Aim:This study was carried out to assess various factors responsible for the development of avascular necrosis and the effect of treatment on clinical outcome.

Methods: We studied the clinical notes and radiographs of patients presenting with SCFE during the period between 1994 and 2003.

Results: Seventy three patients (n=73) with ninety two (n=92) hips were included in the study. There were 16 acute, 43 acute-on-chronic, 29 chronic and 4 preslips. Seventy Seven (n = 77) slips were classified as stable and 15 as unstable slips. Fifty three slips (57.6%) were mild, 34 (37%) were moderate and five (5.4%) were severe slips. Despite no deliberate attempts to reduce the slip at the time of surgery eighteen hips (n=18) showed a median decrease in slip angle of 8 degrees (range 2–36) in acute and acute-on-chronic slips. The mean preoperative slip angle was 32 degrees (range 9–76) compared to postoperative slip angle of 29.9 degrees (range 10–75) (p=0.004). Four patients developed avascular necrosis (AVN). Intraoperative reduction of the slip was significantly related to development of AVN (p< 0.001). According to the criteria of Heyman and Herndon eight patients had functional deficit at the time of final follow up and clinical outcome was fair, poor or failure. All of these patients had a reduction in the angle of slip at the postoperative radiographs compared to their preoperative radiographs.

Conclusion: Reduction of slipped capital femoral epiphysis is responsible for poor outcome and also related to the development of avascular necrosis. We recommend single in situ pinning for these cases regardless of severity of slip.

Cobalt chrome-on-cobalt chrome bearing surfaces have been re-introduced despite some concerns regarding potential risks posed by soluble metallic by-products. We have investigated whether there are metal-selective differences between the levels of genetic damage caused to a human cell line when cultured with synovial fluids retrieved from various designs of orthopaedic joint replacement prostheses at the time of revision arthroplasty.

Synovial fluids were retrieved from revision hip and knee arthroplasty patients with bearings made from cobalt chrome-on-cobalt chrome, cobalt chrome-on-polyethylene and stainless steel-on-polyethylene. Control synovial fluids were retrieved from primary arthroplasty cases with osteoarthritis. Synovial fluid was cultured with human primary fibroblasts for 48 hours in a cell culture system under standardised conditions. The “Comet” assay was used with an image analysis system to measure levels of DNA damage caused by the various synovial fluid samples.

Synovial fluids from cobalt chrome-on-cobalt chrome and cobalt chrome-on-polyethylene joint replacements both caused substantial levels of genetic damage as detected by the Comet assay. Synovial fluids retrieved from stainless steel-on-polyethylene joints caused low levels of damage. The difference between these groups was highly statistically significant (p< 0.001). Control synovial fluids from osteoarthritic joints caused minimal changes. Atomic absorption spectroscopy demonstrated that the metal-on-metal synovial fluids contained the highest levels of cobalt and chromium. Different alloys used in orthopaedic implants are associated with different levels of DNA damage to cultured human cells in vitro. We are able to demonstrate that this damage is attributable at least in part to the metal content of the synovial fluid samples. We have no evidence for any long-term health risk to patients with such implants.

Metal-on-metal bearing surfaces have been reintroduced for use in total hip replacement, despite concerns regarding the potential risks posed by metallic by-products. We have compared periprosthetic tissues from metal-on-metal and metal-on-polyethylene hip replacements at revision surgery with control tissues at primary arthroplasty.

Tissues were obtained from 9 control, 25 contemporary metal-on-metal, 9 CoCr-on-polyethylene and 10 titanium-on-polyethylene hip replacement arthroplasties. Each was processed for routine histology with Haematoxylin and Eosin. Quantitative stereological analysis was performed at the light microscopic level.

Metal-on-metal sections showed more surface ulceration and this was correlated with the density of inflammation in the deeper tissues layers. Metal-on-metal tissues displayed a pattern of well-demarcated tissue layers, which were rarely seen in metal-on-polyethylene cases. In metal-on-polyethylene cases, the inflammation was predominantly histiocytic. Metal-on-metal cases by contrast showed a lymphocytic infiltrate with abundant plasma cells. Metal-on-metal tissues showed a striking pattern of peri-vascular inflammation with prominent lymphocytic cuffs especially deep to areas of surface ulceration. Levels of inflammation were higher in cases revised for failure than in those retrieved at autopsy or exploratory surgery. Total replacement and surface replacement designs of metal-on-metal arthroplasty showed similar histological changes. Plasma cells were not seen in any of the metal-on-polyethylene cases. The differences between the patterns of inflammation and cellular infiltration seen in metal-on-metal and metal-on-polyethylene tissues were highly statistically significant.

