Background

Ankle fractures are extremely common but unfortunately, over 20% fail to obtain good to excellent recovery. For those requiring surgical fixation, usual-care post-surgery has included six-weeks cast immobilisation and non-weightbearing. Disuse atrophy and joint stiffness are detrimental sequelae of this management. While rehabilitation, starting at two-weeks post-surgery is viewed as safe, the literature contains methodological flaws and a lack of focus on early exercise, perpetuating the controversy over the effectiveness of early exercise interventions.

Abstract

Protocols for processing of tissue from arthroplasty infections vary and might affect the recovery of bacteria. We compared homogenization, bead beating and enzymatic disruption for recovery of live bacteria from tissue samples.

Suspensions of Staphylococcus aureus and Escherichia coli were prepared as controls. Three samples were taken from each and the first was bead beaten, the second homogenized, and Proteinase K was added for 10 and 30 minutes to the third sample before culturing. In addition, artificially inoculated pork tissue and known infected human tissue samples were processed by either homogenization or bead beating prior to cultures and results were compared.

Number of cycles of bead beating and homogenization and duration of Proteinase K treatment had significant effects. Bead beating for 2 and 4 cycles reduced the yield of S.aureus to 52% and 20% of control, and E.coli to 33% and 8%. Homogenization for 2 and 4 cycles reduced S.aureus to 86% and 65% of control, and E.coli to 90% and 87%. Proteinase K for 10 minutes and 30 minutes reduced the yield of S.aureus to 75% and 33% of control, and E.coli to 91% and 49% respectively. Inoculated Pork tissue showed a reduction in S.aureus recovery of 90% for bead beating compared to homogenization, and 80% in the case of E.coli. Bead beating of infected human tissue samples reduced the yield by 58% compared to homogenization.

Bead-beating is a common recommended method of processing tissue from arthroplasty cases. However, even though it produces a homogeneous sample, it does so at the cost of significant loss of viable bacteria. Homogenization and 10 minutes of Proteinase K incubation are almost equivalent, but the homogenizer is preferred being more controllable and cheaper. This should help to define guidelines for diagnosing infections using tissue samples.

A subgroup of patients that undergo TKR surgery have evidence of neuropathic pain and central sensitization that may predispose to severe postoperative pain. This study assesses the correlation of MRI detected bone marrow lesions (BMLs) and synovitis with markers of neuropathic pain and central sensitization in patients undergoing TKR surgery and healthy volunteers.

31 patients awaiting TKR and 5 healthy volunteers were recruited. Each subject underwent a 3-T knee MRI scan that was graded for BMLs (0–45) and synovitis (0–3) using subsets of the MRI Osteoarthritis Knee Score (MOAKS). All subjects were asked to complete the PainDetect questionnaire to identify nociceptive pain (< 13), unclear pain (13–18) and neuropathic pain (>18). Correlation between BMLs and PainDetect score was the primary outcome measure. Secondary outcomes included the correlation of synovitis to PainDetect and temporal summation (TS) a measure of central sensitization to the PainDetect score. TS was determined using a monofilament to evoke pain. Pilot histological analysis of the prevalence of osteoclasts (TRAP⁺) within BMLs versus normal subchondral bone was performed, implying a role in BML pathology.

Increasing BML MOAKS score correlated with neuropathic pain (painDetect), r_s = 0.38, p=0.013 (one-tailed). There was a positive correlation between synovitis and PainDetect score, τ =0.23, p= 0.031 (one-tailed). TS was greater in the neuropathic pain than in nociceptive pain patients, U = 18.0, p=0.003 (one-tailed). TRAP staining identified more osteoclasts within BMLs than contralateral condyle lesion free subchondral bone, z = −2.232, p = 0.026 (Wilcoxon Signed Rank Test, one-tailed).

BMLs and synovitis are more prevalent in neuropathic pain and central sensitization in knee OA. Higher osteoclast prevalence was seen within BMLs which may help explain the association with BMLs and pain in OA.

Painful OA is linked to CNS changes in pain processing. Temporal summation of pain (TSP) is a measure of one such CNS change, central sensitization. TSP is defined using a series (≥0.33Hz) of painful stimuli and is a predictor of postoperative pain, experienced by 20% of patients after total knee replacement (TKR) surgery. This study has developed a protocol to use functional MRI to assess CNS changes in OA pain processing.

