Introduction:

The direct anterior approach for total hip arthroplasty has shown to improve multiple early outcome measures. However, criticisms suggest improved results may be due to selection bias and protocol changes. This study compares mini-incision posterior approach to direct anterior approach performed by one surgeon, controlling for influences other than the surgical approach itself.

Compartment syndrome (CS) is a unique form of skeletal muscle ischaemia. N-acetyl cysteine (NAC) is an anti-oxidant in clinical use, with beneficial microcirculatory effects.

Sprague-Dawley rats (n=6/group) were randomised into Control, CS and CS pre-treated with NAC (0.5g/kg i.p. 1 hr prior to induction) groups. In a post-treatment group NAC was administered upon muscle decompression. Cremasteric muscle was placed in a pressure chamber in which pressure was maintained at diastolic minus 10 mm Hg for 3 hours inducing CS, muscle was then returned to the abdominal cavity. At 24 hours and 7 days post-CS contractile function was assessed by electrical stimulation. Myeloperoxidase (MPO) activity was assessed at 24-hours.

CS injury reduced twitch (50.4±7.7 vs 108.5±11.5, p<0.001; 28.1±5.5 vs. 154.7±14.1, p<0.01) and tetanic contraction (225.7±21.6 vs 455.3±23.3, p<0.001; 59.7±12.1 vs 362.9±37.2, p<0.01) compared with control at 24 hrs and 7 days respectively. NAC pre-treatment reduced CS injury at 24 hours, preserving twitch (134.3±10.4, p<0.01 vs CS) and tetanic (408.3±34.3, p<0.01 vs CS) contraction. NAC administration reduced neutrophil infiltration (MPO) at 24 hours (24.6±5.4 vs 24.6±5.4, p<0.01). NAC protection was maintained at 7 days, preserving twitch (118.2±22.9 vs 28.1±5.5, p<0.01) and tetanic contraction (256.3±37 vs 59.7±12.1, p<0.01). Administration of NAC at decompression also preserved muscle twitch (402.4±52; p<0.01 versus CS) and tetanic (402.4±52; p<0.01 versus CS) contraction, reducing neutrophil infiltration (24.6±5.4 units/g; p<0.01).

These data demonstrate NAC provided effective protection to skeletal muscle from CS induced injury when given as a pre- or post-decompression treatment.

A new apparatus and technique of syndesmosis fixation is tested in a prospective clinical study. Buttons on both sides of the ankle anchor a strong suture under tension following syndesmosis reduction. This syndesmosis suture acts like a tightrope when under tension. Implantation is simple with a minimally invasive technique, as the medial side is not opened. It allows physiological micromotion whilst resisting diastasis, does not require routine removal, and allows patients to weight-bear earlier.

Sixteen patients with Weber C ankle fractures with a syndesmosis diastasis underwent suture-button fixation and the results compared to 16 consecutive patients with syndesmosis screw fixation. Patients were, in effect, quasi-randomised according to surgeon preference. Mean A,O,F,A,S, ankle scores were significantly better in the suture-button group at three months post-op (91 vs 80, p=0.01, unpaired t-test) and at twelve months (93 vs 83, p=0.04, unpaired t-test). Return to work was also significantly faster (2.6 months vs 4.6 months, p=0.02, unpaired t-test). No suture-buttons required implant removal. Axial CT scanning at three months showed implants to be intact with maintenance of reduction, as compared to the uninjured contralateral side.

Suture-button syndesmosis fixation is simple, safe and effective. It has shown improved outcomes and faster rehabilitation, without needing routine removal. Although the apparatus design may undergo further refinement, we believe this technique will become the treatment of choice in Weber C ankle fractures with a syndesmosis injury.

Purpose: Compartment syndrome (CS) is a unique form of skeletal muscle ischaemia. N-acetyl cysteine (NAC) is an anti-oxidant with beneficial microcirculatory effects. We aim to assess the effect of NAC administration on CS induced muscle injury.

Methods: Sprague-Dawley rats (n=6/group) were randomised into Control, CS and CS pre-treated with NAC (0.5g/kg i.p. 1 hr prior to induction) groups. In a post-treatment group NAC was administered upon muscle decompression. Cremasteric muscle was placed in a pressure chamber in which pressure was maintained at diastolic minus 10 mm Hg for 3 hours inducing CS, muscle was then returned to the abdominal cavity. At 24 hours and 7 days post CS contractile function was assessed by electrical stimulation. Myeloperoxidase (MPO) activity were assessed at24-hours.

Results: CS injury reduced twitch (50.4 ± 7.7 vs 108.5 ± 11.5, p< 0.001; 28.1 ± 5.5 vs. 154.7 ± 14.1, p< 0.01) and tetanic contraction (225.7 ± 21.6 vs 455.3 ± 23.3, p< 0.001; 59.7 ± 12.1 vs 362.9 ± 37.2, p< 0.01) compared with control at 24hrs and 7 days respectively. NAC pre-treatment reduced CS injury at 24 hours preserving twitch (134.3 ± 10.4 , p< 0.01 vs CS) and tetanic (408.3 ± 34.3, p< 0.01 vs CS) contraction. NAC administration reduced neutrophil infiltration (MPO) at 24 hours (24.6 ± 5.4 vs 24.6 ± 5.4, p< 0.01). NAC protection was maintained at 7 days preserving twitch (118.2 ± 22.9 vs 28.1 ± 5.5, p< 0.01) and tetanic contraction (256.3 ± 37 vs 59.7 ± 12.1, p< 0.01). Administration of NAC at decompression also preserved muscle twitch (402.4 ± 52; p< 0.01 versus CS) and tetanic (402.4 ± 52; p< 0.01 versus CS) contraction, reducing neutrophil infiltration (24.6 ± 5.4 units/g; p< 0.01).

Conclusions: |NAC provides extended protection to skeletal muscle against compartment syndrome induced injury by both direct reducing neutrophil mediated tissue toxicity and by reducing neutrophil recruitment to the site of injury.

Introduction: The beneficial effects of insulin in the maintenance of normoglycaemia in non-diabetic myocardial infarct and intensive care patients have recently been reported. Hyperglycaemia and neutrophilia have been shown to be independent prognostic indicators of poor outcome in the traumatised patient. The role of insulin and the maintenance of normoglycaemia in the trauma patient have as yet not been explored. We hypothesised that through the already described anti-inflammatory effects of insulin and the maintenance of normoglycaemia, that the systemic inflammatory response would be attenuated, in the injured patient. This might result in less adult respiratory distress syndrome (ARDS) and multi-organ dysfunction and therefore less morbidity and mortality in trauma patients.

