 2–3 level apical vertebrectomy, followed by 2–3 weeks in Halo traction, followed by instrumented posterior spinal fusion and anterior rib strut grafting. Three patients had non-dystrophic curves (group II). Two underwent posterior instrumented fusion and one (aged 8 years) underwent convex epiphyseodesis with posterior Luque trolley.

Outcome Measures: Cobb angle, thoracic kyphosis, lumbar lordosis, global apical vertebral translation (AVT), regional AVT, coronal and sagittal balance, complications and Modified SRS Outcomes Instrument completed at final follow.

Results: For the dystrophic curves the Cobb angle improved from a mean of 81.5 degrees (mean bending film to 76 degrees) to 26.6 degrees post-operatively (68% correction) and 35.8 degrees at final follow-up (56% correction) and the global AVT improved from 61.5 mm to 29 mm at final follow-up. The average score for the modified SRS outcome instrument was 91.6 (Good). For the non-dystrophic curves the Cobb angle improved from a mean of 57.5 degrees (mean bending film to 47 degrees) to 23.5 degrees post-operatively ( 60% correction) and 24.6 degrees at final follow-up (57% correction) and the global AVT improved from 56.8 mm to 27.8 mm at final follow-up. The average score for the modified SRS outcome instrument was 98.5 (Good). All complications occurred in the dystrophic group including superficial infection in 2, dural leaks in 3, temporary brachial plexus injury in 1, worsening of lower limb neurological deficit in 1 and one death (upper GI haemorrhage). There was no failure of metalwork or evidence of pseudarthrosis identified. Seven of eight patients stated that they would have the surgery done again.

Conclusions: Non-dystrophic curves maybe treated by posterior fusion alone achieving 60% Cobb correction and 55% AVT correction. Close observation should be maintained for the appearance of dystrophic features and deterioration of correction. Dystrophic curves should be treated early and aggressively by two/three stage apical vertebrectomy, grafting and posterior spinal fusion. In this series 68% coronal Cobb and 63% AVT correction was achieved post-operatively. Complications can be expected with scoliosis associated with more than 50 degrees of kyphosis.

Introduction: Although there is evidence that laminar flow operating theatres (LFOTs) can reduce the incidence of wound infection over standard operating theatres (STOTs) when no routine peri-operative antibiotics were used, the evidence for the use with concurrent parenteral antibiotics is less compelling. A number of prior studies have compared the bacterial load observed in LFOTs and STOTs by wound culture and air sampling during surgery. However many organisms responsible for low grade infection after THR are not readily identified on routine culture and may be detectable only by more sensitive techniques such as the polymerase chain reaction (PCR), a molecular biology test for the presence of bacterial DNA. The purpose of this study was to compare the wound contamination rate during THRs performed in STOT with that in LFOTs using PCR.

Method: Patients undergoing primary THR for osteoarthritis without a history of joint infection were recruited for the study. Surgery was performed in either STOTs or LFOTs, using identical skin preparation solutions, surgical drapes and operating attire. Specimens of the deep tissue, taken at the beginning and end of surgery, were each immediately separated into two sterile containers, one sent for culture (aerobic, anaerobic and enriched meat broth) and the other frozen at minus 80 degrees Celsius for PCR at a later date.

Results: In each theatre type, 40 specimens from 20 THRs were analysed by both PCR and culture (80 specimens and 40 THRs in total).

Using PCR, bacterial DNA was identified on 12 of 40 specimens (30%) from STOTs. Of these 12, three were taken at the start of surgery and nine at the end of the surgery, equivalent to a 45% wound contamination rate (9 of 20). Only two specimens (5%), both taken at the end of surgery, were positive on enriched culture.

In LFOTs, bacterial DNA was identified by PCR on eight of 40 specimens (20%). Of these eight, two were taken at the start of surgery and six at the end of surgery, equivalent to a 30% wound contamination rate (6 of 20). None of the specimens were positive on enriched culture.

Discussions: We concluded that wound contamination of primary THR occurs frequently in both STOTs and LFOTs. Although STOTs showed evidence of more frequent wound contamination than LFOTs, with the numbers available, no significant difference was detected. These data are important in that they confirm that continued vigilance to technique continue to be important as significant wound contamination can occur despite the use of ultra clean air operating theatres.

The use of designer scaffolds to deliver biologically active osteogenic growth factors such as recombinant human bone morphogenetic protein-2 (rhBMP-2) to the sites of tissue regeneration in for example orthopaedics, has tremendous therapeutic implications. The aims of this study were to generate biomimetic biodegradable porous osteogenic scaffolds using a supercritical fluid process to encapsulate rhBMP-2, and to examine the ability of the scaffolds to promote human osteoprogenitor differentiation and bone formation in vitro and in vivo.

The rhBMP-2 encapsulated in Poly(-lactic acid) (PLA) scaffolds (100ng/mg PLA) were generated using an innovative supercritical fluid mixing method. The bioactivity of rhBMP-2 encapsulated PLA scaffolds were confirmed by induction of the C2C12 promyoblast cell line into the osteogenic lineage as detected by alkaline phosphatase expression. No induction of alkaline phosphatase-positive cells was observed using blank scaffolds. BMP-2 released from encapsulated constructs promoted adhesion, migration, expansion and differentiation of human osteoprogenitor cells on 3-D scaffolds. Enhanced matrix synthesis and cell differentiation on growth factor encapsulated scaffolds was observed following culture of human osteoprogenitors on explants of chick femoral bone wedge defects in an ex vivo model of bone formation developed using the chick chorioallantoic membrane model. In vivo studies using diffusion chamber implantation and subcutaneous implantation of human osteoprogenitors on rhBMP-2 encapsulated scaffolds showed morphologic evidence of new bone matrix and cartilage formation in athymic mice as assessed by x-ray analysis, immunocytochemistry and birefringence. These studies provide evidence of controlled release of BMP-2 from biodegradable polymer scaffolds initiating new bone formation in vivo.

The generation of 3-D biomimetic structures incorporating osteoinductive factors such as BMP-2 indicates their potential for de novo bone formation that exploits cell-matrix interactions and, significantly, realistic delivery protocols for growth factors in musculo-skeletal tissue engineering.

Introduction: Metal-on-metal (MOM) bearings after total hip arthroplasty are known to elevate the serum concentrations of metal ions, raising concerns about the long term effects. One potential modifier of ion release is the bearing diameter used. Resurfacing MOM bearings have a large surface area available for corrosion compared to the typical bearing size of 28 mm in total hip replacement (THR) but may benefit from improved lubrication and reduced production of corrodible wear debris. The net effect of these two variables on metal ion release is unknown. In this study, we compared the level of ion release in patients after large bearing MOM hip resurfacing arthroplasty with patient after small bearing MOM THR.

Methods: We measured the serum cobalt and chromium levels from 22 patients with large bearing diameter MOM hip resurfacing arthroplasty (Cormet 2000 and Birmingham Hip Resurfacing) and compared them to the serum cobalt and chromium levels of 22 patients with small bearing diameter (28 mm) MOM THR (Ultima). Patients were prospectively matched for activity level, body mass and date after surgery at blood sampling. All were at least 6 months after surgery.

Results: We found the median cobalt and chromium levels after hip resurfacing arthroplasty to be 7.6 times normal (median 38 nmol/L, range 14 to 144 nmol/L) and 10.5 times normal (median 53 nmol/L, range 25 to 165 nmol/L) respectively. This is compared to 4.4 times normal (median 22 nmol/L, range 15 to 87 nmol/L) for cobalt and 3.8 times normal (median 19 nmol/L, range 2 to 58 nmol/L) for chromium after 28 mm MOM THR (p=0.0021 and p< 0.0001).

Discussion: We concluded that large diameter MOM bearings result in greater release of cobalt and chromium ions than do small diameter MOM bearings. This may be of relevance when the potential side-effects of long-term exposure to elevated these metal ions is considered. It is not known to what extent this difference is due to corrosion of the component surfaces or of the wear particles produced.

Aims: Elevated serum cobalt and chromium ion levels associated with carcinogenesis and chromosomal damage in animals has raised concerns that metal-on-metal (MOM) total hip replacement (THR) in humans may produce the same effects over time. Considering that the risks may be related to the level of these ions in the body, this study compared the serum cobalt and chromium ion levels in patients with unilateral versus bilateral 28 mm diameter MOM THR.

Methods: All patients having THR at our institution were prospectively registered on a computerised database. From our database, we identified 108 patients with Ultima (Johnson and Johnson, Leeds) MOM THR with 28 mm bearing made of cobalt-chromium alloy. After patient review in clinic and before blood results were known, patient matching was performed by date after surgery at blood sampling, activity level and body mass. Using these stringent criteria, 11 unilateral THR could be adequately matched with 11 bilateral THR. Blood serum was taken with full anti-contamination protocols and serum analysed via inductively coupled plasma mass spectrometry.

Statistical analysis used the Mann-Whitney U test.

Results: The serum cobalt ion level after unilateral MOM THR was 4.4 times normal (median 22 nmol/L, range 15 to 37 nmol/L) compared to 8.4 times normal (median 42 nmol/L, range 19 to 221 nmol/L) for bilateral MOM THR (p=0.001). The serum chromium ion level after unilateral MOM THR was 3.8 times normal (median 19 nmol/L, range 2 to 35 nmol/L) compared to 10.4 times normal (median 52 nmol/L, range 19 to 287 nmol/L) for bilateral MOM THR (p=0.04).

Conclusions: This study has shown that the serum cobalt and chromium ion levels in patients with bilateral MOM THR are significantly higher than those in patients with unilateral MOM THR. With levels of up to 50 times the upper limit of normal, this finding may be of relevance for the potential development of long-term side effects.

Study Design. A reliability study of the Modic classification.

Objective. To determine the reliability and reproducibility of the Modic classification for lumbar vertebral marrow changes.

Summary of Background data. In 1988, Modic with colleagues described two degenerative stages of vertebral marrow and endplate morphology. These were Type I (inflammatory phase) and Type II (fatty phase). Later in 1988, he added a third variety; Type III where there was marked sclerosis adjacent to the endplates. No formal reliability or reproducibility studies had been performed on the Modic classification.

Methods. This study involved five independent observers of differing spinal experience using the Modic classification to grade fifty sagittal T1 and T2 weighted MRI scans. The observers repeated the assessment at three weeks. Intra- and inter-observer reliabilities were assessed using kappa statistics.

Results. There were 7 type I, 40 type II, 1 type III and 2 normal levels. The individual intra-observer agreement was substantial or excellent with kappa values ranging from 0.71 to 1.00. The overall inter-observer agreement was excellent with a kappa value of 0.85. There was complete agreement in 78% of the levels, a difference of one type in 14% and a difference of two or more in 8% of levels. The level of experience of the observer did not correlate with a better score.

Conclusions. We have shown that the Modic classification is both reliable and reproducible. It is simple and easy to apply for observers of varying clinical experience. We therefore recommend its use in clinical research and practice.

We have assessed the proximal capsular extension of the ankle joint in 18 patients who had a contrast-enhanced MRI ankle arthrogram in order to delineate the capsular attachments.

We noted consistent proximal capsular extensions anterior to the distal tibia and in the tibiofibular recess. The mean capsular extension anterior to the distal tibia was 9.6 mm (4.9 to 27.0) proximal to the anteroinferior tibial margin and 3.8 mm (−2.1 to 9.3) proximal to the dome of the tibial plafond. In the tibiofibular recess, the mean capsular extension was 19.2 mm (12.7 to 38.0) proximal to the anteroinferior tibial margin and 13.4 mm (5.8 to 20.5) proximal to the dome of the tibial plafond.