This pilot includes 3 participants with chronic knee OA pain awaiting TKR (62 ± 4.4) and 5 healthy volunteers (50 ± 13.6). 3-Tesla BOLD fMRI brain scans were recorded during short series of one second painful stimuli, applied using an automated inflatable cuff to the calf muscle of the leg with the affected knee or left side in healthy volunteers. The pain intensity at onset and during the 10 painful stimuli were recorded using a numerical rating scale. The pattern of brain activation was averaged across noxious stimuli, and the differential activation compared the 1st vs. 10th (last) stimulus. Bone marrow lesions (BMLs), synovitis and effusion size were scored from 3-Tesla knee MRI's using MOAKS scoring.

TSP was raised in OA patients compared to control group (p=0.023). TSP brain activity in the chronic OA patients displayed higher signal within the subgenual anterior cingulate (sgACC) compared to healthy volunteers. Knee MRI identified OA patient's exhibited higher BML scores (p=0.038) and more knee effusion (p=0.018), but the lack of synovitis did not differ from control group (p=0.107).

Enhanced TSP in chronic knee OA pain may be linked with augmented responses in emotional circuitry. BMLs and effusion size appear to contribute more with pain than synovitis. These results may help understand sensitization to improve outcomes for patients with knee OA undergoing TKR surgery.

Background

Diabetes is bad, common and diabetic foot ulcers (DFU) once established lead to high rates of amputation. In Nottingham our standard management for infected diabetic foot ulcers is surgical debridement, microbiological sampling, packing with gentamicin beads and targeted antibiotic therapy. Recently we have switched to packing with Stimulan, which is a purified synthetic calcium sulphate compound that can be mixed with patient appropriate antibiotics, is biodegradable and delivers better elution characteristics compared to gentamicin beads.

Background

Bioresorbable materials offer the potential of developing fracture fixation plates with similar properties to bone thereby minimising the “stress shielding” associated with metal plates and obviating the need for implant removal. Phosphate glass fibre reinforced (PGF)-polylactic acid (PLA) composites are bioresorbable and have demonstrated sufficient retention of mechanical properties to enable load bearing applications.

The type, duration and intensity of exercise required to induce mechanical hypoalgesia is poorly defined. We are interested in identifying the exercise parameters required to induce raised pressure pain thresholds. This pilot study investigates the effect of indoor rowing on pressure pain threshold (PPT) in high performance rowers. Our ultimate aim is to investigate the potential of utilising exercise in the treatment of chronic pain and specifically in relation to the management of knee osteoarthritis. 20 high performance rowers (13M:7F; Mean Age 20.8 years; SD 1.74) were recruited from the University of Nottingham and Nottingham Boat Club high performance rowing teams under a research protocol approved by the University of Nottingham Ethics Committee. PPT measurements were made in triplicate using an algometer (SOMEDIC, Sweden) at the medial knee joint line, anterior tibia and sternum, pre- and post-exercise. Anthropomorphic and rowing ergometer power output data were also recorded. There was significant increase in PPT values at all sites following exercise (Medial joint line: 127.6Nm-2, 26%, p=0.001; Tibia: 110.8Nm-2, 24.7%, p<0.001; Sternum: 48.9Nm-2, 11.7%, p=0.005 – Wilcoxon Signed Rank) statistical power was 97.1%, 100% and 88.1%, respectively. PPT was greater at baseline at the medial joint line compared to other sites, reaching highly significant relative to the sternum (p<0.001). We determined that ten minutes of high intensity indoor rowing induced hypoalgesia in high performance rowers. Further research is required to investigate the detailed interplay between exercise and hypoalgesia, including its duration post exercise, to identify suitability for use in pain management strategies.

Background

Bioresorbable materials offer the potential of developing fracture fixation plates with similar mechanical properties to bone thereby minimizing stress shielding and obviating the need for implant removal.

Aim

To test the hypothesis that surface skin swabs taken after skin preparation with alcoholic povidone iodine (APVPI) would not grow bacteria, whereas full thickness biopsies taken from the line of surgical incision would grow bacteria.

Background

Charcot neuropathic osteoarthropathy is a rare, destructive process affecting the bones and joints of feet in patients with diabetic peripheral neuropathy. The aetiology of Charcot remains unknown, although it has been suggested that it is triggered by the occurrence of inflammation in the foot of a susceptible individual, and that the inflammation results in increased osteoclastic activity.

Background/Study Aim

Injectable scaffolds which also deliver cells and bioactive molecules to augment bone healing overcome many of the limitations associated with current bone graft substitutes. The aim of this study was to develop and test a novel injectable scaffold that self-assembles isothermically in situ to form a biodegradable porous osteoconductive material, and to assess the viability of human mesenchymal stem cells (hMSC) seeded onto the scaffold.