Materials and Methods: We used a previously validated rodent trauma model. There were 3 groups, two groups underwent bilateral femur fracture and 15% blood loss via cannulation and aspiration of the external jugular vein. The third group were anaesthetised only. The treatment group immediately receive subcutaneous insulin according to a recently identified sliding scale, and thereafter subcutaneous boluses, dependent on ½ hourly blood sugar estimations. The control groups received the same volume of normal saline ½ hourly, subcutaneously. The animals were maintained under anaesthetic for 4 hours from injury via inhaled isoflurane and oxygen. Core temperature and O2 saturations were recorded throughout. At 4 hours, each animal underwent midline laparotomy and cannulation of the IVC for blood sampling for full blood counts and lactate levels. Serum was also taken for flow cytometric analysis of neutrophil activation via respiratoy burst and CD11b levels. Broncho-alveolar lavage (BAL) was performed for neutrophil content and total protein estimation. The left lower lobe was harvested for wet-dry lung weight ratios.

Results: While O2 saturations were equal throughout in both groups, respiratory rates were persistently elevated in the controls. Wet:Dry lung weight ratios (p< 0.05) and lactate levels were reduced in the insulin treated animals compared to controls. There were similiarly fewer neutrophils in the BAL specimens of the insuliln treated animals compared to injured controls (p< 0.05).

Conclusions: Insulin reduces leukocyte lung sequestration in the injured animal model. This work confirms that insulin may have a role in reducing ARDS in the trauma patient, be that as an anti-inflammatory agent or anti-hyperglycaemic agent, or both, indicating that outcomes might be improved by treating hyperglycaemic trauma patients with insulin. Further work needs to done to elucidate its exact mechanism of action and role in the injured patient.

Phenytoin has previously been shown to accelerate wound healing through upregulation of angiogenesis and promotion of collagen deposition. These reported effects led us to hypothesise that phenytoin could be used locally at the tendon repair site to increase the rate and strength of healing. Systemic treatment with phenytoin has also been shown to increase the thickness and density of calvarial and maxillary bones in humans, and promote fracture healing in rabbits, rats and mice. Based on these and similar studies we hypothesised that local percutaneous injection of phenytoin solution into a fracture site would result in improved fracture healing without the risk of the side effects of systemic administration of the drug.

Methods: For the tendon repair study, a previously validated rabbit tendo-achilles tenotomy model was chosen. Animals underwent a transverse tenotomy of the FDL and TA tendons. These were immediately repaired using 3/0 ethibond sutures using the modified Kessler technique, prior to local application of either a phenytoin or buffer gel formulation. At 21 days post-op, the animals were euthanased and the TA harvested for tensiometry testing and collagen content estimation, and the FDL was harvested for histological analysis.

For the fracture study, a rat femur fracture model was utilised. Adult male Sprague-Dawley rats were anaesthetised. Following a medial parapatellar approach, the femur was cannulated using an 18 gauge cannula. The cannula was cut flush with the distal femur and countersunk. The skin and retinaculum were closed with 5.0 monocryl. The nailed femur was then fractured using a 3 point bending technique. The femurs were xrayed to ensure each fracture was mid-diaphyseal and transverse. At 6 hours post op animals underwent either 1) Fracture site percutaneous injection with 100 μmol phenytoin solution 2) Fracture site percutaneous injection with phosphate buffer solution (PBS) 3) No percutaneous injection. This procedure was once again repeated at 72 hours. At 2 and 4 weeks post op 6 animals from each group were euthanased, their femurs were harvested for biomechanical analysis of stiffness and strength.

Results: There was no difference in tendon diameter, gross adhesion formation, ultimate tensile strength or collagen content between the groups. Histologically, however, there were a significantly greater number of inflammatory cells (p< 0.05) and blood vessels (p< 0.05) in the phenytoin treated tendons compared to controls.

At both 2 and 4 weeks there was no statistical difference in stiffness or strength of the phenytoin treated fractures compared to controls.

Conclusions: The study phenytoin formulations whilst apparently promoting neovascularisation in the healing tendon, did not augment healing strength in either tissue suggesting that at these doses and dosing schedules the role of phenytoin is limited in these tissues.

Introduction: The use of allogeneic blood is associated with many complications. A baseline audit performed in our institution in 2000 showed that 11% of patients undergoing primary total knee arthroplasty required post-operative transfusion. Following this audit, patients undergoing primary knee arthroplasty were no longer routinely cross matched, a Haemovigilance Nurse was employed in compliance with the National Blood Users Group guidelines, and post-operative cell salvage was introduced for patients with a pre-operative haemoglobin level of less than 12 g/dL.

Aim: To assess the impact of these changes on our transfusion practice

Methods and materials A prospective audit was performed over a nine month period, from 1^st January to 30^th September 2003. Data was collected on 233 patients who had primary total knee arthroplasty performed during this period. Patients were transfused if their blood loss exceeded a pre-calculated maximal allowable loss, or based on a 48 hour post-operative haemoglobin level.

Results: Seventeen of the 233 patients (7%) received allogeneic blood. The average amount received was two units. Pre-operative anaemia and advanced patient age were predictive for increased risk of transfusion. Thirty six per cent of patients who were given a cell saver did not collect sufficient blood for re-transfusion. Ten per cent of this group required further transfusion with allogeneic blood.

Conclusion: There was no statistically significant difference in either the percentage of patients transfused or the volume of blood given to each patient between the two periods of audit. We did not find post-operative cell salvage to be an effective method of reducing allogeneic blood use.

Background Joint replacement remains the most effective healthcare measure in improving patient health related quality of life (HRQOL) and pain incompatible with normal daily living remains the primary indication for both hip and knee arthroplasty. Quality of life outcome and patient satisfaction after total hip arthroplasty are complex phenomena and many confounding determinants have been identified. Degenerative disease of the hip joint may present with variable patterns of pain referral in the lower limb. However the effect of varied pain referral patterns on patient outcome and satisfaction after total hip arthroplasty has not previously been examined. Methods From 2000 to 2003, 236 eligible patients scheduled to undergo primary total hip arthroplasty were prospectively enrolled. The principle pain referral pattern (as hip, thigh or knee) was identified in all patients. HRQOL was examined using the Harris Hip score (HHS), the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and the 36-Item Short-Form Health Survey (SF-36) pre-operatively, 1 year and 2 years postoperatively and with the HHS at 3 months postoperatively. All patients were followed up for a minimum of 2 years. Results The frequency of the pain referral distributions were; hip pain 41%, knee pain 32% and thigh pain 27%. Patients in all groups were comparable preoperatively with respect to age; HHS, and both mean and domain specific WOMAC and SF-36 scores. The mean duration of symptoms was significantly greater in patients with knee pain when compared to the remaining two pain patterns. All patients demonstrated as expected improvements in HHS, SF-36 and WOMAC scores after surgery. At all times postoperatively there were significant differences in mean HHS and mean and domain specific WOMAC and SF-36 scores between patients with hip or thigh pain and those with knee pain (p< 0.001). While notable, differences between hip and thigh pain were not as consistent however. Conclusions Pre-operative pain referral patterns of hip arthritis determine patient outcome and satisfaction after total hip arthroplasty, as measured using validated HRQOL scoring systems. Level of evidence Level I-1 (Prognostic Study-Investigating the Outcome of Disease. Prospective study).

Introduction: This retrospective study examined the clinical characteristics, radiological findings, management, and functional outcome in 34 rehabilitated patients who presented with traumatic central cord syndrome.