These areas of proximal capsular extensions run the risk of being traversed during the insertion of finewires for the treatment of fractures of the distal tibia. Surgeons using these techniques should be aware of this anatomy in order to minimise the risk of septic arthritis.

Introduction: To review the medium term outcome of staged surgery for treating recalcitrant idiopathic talipes equinovarus.

Methods: Between 1988 and 1995, we studied 91 club feet from a series of 120 recalcitrant feet in 86 patients requiring surgical treatment. The initial results have been reported previously and this cohort has been subsequently followed up for between 7 and 15years. The mean age at initial operation was 8.9 months. Surgery consisted of an initial plantar medial release followed two weeks later by a posterolateral release. This strategy was used specifically to address the problems of wound healing associated with single-stage surgery and to ascertain the rate of relapse after a two-stage procedure. The feet were classified preoperatively and prospectively into four grades according to the system suggested by Dimeglio et al. Reported relapse at last review was 0.0% in grade 2, 20.4% in grade 3 and 65.4% in grade 4 feet. The rate of overall relapse was 30.8%. At 7 to 15 year review an additional 9.1% in grade 2, 7.4% in grade 3, 11.5% in grade 4 had relapsed. Overall a further 8.8% had relapsed and were treated with further surgery. Functional outcome of the group remains good with 95.6% overall finding no restrictions to activities.

Conclusion: This review confirms that the strategy of staged surgery is supported in the medium term when considering rates of relapse and functional outcome.

Introduction: It has been proposed that the presence of the capital femoral ossific nucleus confers protection against ischaemic injury or avascular necrosis (at the time of reduction of a congenitally dislocated hip). The current literature is contradictory.

Materials & Methods: A prospective study was undertaken of the clinical and radiological outcomes following closed or open reduction. 50 hips were included in the study. These cases had either presented late or had failed conservative treatment. In 28 hips treatment was intentionally delayed until the appearance of the ossific nucleus (but not beyond 13 months) and in 22 the ossific nucleus was present at clinical presentation. 6 hips reached the age of 13 months without an ossific nucleus appearing and progressed to treatment. The significant avascular necrosis rate (> grade 1) was 7% for closed reduction and 14% for open. However, the amended rate if hips were excluded that had failed Pavlik harness treatment was 0.0% and 9% respectively (4% overall). Further surgical procedures were necessary in 57% of hips undergoing closed reduction and 41% after open, which compares favourably with other series.

Discussion: It is concluded that the presence of the ossific nucleus is an important factor in the prevention of AVN, particularly after late closed reduction. Intentional delay in the timing of surgery does not condemn a hip to open surgery but there is a comparable rate of secondary procedures becoming necessary particularly after closed reduction. The delayed strategy to await the appearance of the ossific nucleus for previously untreated dislocation allows a simple treatment algorithm to be employed which produces good clinical and radiological outcomes. The use of the Pavlik harness has been abandoned in cases of irreducible dislocation of the hip.

We describe a surgical procedure used to achieve glenothoracic fusion after one-stage radical, near total scapulectomy for primary or secondary malignant lesions in six patients. The aim was complete excision of the lesion and preservation of the glenoid to provide a fulcrum for movement of the arm.

Post-operative assessment involved determination of the range of movement and the application of the Musculoskeletal Tumour Society score and the Constant score to evaluate function. The results showed that a functional range of movement was attainable despite such radical surgery, although there was a considerable reduction in power and ability to lift.

Alumina has been the dominant ceramic used in orthopaedics since 1970. It is near diamond hardness is superior to all other biomaterials and its wettability has been a great benefit for tribological reasons. Over the past 30 years, this ceramic has gradually been optimized with superior processing, higher purity, greater density, and somewhat higher strength. Also serial numbers have been added to uniquely identify implant components and proof-testing now ensures that every implant is pre-clinically tested, compared to prior methods of sampling only 2–3% for destructive tests. The clinical downside remaining has been the small but troublesome fracture incidence of alumina implants. Historically, this has averaged 0.015% (15 per 100,000 cases) overall but varied from 0.08% up to 13% in those clinical series experiencing fractures (Heros, Sem. Arthrop-98). As well as creating patient hardships, fracture of any implant in the USA frequently leads to major lawsuits. Thus ceramic implants must be treated w While there has as yet been no FDA-approval given to market ceramic cups in the USA, there are a number of ceramic candidates being developed for both THR and TKR. These include zir-conia-alumina composites as well as new zironia/zirconia or zirconia/alumina combinations for THR. In addition, there are new combinations of toughened aluminas and also other choices such as silicone nitrides proposed for use with either metal CoCr heads or CoCr cups. Finally an alternate approach has been to provide a metal zirconium knee joint with a ceramic zirconia coating for improved bearing performance. Thus, the state of the art of alumina implants will be reviewed and put into perspective with the “new and improved” ceramics currently on the horizon. This survey will put into perspective the physical and mechanical attributes as well as the clinical performance of ceramic implants.

Major long-term complication of total hips is osteolysis in the more active patients. Osteolysis is a result of the biological response to the wear debris particles. This has resulted in the search for improved bearings such as metal and ceramic on polyethylene, all ceramic, and all metal total hips. Wear ranking of metal-polyethylene, ceramic-polyethylene, metal-metal, and ceramic-ceramic total hips has become clear at ratios of 1,000:500:10:1. However, wear debris from polyethylene, ceramic, and metal wear tests average about 0.6, 0.3, and 0.02 microns, respectively. From this information we can now deduce the number of particles librated is millions for ceramics, billions for polyethylene, and trillions for metal.

In recent years, studies have revealed new information on the biological response to various types of wear debris. Factors such as number of particles, particle morphology (size and shape), and surface to volume ratio are becoming keys to a partial comprehension of this biological response and osteolysis. Recent studies have demonstrated that smaller particles (< 0.1 microns) may be more toxic to cells than larger particles (> 0.1 microns). Studies have shown that crosslinking of polyethylene reduces the size of the wear debris particles and that for gamma irradiated polyethylene this reduction in size is proportional to the radiation dose. It has also been shown that crosslinking results in a significant reduction in fibril particles. Therefore, large reductions in wear rate do not necessarily mean that the total joint will be more successful. Thus, two factors, which interact, are the volume rate of wear and the morphology of the wear debris particles. Some investigators have developed a biological ind

Ceramic on ceramic hip-joint replacements (THR) are known for their excellent wear resistance. Such rigid-rigid bearings generally exhibit a biphasic wear-performance, i.e. a rapid run-in phase decreasing into a steady-state phase. However, due to the ultra-low wear of ceramics, few studies have adequately characterized these wear phases. Since this behavior was not well defined for modern alumina-on-alumina hips, we studied this phenomenon using hip simulator techniques. We also compared all-ceramic THR to UHMWPE wear-rates for exact comparison. Run-in wear was measured at 200,000 cycle intervals to 1 million cycles (1 Mc) followed by 500,000 cycle intervals to 14 Mc.

Alumina heads started off with high wear but then demonstrated a curvilinear run-in phase that smoothly transited into steady-state wear. The alumina liners had linear run-in to 0.6 Mc and then abruptly transited into steady-state by 0.8 Mc. During run-in, the liner wear was 40% greater than for the mating heads. Steady-state liner wear varied from 0.002 to 0.007 mm3/Mc. It was also clear that at least 10 million cycles were required to define the steady-state wear for alumina implants due to their ultra-low wear magnitudes. Combined head and cup run-in wear averaged 0.33 mm3/Mc and was completed within 0.8 Mc while steady-state wear was < 0.01 mm3/Mc up to 20 Mc. This was a remarkable 30-fold reduction from run-in.

The run-in phase would probably be completed by the first year of follow-up. Compared to UHMWPE cups, the alumina implants demonstrated a 9,000-fold wear-reduction over 20 million cycles in the simulator. This may correspond to 20 years in the typical patient. In addition, the alumina/UHMWPE combination has been favored historically because using CoCr/ UHMWPE bearings resulted in a doubling of the wear-rates in comparative clinical studies. Clearly the all-ceramic THR offers a much superior alternative with its massive reduction in wear-debris volume.

Aims: Cobalt (Co) and chromium (Cr) ion associated carcinogenesis and chromosomal damage in animals has raised concerns that metal-on-metal (MOM) total hip replacement (THR) in humans may produce the same effects over time. Considering that the risks may be related to the level of these ions in the body, this study compared the serum Co and Cr levels in patients with unilateral versus bilateral 28 mm diameter MOM THR. Methods: All patients having THR at our institution were prospectively registered on a computerised database. From our database, 108 Ultima MOM THR with 28 mm CoCrMo bearing were identiþed. After patient review in clinic and before blood results were known, patient matching was performed by date after surgery, activity level and weight. Using these stringent criteria, 11 unilateral THR could be adequately matched with 11 bilateral THR. Blood serum was taken with full anti-contamination protocols and serum analysed via atomic absorption spectrometry. Statistical analysis used the Mann-Whitney U test. Results: The median serum Co level after unilateral MOM THR was 22 nmol (range 15 to 37 nmol) compared to 42 nmol (range 19 to 221 nmol) for bilateral MOM THR (p=0.001). The median serum Cr level after unilateral MOM THR was 19 nmol (range 2 to 35 nmol) compared to 52 nmol (range 19 to 287 nmol) for bilateral MOM THR (p=0.04). Conclusions: This study has shown that the serum Co and Cr levels in patients with bilateral MOM THR are signiþcantly higher than those with unilateral MOM THR. With levels of up to 50 times the upper limit of normal, this þnding may be of relevance for the potential development of long-term side effects.

Aims: Identifying low-grade infection in failed total hip replacements (THR) is an important but often difficult task. Recently, there has been interest in the use of molecular biology techniques as potential sensitive tests for low-grade infection by identifying fragments of bacterial DNA within human tissue. Methods: We investigated the ability of a molecular biology technique known as the polymerase chain reaction (PCR) to identify low-grade infection during revision of THR considered to have failed from aseptic causes. We analysed 113 specimens of tissue and synovial fluid from 31 THR revised for aseptic loosening and compared them to 105 control specimens taken during 28 primary THR. All cases were performed in laminar flow theatres. No primary or revision specimen had positive microbiological cultures. No revision specimen had histological evidence suggestive of infection. Results: Using PCR, we identified bacterial DNA in 39 of 85 revision THR tissue specimens (46%) compared to 18 of 84 primary THR specimens (21.4%, p=0.001). Bacterial DNA was identified within the synovial fluid in three specimens taken from 28 revision THR (10.7%) and in two specimens taken from 21 primary THR (9.5%, p=0.36). As multiple specimens were sent per case, 16 of 31 revision THR (52%) and eight of 28 primary THR (29%) were considered to be infected (p=0.072). Conclusions: Our results suggest that many aseptically loose revision THR actually contain bacterial DNA within the peri-prosthetic tissue, but infrequently within the synovial fluid. With an overall specimen contamination rate of 19%, however, PCR has poor specificity for routine diagnostic use in revision THR.