Introduction

Both the RANK/RANKL system and the endocannabinoid system have roles in bone remodelling. Activation of CB1 receptors on sympathetic nerve terminals in trabecular bone modulates bone remodelling by attenuating adrenergic inhibition over bone formation. CB2 receptors are involved in the local control of bone cell differentiation and function. Osteoblastic CB2 receptor activation negatively regulates RANKL mRNA expression indicating an interaction between the two systems and that efficient bone remodelling requires a balance between these two systems. The aim of the study was to establish the presence of the different components of the endocannabinoid system and the RANK/RANKL signalling pathway in human bone and osteoclast culture.

Background

Deep infection rates of 1 - 2% following primary hip and knee arthroplasty are mainly due to endogenous contamination of the surgical site from bacteria within the patient's own skin. However surgical skin preparation removes only bacteria from the surface of the skin, leaving viable bacteria in the deeper layers of the skin within hair follicles and sweat and sebaceous glands. The aim of our study was to test the hypothesis that surface skin swabs taken after skin preparation with alcoholic povidone iodine would not grow bacteria, whereas full thickness biopsies taken from the line of surgical incision would grow bacteria.

Introduction

Open fractures occur with an annual incidence of 11.5 per 100,000 (6900 pa in UK). Infection rates, even with intravenous broad-spectrum antibiotics, remain as high as 22%. For this reason necessary bone grafting is usually delayed until soft-tissue cover of the bone injury is achieved. A biodegradable bone graft that released sustained high concentrations of antibiotics and encouraged osteogenesis, that could be implanted safely on the day of injury would reduce infection rates and avoid reoperation and secondary grafting. The non –union rate (approx 350 pa in UK) should also be reduced. Such a graft, consisting of a PLA/PGA co –polymer and containing antibiotics, is under development and here we report assessment of spectrum and duration of antimicrobial activity and effect of addition of antibiotics on mechanical properties.

Objective

To determine the reliability, reproducibility, variability and validity of the Osteoarthritis Research Society International (OARSI) Osteoarthritis Cartilage Histopathology (OACH) system and Mankin Histopathology – Histochemical Grading System (HHGS) when applied to the characterisation of the osteoarthritic human knee.

Background

Osteoarthritis (OA) has been described as a non-inflammatory arthritis and yet the choice of drug treatment is NSAIDs.

Background: Autologous bone graft remains the “gold standard”, but the associated morbidity and finite supply of tissue has resulted in surgeons seeking methods of enhancing healing with bone graft substitutes and bone morphogenic proteins (BMPs). There are 54 bone graft substitutes and 2 BMPs currently on sale in the UK. The aim of this study was to review the published clinical evidence in support of their use in spinal surgery.

Methods: The 19 manufacturers of bone graft substitutes and BMPs were contacted asking for details of their products on the market. A systematic literature review was conducted using the ISI Web of Knowledge, EMBASE (1980–2008) and OVID databases. Publications providing clinical data were classified according to the hierarchy of clinical evidence published in the Journal of Bone and Joint Surgery Am in 2003. Level I evidence is a prospective randomised control trial with definitive results to support the use of an intervention in a clinical setting. Level V evidence is isolated case reports. A Grade of recommendation A-i was accredited to each product to assist the clinical spinal surgeon in making decisions on which product to use based on the evidence in the literature.

Results: 102 clinical studies found, most of which were level IV or V evidence. Both BMPs, InductOS® and OP-1® have Level I papers and have Grade A recommendation. There is very poor evidence for the use of bone graft substitutes in spinal surgery with no products receiving Grade A recommendation and only 6 out of 54 products having Grade B recommendation.

Conclusions: There is a lack of evidenced based clinical data for the use of bone graft substitutes in spinal surgery. Regarding BMPs there is good evidence for the use of these products in spinal surgery but surgeons must be aware of the reported complications.

Background: The mechanisms underlying the increased prevalence of arterial calcification in diabetes are not understood. An association with distal neuropathy has been reported and a particularly high prevalence was found in patients with Charcot’s disease.

Aim: The aim of this study was to confirm this high prevalence and to determine whether it is specific to that disorder by comparing the results to patients with other types of foot disease.

Methods: A retrospective survey was conducted in three groups of patients with X-rays managed by a specialist service for the diabetic foot between 2002 and 2005. Group A (n=34) comprised patients with an acute Charcot foot, Group B (n=53) included patients with osteomyelitis and Group C (n=35) consisted of patients who had neither osteomyelitis nor Charcot’s disease. All X-rays were independently examined by three observers blinded to the underlying diagnosis, with films from each group being mixed.