Methods: Between 1994 and 2004 a total of 34 patients with central cord syndrome were admitted to the National Spinal Injuries Unit. There were 29 men and 5 women. The mean age was 56.1 years (15 to 88). The mean follow up time was 4.9 years. Patients were divided into three groups by age, < 50 years (10 patients), 50–70 years (16 patients), and > 70 years (8 patients). The American Spinal Injury Association (ASIA) system recorded the motor and sensory scores, of upper and lower limbs, on admission, discharge and during rehabilitation. Patients underwent radiological investigation that included plain film, CT, and MRI of the cervical spine.

Results: The mechanism of injury was a fall in 58.8%, road traffic accident in 35.2% and other in 6%. Alcohol was a contributing factor in 32.4% of cases. Seven patients had a spinal fracture. The cervical spine was involved in 5 cases with the remaining 2 cases involving the thoracic spine. Seventy percent of patients received intravenous steroids. Over half (53%) of the patients had some degree of cervical spondylosis while cord changes were seen in almost all of the patients (79.4%). In the majority of cases (70.4%) the affected level was C3/4. Disc herniation was present in one third of cases (33.2%). The mean upper limb ASIA score on admission was 7.6, on discharge was 12.4 and at follow up was 20.2. A similar pattern was also observed in the lower limb with scores of 12.1, 13.7, and 20.5 respectively. Sensory loss also improved with time. 88.2% of those admitted required urinary catheterization, with 23.5% being discharged to the National Rehabilitation Hospital with a catheter in situ. Surgical decompression was performed in 7 cases. The remainder of patients wore a Miami-J cervical collar.

Conclusion: As was shown in the original paper by Schneider et al (1954), hyperextension of a degenerative cervical spine was the predominant mechanism of injury. The return of lower limb function precedes that of upper limb, with autonomic function recovering in the majority of cases.

Discussion: In this study patients in the younger age groups had better recovery of function and had fewer complications. The original paper by Schneider et al. stated that conservative treatment was most appropriate, however, in this review surgery was performed in specific cases such as those with cord compression secondary to disc herniation. Alcohol was a significant contributing factor.

Introduction: The majority of patients with osteoarthritis of the knee suffer from femorotibial pain with a smaller proportion suffering predominantly patellofemoral symptoms. No clear consensus exists as to the need for patellar resurfacing when performing total knee replacement for patients with symptomatic femorotibial osteoarthritis but without prominent patellofemoral symptomatic and radiographic disease.

Aims: To identify the advantages and disadvantages of both resurfacing and non-resurfacing of the patella during cemented total knee replacement performed for osteoarthritis predominantly of the femorotibial joint. To objectively clarify the rationale for the use of either procedure in clinical practice.

Methods: Prospective randomised double blinded clinical trial. Patients with osteoarthritis of the knee and principally femorotibial symptoms were included. Patients with rheumatoid arthritis, gross deformity of the knee and gross radiological or clinical patellofemoral arthritis were excluded. The implant used was a cemented posterior stabilised AMK (DePuy, Leeds UK) prosthesis. Preoperative American Knee Society Score, SF-36 questionnaire and WOMAC scores were calculated for each patient. These instruments were repeated and combined with clinical and radiological follow up at 3 months, 6 months and 1 year.

Results: 58 patients were recruited into the study, 53 of whom completed follow up and were in included in the analysis. Baseline characteristics were similar in each group. Operating room time was less in the non-resurfaced group (p< 0.05). At 2 years, 3 patients in the non resurfaced group had undergone a revision procedure. There was no difference between the resurfaced and non-resurfaced groups in terms of global functional outcome as measured by SF36 and WOMAC scores at 1 and 2 years post-operatively. The American Knee Society score showed no difference between the two groups (p=0.86) at 1 year post surgery.

Conclusion: There is no significant difference in clinical outcome at 1 and 2 years following surgery vis-à-vis those who did and did not have patellar resurfacing performed during knee replacement for predominantly femorotibial symptomatic osteoarthritis. There was a higher revision rate in the non-resurfaced group. In TKR using a PS AMK prosthesis routine resurfacing of the patella should be performed.

Introduction and Aims: To determine whether taurine influences skeletal muscle ischaemia-reperfusion injury in a rat hindlimb model.

Method: Twenty-three rats in five groups were subjected to right hindlimb ischaemia-reperfusion injury. The right femoral vein was exposed and cannulated, and a tourniquet applied to the right hindlimb. The left hindlimb acted as a control in each animal. In group 1 there was no treatment, group 2 had normal saline injected into the femoral vein distal to the tourniquet, group 3 had taurine 200mg/Kg injected distal to the tourniquet, group 4 had taurine 200mg/Kg injected proximal to the tourniquet, and group 5 had taurine 100mg/Kg distally and 100mg/Kg proximally. After ischaemia (four hours) and reperfusion (30 minutes), right and left gastrocnemius biopsies were taken and their contraction strength in response to a standardised electrical impulse was measured.

Results: Histology of all right-sided biopsies confirmed inflammatory changes consistent with ischaemia-reperfusion injury. In groups 1, 2, 4, and 5, the mean contraction strength of the right (ischaemia-reperfusion injury) biopsies was significantly less than that of the left (control) biopsies. In group 3 (taurine distal to the tourniquet) the difference in strength between right and left was an order of magnitude less than in the other groups, and was not statistically significant.

Conclusion: These data suggest that taurine during ischaemia confers some protection against ischaemia-reperfusion injury mediated functional impairment in rat skeletal muscle.

Introduction: Anterior knee pain is a commonly encountered orthopaedic symptom. Textbooks list a number of clinical symptoms and physical signs that are specific for the PF joint in the assessment of the patient with knee pain. Radiological evaluation of the PF joint is rarely helpful. The authors have investigated the value of these symptoms and signs in predicting the presence of PF pathology.

Patients and Methods: All patients presenting for diagnostic knee arthroscopy were enrolled prospectively. A detailed proforma was completed with each patient pre-operatively recording the presence or absence of specific PF symptoms and clinical signs. A blinded independent observer recorded the operative findings of the PF joint, the presence / absence of a plica and / or anterior synovitis. Chondromalacia (CM) was graded using the Outerbridge classification and grade 2 or greater was considered a positive finding.

Pre-operative symptoms and signs were correlated with arthroscopic findings and their positive predictive value (PPV) was determined.

Results: Thirty patients were enrolled over a 2-month period. Pure anterior knee pain was present in 10 patients. The remainder had medial (15), lateral (2) or generalised pain (3). 20 of the thirty patients had degenerative changes in the PF joint. One patient had a plica and no patients had significant anterior synovitis. 20 of the 30 patients had pathological findings elsewhere in their joint.

In the prediction of PF degenerative changes, the PPV of symptoms exacerbated by squatting was 0.53; stairs – 0.55; kneeling – 0.57; rising from low chair – 0.6 and night pain – 0.5.

Analysis of specific signs in predicting PF changes showed that the PPV of PF crepitus was 0.5; pain exacerbated by patellar compression 0.6; and patellar facet compression was 0.62.