Aims: There are no large published studies examining the complication rates associated with use of Kirschner wires in þxation of a wide variety of paediatric fractures. The aim of this study is to analyse the outcomes of fracture þxation using K-wire in upper limb fractures in children and to critically assess the incidence and type of complications. Methods: This study is a retrospective review of a consecutive series of 107 fractures in 105 paediatric trauma cases treated with K-wire in between 01.09.99 to 10.09.01. Results: The fractures were fractures around Wrist (47%) and around elbow (45%). 66 (61.68%) were performed by closed percutaneous technique, 27 (25.23%) by open method and in 14 (13.08%) combined approach was used. Around there were 13 cases with over-granulation at wound site, 6 cases of Soft tissue infection, 2 cases with tendinitis, 1 case of Osteo-myelitis and 1 case with hyper-sensitive scar. 3 cases found to have postoperative neurapraxia and 1 case with axonotmesis. Metal migration was detected in 4 cases and 14 cases found to have shown wire loosening. 10 fractures have lost position in postoperative period out of which 2 cases were reoperated for Re K-wire, 1 had undergone Re-MUA and 7 left for remodelling. Conclusions: K-wires are versatile but are not inherently benign. We conclude that best results could be achieved if total life of K-wire can be restricted to 3–4 weeks. We recommend one should explain all these risks and complications during consenting for K-wiring procedures.

Aim: Unicameral bone cysts are difficult to treat as partial cyst healing may reverse and it may be difficult to assess between active and latent types.

Materials and Methods: 19 patients with unicameral bone cysts were reviewed with a mean age of 8.5 years (16 males and 3 females). These 19 patients were reviewed over a period of fifteen years and all except one, had an active cyst abutting the growth plate. 18 cases were treated with curettage and burring using a dental burr and six cases were treated with elastic nailing. 12 cases were treated with bone marrow injection either alone or in combination with the above procedures. 2 cases were treated with steroid injections. No cases were bone grafted.

Results: The best results were obtained with curettage and burring of the lining of the cysts. Bone marrow injection alone did not produce resolution of any of the cysts. Migration of the cysts away from the growth plate in response to treatment (conversion from active to latent status) was predictive of successful treatment with no symptoms and no further fractures, irrespective of the age of the patient.

Conclusion: Successful treatment of unicameral bone cysts can be predicted by the appearance of normal bone formation by the physis and subsequent migration of the cyst away from the growth plate. The association of successful treatment and conversion to latency of the cyst has not previously been reported.

Lubricated metal-on-metal (MOM) bearing surfaces are not easily separated, unlike ceramic- or metal-on-UHMWPE (COP, MOP), due to interfacial forces and low diametric clearance that provides a ‘suction-fit’. In vivo videofluoroscopic studies have shown that patients with MOP/COP THRs exhibit separation of bearing surfaces by up to 3.1 mm during normal gait and 5.4 mm during active abduction while patients with MOM bearings do not. In this regard, MOM bearings may have similarities to constrained bearings with the potential to lower dislocation rates.

All patients under 70 years old undergoing primary THRs for primary osteoarthritis were prospectively registered on a computer database. From 1993–8, patients were offered a 28 mm COP bearing. After 1998, as part of a clinical trial, a 28 mm MOM bearing was inserted instead. For all cases, we used a metal-backed, uncemented acetabulum allowing a modular 10-degrees posteriorly augmented insert (Duraloc/PFC/Ultima, J& J) and the same cemented femoral stem (Ultima, J& J). The same experienced surgeon performed all operations using the posterior approach. Interfacial forces between bearing surfaces were assessed in vitro with a variable-speed-motor winch (APT) and a load-cell (E375/RDP) by recording peak-retaining-forces of bearing couples during separation with variable impact-distraction velocities. Statistical analysis used the Chi-square and student’s t-test.

We identified 140 COP THRs in 129 patients and 109 MOM THRs in 100 patients. Nine of 140 (6.4%) COP bearings dislocated within 3 months of surgery compared to 1 of 109 (0.9%) in the MOM group (p=0.024). No significant differences were identified between groups when comparing patient and prosthesis factors. In vitro assessment demonstrated that MOM bearing possessed interfacial retaining forces up to 30N more than COP bearing (p< 0.001).

This study demonstrates a significantly lower dislocation rate in THR with MOM bearing compared with COP. A potential explanation is the differential ease of separation that the two lubricated bearing couples possess due to interfacial retaining forces (viscous tension and ionic adhesive forces) exerted by the lubricating fluid.

Aims: Cobalt (Co) and chromium (Cr) ion associated carcinogenesis and chromosomal damage in animals have raised concerns that metal-on-metal (MOM) total hip replacement (THR) in humans may produce the same effects over time. Considering that the risks may be related to the level of these ions in the body, this study compared the serum Co and Cr levels in patients with unilateral versus bilateral 28 mm diameter MOM THR.

Methods: All patients having THR at our institution were prospectively registered on a computerised database. From our database, 108 Ultima MOM THR with 28 mm CoCrMo bearing were identified. After patient review in clinic and before blood results were known, patient matching was performed by date after surgery, activity level and weight. Using these stringent criteria, 11 unilateral THR could be adequately matched with 11 bilateral THR. Blood serum was taken with full anti-contamination protocols and serum analysed via inductively coupled plasma mass spectrometry (ICP-MS) Statistical analysis used the Mann-Whitney U test.

Results: The median serum Co level after unilateral MOM THR was 22 nmol (range 15 to 37 nmol) compared to 42 nmol (range 19 to 221 nmol) for bilateral MOM THR (p=0.001). The median serum Cr level after unilateral MOM THR was 19 nmol (range 2 to 35 nmol) compared to 52 nmol (range 19 to 287 nmol) for bilateral MOM THR (p=0.04).

Conclusions: This study has shown that the serum Co and Cr levels in patients with bilateral MOM THR are significantly higher than those with unilateral MOM THR. With levels of up to 50 times the upper of limit of normal, this finding may be of relevance for the development of potential long-term side effects.

According to the knee simulator test results in 1970s, the total decrease in thickness of UHMWPE tibial tray in combination with ceramic femoral component [F-Comp] was less than one tenth as that of the combination with metal [1]. These advantages led to development of total knee prosthesis [TKP] with alumina ceramics. In this study, we report the wear surface observation, the clinical wear and the oxidation of the retrieved TKP used clinically for 23 years, comparing with a metal TKP.

The retrieved TKP was implanted in 1979, and retrieved on January 9th in 2002. This TKP consisted of an alumina ceramic F-Comp and a UHMWPE tray combined with a alumina ceramic tibial component. Observations of the surface of alumina F-Comp and UHMWPE tray were carried out using SEM. Shape of UHMWPE tray was determined three-dimensionally. Comparing the result with original shape based on the product’s plan, liner wear and volumetric wear were calculated. Oxidation index was determined by Fourier transform infrared spectrophotometry.

Alumina F-Comp did not have any scratch on the surface by seeing with naked eye. UHMWPE tray had deformation and scratches obviously. The liner wear rate was 37 micrometer/year and volumetric wear rate was 18.8 mm3/year. The oxidation indexes were 0.6 in the unworn area, 1.2 in the worn area and 0.2 in the inner area.

SEM observations of the F-Comp demonstrated no scratch or pit. In contrast, many scratches were clearly observed on the UHMWPE tray. However, higher magnification observations did not demonstrate severe wear, which was shown on the wear analysis of a metallic F-Comp. Oxidation degradation is a problem to solve. However, the low wear rate and mild wear pattern demonstrate that ceramic F-Comp reduced UHMWPE wear.

Synthetic bone substitutes provide an alternative to autograft but do not give equivalent clinical results. Their performance may be enhanced by adding osteogenic growth factors. In this study, TGFβ1 was absorbed on to a carrier of β tricalcium phosphate and Gelfoam® and used to fill a defect around a tibial implant in a rat model of revision arthoplasty.

We added 0.0, 0.02 μg, 0.1 μg or 1.0 μg of TGFβ1 to the carrier and then implanted it around an hydroxyapatite-coated stainless-steel pin in the proximal tibia of rats. The tibiae were harvested at three, six or 26 weeks and the amount of bone formation and ceramic resorption were assessed.

TGFβ1 had no effect on the amount of bone in the defect, the amount of fluorescent label incorporated or the rate of mineral apposition. The growth factor did not significantly affect the amount of β TCP remaining in the tissue at any of the time points.

Aims: Metal-on-Metal (MOM) bearings for Total Hip Arthroplasty (THA) are known to elevate the serum concentrations of metal ions, raising concern about possible long-term side-effects. One potential modifier of ion release is the bearing diameter used. Resurfacing MOM bearings have a large surface area available for corrosion, but may benefit from improved lubrication and reduced production of corrodible wear debris. The net effect of these two variables on metal ion release is unknown.

Methods: In this study, we measured the serum cobalt and chromium levels from 22 large diameter MOM resurfacing arthroplasties (Cormet2000 & Birmingham Hip Resurfacing) and compared them to 22 THA (Ultima) with a bearing diameter of 28 mm. Patients were prospectively matched for activity level, weight and date after surgery. All were at least 6 months after surgery.

Results: At a median of 16 months (range 7 to 56) after resurfacing arthroplasty, we found the median serum cobalt and chromium levels to be 38 nmol/l (14 to 44) and 53 nmol/l (23 to 165) respectively. Both these figures were significantly greater than the levels after 28 mm MOM THA, which were 22 nmol/l (15 to 87, p=0.021) and 19 nmol/l (2 to 58, p< 0.001) for cobalt and chromium respectively.

Conclusions: As the upper limit of normal in patients without implants is typically 5 nmol/l, both groups had significantly raised metal ion levels, albeit at a relatively short median follow-up period. Large diameter MOM bearings resulted in a greater systemic release of cobalt and chromium ions than did small diameter bearings. This may be of relevance for potential long-term side-effects. It is not known to what extent this difference is due to corrosion of the component surfaces or of the wear particles produced.

The purpose of the project was to develop a questionnaire for completion by patients with elbow pathologies which is short and practical, internally consistent, valid, responsive and sensitive to changes of clinical importance.

The first, pilot phase included 43 patients who each completed a 19 item questionnaire relating to elbow function. The 19 ADLs produced a total scale Cronbach Alpha of 0.96., two different groups of ADLs were identified by multivariate analysis. Group 1 consisted of ADLs requiring moderate to high isometric loading and Group 2 of ADLs requiring high flexion. From the 19 items the best 10 which represented both groups were selected. A summary score was used to create the Wrightington Elbow Disability Score (WEDS).

In the second phase 89 patients completed the new WEDS form, reliability studies produced a Cronbach’s alpha value of 0.91. Internal validity of the groups of ADLs all correlated at p< 0.001 level with strength (Group1) and flexion (Group 2). A sub set of 40 patients undergoing total elbow arthroplasty were assessed for sensitivity to change in disability, the WEDS indicated a significant improvement at the p< 0.001. Convergent validity was demonstrated by the correlation with the ASES-e score at p< 0.001 level. The WEDS was significantly correlated with the ASES-e but not the DASH score.

Our study confirms that the WEDS questionnaire which is short and practical, is internally consistent, valid, responsive and sensitive to changes of clinical importance.

Aims: After Total Hip Replacement (THR), bearing surface pistoning during the gait cycle can affect wear rates. This ‘micro-separation’ has been shown clinically by video-fluoroscopy to be greater with a Metal-on-Polyethylene (MOP) bearing than a Metal-on-Metal (MOM) one. In this study, we quantified the suction forces that these bearings generate during the swing phase of the gait cycle as a result of interfacial tension from the thin fluid film present at the bearing surface. Methods: We used a servo-hydraulic universal testing machine with 250N load cell and programmed a sinusoidal waveform that could vary the loads and frequencies applied to MOP or MOM bearings submerged in 25% serum. We measured the bearing separation (±1μm) at tensile loads of 10N to 100N lasting 0.1s to 0.5s per 1Hz cycle.