Results: No differences existed (p> 0.05) in the mean age of the patients (60, 72 and 68 years, respectively), the proportion of men (68%, 64% and 51%) and the prevalence of nephropathy (41%, 30% and 14%). 100% patients in Group A, 94% in Group B and 80% of Group C had evidence of neuropathy. The overall prevalence of calcification in the three groups was 53%, 66% and 54% (p> 0.05). With all three groups combined, the only factor associated with calcification was disease duration (p=0.004). The prevalence of calcification was higher than the 40% previously reported in patients with neuropathy, but lower than that reported in patients with Charcot.

Conclusion: As there was no difference in the prevalence of calcification between the three groups, it is concluded that the increase is not specific to Charcot’s disease. It is possible that the increase in calcification in each group reflects the effect of local inflammation, possibly by activation of the RANKL/OPG signalling system.

Aim: To reduce the amount of blood wastage in our unit.

Method: In 72 patients, the number of blood units cross-matched and the haemoglobin/haematocrit fall were audited for primary total shoulder replacement (n=44), primary hemiarthroplasty (n=21), and revision shoulder replacement (n=7) over twelve months (January 2008 to December 2008). The amount of crossmatched blood was compared to the amount of blood transfused, pre-operative haemoglobin and fall in haemoglobin/haematocrit.

Results: 23 of 44 primary total shoulder replacements and 5 of 21 hemiarthroplasties were crossmatched 55 units preoperatively. 4 of the 7 revision arthroplasties were crossmatched 7 units preoperatively. No units were transfused. 4 patients were later transfused 2 units each for symptomatic low haemoglobin at day 3–5 postoperatively from postoperatively crossmatched blood. No correlation existed between preoperative haemoglobin and number of units blood ordered. A haemoglobin reduction of ~2.5 g/dl was seen for both primary and revision surgery. There was significant correlation between low preoperative haemoglobin and need for transfusion (p< 0.05). Nearly all patients in whom blood was crossmatched rather than group and saved, belonged to one consultant. No patients had an adverse outcome due to a lack of immediately available cross-matched blood.

Conclusion: A large amount of blood was crossmatched and no units used in primary and revision shoulder replacement surgery. We recommend group and save only in primary shoulder arthroplasty and crossmatch of 2 units for revision shoulder surgery. Providing pre-operative haemoglobin is > 11.5 g/dl, group and save is safe even for revision shoulder arthroplasty. Wastage of blood could be reduced to zero in our unit. We recommend regular audit as a tool to ensure compliance with guidelines, and for clinical governance purposes ensuring guidelines remain best practice.

Prosthetic joint infection (PJI) is an increasing problem and management commonly involves prosthesis removal with serious consequences. Biofilm-forming staphylococci are the most common causative organisms with Staphylococcus aureus being most virulent and methicillin-resistant Staphylococcus aureus (MRSA) more than doubling the infection mortality rate. Bacterial adhesion is an essential primary event in biofilm formation and infection establishment. The development of a novel combination vaccine programme to prevent staphylococcal PJI by directing antibody against factors involved in adhesion and biofilm formation, and investigation of S. aureus binding-domains as potential vaccine components for adhesion inhibition is described.

Selected target antigens included the S. aureus fibronectin-binding protein (FnBP) and iron-regulated surface determinant (IsdA), which have been shown to be important for infection establishment and predominantly bind to host fibronectin and fibrinogen respectively. Escherichia coli clones harbouring recombinant S. aureus binding-domain DNA sequences were used for expression and purification of antigen domains. In vitro antibody evaluation determined whether immune inhibition of bacteria - ligand binding can significantly impact on attachment to plasma-conditioned biomaterial (in presence of other bacterial ligands).

Adhesion of homologous and heterologous (MRSA PJI isolate) S. aureus to plasma-conditioned steel was significantly reduced (approximately 50 percent average reduction, p < 0.0001) when pre-exposed to anti-rFnBP-A antiserum (with pre-immune serum control) that was 50-fold more dilute than the actual titre from immunisation. Inhibition was related to ligand presence but not staphylococcal Protein A, and reduced adhesion was not observed with the mutant strain, indicating specific inhibitory antibody involvement, and demonstrating for the first time the potential of rFnBP-A for prevention of S. aureus PJI. Adhesion-inhibitory activity was also observed with a purified IgG-fraction of rIsdA antiserum but this activity appeared to be masked by non-IsdA - related interactions when non-IgG - purified antiserum was assessed.