Conclusion: Degenerative changes of the PF joint are common in our patient population. The value of knee arthroscopy in patients with isolated PF symptoms is questionable. Our assessment of these patients with specific questions and physical signs has been shown to have a low PPV in predicting ultimate arthroscopic findings in the PF joint.

Introduction: Histamine is an integral mediator following traumatic injury. Histamine-2 receptors have previously been identified on lymphocytes and monocytes.

Materials and methods: Two rodent models (1) Bilateral femoral fracture and intramedullary nailing, with resulting indirect lung injury (n=30). (2) In vivo model of orthopaedic implant contaminated by Staphylococcus epidermidis (n=36). Animals were randomised to receive ranitidine or placebo (saline).

Results: Markers of lung injury (MPO activity, BAL proteins and wet:dry ratios) increased 24 hours following bilateral femoral fracture, but were reduced if ranitidine was administered systemically after the injury. Production of Th-1 cytokines was blocked by ranitidine, whilst Th-2 cytokine production remained unaffected by ranitidine. These suggest an anti-inflammatory effect of ranitidine, blocking the early (Th-1) pro-inflammatory response following major injury.

Ranitidine’s effect on implant infection rates showed higher rates (44% versus 17%, relative risk 1.8 (95% CI 1.0 to 3.3)) when systemic ranitidine was delivered peri-operatively, suggesting an immunosuppressive effect.

Conclusions: The findings highlight the complex balance in vivo, a double-edged sword: the risk of increasing implant infection versus reducing indirect lung injury following major injury. The administration of ranitidine in major trauma patients with severe pro-inflammatory responses may block and reduce early multi-organ dysfunction and improve survival. However, owing to infection, the peri-operative administration of ranitidine should be avoided in elective cases.

Introduction: The National Bone Bank of Ireland was established in June 1996 at Cappagh National Orthopaedic Hospital, Dublin in response to the increased demand of allogenic bone grafts in Ireland. We reviewed the Bone Bank performance since it started with special emphasis on Microbiological monitoring of bone allograft as infection is the main complication of bone allograft (Chapman and Villar 1992).

Material and Methods: The femoral head allograft is harvested from living volunteer donors who are undergoing primary total hip replacement at Cappagh Hospital and have been assessed by the Bone Bank Co-Ordinator.

Harvesting: The bone is retrieved and harvested at the time of total hip replacement according to a strict protocol.

Storage: The bone is stored in the “Quarantine” freezer at −80 degrees C for a minimum period of 180 days. Each specimen is subjected to a full technical review by the Bone Bank Co-Ordinator and Medical Director and only when results of screening confirmed negative, the bone designated suitable for “Issue Stock” freezer.

Issue of Allografts: Bone is supplied for use, only after receiving full details of recipient to allow tracking. The results of the culture swab taken at the time of implantation and details of any post operative infection in recipients are forwarded to the bone bank.

Results: From June 1996 to December 2003, 5089 Primary Total Hip Replacements done at Cappagh Hospital and 1921 (38%) femoral heads were harvested. 109 (5.7%) of grafts had initial positive swabs/chips and 22 of these were discarded because of second positive chips. 1457 femoral head grafts supplied to 876 recipients and were used in Revision Total Hip Replacement (60%), Spine Surgeries (15%), Revision Total Knee (12%), Fractures, Tumours, Foot and Ankle (12%). 6 swabs at the time of grafting in recipients grew Staphylococcus Epidermidis but no clinical infection reported in our follow-up system. To double check, we posted a questioner to all consultants with list and details of their recipient patients and only 2 cases of suspected grafts related infection reported.

Discussion and Conclusion: Microbiological surveillance of bone grafts protect recipients from infection and is useful as a quality control of the process of bone banking (Farrington et al 1998). Our study showed contamination rate of 5.7%. Minimum infection rate post Revision Hip Replacement has been reported by Tomford in 1990, but after massive femoral allograft, infection has been reported 4% – 5% (Tomford 1990) and over 11% by Lord et al in 1988. Our experience showed only 2 cases in spite of strict follow-up protocol. We follow the policy of discarding the heavily contaminated grafts (Chapman 1992).

The quality performance of a Bone Bank depend on a full time bone bank co-ordinator, identification of donors, retrieval and harvesting of grafts, blood and microbiological assessment, medical supervision for decisions about contaminated grafts, a strict follow-up protocol and a regular audit of bone bank (Ivory and Thomas 1993). We also suggest that regular correspondence to the consultant using the bone grafts will improve the accuracy of follow-up.

The beneficial effects of insulin in the maintenance of normoglycaemia in non-diabetic myocardial infarct and intensive care patients have recently been reported. Hyperglycaemia and neutrophilia have been shown to be independent prognostic indicators of poor outcome in the traumatised patient. The role of insulin and the maintenance of normoglycaemia in the trauma patient have as yet not been explored. We hypothesised that through the already described anti-inflammatory effects of insulin and the maintenance of normoglycaemia, that neutrophil activation and endothelial dysfunction would be attenuated, in the injured patient. This might result in less adult respiratory distress syndrome (ARDS) and multi-organ dysfunction and therefore less morbidity and mortality for the trauma patient.

Materials and Methods: To study this we used a previously validated rodent trauma model. There were 2 groups, both groups underwent bilateral femur fracture and 15% blood loss via cannulation and aspiration of the external jugular vein. The treatment group immediately receive subcutaneous insulin according to a recently identified sliding scale, and thereafter subcutaneous boluses, dependent on half hourly blood sugar estimations. The control group received the same volume of normal saline half hourly, subcutaneously. The animals were maintained under anaesthetic for 4 hours from injury via inhaled halothane and oxygen. Core temperature and 0₂ saturations were recorded throughout. At 4 hours, each animal underwent midline laparotomy and cannulation of the IVC for blood sampling for full blood counts, lactate levels and for flow cytometry to estimate neutrophil activation via respiratory burst and CD11b upregulation. Bronchoalveolar lavage (BAL) was performed for neutrophil content and total protein estimation. The left lower lobe was harvested for wet-dry lung weight ratios.

Results: While 0₂ saturations were equal throughout in both groups, respiratory rates were persistently elevated in the controls. Wet:Dry lung ratios and lactate levels were reduced in the insulin treated animals compared to controls. There were similarly fewer neutrophils in the BAL specimens of the insulin treated animals (p< 0.05).

Conclusions: Insulin reduces leukocyte lung sequestration in the injured animal model. This work confirms that insulin may have a role in reducing ARDS in the trauma patient, be that as an anti-inflammatory agent or anti-hyperglycaemic agent, or both, indicating that outcomes might be improved by treating hyperglycaemic trauma patients with insulin. Further work needs to be done to elucidate its exact mechanism of action and role in the injured patient.

Compartment syndrome is a unique form of ischaemia of skeletal muscle which occurs despite patency of the large vessels. Decompression allows the influx of activated leucocytes which cause further injury. Vitamin C is a powerful antioxidant which concentrates preferentially in leucocytes and attenuates reperfusion-induced muscle injury. We have evaluated the use of pretreatment with oral vitamin C in the prevention of injury caused by compartment syndrome in a rat cremasteric muscle model.