Results: MOM bearings resisted tensile loads of up to 35N when applied for 0.1s to 0.5s of the simulated gait cycle. Bearing separation was measured at a maximum of 198 microns. Above 50N, the MOM bearing was unable to prevent separation occurring even when applied for only 0.1s of the simulated gait cycle (p< 0.001). The MOP bearing could not resist separation at any of the applied tensile loads (p< 0.0001).

Conclusions: The suction-fit of the MOM bearing used in this study is insufficient to prevent bearing separation due to gravity (110N). However, it may reduce the total bearing separation distance by delaying the time point at which separation occurs during the finite period of the swing phase (< 0.5s) during the gait cycle. This effect is crucially dependent upon the bearing clearance, bearing diameter, weight of the leg, speed of walking and soft tissue tension around the hip. This ultimately relies upon prosthetic design, patient selection and surgical technique.

Metal-on-metal (MOM) bearings for hip arthroplasty are increasing in popularity. Concern remains, however, regarding the potential toxicological effects of the metal ions which these bearings release.

The serum levels of cobalt and chromium in 22 patients who had undergone MOM resurfacing arthroplasty were compared with a matched group of 22 patients who had undergone 28 mm MOM total hip arthroplasty (THA).

At a median of 16 months (7 to 56) after resurfacing arthroplasty, we found the median serum levels of cobalt and chromium to be 38 nmol/l (14 to 44) and 53 nmol/l (23 to 165) respectively. These were significantly greater than the levels after 28 mm MOM THA which were 22 nmol/l (15 to 87, p = 0.021) and 19 nmol/l (2 to 58, p < 0.001) respectively.

Since the upper limit for normal patients without implants is typically 5 nmol/l, both groups had significantly raised levels of metal ions. MOM bearings of large diameter, however, result in a greater systemic exposure of cobalt and chromium ions than bearings of small diameter. This may be of relevance for potential long-term side-effects. It is not known to what extent this difference is due to corrosion of the surfaces of the component or of the wear particles produced.

Metal-on-metal (MOM) is a commonly used bearing notable for its ‘suction fit’ when lubricated. In this study, we examined the capacity for MOM bearings to protect against dislocation after total hip replacement (THR).

We undertook a clinical investigation to compare the rate of dislocation of MOM bearings with those of ceramic-on-polyethylene (COP) bearings and found that one MOM bearing dislocated in a series of 109 hips (0.9%) compared with nine of 145 hips (6.2%) in the COP group (p = 0.02).

We also performed an in vitro investigation comparing the peak forces generated during forced separation of the two bearings of the same dimensions at velocities from 1 to 50 cm/s. This revealed that the MOM bearing generated significant resistance to separation at all velocities (maximum mean 24 N), whereas the COP did not (maximum mean 1.9 N, p < 0.001). We conclude that MOM bearings are more stable to dislocation than COP bearings as a result of the interfacial forces provided by a thin, lubricating fluid.

Background: The necessity for radiographic follow up of infants with hip clicks and normal ultrasound is not clear.

Materials and methods: Infants referred to a paediatric hip clinic whose sole risk factor for DDH was a soft tissue hip click who had a normal ultrasound scan on initial assessment were identified. A follow up six month AP pelvis radiograph was assessed and acetabular index(A.I), position of femoral ossific nucleus and Shen-ton’s line measured. Infants with rotated pelvis Xrays were excluded. Inter-observer variability for acetabular index was measured and dysplasia defined according to Tonnis.

Results: 171 infants (193 clicking hips) met the criteria for inclusion. 48 male and 109 female with unilateral clicks (57 right, 64 left) and 36 bilateral clicks. 10 were excluded due to rotation of the AP pelvis Xray. Inter-observer error for A.I. was 4°. All A.I. were within normal ranges. Shenton’s line was unbroken and all hips were located.

Conclusion: In this study infants with soft tissue hip clicks and a normal ultrasound scan on initial assessment had a normal Xray at six months.

Clinical screening aims to identify and treat infants with neonatal hip instability in order to reduce the risk of subsequent hip displacement but risks failures of diagnosis and treatment (abduction splinting) and potential iatrogenic effects. The Hip Trial aims to assess the clinical effectiveness of ultrasound (US) imaging compared to clinical assessment alone to guide the further management of infants with clinical hip instability.

Infants with clinical hip instability confirmed by a second senior doctor were recruited from 33 UK centres and randomised to standardised US hip examination at age 2–8 weeks [US group: n=314] or clinical assessment alone [no ultrasound (NU) group: n=315. ] Primary outcomes by two years were hip X-ray appearances, operative treatment, abduction, splinting and walking. Analysis was ‘intention to treat’.

Key prognostic factors were similar between the randomised groups. Protocol compliance was high (90% US; 92% NU). X-ray information was available for 91% by 12–14 months and 85% by two years. Fewer children in the US group had abduction splinting in the first two years (RR 0. 78; 95% CI 0. 65–0. 94; p=0. 01). Operative treatment was required by 21 US (6. 7%) and 25 NU (7. 9%) infants (RR 0. 84; 95% CI 0. 48–1. 47. ) By two years, subluxation, dislocation, acetabular dysplasia or avascular necrosis were identified on X-ray on one or both hips of 21 US and 21 NU children (RR 1. 00; 95% CI 0. 56 – 1. 80. ) One US and 4 NU children were not walking by two years (RR 0. 25; exact 95% CI 0. 03–2. 53; p=0. 37)

The use of US imaging in infants with screen-detected clinical hip instability allows abduction splinting rates to be reduced, and is not associated with an increase in abnormal hip development or higher rates of operative treatment by two years of age.

Between June 1988 and December 1997, 332 babies with 546 dysplastic hips were treated in the Pavlik harness for primary Developmental Dysplasia (DDH) as a product of the Southampton selective screening program. Each was managed by a strict protocol including ultrasonic monitoring of treatment within the harness. The group was prospectively studied over a mean duration of 6. 5 years (SD=2. 7y) with 89. 1% follow-up. The Acetabular Index (AI) and Centre-Edge angle of Wiberg (CEA) were measured on annual radiographs to determine the natural history of hip development following treatment in the Pavilik harness. These were compared to published normal values.

We observed a failed reduction rate of 15. 2% of all complete hip dislocations; these required alternative surgical treatment. The development of those hips of infants successfully treated in the harness showed no significant difference from the normal values of Acetabular Index for female left hips, after eighteen months of age. Of those dysplastic hips that were successfully reduced in the harness; 2. 4% exhibited persisting significant late dysplasia (CEA< 20°) and 0.2% demonstrated persistent severe late dysplasia (CEA< 15 °) All such cases could be identified at sixty months. Dysplasia was clinically deemed sufficient to merit innominate osteotomy in 0. 9% dysplastic hips treated. Avascular necrosis was noted in 1% of hips treated in the harness.

We conclude that using our protocol, successful initial treatment of DDH with the Pavlik harness appears to revert the natural history of hip development to that of the normal population. We recommend that regular radiographic surveillance up to 60 months of age constitutes safe and effective practice.

Differentiating cases of aseptic loosening of total hip arthroplasty (THA) from loosening due to low-grade infection can often be difficult. It is possible that some cases of ‘aseptic’ loosening may be related to unidentified bacterial infection.

Using Polymerase Chain Reaction (PCR), this study attempted to identify the frequency with which bacterial DNA could be observed at revision arthroplasty for what was considered ‘aseptic’ loosening.

All revision cases had to fulfil strict criteria to be considered aseptically loose In all cases operative specimens from the synovial fluid, synovium, femoral and acetabular membranes where possible were sent for analysis by histology, bacteriology and by PCR to identify the presence of the 16S bacterial ribosomal fraction, an indicator of bacterial DNA. Ten bacteria per millilitre of tissue/fluid were the threshold for detection. As a control for environmental contamination, specimens from primary THA were also sent for analysis in the same manner as revisions.

The identification of bacterial DNA in at least one sample from a patient was considered a positive case result.

45 revision THA were identified over a 3-year period (1998–2001). From those 45 revision cases, 163 specimens were sent for analysis by PCR. These specimens were compared to the control group of 34 primary THA from which 91 specimens were sent for analysis by PCR. When analysed by specimens positive by PCR, bacterial DNA was identified in 55 of 163 specimens sent from the 45 revision THA. This compared with 21 of 91 specimens positive by PCR sent from the 34 primary THA (p=0. 07).

When analysed by cases positive by PCR, bacterial DNA was identified in 29 of 45 revision THA and in 8 of 34 primary THA (p< 0. 001).

PCR is a sensitive test for detecting infection in revision THA. Results from the primary THA cases would suggest there is at least a 23% false positive rate even with negative bacterial culture. The increased frequency with which bacterial DNA has been identified in ‘aseptically’ loose revision THAs, however, is unlikely to be due solely to environmental contamination. These results may have relevance for our interpretation and understanding of aseptic loosening as well for the diagnosis of prosthetic infection.

The objective of this study was to compare the wear mode of 100 Mrad PE cups run in a hip simulator to retrieved 100 Mrad PE cups, and to evaluate the efficacy of the PE wear model.

15 In-vitro PE cups: 3 each 0,2.5.50,100 and 150 Mrad (9 channel hip simulator, 6.2 million cycle duration, physiological load profile by Paul, 2000N maximum load at 1Hz using 30% bovine serum). 5 Retrieved PE cups: three SOM cups (Mizuho Medical Instrument Co., COP alloy 28 mm head)-0 Mrad after 8 years of clinical use, two 100 Mrad cups after 15 years of clinical use, two T28 PE 2.5 Mrad cups (Zimmer): 18 years and 13 years of clinical use. The cups were examined using a SEM (Philip XL30 FEG) for wear scar locations and PE wear-topography.

Original machine marks were observed in the weight-bearing areas of the highly cross-linked in-vitro PE. No machine marks were observed for the 0 and 2.5 Mrad in-vitro cups and none were seen in any of the retrieved cups. The formation of more nodules and fibrils in the 0Mrad cups compared to the extensivley cross-linked cups (in-vitro and retrieved) was striking. The frequency of occurrence and length of the fibrils and nodules was dependent on the dose of gamma irradiation. More ripples were formed in the 2.5 Mrad and higher cups compared to the non-irradiated cups (in-vitro and retrieved). The in-vitro cups formed more ripples than the retrieved cups. In general, the SEM features for in-vitro Mrad cups appeared similar to those of the retrieved Mrad cups.

The in-vitro Mrad cups accurately reflected the conditions of the artificial joint in living body. Therefore, comparisons of retrieved PE cups with simulator PE cups appeared to be a very powerful research tool.

(2) SEM observation demonstrated far less wear damage in the extensively cross-linked cups than in the non-extensively cross-linked PE. Thus the extensive cross-linked PE cups appeared to be a significant improvement over conventional PE cups in terms of wear resistance.

Programmed cell death (PCD) contributes to the pathogenesis of many diseases including osteoarthritis. The principal method is apoptosis that has a well-defined and very characteristic morphology and biochemistry.

The aim of the present study was examine whether the mechanism of cell death in OA chondrocytes was classical apoptosis.