The pattern and type of inflammation in periprosthetic tissues from metal-on-metal and metal-on-poly-ethylene arthroplasties is very different. Our findings support the conclusion that metal-on-metal articulations are capable of generating a form of immunological response to metallic wear debris that has not been described previously. The incidence and clinical implications of these immunological responses in failed metal-on-metal joints are unknown.

Purpose: The aim of this part retrospective and part prospective study was to establish the incidence of pinsite infections and assess evolution of changes in practice

Methods: Data was collected retrospectively and prospectively for pin site infections from the inception of limb reconstruction service viz. 1985 to January 2002. There were 812 patients, 1042 limb segments, and 9935 pins. The various external fixators used were limb reconstruction system (LRS) 549; Ilizarov 397; Sheffield ring fixator (SRF); Dynamic axial fixator (DAF) 35; LRS/Sequoia 8; LRS/Garche 7; and Pennig 5.

Results: The pin site infections were graded from 0 to 6 ( Saleh & Scott). There were no infections in 206 segments. The infection grade is shown below:

We changed our pin tract care practice from 1996. We had a significant decrease in pin tract infections since then (p< 0.0001). We also found that using Ilizarov wires had significantly less infections than with half pins used with monolateral fixators (p< 0.0001; linear trend, p= 0.0338). There were 48 patients that required hospital admissions for IV antibiotics. and of these 10 patients required debridement. There were no residual long lasting infections or chronic osteomyelitis.

Conclusion: Attention to detail in insertion of wires and half pins is crucial to avoid pin site infections. This audit supports the fact that external fixation is a safe method from the point of view of infection contrary to general belief.

Purpose: To identify the risk of metastases at the time of diagnosis in patients with soft tissue sarcomas and to estimate the cost effectiveness of identifying these.

Methods: A retrospective database review was used to identify all new soft tissue sarcoma patients referred to our unit and to find those identified to have metastases at diagnosis. Data of tumour size, depth, grade, age, type of tumours, Chest x-ray (CXR)/CT chest results were available in all patients. We estimated the efficacy of CXR in identifying metastases and the costs of various staging strategies.

Patients: 1170 with newly diagnosed STS in 7.5 years (1996–2004) were included.

Results: The incidence of metastases at diagnosis was 10% (116 patients), 8.25% (96 patients) had lung metastases and 20 had metastases elsewhere. The risk of having lung metastases at diagnosis was 11.8% in high grade tumours, 6.95% in intermediate grade and 1.2% in low grade tumours. The risk increased almost linearly with size at presentation and was higher in deep tumours and older patients. CXR alone detected 2/3 of all lung metastases. The positive predictive value of the CXR was 93.7%, the negative predictive value was 96.7%, the sensitivity 62.5% and the specificity 99.6%.

The accuracy was 96.9%. CT overestimated metastases in 4%.

Discussion: We recommend that all patients with a newly diagnosed STS should have a CXR and only those with an abnormality or who have large, deep high grade tumours should have a CT chest. This strategy will save £7500 per 100 new patients with STS and will detect 93% of all chest metastases, missing 1 patient with metastases per 166 patients.

Metal-on-metal joint replacements have been reintroduced despite some concerns regarding the potential risks posed by soluble metallic by-products. We have investigated whether there are metal selective differences between the levels of genetic damage caused to a human cell line when cultured with synovial fluids retrieved from orthopaedic joint replacement prostheses at the time of revision arthroplasty.

Methods: Synovial fluids were retrieved from revision hip and knee arthroplasty patients with bearings made from Cobalt chrome-on-Cobalt chrome, Cobalt chrome-on-polyethylene and Stainless Steel-on-polyethylene. Control synovial fluids were retrieved from primary arthroplasty cases with osteoarthritis and no implant in situ. Synovial fluid was cultured with human primary fibroblasts for 48 hours in a cell culture system under standardised conditions. The ‘Comet’ assay was used with an image analysis system to measure levels of DNA damage caused by the various synovial fluid samples. Metal levels were measured in the synovial fluid samples using atomic absorption spectroscopy.