Acute and delayed effects of pretreatment with vitamin C were assessed at one and 24 hours after decompression of compartment syndrome. Muscle function was assessed electrophysiologically. Vascular, cellular and tissue inflammation was assessed by staining of intercellular adhesion molecule-1 (ICAM-1) and by determination of the activity of myeloperoxidase (MPO) in neutrophils and tissue oedema.

Compartment syndrome impaired skeletal muscle function and increased the expression of ICAM-1, activity of MPO and muscle weight increased significantly. Pretreatment with vitamin C preserved muscle function and reduced the expression of ICAM-1, infiltration of the neutrophils and oedema.

Introduction A new technique of ankle syndesmosis fixation is proposed. Buttons are placed on both sides of the ankle, connected by a strong non-absorbable suture. The technique is simple and minimally invasive: a medial incision is not required. It resists diastasis whilst allowing physiological micromotion and does not require routine removal.

Methods The technique was tested on a cadaver model of a Maisonneuve injury under increasing torque loads. Sixteen embalmed cadaver legs were randomised to receive suture-button fixation or four-cortical 4.5 mm syndesmosis screw fixation. A prospective clinical study involving 16 patients with Weber C fractures and syndesmosis diastasis is presented. They underwent suture-button fixation and the results were compared to 16 consecutive patients with syndesmosis screw fixation.

Results In the cadaver study, both groups had similar rates of diastasis following torque loading. However, the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001) than the screw group. In the clinical study, both groups were evenly matched as regards patient age, male: female ratio, and fracture patterns. Mean AOFAS ankle outcome scores at three months were significantly better in the suture-button group (91 versus 82, p=0.01). No suture-button patients required implant removal. They had a faster return to work compared to the screw group (three months versus five months). Axial CT scanning performed at three months post-op showed all implants to be intact with no loss of reduction.

Conclusions Suture-button syndesmosis fixation is simple, safe, effective and physiological. It has shown improved outcomes and faster rehabilitation, without needing routine removal. It may become the treatment of choice in Weber C ankle fractures with a syndesmosis diastasis.

In relation to the conduct of this study, one or more the authors have received, or are likely to receive direct material benefits.

Aims: A new technique of syndesmosis fixation is proposed; placing buttons on both sides of the ankle, without opening the medial side, connected by a strong non-absorbable suture. We tested this against syndesmosis screw fixation in a cadaver model of a Maisonneuve injury and subsequently in a prospective clinical study. Methods: 16 cadaver legs were randomised to have suture-button or syndesmosis screw fixation and tested under torque loading. In the clinical study, 16 patients with a syndesmosis diastasis underwent suturebutton fixation and the results compared to 16 patients with syndesmosis screw fixation. Results: In the cadaver study, both groups had similar rates of diastasis, although the suture-button did give a more consistent performance: standard deviations were significantly lower (p=0.001). In the clinical study, mean A.O.F.A.S. scores at 3 months were significantly better in the suturebutton group (91 vs 82, p=0.01). No suture-button implants required removal, compared to 13/16 of the screw group (p=0.001). Conclusions: Suture-button syndesmosis fixation is simple, safe and physiological. Biomechanically it performs at least as well as screw fixation. Clinically it has shown improved outcomes, without needing routine removal. It may become the treatment of choice in syndesmosis injuries.

Pathological conditions of the hip joint may present with variable patterns of pain referral in the lower limb. Literature reports suggest that up to 35% of total hip arthroplasties are performed on patients whose primary compliant is obturator nerve referred “knee pain”. However the effect of varied pain patterns on patient outcome and satisfaction has not previously been examined. This prospective study was undertaken to determine the most common referral patterns of hip pain in patients scheduled to undergo primary total hip replacement and to examine whether initial pain referral pattern predicted ultimate patient outcome. Patients were assessed using the Harris Hip score, SF 36 and WOMAC scoring systems measured preoperatively, at 6 months, 1 and 2 years post operatively.

236 patients were identified with isolated single hip joint disease. Patients who demonstrated multi joint disease, and particularly ipsilateral knee pathology were excluded. Forty-five percent of patients with primary hip disease had pain primarily at or about the knee. There was no difference in preoperative demographics, physical function, social function, perceived general health, Harris Hip score (p=0.74), SF 36 (p=0.66) or WOMAC scores (p=0.81) between the pain pattern groups. Operator status and operative techniques were comparable. At 1 and 2 years postoperatively the groin and thigh pain groups were similar in all respects. However at 6 months, 12 months and 2 years, Harris hip scores (p=0.04, p=0.037, p=0.021) and SF 36 scores (p=0.035, p=0.027, p=0.01) were significantly lower in those patients presenting initially with knee pain. Multivariate regression analysis confirmed that no other confounding variables could account for the observed differences between the groups. These results indicate that, using current outcome measures, patients with “knee pain” who undergo total hip arthroplasty, and in whom ipsilateral knee disease has been excluded, have poorer long-term physical and social function and perceived general health. We believe this is the first report of its kind and suggest that patient and surgeon expectations of the results of total hip arthroplasty should be tailored according to the individual initial pain referral pattern.

Introduction: Hip arthroplasty is growing in importance and relevance in the detection and treatment of various pathologies affecting the hip joint. A growing number of indications exist including the diagnosis and treatment of synovial-based disease, extraction of loose bodies within the joint, and treating chondral flaps and labral tears. Hip arthroplasty represents a minimally invasive, joint preserving, effective and reproducible tool to achieve these. The literature cites few complications arising from the procedure.

Study: Retrospective study of the outcomes of 20 patients who underwent hip arthroplasty between March 1999 and October 2002.

Methods: All the patients were first clinically assessed and then underwent Magnetic Resonance Imaging of their hips prior to undergoing arthroplasty. The indications for the MR arthrography included hip or groin pain, joint stiffness with associated impaired exercise tolerance. Arthroscopy was performed as a day case under general anaesthetic. The patients were placed supine on a fracture table and traction applied, under image control 30 and 70 degree arthoscopes were placed through an anterior and peritrochanteric portals. The patients followed up for an average of 20 months (6–44 months) and assessed for pain, mechanical symptoms, activity level, work status, sports ability and performance of activities of daily living. Data collected was retrospectively reviewed.

Results: The correlation between MR imaging and arthroscopy was approximately 80%. MR imaging detected all the labral tears present in 10 patients. This sensitivity was however reduced for the detection of small osteophytes (105), synovitis (5%), and minor labral radial fibrillation (5%). Four patients had loose bodies, which were successfully extracted. The patients whose symptoms were the result of mechanical pathology achieved complete resolution of their symptoms post operatively. No complications were seen.

Conclusion: Hip arthroplasty can be performed for a variety of conditions with reasonable expectations of success and minimal complication rate.

There have been multiple approaches described for internal fixation of acetabular fractures. We discuss the results of acetabular fractures treated in our institution via a Stoppa intrapelvic approach. Between July 1997 to October 2002, the senior author surgically treated 14 acetabular fractures using this approach. Indications for utilizing this approach include displaced anterior column fractures, transverse fractures, T shaped fractures, both column fractures and anterior column or wall fractures associated with a posterior hemi transverse component. The fractures were classified according to Letournel and Judet. There were 10 males, 4 females with a mean age of 34 years (20–57 years).