Background: Prosthetic joint infection (PJI) is most commonly caused by skin-derived, biofilm-forming staphylococci, with Staphylococcus aureus being most virulent and MRSA becoming a substantial problem. Cephaloporins are almost universally used as prophylaxis against PJI, yet Methicillin - resistant S aureus (MRSA) is becoming increasingly common in hospitals, nursing homes and now in the community. Such strains are not susceptible to cephalorsporins or to a range of other antimicrobials. In view of this increasing antibiotic resistance, an alternative approach to preventing S. aureus PJI is needed, and we propose that vaccination is a promising approach. Having regard to the distinct pathogenesis of PJI, this must target key events in infection establishment, such as adhesion to the implant, via the plasma conditioning film, mediated by bacterial binding proteins. It must also have the potential to protect against all S. aureus regardless of antibiotic resistance profile. Fibronectin-binding protein-A (FnBP-A) is one example, but the potential of FnBP-A as a PJI vaccine candidate has not been thoroughly investigated and data in previous literature are contradictory.

Methods: Here, polyclonal rabbit antibody against recombinant(r) FnBP-A binding domain was produced and investigated for the first time for activity against S. aureus adhesion to rabbit plasma-conditioned steel coupons in-vitro.

Results: The adhesion of homologous S. aureus 8325-4 (fnbA+, fnbB+), and a heterologous MRSA arthroplasty isolate was significantly (p < 0.05) reduced when pre-exposed to anti-FnBP-A antiserum (un-purified and IgG-purified), compared to pre-exposure with pre-immune serum. This was not observed with mutant strain S. aureus DU5883 (fnbA?, fnbB?), indicating the involvement of FnBP-A – specific inhibitory antibody (IgG). Results clearly demonstrate the potential of rFnBP-A binding domain as a vaccine antigen for prevention of PJI and merit further investigation.

The implications of this are that vaccination using this peptide might be expected to protect patients about to undergo elective arthroplasty from infection with S aureus whatever its antibiotic susceptibility, so offering a realistic solution to the problem of increasing resistance.

Femoral head allograft bone used in complex orthopaedic surgery may transmit infection from donor to recipient. In order to minimise the risk all donors are serologically screened for Hepatitis B and C, HIV, HTLV, and syphilis at the time of donation and again at 6 months post-donation. Culture swabs are taken from the acetabulum and femoral head for 48 hour anaerobic and aerobic culture, and a sample of bone is incubated for 5 days in enrichment broth culture.

We have audited the culture results and screening tests performed in our bone bank from 2000 to 2005 inclusive.

1,528 allografts were received of which we had to discard 52 (3.4%) because of either positive cultures or serology. The vast majority of the positive cultures were due to S. epidermidis (30/43). All cultures were bacteria one might expect to find as normal skin flora. 3 patients had positive hepatitis C serology and 6 were syphilis EIA positive.

In May 2004 we decided in line with National Transfusion Guidelines for blood donation, to exclude donors who had had a blood transfusion since 1980 to mini-mise the risk of transmission of CJD. This and the opening of an Independent Treatment Centre (ITC) in our area drastically limited the number of possible donors to our bone bank. There was a significant reduction in the number of femoral heads received in 2004 and 2005 when compared with years 2000-2003 (p = < 0.00001).

We conclude that negligible numbers of femoral head allografts are lost due to our serological and microbio-logical screening tests. However measures introduced to limit the theoretical transmission of CJD via a bone allograft and the opening of a local ITC have had a huge impact on the number of potential donors available to us. To date the CJD prion has not been isolated from bone, but there have been 3 reported cases of transmission of infection by blood transfusion. We fear that the imminent introduction of a serological test for CJD will limit the number of possible bone donors even further.

Objective: To compare the in-vitro antimicrobial action of surgical irrigation fluids: 0.9% saline, 2g/L cephradine, 80mg/L gentamicin, 10% povidone-iodine (PVP-I) and 40ppm aqueous iodine (laq) for activity against Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli in the presence of blood, plasma and saline.

Materials and Methods: 5mL of antimicrobial agent was added to 5ml of blood, plasma or saline containing 10^5–10⁶ CFU/mL of the test bacterium. At 15 seconds, 1 minute, 5 minutes, 1 hour and 2 hours, a 1mL sample was inactivated in 9mL of 0.5% sodium thiosulphate. The bacterial numbers were determined using a biochemical assay (Chemiluminescence) with a calibration curve and by spread plate counts. The data were transformed by a logarithmic function and analysed by linear regression to give 95% confidence intervals for their gradient of change over 2 hours. Significant differences were defined at the 5% level.

Results: In saline. All bacteria were killed within 15 seconds with PVP-I and Iaq, but showed no significant reduction with saline, cephradine or gentamicin. In plasma. E. coli was killed within 15 seconds with all irrigation fluids. S. aureus and S. epidermidis showed no significant reduction with saline, Iaq or cephradine, but did show a significant reduction in the presence of gentamicin. With PVP-I, all S. epidermidis were killed within 15 seconds and all S. aureus within 5 minutes. In blood. E.coli with PVP-I, Iaq and cephradine showed no significant reduction. E. coli with gentamicin did show a significant reduction. Both staphylococci showed a significant reduction over 2 hours with PVP-I and gentamicin, but no significant reduction with saline, cephradine and Iaq.