Rat thymocytes were used as controls since these cells are known to undergo classical apoptosis. Human OA cartilage was obtained from femoral head of patients (50 – 80 years) who were undergoing joint replacement surgery. Pieces of OA samples were processed into paraffin and sections incubated with the following antibodies: M3O, an antibody that recognizes the cleavage of cytokeratin 18 by caspases; annexin V, which recognizes phosphatidylserine “flip-flop” that occurs early in the apoptotic process; bcl-2, a protein whose presence protects apoptosis and c-myc, a transcription factor thought to be associated with apoptosis. To induce apoptosis, some samples were incubated with etoposide and staurosporine.

In sections of thymus we noticed the presence of numerous apoptotic bodies. The number increased when the tissue was treated with etoposide and staurosporine. Some thymocytes were immunopositive for M3O and annexin V, and the number of positive cells increased when treated for 2h with etoposide. Chondrocytes of the articular cartilage showed chromatin condensation and many vacuoles but no fragmentation into apoptotic bodies, even when treated with etoposide or staurosporine. The OA chondrocytes were immunonegative for M3O and annexin-V, even after incubation with etoposide and staurosporine. With respect to c-myc and bcl-2, both non-weight bearing and weight-bearing areas in OA sample showed more positive cells then the thymus. More chondrocytes stained for c-myc in the superficial zone of the articular cartilage in the non-weight bearing, while in the weight-bearing areas it was more in the intermediate zone. On the other hand, there were no differences in the distribution of the cells stained for bcl-2 in the articular cartilage. It is known that some events like the phosphatidylserine flip, caspase activation and apoptotic bodies fragmentation occur quickly during apoptosis, so may be difficult to detect.

The results suggest that some features of classical apoptosis, such as phosphatidylserine flip,caspase activation and apoptotic bodies formation did not take place in OA cartilage. It is known that the molecular machinery for apoptosis is not always present in tissues that are undergoing programmed cell death, which seems to be case for OA chondrocytes.

The formation of biomimetic environments using scaffolds containing cell recognition sequence and osteo-inductive factors in combination with bone cells offers tremendous potential for bone and cartilage regeneration. In tissues, collagen forms the scaffold by mediating the flux of chemical and mechanical stimuli. Recently, a synthetic 15-residue peptide P-15, related biologically to the active domain of type I collagen, has been found to promote attachment and the osteoblast phenotype of human dermal fibroblasts and periodontal ligament fibroblasts on particulate anorganic bone mineral (ABM). The aim of this study was to exam the ability of the collagen peptide, P-15, to promote human osteoprogenitor attachment, proliferation and differentiation on cell culture surfaces and 3-D scaffolds.

Selected human bone marrow cells were cultured on particulate microporous anorganic bone mineral (‘pure ‘ hydroxyapatite based on x-ray diffraction standard JCPDS9-432) phase and polygalactin vicryl mesh adsorbed with or without P-15 in basal or osteogenic conditions. Cell adhesion, spreading and patterning were examined by light and confocal microscopy following incorporation of cell tracker green and ethidium homodimer fluorescent labels. Osteoprogenitor proliferation and differentiation was assessed by DNA content and alkaline phosphatase specific activity. Growth and differentiation on 3-D ABM structures were examined by confocal and scanning electron microscopy (SEM).

P-15 promoted human osteoprogenitor cell attachment and patterning on particulate bovine anorganic bone mineral phase and polygalactin vicryl mesh over 5–24 hours compared to culture on ABM and vicryl mesh alone as observed by photomicroscopy. Increased alkaline phosphatase specific activity was enhanced following culture on P-15 adsorbed matrices as recognized by enhanced expression of alkaline phosphatase, type I collagen, osteocalcin and cfba-1. The presence of mineralised bone matrix and extensive cell ingrowth and cellular bridging between 3-D ABM matrices and polygalactin vicryl mesh adsorbed with P-15 was observed by confocal microscopy and alizarin red staining. SEM confirmed the 3-D structure of newly formed cell constructs and cellular ingrowth on and between the P-15 modified inorganic bone mineral materials. Negligible cell growth was observed on ABM alone or polygalactin vicryl mesh alone.

These observations demonstrate that the synthetic 15-residue collagen peptide, P-15, when adsorbed to ABM or polygalactin vicryl mesh, can stimulate human osteoprogenitor attachment and spreading. They also demonstrated that P-15 coupled 3-D matrices stimulate human osteoprogenitor differentiation and materialisation. The studies indicate that a synthetic analogue of collagen provides a biomimetic environment supportive for cell differentiation and tissue regeneration and indicate a potential for the use of extracellular matrix cue in the development of biomimetic environments for bone tissue engineering.

Background: Metal-on-metal (MOM) bearing surfaces with low diametric clearance possess a surface tension that prevents easy separation of the surfaces when lubricated. Potentially this ‘suction-fit’ may increase the torque required for dislocation. This study assessed the protective role of a MOM bearing surface as a single risk factor for dislocation.

Method: Prospective data was recorded on a series of 229 patients undergoing 249 primary THR for osteoarthritis. From 1993–8, patients under 70 years old were routinely given a 28mm ceramic-on-polyethylene (COP) bearing surface. Due to a high dislocation rate (see results below), an alternative was sought (1998–2001) and a 28mm metal-on-metal (MOM) bearing system chosen. For all cases in both groups, the acetabulum was uncemented with a modular 10° posterior lip insert allowing the same primary arc range (Duraloc/PFC/ Ultima, Johnson & Johnson). The cemented femoral component was the same in all cases (Ultima). All operations were performed by the same surgeon using the posterior approach. Variables in patient and prosthesis factors were compared. Statistical analysis was performed by the Chi-square and student’s t-test where appropriate.

Results: We identified 140 THR in 129 patients who received a COP bearing and 109 THR in 100 patients who received a MOM bearing. Nine of 140 (6.4%) COP bearings dislocated within 3 months of surgery compared to 1 of 109 (0.9%) in the MOM group (p=0.028). No significant differences were identified between groups when comparing factors relating to the patient or prosthesis.

Discussion: This study has shown a high dislocation rate for a COP bearing that was reduced to a low dislocation rate by changing the bearing surface to a MOM design. A potential mechanism for this may be the ‘suction fit’ from the surface tension of the low clearance, high tolerance that the metal-on-metal bearing possesses, requiring increased torque to dislocate during impingement.

Purpose: To describe the characteristic examination findings post whiplash injury of relevance to the shoulder surgeon and an injection test, which can be used to abolish these signs and distinguish neck from shoulder pathology.

5A large amount has been written about whiplash injuries of the neck, but many of these patients are often referred to shoulder units for assessment either acutely or years after the accident because of continuing symptoms. Although neck pain is the commonest complaint tenderness on examination is sided and within the trapezius muscle in virtually all cases. Pain referred to the shoulder is also reported in 36 – 67% whilst interscapular pain occurs in 20 – 72%, depending on the time from injury.

We have reviewed a personal series of the senior author of over 700 cases. The consistent finding in these patients is tenderness localised to a specific part of the trapezius in the base of the neck, which is sided. Tenderness on the same side is also present along the vertebral border of the scapula to its lower pole in over 90%, provided the scapula is protracted. A further finding in some patients is a high arc of pain on abducting the arm, thus simulating an acromioclavicular joint problem, but in these cases the pain is localised to the trapezius. These findings are in addition to those of the neck, which may show some restricted movement due to pain.

The trapezius tenderness can be abolished by the injection of local anaesthetic into the trigger spot at the base of the neck (whiplash injection test), which also resolves most of the above signs and allows further assessment of the shoulder without the referred pain from the injected area.

Conclusions: Shoulder examination in patients who have suffered whiplash injuries is often difficult due to referred pain. Knowledge of the signs specifically due to the whiplash injury is required so that shoulder pathology is not assumed. A new whiplash injection test not previously described has been found very useful in abolishing the whiplash signs to enable accurate shoulder assessment in our practice.

The growth plates of rapidly growing animals have been studied extensively. Nevertheless, several questions remain unanswered, partly because many events happen simultaneously, especially at the vascular front. Terminal chondrocytes are thought to undergo programmed cell death, but the fate of the cell remnants remains unclear. Are the dying cells released into the vascular space and phagocytosed by macrophages, as one would expect for apoptosis? Or are the cells eliminated prior to opening of the lacunae, leaving empty lacunae? Do all terminal chondrocytes die or do some become bone-forming cells? Rodents maintain a growth plate into old age, long after longitudinal growth has ceased. These stationary growth plates have several features not found in the growth plates of rapidly growing animals and closer study of these features may provide answers to the above questions. Femurs and tibiae from 4–16 week-old and 62–80 week-old rats were decalcified, processed into paraffin, and the morphological changes were documented.

Between 4–16 weeks, the heights of the growth plates decreased due to loss of the large hypertrophic chondrocytes, but the various zones were still present. In the aged rats, the growth plates were identifiable as a narrow cartilaginous band with some short columns of inactive cells. The vascular front was irregular, the narrow spicules of primary spongiosa were absent and the much thicker spicules, which are normally seen in secondary spongiosa, directly abutted to the cartilage. Horizontal apposition of bone matrix onto the cartilage edge was frequently present. In addition, the following features were noted. 1) Acellular areas: Nearly all growth plates contained regions of cartilage from which all cells and their lacunae had disappeared. In some cases, these acellular regions stretched from the reserve zone to the vascular front and even persisted as a relatively wide core within the spicules of spongiosa, indicating increased resistance of acellular cartilage to resorption. The absence of cells or cell debris was consistent with an autophagic mode of cell death and subsequent collapse of the lacunae. 2) Remodelling within the growth plate; in some growth plates, large regions of growth plate cartilage had been resorbed and new bone had been laid down in a pattern similar to the remodelling of cortical bone. This suggested that the normal resistance of cartilage to vascular invasion had been lost locally, but was maintained in adjacent non-remodelled regions. 3) Trans-differentiation of chondrocytes to bone-forming cells; extensive new medullary bone formation was noted in the diaphysis of approximately 30% of the aged rats, suggesting that they had received an (unknown) osteogenic stimulus. In these rats, bone matrix was identifiable inside chondrocytic lacunae, and spreading beyond the confines of the lacunae, thus directly replacing growth plate cartilage with bone matrix.

The results suggest that i) chondrocytes are capable of self-elimination, perhaps by a mechanism similar to the autophagic cell death that occurs during insect metamorphosis; ii) resorption of cartilage and vascular invasion requires the presence of the viable chondrocytes; and iii) chondrocytes have the capacity to transdifferentiate to bone-forming cells, but only do so when receiving an increased osteogenic stimulus.

Ex vivo gene transfer of osteogenic factors into multipotential stem cells offers potentially important therapeutic implications in a variety of musculoskeletal diseases. One possible approach is the development of a cellular vehicle, namely bone morphogenetic protein (BMP)-producing bone marrow cells, created using adenoviral gene transfer. These transduced cells provide local delivery of BMP for bone formation. The aims of this study were to study the feasibility of gene transfer to human bone osteoprogenitor cells, using adenoviral vectors. Specifically, the aims were to study the efficacy of transduction with an adenoviral vector expressing BMP-2 and then to determine the ability of the transduced cells to produce active BMP-2 and to generate bone ex vivo.