Patients were followed up for an average of 26 months (8–60 months). All fractures went on to union at an average of 12 weeks. There was one superficial wound infection, which was successfully treated with antibiotics. No patients suffered loss of fixation. There were no nerve or visceral injury in our series.

Clinical results evaluated were based on the Harris Hip Score (out of 100). Our results show 13 patients had good to excellent results (Score 80–100), whereas one patient had a fair result.

The Stoppa intrapelvic approach offers improved reduction and fixation techniques with a decrease in complications associated with extensile approaches.

Introduction: The majority of patients with osteoarthritis of the knee suffer from femorotibial pain with a smaller proportion suffering predominantly patello-femoral symptoms. No clear consensus exists as to the need for patellar resurfacing when performing total knee replacement for patients with symptomatic femorotibial osteoarthritis but without prominent patello-femoral symptomatic and radiographic disease.

Aims: To identify the advantages and disadvantages of both resurfacing and non-resurfacing of the patella during cemented total knee replacement performed for osteoarthritis predominantly of the femorotibial joint. To objectively clarify the rationale for the use of either procedure in clinical practice.

Methods: Prospective randomized double blinded clinical trail. Patients with osteoarthritis of the knee and principally femorotibial symptoms were included. Patients with rheumatoid arthritis, gross deformity of the knee and gross radiological or clinical patello-femoral arthritis were excluded. The implant used was a cemented posterior stabilized AMK (Depuy, Leeds UK) prosthesis. Pre-operative American Knee Society Score, SF-36 questionnaire and WOMAC scores were calculated for each patient. These instruments were repeated and combined with clinical and radiological follow up at 3 months, 6 months and one year.

Results: 58 patients were recruited into the study, 53 of whom completed follow-up and were included in the analysis. Baseline characteristics were similar in each group. Operating room time was less in the non-resurfaced group (p< 0.05). At one year, no patient in either group had needed to undergo a revision procedure. There was no difference between the resurfaced and non-resurfaced groups in terms of global functional outcome as measured by SF36 and WOMAC scores at one-year post operatively. The American Knee Society score showed no difference between the two groups (p=0.86) at one-year post surgery.

Conclusion: There is no significant difference in clinical outcome at one year following surgery vis-à-vis those who did and did not have patellar resurfacing performed during knee replacement for predominantly femorotibial symptomatic osteoarthritis. Patellar resurfacing as a procedure is not without complications. In patients with osteoarthritis of the knee and predominantly femorotibial disease based on clinical and radiographic findings, we do not advocate the routine use of patellar resurfacing.

Introduction: The paradoxical further damage done to ischaemic tissue when blood flow and oxygenation are restored is termed ischaemia-reperfusion injury. The underlying mechanisms are complex but centre on oxidative damage to the cell membrane, which suggest a therapeutic role for antioxidants such as endogenous amino acid taurine.

Methods: In this study, 23 rats in 5 groups were subjected to right hind limb ischaemia-reperfusion injury. The right femoral vascular bundle was exposed and the femoral vein cannulated, and a tourniquet applied to the right hind limb. The left hind limb acted as a control in each animal. In group 1 there was no treatment administered, group 2 had normal saline injected into the femoral vein distal to the tourniquet, group 3 had turbine 200mg/Kg injected distal to the tourniquet, group 4 had taurine 200mg/Kg injected proximal to the tourniquet, and group 5 had taurine 100mg/Kg distally and 100mg/Kg proximally. After 4 hours of ischaemia and 30 minutes reperfusion, gastrocnemius biopsies were taken from right and left hind limbs and their contraction strength in response to a standardised electrical impulse was measured.

Results: There was a statistically significant difference in contraction strength between right and left hind limb samples in all groups. The difference in-group 4 was an order of magnitude less than that in groups 1, 2, and 3, with an intermediate value in-group 5. Histological examination confirmed inflammatory changes consistent with ischaemia-reperfusion injury and not simple necrosis.

Conclusion: These data suggest that taurine in the reperfusing blood, rather than in the ischaemic tissues, confers some protection against ischaemia-reperfusion injury mediated functional impairment in rat skeletal muscle.

Introduction: Patients with multiple skeletal injuries are susceptible to Systemic Inflammatory Response Syndrome (SIRS) and consequently Acute Respiratory Distress Syndrome (ARDS). Fracture haematoma contains pro-inflammatory mediators. The aim of our study was to show in vitro that fracture haematoma is implicated in neutrophil mediated injury, SIRS, ARDS and MOF.

Methods: Fracture haematoma was isolated from 10 patients at the time of surgery. Neutrophils (PMN) were isolated from 10 healthy volunteers. PMN were exposed to the fracture haematoma supernatant and PMN activation in both primed and unprimed neutrophils were examined (CD11b and CD18 adhesion receptor expression and respiratory burst). PMN phagocytosis and apoptosis were also assessed using flow cytometry. Transmigration across an endothelial barrier was also measured following exposure to fracture haematoma.

Results: Fracture haematoma had a marked effect on respiratory burst in primed PMNs (control = 100% vs 20% fracture haematoma = 1044% ± 405, p=0.04). CD11b and CD18 adhesion receptor expression were not upregulated in the fracture haematoma group. PMN phagocytosis of E coli was increased following treatment with fracture haematoma (control = 100% vs fracture haematoma = 171% ± 6SE, p=0.0001). Transendothelial migration of treated neutrophils was unaffected. Treatment of endothelial monolayers with fracture haematoma did not result in upregulated ICAM1 expression but was observed to induce significant endothelial cell death. PMN apoptosis was significantly delayed following exposure to fracture haematoma (control = 46% ± 5 vs fracture haematoma = 8% ±2, p=0.0005).

Discussion: We have shown that fracture haematoma activates neutrophils, increases phagocytosis and respiratory burst whilst delaying apoptosis. These effects, whilst beneficial at the site of injury, may cause neutrophil mediated tissue injury systemically.

Aseptic loosening of implants following hip arthroplasty is a cause of significant patient morbidity. We genotyped 99 revision hip arthroplasty patients and 116 primary hip arthroplasty patients for the C282Y and the H63D mutations, which cause Haemochromatosis. Haemochromatosis is an inherited condition leading to excessive iron absorption and deposition in the body. All patients at the time of their primary hip arthroplasty were diagnosed as having osteoarthritis. We identified 9 of the 99 revision arthroplasty patients as being homozygous for the C282Y mutation. The time to revision in this group was significantly lower (p< 0.005) when compared to the remaining 90 patients in the group (mean 8.7 years vs 14.8 years). Analysis of variables such as patient age and sex and also type of prosthesis, place of surgery and operating surgeon had no confounding influence. We hypothesise that undiagnosed iron overload in the patients homozygous for the C282Y mutation is likely to cause premature failure of their primary hip arthroplasty.