Results: Synovial fluids from Cobalt Chrome-on-Cobalt Chrome and Cobalt Chrome-on-polyethylene joint replacements both caused substantial levels of genetic damage as detected by the Comet assay. Synovial fluids retrieved from Stainless Steel-on-polyethylene joints caused low levels of damage. The difference between these groups was highly statistically significant (p< 0.001). Control synovial fluids from osteoarthritic joints caused minimal changes. Atomic absorption spectroscopy demonstrated that the metal-on-metal synovial fluids contained substantially more cobalt and chromium than the fluids retrieved from cobalt chrome-on-polyethylene joints. Stainless steel-on-polyethylene synovial fluids contained the least metal.

Conclusions: Different alloys used in Orthopaedic implants are associated with different levels of DNA damage to cultured human cells in vitro. We are able to demonstrate that this damage is attributable at least in part to the metal content of the synovial fluid samples. We have no evidence for any long-term health risk to patients with such implants. Further research is needed in this field.

Aims: Irradiated allograft bone may help to reduce the risk of transmission of infectious agents from donor to recipient. The purpose of this study was to establish the results of impaction bone grafting of acetabular defects with froze, irradiated allograft bone. Methods: All patients treated by a single surgeon with impaction bone grafting of acetabular defects at revision total hip replacement were reviewed retrospectively. All operations were performed during the period 1994–2000. The mean follow-up was 50 months (range 30–96 months). Case notes and X rays were reviewed and analysed. The Paprosky grade of acetabular defects was determined from the pre-operative X rays and the surgeonñs operation note. Post-operative X rays were reviewed to establish the extent and rate of new bone in-growth. Functional outcomes were determined by way of self-administered questionnaires. Results: Complete records and X rays were obtained for 33 patients who underwent revision hip arthroplasty with impaction bone grafting of the acetabulum using frozen, irradiated allograft bone. There were no complications associated with the bone grafts and no patient required a re-operation. Review of serial X rays conþrmed in-growth of host bone and the functional outcome was satisfactory. Overall 29 patients (88%) declared themselves satis-þed with the outcome of their operation and 32 patients (97%) improved functionally after the operation. Conclusions: These results indicate that satisfactory results can be achieved with impaction bone grafting using frozen, irradiated allograft bone. The use of irradiated bone graft can potentially reduce the risk of disease transmission from donor to recipient without compromising the surgical results.

Irradiated allograft bone may help to reduce the risk of transmission of infectious agents from donor to recipient. The purpose of this study was to establish the results of impaction bone grafting of acetabular defects using irradiated allograft bone.

Patients treated with impaction bone grafting of ace-tabular defects between 1994 and 2000 were reviewed retrospectively. The mean follow-up was 50months (range 30–96months). Case notes and Xrays were reviewed and analysed. The Paprosky grade of acetabular defects was determined. Functional outcomes were determined by way of self-administered questionnaires.

Complete records and Xrays were obtained for 33 patients who underwent impaction bone grafting of the acetabulum using freeze-dried, irradiated bone. The Paprosky classifications of the defects were as follows: 3 type 1, 10 type 2A, 4 type 2B, 4 type 2C, 10 type 3A and 2 type 3B.

There were no complications associated with the bone grafts and no patient required reoperation. Review of serial Xrays confirmed ingrowth of host bone. The functional results obtained were as follows: 17 patients (52%) could walk an unlimited distance. 11 patients (33%) required no walking aids whilst a further 17 (52%) required a single cane to mobilise. 21 patients (64%) were able to use public transport after the operation. 20 patients (61%) reported little or no pain. 9 patients (28%) had no limp and 14 patients (42%) had a slight limp. Overall 29 patients (88%) declared themselves to be satisfied with the outcome of their surgery. 32 patients (97%) improved functionally after their operation.

These results indicate that satisfactory results can be achieved with impaction bone grafting using irradiated, frozen allograft bone. The use of irradiated bone graft can potentially reduce the risks of disease transmission from donor to recipient without compromising the surgical results.