Primary human bone marrow osteoprogenitor cells were expanded in culture and infected with AxCALacZ, a replication-deficient adenoviral vector carrying the E. coli lacZ gene, with a range of multiplicity of infection (MOI) of 6.25 to100. Transduced cells showed positive staining for β-galactosidase using X-Gal with an efficiency close to 100%. Uninfected cells showed no β-galactosidase activity. Efficiency was independent from MOI, however cells infected at the lower MOIs expressed lower levels of β-galactosidase. Following confirmation that primary bone marrow cells could be infected by adenoviral constructs, additional osteoprogenitors were infected with AxCAOBMP-2, a vector carrying the human BMP-2 gene, at a multiplicity of infection of 10–20. In order to determine BMP-2 activity, conditioned media from bone marrow cells expressing BMP-2 was added to promyoblast C₂C₁₂ cells. The promyoblast C₂C₁₂ cells are exquisitely sensitive to BMP-2 with induction of alkaline phosphatase activity (ED₅₀ 20 nM) in a dose-dependant manner. Alkaline phosphatase activity was induced following culture with conditioned media from BMP-2 expressing cells, in a dose dependant manner, confirming successful secretion of active BMP-2. Immunohistochemical staining for alka- line phosphatase in C₂C₁₂ cells also confirmed the bio-chemical observations. Media from uninfected control human bone marrow cells failed to produce a similar effect. The concentration of BMP-2 in the media was estimated to be 5–10 nM/10⁷ cells.

To examine whether adenoviral transfection affected the osteoblast phenotype and their ability to mineralise in vitro, adenovirally-transduced bone marrow cells expressing BMP-2 were seeded onto poly(-lactic acid co÷glycolic acid) (75:25) porous scaffolds (provided by K. Shakesheff and S. Howdle; Nottingham University) and cultured for up to 6 weeks. Expression of alkaline phosphatase activity, type I collagen formation, as well as the synthesis of osteoblast stimulating factor-1 confirmed bone cell differentiation and maintenance of the osteoblast phenotype in extended culture for up to 6 weeks.

These results indicate the ability to deliver active BMP-2 using human bone marrow osteoprogenitor cells following adenoviral infection. The maintenance of osteoblast phenotype in extended culture and generation of mineralised 3-D scaffolds containing such constructs offers a realistic approach to tissue engineer bone for orthopaedic applications.

The ossific nucleus in Developmental Dysplasia of the Hip. A study of relative ossific nuceus size in hips treated in the Pavlik harness and its predictive value in treatment outcome.

Purpose

To assess the value of measuring relative ossific nucleus (ON) size difference in Developmental Dysplasia of the hip (DDH) as a potential predictor of outcome of hips treated in the Pavlik Harness.

Study Design

Prospective study of all unilateral cases (n=68) of DDH identified in Southampton by dynamic ultrasound and treated in a Pavlik harness studying changes in relative ON size and acetabular indices over a mean follow up period of 3.6 years.

Results

All cases responding to the Pavlik harness showed a progressive correction of ON size difference. Initial ON size difference was not associated with any difference in acetabular index at the date of last follow-up. Ultrasound grading of dysplasia did not affect the rate of normalisation of ON size difference.

Conclusion and clinical relevance

In patients responding to treatment of DDH in a Pavlik harness, ON size difference was not found to be a useful prognostic indicator of outcome.

Cohort studies in humans have suggested that the peak bone mass attained at skeletal maturity may be programmed in utero. To investigate which aspects of bone development might be influenced in utero, we utilised a rat model of maternal protein insufficiency, which has previously been used to demonstrate the fetal origin of adult hypertension. In rodents, a growth plate remains present throughout life, even after longitudinal growth ceases. Generally, the height of the growth plate is related to the rate of bone growth. Fast growing bones have maximal height growth plates, and as bone growth slows down the height decreases until it remains stationary.

The aim of this study was to compare the morphology of long bones in aged rats that had been subjected to protein insufficiency in utero with that of controls. Rat dams were fed either an 18% casein control diet or a 9% casein low protein diet from conception until the end of pregnancy. The offspring were fed a normal diet until death (~72 weeks), when bone density was measured by dual energy X-ray absorptiometry (DEXA) and the tibiae and femurs were processed for histology.

The offspring of rats from the low protein group had a significantly lower bone mass, as assessed by DEXA. The major differences in bone structure were found in the growth plates, which were very irregular without the usual zones of resting, proliferating and hypertrophic chondrocytes. A number of unusual cellular events were noted to have taken place subsequent to cessation of growth, including: a) elimination of all chondrocytes in a number of regions, resulting in vast acellular areas; b) formation of chondroid bone and/or transdifferentiation of chondrocytes to bone-forming cells in other regions; c) partial resorption of those latter regions while the acellular regions were not resorbed; d) ‘horizontal’ apposition of bone against a smooth metaphyseal edge of the growth plate.

To compare the growth plates from the low and high protein groups semi-quantitatively, the degrees of the above features were scored. In addition, the heights of the growth plates were were assessed by two independent measurements. In the low protein group, the height of the growth plate were found to be significantly greater (p< 0.001). Additionally, the growth plates from this group of animals were observed to be more irregular with regards to all the features outlined above.

These findings are consistent with the hypothesis that growth trajectory and bone mass are programmed in early life. The increased height of the growth plate in animals undernourished in utero may reflect the cessation of growth at an earlier age. The increased irregularity of the growth plate in this group of animals may infer an earlier onset of age-related changes within the growth cartilage.

From a cohort of 110 idiopathic clubfeet, 26 feet in 18 children requiring surgery for severe relapse have been studied. Surgery was comprised of a lateral column shortening procedure (Lichtblau) plus or minus a plantarmedial release. Surgery was staged to avoid wound complications.

Pre-operatively, feet were prospectively categorised into one of four grades according to a system reported by Dimeglio. Children were reviewed on two subsequent occasions. At review, feet were again graded. In addition, appearance and functional outcome was analysed and included an assessment of gait, activity and functional limitation.

Three children were lost to follow-up, leaving 22 feet in seven male and eight female patients available for review. The mean age at surgery was 43 months (23–82). The mean time from surgery to first and second reviews was 35 and 56 months, respectively.

There was a significant improvement in grading at first review compared to pre-operative grading (Wilcoxon signed ranks test). Although there remained a significant improvement in grading at second review compared to the preoperative grading, there was a significant reduction in the number of feet in which grading had improved when compared to first review.

There was no significant change in function between the two post-operative reviews (Chi-square tests), with the majority of children experiencing little functional limitation. There were no wound complications.

Relapse surgery, involving a lateral column shortening procedure for severe clubfoot, results in a significant initial improvement when assessed using a grading system. This improvement in grading subsequently decreases over time. However, the functional outcome in such cases remains favourable.

Introduction: Aseptic loosening of THR has a multifactorial aetiology. Differentiating such cases from loosening due to low-grade infection can often be difficult. It is possible that at least some cases of ‘aseptic’ loosening may be related to unidentified bacterial infection. This study attempted to identify the frequency with which bacterial DNA could be observed in the periprosthetic membrane and synovial fluid of patients undergoing revision surgery for what was considered ‘aseptic’ loosening.

Methods: Specimens from 39 revision and 31 primary hip replacements were obtained. The latter were used as a control for environmental contamination. All revision THR cases were investigated pre-operatively for infection by CRP, ESR, WCC, Gallium Scan. Operative specimens were analysed by bacteriological culture as well as by PCR to identify the presence of the 16S bacterial ribosomal fraction. Results were analysed by Chi square test.

Results: By PCR, bacterial DNA was identified in 22 of 39 revision hip surgery specimens and 6 of 31 primary hip replacement specimens (p=0.002). By culture none of these specimens had any bacterial growth.

Conclusions: The increased frequency with which bacterial DNA has been identified in ‘aseptically’ loose revision THR is unlikely to be due solely to environmental contamination although this remains a concern. These results may have relevance for our interpretation and understanding of aseptic loosening as well for the diagnosis of prosthetic infection.

Between June 1988 and December 1997, we treated 332 babies with 546 dysplastic hips in a Pavlik harness for primary developmental dysplasia of the hip as detected by the selective screening programme in Southampton. Each was managed by a strict protocol including ultrasonic monitoring of treatment in the harness. The group was prospectively studied during a mean period of 6.5 ± 2.7 years with follow-up of 89.9%. The acetabular index (AI) and centre-edge angle of Wiberg (CEA) were measured on annual radiographs to determine the development of the hip after treatment and were compared with published normal values.

The harness failed to reduce 18 hips in 16 patients (15.2% of dislocations, 3.3% of DDH). These required surgical treatment. The development of those hips which were successfully treated in the harness showed no significant difference from the normal values of the AI for the left hips of girls after 18 months of age. Of those dysplastic hips which were successfully reduced in the harness, 2.4% showed persistent significant late dysplasia (CEA < 20°) and 0.2% persistent severe late dysplasia (CEA < 15°). All could be identified by an abnormal CEA (< 20°) at five years of age, and many from the progression of the AI by 18 months. Dysplasia was considered to be sufficient to require innominate osteotomy in five (0.9%). Avascular necrosis was noted in 1% of hips treated in the harness.

We conclude that, using our protocol, successful initial treatment of DDH with the Pavlik harness appears to restore the natural development of the hip to normal. We suggest that regular radiological surveillance up to five years of age is a safe and effective practice.

Templates are used in the preoperative planning of many orthopaedic procedures. The magnification of the bones on preoperative radiographs can vary despite using standardised radiological techniques. Templates will give misleading measurements unless this magnification is quantified.

A coin may be used to calculate the magnification, with significant improvement in the accuracy of templating (p = 0.05). A group of patients undergoing uncemented arthroplasty of the hip was at high risk for intraoperative fracture of the femur because the magnification of the radiograph was larger than that of the template.

This study investigated the relationship between histological, clinical and radiological features of aseptically loose total joint replacements (TJRs) and synovial fluid levels of interleukin (IL)-1b, IL-6, IL-8 and IL-10.

Tissue and synovial fluid samples were retrieved from patients undergoing primary (hip; n=15: knee; n=13), or revision of aseptically loose TJRs (hip; n=14: knee; n=9). The presence of inflammatory cells, blood vessels and wear debris in the tissue were assessed on a relative scale. Revision TJRs were assessed for sepsis, migration of the implant, gross loosening and the degree of radiolucency. Cytokine levels in the synovial fluid samples were determined by ELISA.

All cytokines were increased in synovial fluid from revision TJRs compared to primary replacements, as were the degree of macrophage and giant cell infiltration (p< 0.01). There was a significant positive correlation between the presence of macrophages and giant cells with the levels of IL-1b, IL-8 and IL-10 (p< 0.05) but not IL-6.

The amount of wear debris was related to the presence of macrophages and giant cells (p< 0.01) but not to any of the cytokines.

There were no relationships between any of the clinical parameters and the presence of wear debris or the levels of any cytokine with the exception of IL-6 and gross loosening (p< 0.01). Similarly there were no differences between hips and knees for any of the parameters except IL-6, for which higher levels were found in hips (p< 0.05).

The results suggest that macrophages and giant cells are responsible for the majority of IL-1b, IL-8 and IL-10 production but another cell type is contributing to IL-6 production. Furthermore, IL-6 does not fit the pattern of the other cytokines as it is upregulated in hip joints compared to knees and correlates with the presence of gross loosening. This may suggest a unique role for IL-6 that requires further investigation.

We reviewed the management of 100 cases of slipped upper femoral epiphysis treated over a period of 26 years. A total of 14 slips was identified as unstable on admission. These underwent reduction and stabilisation within 24 hours of the onset of severe symptoms. Of the 86 stable slips four progressed to avascular necrosis (AVN), which was not seen in the unstable slips. The literature on slipped upper femoral epiphysis suggests that the acute unstable slip is at higher risk of developing AVN. We recommend reduction and stabilisation of unstable slips within 24 hours of the onset of symptoms in order to reduce the risk of AVN.