We have compared the rates of infection and resistance in an animal model of an orthopaedic procedure which was contaminated with a low-dose inoculum of Staphylococcus epidermidis. We randomised 44 Sprague-Dawley rats to have bone cement implanted subcutaneously containing either gentamicin or saline (control). The wound was inoculated with a dilute solution of gentamicin-sensitive Staphylococcus epidermidis. At two weeks the cement was retrieved and microbiologically tested. A lower overall rate of infection was seen in the gentamicin-loaded cement group, but there was a significantly higher rate of gentamicin-resistant infection in this group (Fisher’s exact test, p < 0.01). Antibiotic-impregnated cement has an optimum surface for colonisation and prolonged exposure to antibiotic allows mutational resistance to occur. Gentamicin-loaded cement may not be appropriate for revision surgery if it has been used already in previous surgery.

Previous reports have indicated that elderly patients suffer more operative complications than younger patients undergoing total hip arthroplasty (THR)

We reviewed 46 consecutive patients over 85 years of age at the time of THR. All patients were at least 3 years post-op at the time of review. Pre and post operative D’Aubigne-Postel Hip Scores were assigned. Length of stay, transfusion rates, intra-operative blood loss and patient satisfaction were also noted. Statistical comparisons were mode with a control group of patients, average age 66.3 years.

The average age at the time of operation was 86.6 (range 85–92) years. The average follow up was 52.8 (range 38–86) months. The average hospital stay was 21.1 (range 12–40, median 18) days. Pre-operative D’Aubigne-Postel Score averaged 8.4 (range 1–14) points, post-operative D’Aubigne-Postel Score averaged 13.1 (range 9–18) points. Subjective satisfaction was high. There were no operative complications and no dislocations during the follow up period. There were no deaths within one year of surgery. Four of the 45 patients died during the 3 year follow up period.

When compared to the control group, patients over the age of 85 years had an increased intra-operative blood loss, p< 0.001, they also had an increased blood transfusion at rate, p=0.0005. Patients over the age of 85 remained in hospital longer, p=0.0002. Comparing D’Aubigne-Postel Score, patients over the age of 85 years benefited as much as the control group, p=0.0001.

We conclude that THR is the over 85 years old patients is a safe procedure and yields good functional results.

Introduction: Since the introduction of joint arthroplasty major advances including the introduction of laminar airflow, have been made in reducing infection to current rates of 1 to 2%. Nonetheless infection remains a devastating complication, with major implications in terms of patient suffering, duration of hospital stay and financial burden. We undertook a study to examine the incidence of bacterial wound contamination occurring in the intra-operative period.

Materials and Methods: All patients admitted to our unit for elective hip and knee arthroplasty were entered into the study. On arrival in theatre a skin swab was taken. The patient was then prepared and draped in the anaesthetic room before final draping by the surgical team in the operating theatre. All procedures were performed in theatres equipped with laminar airflow, and all surgical personnel wore isolator suits. During the course of the procedure swabs were taken from the anterior aspect of the femur at 30-minute intervals. In addition the skin and inside blades and the suction tip were harvested at the end of the procedure. All samples were then sent for culture. Patient data including age, comorbid conditions and history of previous surgery were noted on a standardised pro forma. In addition, operative data including duration of the procedure, operating surgeon and type of drape and skin preparation used were noted.

Results: 65 patients have been examined to date. An incidence of contamination of 14% has been noted (9 patients) with the skin blade and suction tip being the most common source of contaminating organisms. Staphylococcus epidermis was cultured in 5 cases, with Gram negative organisms being cultured in the remaining samples. In all 9 cases only small numbers of organisms were identified. None of the patients with positive cultures developed clinical signs of deep or superficial wound sepsis, and all had an uncomplicated postoperative course.

Conclusions: While low levels of contamination are unavoidable in theatre, it is important that strict discipline be maintained in order to minimise this risk. In particular, careful attention to patient skin preparation, the use of prophylactic antibiotics and minimising use of the suction tubing help decrease contamination rates.

Osteoarthritis of the hip exhibits progressive degeneration of articular cartilage frequently resulting in total hip arthroplasty (THA). Expression of cytokines such as tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL6) is increased in the synovium and articular cartilage of these patients. Furthermore, these cytokines have been shown to have a negative regulatory effect on chondrocyte proliferation and articular cartilage metabolism. We investigated the frequency of a G/C polymorphism at position −174 of the promoter region of the IL-6 gene and a G/A polymorphism at position −308 of the TNF alpha gene, both of which cause increased expression of these cytokines. We observed that the G variant of the IL6 gene was significantly higher in patients who had undergone revision THA compared to controls (P=0.05). It was also elevated in primary THA patients compared to controls. The G/A polymorphism in TNF alpha was not significantly associated with THA; however, this may reflect the lower incidence of this polymorphism in the population. These results suggest that an alteration in cytokine expression produced by the IL6 −174G/C mutation may have a role in the aetiology of osteoarthritis and the outcome of total hip arthroplasty.

Injury to the infrapatellar branch of the saphenous nerve has been reported as a complication of arthroscopic examination and surgery of the knee. This can result in altered sensation on the anterolateral aspect of the knee, reflex sympathetic dystrophy and, occasionally, severe deafferentation pain. The aim of this cadaveric study was to delineate the course of the infrapatellar branch as it passes across the anterior aspect of the knee and identify potential safe areas for blind puncture at arthroscopy. The risk of damage to the nerve branch from the various open incisions used for orthopaedic surgery of the knee is also discussed.

The distribution of the infrapatellar branch was studied in both lower limbers of eleven cadavers (22 specimens). Two patterns of nerve distribution could be described in relation to its path across the proximal margin of the tibia. In 28% of examined cadavers, the infrapatellar branch of the saphenous nerve traverses the patellar tendon and runs laterally without ever crossing over the tibia. In the remaining 72% the infrapatellar branch crossed the proximal margin of the tibia prior to crossing the patellar tendon. Using the interior pole of the patella as a landmark, our results indicated that blind puncture is safe within an approximate wedge-shaped area ranging from 10mm inferior and 30mm medial to the inferior pole up to a level 10mm superior and 50mm medial to the inferior pole of the patella. The incidence of injury to this nerve can be reduced by clarifying the distribution of the infrapatellar nerve branch in relation to palpable landmarks.

Introduction: The infrapatellar fat pad was first described in 1904 by Albert Hoffa. Sometimes disregarded, it is apparent that the infrapatellar fat pad is of importance to knee joint function as fat at this site is only lost in severely emaciated individuals. Also, recent MRI studies have described various pathological changes affecting the fat pad. This study examined the anatomy of the infrapatellar fat pad in relation to knee symptoms and surgical approaches.

Materials and Methods: 8 preserved knees were dissected via semicircular parapatellar incisions extending from the tibial tubercle to the superior patellar border and including the quadriceps muscle 13 cm above the superior border of the patella. The synovial membrane of the joint and the ligamentum mucosum were divided and the tibial tubercle was then excised. The resultant tissue complex was removed and the fat pad dissected away from surrounding structures. The appearance, volume and presence of any clefts in the pad were recorded. The cadaveric dissections were then compared to direct observation of the fat pad during total knee replacement, during arthroscopy and on MR imaging.