Conclusions: As blood has a strong chemical inactivating effect on iodine – based formulations, Iaq and PVP-I cannot be recommended for surgical irrigation. Gentamicin should be used in preference to cephradine in surgical irrigation fluids if an antimicrobial agent is required. The residual immunological components (particularly complement) in blood and plasma may enhance the susceptibility of bacteria to antimicrobial agents.

Introduction and Aims: This is a prospective randomised trial comparing the ABG uncemented total hip replacement with the Charnley in 243 patients less than 65 years of age. A standardised protocol and anterolateral approach was used.

Method: The ABG I cup was used in combination with a polyethylene liner. All stems were templated and a 28mm cobalt chrome head was used. Early mobilisation with partial weightbearing for six weeks was allowed. In the Charnley group, Elite polyethylene cups were used in conjunction with 22mm monoblock stems. All hips were inserted with pressurised CMW cement. Patients were followed up annually. Standardised radiographs were taken at each visit and the Harris hip score and Merle d’Aubigné outcome measures recorded.

There were 222 hips available for follow-up, 96 ABG hips and 126 Charnley hips (17 died and 10 were lost to follow-up), with the mean age at surgery and mean length of follow-up comparable. Most hips were replaced due to osteoarthritis.

There was no significant difference in the mean Harris hip or Merle d’Aubigné scores at one year and at latest follow-up.

Results: Radiographic results demonstrated accelerated polyethylene wear in the ABG hips with mean polyethylene wear at seven years being 2.1mm compared with 0.9mm for Charnley hips. Wear associated lysis around the ABG cup was the major reason for failure, with a total of eight cups (8.3%) undergoing revision.

Conclusion: There was no evidence of subsidence of the stem or osteolysis around the stem despite the polyethylene wear. Conversely, in the Charnley group the stem was the major reason for failure with 12 stems (9.5%) being revised for aseptic loosening. The Kaplan Meier Survivorship at 10 years was 66.6% ± 19.1% for the ABG and ± 82% for the Charnley group. This was not significant.

Introduction: Our previous work has shown that angiogenesis occurs within the cartilaginous callus during long bone fracture healing1. Our aim in this study was to investigate the mechanisms involved in endochondral ossification within callus tissue during the secondary stages of fracture healing.

Methods: In this study, immunohistochemical techniques were used to localise the following proteins within the fracture callus at different times following injury. The angiogenic factors vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were localised; bFGF is also involved in matrix remodelling and cell proliferation. In addition, urokinase plasminogen activator and its receptor (uPA and uPAr respectively), a proteolytic enzyme involved in matrix remodelling, was immunolocalised. The model used for the study was a standardised midtibial osteotomy performed on New Zealand white rabbits.

Results: Results showed that from early time points, VEGF and bFGF were detected in pericellular locations around the chondrocytes. However, VEGF was only detected around the chondrocytes in close proximity to infiltrating vessels whereas homogenous localisation of bFGF was seen throughout the cartilage. Urokinase was localised throughout the cartilage callus as well as within vascular cavities and its receptor was detected on the chondrocyte cell surface from early time points.

Discussion: The immunolocalisation of VEGF around large hypertrophic chondrocytes in close proximity to infiltrating vessels suggests that this growth factor plays a role in chondrocyte hypertrophy and death, similar to its role in the growth plate. In contrast, bFGF was strongly detected throughout cartilage from early time points, suggesting that it may also be involved with cartilage proliferation during callus formation and subsequent matrix remodelling. The localisation of urokinase around chondrocytes and within vascular cavities suggests that this enzyme plays an important role in matrix remodelling and the vascularisation of the cartilage. In conclusion, our work suggests that the following sequence of events takes place within the cartilaginous callus. Firstly, bFGF is involved in the rapid proliferation of chondrocytes in the early stages of cartilage formation following fracture. Chondrocytes then express high levels of urokinase and its receptor which is actively involved in the degradation of cartilage matrix and formation of vascular spaces which leads to angiogenesis, VEGF expression, chondrocyte hypertrophy and eventual death.

Introduction and Aims: A phenotypic and proteomic approach has identified novel targets for the development of a DNA vaccine to prevent Staphylococcus aureus infection in orthopaedics.

Approximately 1% of joint replacement operations are complicated by infection. Thirty percent of these infections are due to S.aureus, which is often difficult to treat because of antibiotic resistance. As treatment of these infections is challenging, prevention with a vaccine is a very attractive option.