Splitting fractures of the humeral head are rare; part of the humeral head dislocates and the unfractured part remains attached to the shaft. We report eight cases in young patients. In five the diagnosis was made at presentation: three had minimal internal fixation using a superior subacromial approach, one had a closed reduction and one a primary prosthetic replacement. All five patients regained excellent function with no avascular necrosis at two years. In three the injury was initially unrecognised; two developed a painless bony ankylosis and one is awaiting hemiarthroplasty.

It is important to obtain the three trauma radiographic views to diagnose these unusual fractures reliably. CT delineates the configuration of the fracture. In young patients open reduction and internal fixation seems preferable to replacement of the humeral head, since we have shown that the head is potentially viable.

We have investigated whether the thigh tourniquet used during total knee replacement (TKR) influenced the development of postoperative wound hypoxia and was a cause of delayed wound healing.

We allocated randomly 31 patients (31 TKRs) to one of three groups: 1) no tourniquet; 2) tourniquet inflated at low pressure (about 225 mmHg); and 3) tourniquet inflated to high pressure of about 350 mmHg. Wound oxygenation was measured using transcutaneous oxygen electrodes.

In the first week after surgery, patients with a tourniquet inflated to a high pressure had greater wound hypoxia than those with a low pressure. Those without a tourniquet also had wound hypoxia, but the degree and duration were less pronounced than in either of the groups with a tourniquet.

Use of a tourniquet during TKR can increase postoperative wound hypoxia, especially when inflated to high pressures. Our findings may be relevant to wound healing and the development of wound infection.

Between 1988 and 1995, we studied 91 club feet from a series of 120 recalcitrant feet in 86 patients requiring surgical treatment. There were 48 boys and 20 girls. The mean age at operation was 8.9 months. Surgery consisted of an initial plantar medial release followed two weeks later by a posterolateral release. This strategy was adopted specifically to address the problems of wound healing associated with single-stage surgery and to ascertain the rate of relapse after a two-stage procedure. Immobilisation in plaster was used for three months followed by night splintage. The feet were classified preoperatively and prospectively into four grades according to the system suggested by Dimeglio et al. Grade-1 feet were postural and did not require surgery. All wounds were closed primarily. One superficial wound infection occurred in a grade-4 foot and there were no cases of wound breakdown. The rate of relapse was 20.4% in grade-3 and 65.4% in grade-4 feet.

Two-stage surgery for the treatment of club foot seems to be effective in the reduction of wound problems but does not appear to give significantly better results in terms of relapse when performed for more severe deformities.

Chondrocytes at the lower zone of the growth plate must be eliminated to facilitate longitudinal growth; this is generally assumed to involve apoptosis. We attempted to provide definitive electron-microscopic evidence of apoptosis in chondrocytes of physes and chondroepiphyses in the rabbit. We were, however, unable to find a single chondrocyte with the ultrastructure of ‘classical’ apoptosis in vivo, although such a cell was found in vitro. Instead, condensed chondrocytes had a convoluted nucleus with patchy chromatin condensations while the cytoplasm was dark with excessive amounts of endoplasmic reticulum. These cells were termed ‘dark chondrocytes’. A detailed study of their ultrastructure combined with localisation methods in situ suggested a different mechanism of programmed cell death. In addition, another type of death was identified among the immature chondrocytes of the chondroepiphysis. These cells had the same nucleus as dark chondrocytes, but the lumen of the endoplasmic reticulum had expanded to fill the entire non-nuclear space, and all cytoplasm and organelles had been reduced to dark, worm-like inclusions. Since these cells appeared to be ‘in limbo’, they were termed ‘paralysed’ cells. It is proposed that ‘dark chondrocytes’ and ‘paralysed cells’ are examples of physiological cell death which does not involve apoptosis. It is possible that the confinement of chondrocytes within their lacunae, which would prevent phagocytosis of apoptotic bodies, necessitates different mechanisms of elimination.

We performed an audit of 71 children with consecutive displaced, extension-type supracondylar fractures of the humerus over a period of 30 months. The fractures were classified according to the Wilkins modification of the Gartland system. There were 29 type IIA, 22 type IIB and 20 type III. We assessed the effectiveness of guidelines proposed after a previous four-year review of 83 supracondylar fractures. These recommended that: 1) an experienced surgeon should be responsible for the initial management; 2) closed or open reduction of type-IIB and type-III fractures must be supplemented by stabilisation with Kirschner (K-) wires; and 3) K-wires of adequate thickness (1.6 mm) must be used in a crossed configuration.

The guidelines were followed in 52 of the 71 cases. When they were observed there were no reoperations and no malunion. In 19 children in whom they had not been observed more than one-third required further operation and six had a varus deformity. Failure to institute treatment according to the guidelines led to an unsatisfactory result in 11 patients. When they were followed the result of treatment was much better. We have devised a protocol for the management of these difficult injuries.

The Sheffield Expanding Intramedullary Rod System was developed after experiencing problems with existing rod systems in the management of osteogenesis imperfecta. Between 1986 and 1996 we treated 74 bones in the lower limb in 28 children at a median follow-up of 5.25 years. We have reviewed 24 children with a total of 60 rods.

Before surgery, all children had had multiple fractures of the lower limb. At review eight patients had experienced no further fractures, but three had suffered five or more subsequently.

Before initial stabilisation, 15 children had never walked, and only three (13%) used walking as their main means of mobility. After surgery, half of those who showed motor arrest were able to walk (p = 0.016). The number of patients able to walk, with or without aids, increased to 17 (p = 0.0001).

We have experienced no evidence of epiphyseal damage after the procedure, and complication rates requiring rod exchange have been low (7%).

A total of 110 total knee replacements (TKRs) was randomised to receive either a cemented or an uncemented prosthesis. Postoperative venography at five to seven days was used to compare the prevalence, site and size of deep-vein thrombosis (DVT). We also compared the findings with those of postoperative venography in a group of patients with cemented total hip replacements (THRs).

The total prevalence of DVT was significantly greater after uncemented (81%) than after cemented TKR (55%). Both knee groups had a significantly higher prevalence of DVT than in cemented hip replacements (32%). We found no difference in the proportion with proximal DVT in the three groups (14%, 15% and 16%). The median length of the thrombi was significantly greater after cemented (26.5 cm) than after uncemented TKR (11 cm) or after cemented THR (7 cm). This difference was mainly due to greater lengths of distal rather than proximal thrombi.

We conclude that the use of cement may affect the formation of DVT after joint replacement, but does not appear to lead to an increased incidence.

We report the six-year results of a prospective, controlled demographic trial of developmental dysplasia of the hip (DDH) treated in the Pavlik harness using ultrasound supervision. Our aim was to assess the value of ultrasound and its role in monitoring reduction in the harness, in terms of progression or failure of reduction at an early state.

From 1988 to 1994, a total of 221 patients with 370 ultrasonographically abnormal hips was treated in the Pavlik harness. This represents a treatment rate for the Southampton district of 5.1 per 1000 live births. Sixteen hips in 12 patients were not reduced in the harness and required surgical treatment; 95.7% were successfully reduced. One case of mild avascular necrosis (0.3%) was identified in those treated by harness alone. Of the 221 patients 87.8% remain under radiological review, with 3.2% of affected hips showing continued, mild acetabular dysplasia.

We conclude that ultrasound monitoring has led to an acceptably low level of intervention, a high reduction rate and minimal iatrogenic complications. The trial is continuing.

We performed routine venography after operation in a consecutive series of 252 patients with total joint arthroplasties in whom no form of routine chemical or mechanical prophylaxis had been used.

The prevalence of deep-vein thrombosis (DVT) was 32% (16% distal, 16% proximal) after total hip replacement and 66% (50% distal, 16% proximal) after total knee replacement (p < 0.001). We did not treat distal DVT. There were only two readmissions within three months of surgery because of thromboembolic disease. There were two deaths within this period, neither of which was due to pulmonary embolism.

Fifty-seven Stanmore Total Hip replacements were implanted between 1974 and 1986 in patients under the age of 50 years. We have reviewed the results in terms of survivorship and function, and assessed the reasons for revision.

Of the original 57, 22 (39%) have been revised at an average of 12 years from implantation, usually for aseptic loosening. Most of them had originally been implanted for osteoarthritis. Prostheses cemented with second-generation techniques have lasted significantly longer, and acetabular loosening emerged as a continuing problem. The overall survivorship was 90% at 10 years and 68% at 15 years.

Cemented hip replacement appears to be a viable option in younger patients and the Stanmore implant is comparable with other cemented prostheses in this age group.

Only two cases have been reported of congenital dislocation of the hip in infants born after extrauterine pregnancies. We report a further two and discuss the management and the variable outcome. These cases seem to confirm that congenital dislocation of the hip is associated with moulding forces rather than being a teratological abnormality.

We report a series of 15 children, six male and nine female, of average age 20 months, seen at a paediatric orthopaedic clinic with torticollis. Orthopaedic examination revealed a normal range of neck movement in all cases but in seven there was palpable tightness in the absence of true shortening or contracture of the sternomastoid muscle.

The patients were prospectively referred for ocular examination. In five of the 15 an ocular cause for the torticollis was detected with underaction of the superior oblique muscle in three, paresis of the lateral rectus muscle in one and nystagmus in one. Another two patients were found to have an abnormal ocular examination which was thought to be unrelated to their torticollis. Three of the patients with ocular torticollis required extra-ocular muscle surgery to abolish the head tilt and one of these had a tight sternomastoid muscle. Two of the non-ocular group had surgical release of the sternomastoid muscle; in the rest, the condition either resolved with physiotherapy or required no active treatment.

We recommend that all patients with torticollis and no clear orthopaedic cause are referred for ocular assessment since it is not possible clinically to distinguish ocular from non-ocular causes.

We report 22 patients (19 women and three men) of mean age 20.8 years who had painful snapping sensations in the groin. Most were able to reproduce the click by extending the affected hip from a flexed, abducted and externally rotated position and most were tender in the adductor triangle. Plain radiographs and an arthrogram were normal. A clinical diagnosis of subluxation of the iliopsoas tendon was made. Conservative management failed in 14 patients, two of whom had bilateral pain. All 14 had surgical release of the iliopsoas tendon through a medial approach. At follow-up (mean 17 months) the click had resolved in ten hips, was occasional but painless in five and unchanged in one. The syndrome of a painful 'snapping' psoas may result in disproportionately disabling symptoms. It may be diagnosed on clinical grounds and effectively treated, when severe, by release of the iliopsoas tendon.

Between 1989 and 1992 we admitted 426 children with an irritable hip, 363 (85.2%) once and 63 (14.8%) on 143 occasions. We assessed the records retrospectively to determine whether the groups differed and in particular whether recurrence was followed by pathological sequelae. We identified no feature which distinguished between them at either presentation. The use of bone isotope scans was greatly increased in recurrent cases, without clinical benefit. No relationship between recurrence and subsequent abnormality was identified, with 22 (42%) of the recurrences taking place in the opposite hip. The only difference was a higher incidence of 'psychosocial factors' recorded in the notes of children who presented on more than two occasions. The incidence of recurrent irritable hip is larger than previously indicated and in the presence of normal radiographs and low-grade clinical signs, more detailed investigation on subsequent admission is unlikely to be helpful.