Anterior knee pain attributable to the patellofemoral joint and extensor mechanism dysplasia is a common presentation to Orthopaedic surgeons. Plain radiology is likely to remain the primary investigation of the knee in most centres, but most of the radiological features of extensor mechanism dysplasia are time consuming and difficult to measure reproducibly. 137 consecutive symptomatic knees aged under 30, referred to an Orthopaedic surgeon were studied in order to identify a rapid and reproducible marker for those knees worthy of further in-depth analysis.

Overall, 67 knees (49%) had at least one radiological abnormality and 70 (51%) were considered ‘normal’. There were 5 Dejour Type3 dysplasias of the femoral trochlea, 9 Type2 and 12 Type1. There were 49 cases of patella alta and 5 of patella infera. Four knees had an abnormal lateral patellofemoral (patellar tilt) angle. 15 knees had more than one abnormality. The classification of trochlear dysplasia was difficult and showed poor reproducibility. This was also true for the measurement of lateral patellofemoral angles. Patellar height was more easily measured but took time. The sulcus angle emerged as an easily and rapidly measurable feature that was reproducible and was closely related to the other features of extensor mechanism dysplasia.

The sulcus angle offers a rapid and reliable ‘screening’ measurement on knee radiographs. A normal sulcus angle suggests that seeking the other radiological markers of extensor mechanism malalignment is unlikely to reveal additional useful information. Other diagnoses can then be sought. The more abnormal the sulcus angle, the more severe the other features of extensor mechanism dysplasia are likely to be. Further detailed measurements can then help to define the most appropriate surgical correction.

A prospective clinical investigation to determine the optimum knee flexion angle for the ‘skyline’ patellofemoral joint radiograph.

Plain radiography of the patello-femoral joint includes the axial or ‘skyline’ radiograph. The optimum knee flexion angle for making this image remains unclear.

We therefore performed a prospective clinical study in which patients underwent three skyline radiographs with knee flexion angles of 30(or minimal flexion), 50 and 90 degrees. The patients were new patients, aged between 12 and 30, presenting to a knee clinic with anterior knee pain. Two observers evaluated the radiographs, making a standardised series of measurements. Blinding was organised so that the observers were unable to use any information other than the radiographic image alone. One observer evaluated all the films on two separate occasions to allow calculation of intra- and interassessor agreement.

There were 67 knees from 46 patients. There was a high level of intra- and inter-observer agreement. There were a number of patients in which the radiographic appearance of the patello-femoral varied markedly between the different views; in all cases the abnormality was best demonstrated by the 30-degree view. There were however a number of minimal flexion views in which the film contained incomplete information because part of the patello-femoral joint was missing from the image.

We conclude that whilst a minimal flexion skyline view is the most sensitive method for the detection of patellar tilt and subluxation, not all knees can be successfully imaged at the required position. A flexible approach is therefore needed, to obtain satisfactory images at minimal flexion.

A total of 90 patients with an isolated rupture of the anterior cruciate ligament (ACL) had a reconstruction using the ipsilateral patellar tendon secured with round-headed cannulated interference screws. Annual review for five years showed three failures of the graft (two traumatic and one atraumatic); none occurred after two years. Ten patients sustained a rupture of the contralateral ACL. At five years, 69% of those with surviving grafts continued to participate in moderate to strenuous activity. Using the International Knee Documentation Committee assessment, 90% reported their knee as being normal or nearly normal and had a median Lysholm knee score of 96 (64 to 100). Most patients (98%) had a pivot shift of grade 0 with the remaining 2% being grade 1; 90% of the group had a Lachman test of grade 0. The incidence of subsequent meniscectomy was similar in the reconstructed joint to that in the contralateral knee. Radiological examination was normal in 63 of 65 patients. Our study supports the view that reconstruction of the ACL is a reliable technique allowing full rehabilitation of the previously injured knee. In the presence of normal menisci there is a low incidence of osteoarthritic change despite continued participation in sporting activity.

Skeletal muscle grafts, when thawed after freezing, can be used to repair peripheral nerves. This method was used after transection of the median nerve in the upper arm in marmosets. Examination at 28 days showed total denervation of flexor carpi radialis; at 150 days electrophysiological evidence of recovery of nerve conduction across the graft and of muscle activation was seen. Sections at this time showed nerve fibres and new functional neuromuscular junctions in the muscle. It is concluded that effective reinnervation of target muscles is possible after peripheral nerve repair using skeletal muscle autografts.