Method: To infect a joint replacement, bacteria must first adhere to its surface. This adherence is mediated by specific adhesion proteins; the expression of which is controlled by virulence regulator genes within the bacterial cell. A DNA vaccine is being developed which targets this regulatory apparatus, thus preventing bacterial adhesion, allowing the immune system to rapidly clear any potential S.aureus infection.

Results: Mutations of the agr,sar and sae virulence regulator genes have been made. Their properties have been explored using a flow cell system, which uses a scanning confocal laser microscope and image analysis software to accurately provide quantitative data in real-time of biofilm formation. We have shown that the sae mutant does not form biofilm in the same was as wild-type S.aureus. We have also shown that it does not adhere to steel as well as its wild-type counterpart.

Conclusion: For such a dramatic difference in biofilm forming properties to be evident, there must be a difference in the adhesion proteins produced by the wild-type and the mutant bacteria. Gel-electrophoresis has compared protein expression of sae mutant and wild-type bacteria and identified differences. Those proteins which are not expressed in the non-biofilm-forming mutant are sequenced and from the protein sequences, DNA sequences are identified that will form part of the candidate DNA vaccine.

Introduction and Aims: To establish whether basic fibroblast growth factor (bFGF) plays a role in the changes in chondrocyte metabolism exhibited in human osteoarthritis (OA).

Method: BFGF and its receptor was localised by immunohistochemistry within human OA. The results from OA tissue graded ‘early’ and ‘advanced’ were compared. This was correlated with the identification of proliferating chondrocytes (using by localising PCNA) and dead/dying chondrocytes (using the TUNEL technique).

Results: Results showed that bFGF and its receptor were strongly localised around chondrocytes in proliferating clusters in ‘early’ OA, whereas no bFGF was detected in ‘advanced’ OA. In addition, a loss of bFGF activity in ‘advanced’ OA correlated with the identification of large numbers of dead/dying chondrocytes.

Conclusion: Results suggest that high levels of bFGF activity in OA play an important role in chondrocyte proliferation and the formation of chondrocyte clusters. In addition, the loss of this activity appears to be directly related to an increase in cell death in ‘advanced’ OA, suggesting that bFGF acts as a ‘survival’ factor in this tissue. The more we understand about the metabolic changes in chondrocytes during OA, the closer we come to delaying or preventing this debilitating joint disease.

Objective: To determine whether Propionibacterium acnes is able to adhere to implant materials, and to develop biofilms.

Background: Most orthopaedic implant infections are caused by staphylococci, which express adhesins and can adhere to biomaterials and to plasma glycoprotein conditioning films. They then produce exopolymers and develop biofioms. P acnes, being anaerobic, is often missed as a cause of implant infection and might be more common than is realised, yet little is known about its virulence factors (ability to adhere to biomaterials or conditioning film and biofilm development).

Materials & Methods: Surgical steel or silicone coupons, with and without plasma conditioning film, were exposed to three clinical isolates of P acnes and examined by cultural methods and chemiluminescence for adherence. In further experiments, the coupons were incubated anaerobically with the P acnes strains for several days. They were then rinsed, fixed and processed for scanning electron microscopy (SEM). In a third set of experiments, coupons were again incubated anaerobically with P acnes and examined by laser confocal microscopy (LCM) for biofilm development.

Results: All three isolates of P acnes were able to adhere to the biomaterials, to a degree similar to that of a clinical isolate of Staphylococcus aureus, though not as strongly as Staphylococcus epidermidis. Unlike with the staphylococci, the presence of a conditioning film did not make a significant difference. SEM and LCM revealed biofilm development morphologically similar to that seen with S epidermidis. Exopolymer production was also demonstrated.

Conclusions: P acnes is able to adhere to biomaterials but not so avidly as S epidermidis. The adherence is not enhanced by plasma conditioning film. However, once adhered, P acnes is capable of developing a biofilm morphologically indistinguishable from that of S epidermidis. This probably explains the role of P acnes in implant infection, and the therapeutic difficulty it often poses.

Funding for the health service is limited and this inevitably leads to rationing. However, the allocation of funding to different specialities and clinical areas often has no rational basis. The aim of this study was to evaluate the health status of patients on the orthopaedic waiting list.

The SF-36 was used as a postal questionnaire and sent to all adult patients on the elective orthopaedic waiting list at our hospital. Demographic data was collected and patients were grouped by intended operation. The health domains of the SF-36 were adjusted for demographic variables and compared to population norms using non-parametric statistical methods.