We report the preliminary results of a continuing prospective evaluation of a screening programme for congenital dislocation of the hip (CDH) which uses ultrasound imaging to provide delayed selective screening to complement neonatal clinical screening. Of 26,952 births in the Southampton district, 1894 infants were referred for secondary screening because of a clinical abnormality or the presence of a predetermined risk category for CDH. Pavlik harness treatment was required for only 118 infants, giving a treatment rate of 4.4 per 1000 births. Of those referred with clinical instability, 35% did not require treatment. Dislocation or subluxation was detected in 17 of 643 infants referred only because they fell within one of three risk categories: breech presentation, foot deformity and family history. All 17 had normal clinical examinations and cases were discovered in each category. Six children presented with CDH after 12 weeks of age, giving a late presentation rate of 0.22 per 1000 births. All had normal clinical examinations within 24 hours of birth and none was in a risk category. Surgery has been required in ten children, giving a surgical treatment rate of 0.37 per 1000 births. We conclude that, in Southampton, delayed selective secondary screening with ultrasound is more effective than clinical screening alone. It targets treatment to those infants who need it, and reveals a number of dislocated and subluxed hips that would otherwise be missed.

We have used a modified technique of cervical osteotomy to treat a consecutive series of 23 patients with chronic slip of the upper femoral epiphysis. It has been successful in correcting both moderate and severe deformities with a low incidence of avascular necrosis, comparable to that seen after subtrochanteric osteotomies. We describe the operative details and discuss the features which make cervical osteotomy technically superior to intertrochanteric and subtrochanteric procedures.

We reviewed 35 patients who had an amputation following the failure of treatment for severe lower limb trauma. Seven of the amputations were for ischaemia, within one month of injury; 13 were between one month and one year for infection complicating loss of wound cover in un-united fractures; and 15 were later than one year after injury, mainly for infected non-union. The latter group of patients had had an average of 12 operations and 50 months of treatment, including eight months in hospital. We used a new limb injury score based on damage to the individual tissue elements; this indicated that, even in the absence of neurovascular injury, the presence of severe damage to skin, bone and muscle, with wound contamination, particularly in the lower tibia, had a poor prognosis. We therefore recommend, to avoid multiple operations, with prolonged hospitalisation and suffering, that these patients should have early independent review by orthopaedic and plastic surgeons with the aim of establishing an accurate prognosis for the salvage of a useful limb.

Bone samples from the iliac crest of patients with no signs of bone disorder were treated with collagenase to remove the collagen component and so allow detailed observation of the mineral hydroxyapatite. Both polished and unpolished surfaces were studied in the scanning electron microscope and they showed that the mineral component of bone is composed of small rounded units about 10 nm across which are fused together to form larger spheroidal units roughly 100 nm in diameter. In the unpolished surfaces these 100 nm units are seen to aggregate to form columns approximately parallel to their neighbours and with numerous interconnections forming a continuous mineral phase. The polished sections also show the hydroxyapatite as a continuous phase of contiguous spheroids and the holes from which the collagen fibres were removed are clearly revealed. Lamellations in the surface are interpreted as resulting from adjacent layers of collagen fibres having orientations approximately perpendicular to each other.

Total hip replacement was performed in 27 hips of patients who had sickle cell anaemia with avascular necrosis of the femoral head. The disease was bilateral in 11 patients. Considerable medical problems were encountered although most of the patients had exchange transfusion before surgery (86%), which prevented postoperative sickle cell crises in all but two cases. At the primary operation hard sclerotic bone was seen in nine femora with complete obliteration of the femoral canal. There were four femoral fractures, three following perforation of the shaft due to this hard bone. There was a very high morbidity due to loosening in both cemented and uncemented prostheses. With a rate of 59% over a cumulative 5.5 year period, revision was being performed at an average of only 43 months. Surgeons should be aware of these problems.

Of 4,617 babies born in Coventry in 1986, a total of 448 (9.7%) had either clinical abnormality of the hip or at risk factors for CDH. All were examined by ultrasound, but only 17 required treatment (3.7 per 1,000); in five of these no clinical abnormality had been detected. An additional 81 babies had ultrasound abnormalities but did not require treatment, despite the fact that ultrasound at first showed major hip displacement in 17 of them. Three late cases of CDH have presented among the babies born in 1986, but not examined by ultrasound. This incidence of late CDH is unchanged compared with the previous nine years, although ultrasound had detected covert displacement in a number of hips.

We report the results of 23 soft-tissue release procedures in 15 patients who had juvenile chronic arthritis. The operation, which includes hamstring tenotomies and posterior capsulotomy, is a safe and effective way of eliminating contracture, relieving pain and improving function.

Evidence is presented to support the contention that after slipping of the upper femoral epiphysis there is a potential for the bony epiphysis to grow back to its pre-slipped position. A suggestion is made as to how this recovery may occur.

A technique of examining the infant hip joint with real-time ultrasound is described. Since the cartilaginous femoral head is clearly imaged by ultrasound, anatomical structures and their relationships can be accurately determined. Dislocated hips are easily detected and subluxations also can be visualized. We report our experience with 131 examinations in 104 patients, comprising 259 single hip studies. Of 83 patients who were previously untreated, there were 178 hip studies with three false-negative and four false-positive ultrasound results. No dislocations were missed. Twenty-seven patients who were already being treated were examined to assess hip location, comprising a total of 81 hip studies. In some cases the patients were examined while in an abduction device, cast, or Pavlik harness. In one case a dislocation was not detected. The method of examination using real-time ultrasound is considered to be reliable, accurate, and a useful adjunct to radiography. The advantages are that it is non-invasive, portable, and involves no exposure to radiation.

Certain features of the sagging rope sign recently analysed by Apley and Weintroub (1981) are examined in detail. Evidence is presented to show that the line is a radiological shadow cast by the lateral edge of a severely deformed femoral head rather than a condensation of the spongiosa within the neck. An explanation is offered to explain the common association of the presence of this radiological sign with premature epiphysial fusion.

1. The fibrillar networks of adult human articular cartilage, taken from femoral and acetabular specimens, have been systematically examined by scanning electron microscopy. The internal structures revealed by rupturing the tissue were compared with published findings from transmission electron microscope studies.

2. Though this technique demonstrated the internal fibrillar appearance of cartilage to a remarkable degree, it had several attendant limitations. On final drying, specimens generally exhibited shrinkage which varied within wide limits; this could have altered the internal architecture to some extent. In addition, the rupturing technique, which at the time of this investigation was the only satisfactory method of revealing the fibrillar cartilage structure, may well have had a great influence on the fibril orientations.

3. The fibrils revealed no characteristic collagen periodicity and were considerably thicker than those observed by transmission electron microscopy. It is suggested that a coating of mucin on the collagen fibrils might account for this.

4. At low magnifications the torn layers in the fractured surfaces extended radially from the calcified zone and turned obliquely at or near the articular surface to merge with the distinctly layered superficial zone, thus forming arcade-like structures. That these were not artefacts produced by the fracturing technique was shown by their similarity to the classical arcade pattern of light microscopy. However, the factor which governed the direction of these planes of weakness, be it collagen, mucopolysaccharides or cells, could not be satisfactorily determined.

5. At higher magnifications only three regions of distinct fibrillar organisation could be identified: 1) a surface layer consisting of a random fibrillar network; 2) a superficial zone composed of layers of fibrillar network, intersecting and overlapping in planes parallel to the surface; and 3) elsewhere below the superficial zone a network of virtually random fibrils which extended to the calcified region with apparently little variation in thickness or density. There was little variation from this pattern even in aged fibrillated specimens.

6. At the lower magnification range the scanning electron microscope has revealed the arcade pattern described by light microscopy, while at the higher magnifications the fibrillar organisation as seen by scanning electron microscopy correlated well with the concepts developed by transmission electron microscopy, that is, a random network of fibrils overlaid at the articular surface by a membrane-like system of bundled fibrils.

7. A possible role in the transmission of joint forces is outlined for the above fibrillar organisation.

1. The methods of treating flayed limbs are enumerated, with mention of the reasons against conserving the injured skin.

2. The reasons for conserving the injured skin are presented and they are backed by the results in the patients described.

3. The factors that may influence the survival of injured skin are discussed, and the indications for, and methods of, conserving injured skin are described.

1. Radiological and histological observations of the tissue changes resulting from the implantation of various metals in the long bones of dogs are recorded.

2. Of the metals employed, tantalum, Vitallium, alloys "C" and "S" and F.M.B. steel were inert; silver and mild steel were reactive; F.S.T. steel occupied an intermediate position.

3. A correlation has been demonstrated between the anodic back E.M.F., the weight loss due to corrosion and the histological changes produced.

1. Attention is drawn to that type of rigid congenital flat foot in which the talus lies vertically instead of horizontally.

2. This deformity is rare, but if not treated successfully leads to an ugly, painful foot in adolescence.

3. The experience of five patients forms the basis of the present preliminary account. One adolescent and two young children under the age of five were treated unsuccessfully by both conservative and operative measures. More recently in two children with bilateral deformity open operation has been successful in restoring the shape of the foot.

4. The operation is essentially a reduction of a subluxation at the talo-navicular and subtalar joints. It entails freeing the head of the talus sufficiently to allow it to be lifted dorsally and laterally. The talus is then anchored in position by transplanting the distal end of the peroneus brevis tendon through the neck of the bone.

1. The literature dealing with the reaction of tissues to metals has been briefly reviewed and discussed.

2. It is suggested that the "anodic back EMF" of metals, under the conditions of the experiment, is a measurable electrical quantity which can be correlated with their behaviour in tissues.

3. Details of the method for obtaining this "anodic back EMF" are given.

4. A correlation between the "anodic back EMF" and the loss of weight due to corrosion in vitro has been demonstrated.

5. The inertness of eighty-seven metals has been classified by this method.

6. It must be emphasised that these results are based on in vitro experiments only. In vivo experiments are in progress and the results will be published in due course. Preliminary work suggests that there is some correlation between the ABE and the behaviour of metals in tissue (Hickman 1953).

It has been fascinating to trace the gradual erection of the British edifice of orthopaedics, and nostalgic to recapture a memory, however fleeting, of some of the figures who built it and taught us so much of our sum of knowledge half-way through the twentieth century—the remarkable spell of Robert Jones, the lofty, ascetic Tubby, the pugnacious Openshaw, the forceful and enthusiastic Hey Groves, the earnest but irascible Laming Evans, the equable and thoughtful Elmslie, the restless and exuberant Trethowan. It is always tempting to conclude: "those were the days." It is probably wise to do no more than record the events and leave judgment of progress to a later century. But we are being judged already and not always kindly or even truthfully. We are justified surely in priding ourselves on what has already been achieved, and on the service that orthopaedic surgery now gives to the community and promises for the future. In concern for this aspect of our work we have perhaps tended to neglect our capacity for basic research. But we are aware of this shortcoming, as witness our closer relationships with research departments of universities and royal colleges, and our increasing contacts with colleagues in the basic sciences. Finally, apart from the most intellectual snob and the pessimistic cynic, all must surely rejoice at the enthusiasm, industry and ability of our young colleagues—the orthopaedic surgeons of to-morrow.

1. The history of the genesis of the Putti-Platt operation for habitual dislocation of the shoulder is outlined so far as it is known.

2. The operation is described and briefly commented upon.

3. Since there is both gleno-labrial detachment and defect in the humeral head successful treatment depends upon: i) a block to the exit of the humeral head in front and ii) limitation of external rotation movement.