The SF-36 was sent to 1586 patients and 1155 responded (73%). Analysis was undertaken for hip replacement (n=194), knee replacement (n=291), knee arthroscopy (n=232), foot and ankle (n=147) and cruciate ligament reconstruction (n=46). All diagnostic groups had significantly worse (p< 0.05) scores for all domains of health when compared to population norms. Patients awaiting joint replacement had worse disability (p< 0.001) than other groups, particularly for pain and physical function. Patients over 40 years awaiting arthroscopy had disability approaching these levels and those awaiting ACL reconstruction had poor physical function. In general, patients awaiting foot or ankle surgery had better health than other diagnostic groups but still had significant reductions when compared to normal. Health scores were not related to the Townsend index for social deprivation, indicating equity of access within the health service.

Patients awaiting hip and knee replacement have worse health than others on the waiting list. The SF-36 could be a useful tool if priority on waiting lists were to be determined by pain and disability rather than waiting time.

The New Zealand health score was developed by the New Zealand government to ensure that patients with the greatest needs were given priority. It allows explicit rationing of health care by clinical priority rather than waiting time (the current UK system). The scoring system has not been validated against an accepted measure of health status and the aim of this study was to compare the New Zealand score with the SF-36.

Patients on the orthopaedic waiting list for hip or knee replacement were sent postal questionnaires to collect demographic data and complete an SF-36 and New Zealand score.

581 patients were sent questionnaires. The response rate was 72% and data was available on 243 knee replacement and 168 hip replacement patients. For patients awaiting hip replacement there was good correlation between the NZ and all health domains of the SF-36 (correlation coefficient: 0.19 – 0.62). In contrast, there was poor correlation between the NZ score and the SF-36 for patients awaiting knee replacement with only physical function having a significant correlation (coefficient 0.25). Breakdown of the NZ score into pain and function components did not improve the correlation with SF-36 scores for these patients.

The New Zealand clinical priority scoring system correlates well with health status, as measured by the SF-36, for patients with hip arthritis awaiting hip replacement. However, the NZ score does not correlate with the SF-36 for patients awaiting knee replacement. This system is now being used by some centres in the UK for waiting list management but has been introduced without comparison to any well-established measures of health status. Its use for the prioritisation of patients who require knee replacement should be questioned.

Most infections in arthroplasty are caused by staphylococci, about half being due to S. aureus. One of the most worrying aspects of this organism, and particularly of MRSA, is increasing multiple drug resistance, so that antimicrobial prophylaxis is probably already compromised. Vaccination offers a novel approach to overcome this. Detailed consideration of the pathogenesis of prosthesis–related infection indicates that a) prosthetic material rapidly becomes coated after implantation with plasma–derived conditioning film, and b) attachment of the bacteria to the conditioning film, by means of specific bacterial surface binding proteins, is an essential primary event. We hypothesise that antibodies to these binding proteins will block bacterial adhesion to the prosthesis, so reducing the incidence of infection. The aim of this research was to determine the effect of specific antibodies to two binding proteins (fibronectin - and fibrinogen–binding proteins, Fnbp and Fgbp respectively) on bacterial adherence to orthopaedic biomaterials coated with plasma conditioning film.

Antibodies to recombinant sequences of Fnbp and Fgbp were raised in rabbits. A strain of S. aureus bearing a genetically inserted fluorescent reporter (GFP) was used. Orthopaedic biomaterials (steel, titanium and PMMA) were coated with FFP–derived conditioning film, placed in a specially–designed flow cell and exposed to a flow of S. aureus for 3h. Images were captured every 15min and analysed for adherent bacteria using image analysis software. The experiment was repeated in the presence of the antibodies and the results compared.

Each antibody reduced the number of bacteria binding to all three materials by greater than 50%. Combining the two antibodies gave similar results to those when they were used individually.

These preliminary results suggest that while further research is required, vaccination aimed at blocking bacterial attachment to conditioning film on implanted prostheses might reduce the incidence of S. aureus infection in arthroplasty. If so, this would apply even to MRSA. Questions remaining to be addressed include the clinical relevance of a 50% reduction in attachment, and future research will attempt to link this to a reduction in infection.

Many methods of reconstruction for ACL deficiency have been described, but little is known about their biomechanical properties. We examined extra-articular (EA), intra-articular (IA) and combined (EA+IA) reconstructions in ten cadaver knees after the ACL had been ruptured by the performance of a rapid anterior drawer movement. Stability at each stage before and after rupture and reconstruction was tested by anterior drawer, Lachman, varus-valgus and tibial rotation tests. Both IA and IA+EA reconstructions restored normal stability, while EA reconstructions improved stability but did not restore it to normal. The addition of an EA procedure to an IA procedure made no difference to knee stability. We conclude that in cases of isolated ACL deficiency there is no biomechanical basis for EA reconstruction, either alone or in addition to an IA reconstruction.