Results: The infrapatellar fat pad was found to be present in all cases. It had a consistent shape consisting of a central mass with medial and lateral extensions. The ligamentum mucosum was attached to the intercondylar notch of the femur in all cases and measured an average of 15.7mm at its base. A horizontal cleft was found in 6 cases and a vertical cleft was found in 7 cases. Both have been previously noted. A tag extended superiorly from the posterior aspect of the fat pad in 7 cases. The volume of the fat pad had quite a large range among individual cadavers (average volume was 24 ml, range: 12–36ml). The intra-individual variation was smaller with an average difference of 4ml (range:2.7ml) between knees.

Discussion: The infrapatellar fat pad has been implicated in a wide variety of conditions affecting the knee joint. It has been shown to be involved in arthofibrosis of the knee following surgery, patellar tendonitis, formation of intra-articular fibrous bands, and a site of an ossifying chondroma. It seems that fat pad pathology is usually secondary to other knee joint pathology and primary involvement is rare. The presence of clefts in the fat pad is of importance as a distended cleft may mimic an abnormality and an abnormality in the cleft may be overlooked on imaging of the knee joint. The appearance of the fat pad on direct visualisation in the living person presented a fat pad with a more globular appearance than that seen in the cadaver. The clefts were clearly visualised on MRI.

Conclusion: The infrapatellar fat pad is a structure that is consistently present in the knee joint. It consists of a central body with medial and lateral and medical extensions. It usually contains a vertical cleft located superiorly and a horizontal cleft located inferiorly as well as a tag of fat extending superiorly, which forms the roof of the vertical cleft. The infrapatellar fat pad is attached to the intercondylar notch of the femur by the ligamentum mucosum and is firmly anchored to the patella by dense fibrous tissue.

Matsen in 1975 described Compartment Syndrome (CS) as a condition in which the circulation and function of tissues within a closed space are compromised by increased pressure within that space. Raised intra-compartmental pressures result in progressive venous obstruction, capillary stagnation and microvascular hypoxia.

N-acetyl cysteine (NAC) is an anti-oxidant used clinically to reduce liver injury following paracetamol overdose. NAC has been shown previously to reduce lung injury following exposure to endotoxin. Our aim was to evaluate the efficacy of n-acetyl cysteine in the prevention of CS induced acute muscle injury.

Sprague-Dawley rats (n=6/group) were randomised into Control, CS and CS pre-treated with N-Acetyl Cysteine (0.5g/kg i.p. 1 hr prior to induction). Cremasteric muscle was isolated on its neuro-vascular pedicle and CS injury was induced by placing the muscle in a specially designed pressure chamber. Arterial blood pressure was measured via a cannula placed in the carotid artery. To induce compartment syndrome chamber pressure was maintained at diastolic-10 mm Hg. After three hours pressure was released stimulating surgical fasciotomy. One hour after decompression muscle function was assessed by electrical field stimulation: peak twitch (PTV) and maximum tetanus (MTV) values were recorded. Tissue oedema was assessed by wet to dry ratio (WDR).

Compartment Syndrome (CS) resulted in a significant decrease in muscle function (PTV, MTV). CS also resulted in a significant increase in tissue oedema (WDR). Pre-Treatment with N-Acetyl Cysteine attenuated CS injury as assessed by these parameters. These data show that administration of the anti-oxidant N-Acetyl Cysteine results in significant attenuation of the muscle injury and oedema caused by Compartment Syndrome.

This work was supported by a grant from the Cappagh Trust.

Acute respiratory distress syndrome is a long established complication and continuing cause of significant morbidity and mortality in the multiply injured patient. Systemic inflammatory response syndrome (SIRS) is classically associated with acute pulmonary dysfunction. A variety of insults including trauma, sepsis, hypoxia, ischaemia reperfusion, can trigger systemic inflammatory response and acute lung injury. In models of sepsis, endotoxaemia and ischaemia-reperfusion, acute lung injury is characterised by widespread endothelial-neutrophil interaction and neutrophil activation.

Another associated finding in these models of injury, is evidence of induced diaphragm muscle dysfunction, by electrophysiological testing of muscle strips post injury.

An established model of incremental increasing skeletal trauma was employed. Adult male sprague dawley rats (mean weight 476grams, 370–520g) were randomised to control, single hindlimb fracture, bilateral hindlimb fracture and bilateral hind limb fracture + 20% haemorrhage.

Indices of acute lung injury studied 2 hours post injury were bronchalveolar lavage, cell counts, and protein assays. Pulmonary tissue myeloperoxidase activity was assayed as an indicator of neutrophil activation and pulmonary wet/dry weights were measured as a marker of pulmonary oedema.

Diaphragmatic electrophysiological testing was also performed 2 hours post injury. Freshly harvested diaphragmatic muscle strips had peak evoked muscle twitches measured, the maximal tetanic twitch and muscle strip fatigue times were also assessed.

Statistical analysis was performed by means of analysis of variance (ANOVA).

Results: The cohort of animals with the greatest injury severity manifested evidence of acute lung injury when compared with controls, this was associated with evidence of interstitial leucosequestration. This data suggests that neutrophils are involved in mediating an acute lung injury following musculoskeletal trauma.

Following ischaemia-reperfusion (I-R) tissues undergo a neutrophil mediated oxidant injury. Vitamin C is a water-soluble endogenous anti-oxidant, which has been shown in previous studies to abrogate neutrophil mediated endothelial injury. Our aim was to evaluate Vitamin C supplementation in the prevention of I-R induced acute muscle injury.

Sprague-Dawley rats (n-6/group) were randomised into control, I-R and I-R pretreated with Vitamin C (3.3g over 5 days). Cremasteric muscle was isolated on its neuro-vascular pedicle and I-R injury induced by clamping the pedicle for 3 hours, the tissue was subsequently reperfused for 60 minutes. Following reperfusion muscle function was assessed by electrical field stimulation: peak twitch (PTV), maximum tetanus (MTV) and fatigability values were recorded. Tissue neutrophil infiltration was assessed by tissue myeloperoxidase (MPO) activity and tissue oedema by wet:dry ratio (WDR).

Ischaemia-reperfusion (I-R) resulted in a significant decrease in muscle function (PTV< MTV) there was no difference in fatigability values between groups. I-R also resulted in a significant increase in neutrophil infiltration (MPO) and tissue oedema (WDR). Pre-treatment with Vitamin C attenuated I-R injury as assessed by these parameters. This data suggests that oral Vitamin C reduce I-R induced acute muscle injury, possibly by attenuating neutrophil mediated tissue injury.

Ischaemia-reperfusion injury (IRI) is caused by endothelial and subendothelial damage by neutrophil-derived oxidants. Vitamin C is an antioxidant which attenuates endothelial injury after IRI. Our aim was to evaluate the effect of oral vitamin C in the prevention of IRI in skeletal muscle. We used a model of cross-clamping (3 hours) and reperfusion (1 hour) of the cremaster muscle in rats. Muscle function was assessed electrophysiologically by electrical field stimulation. Infiltration by neutrophils was determined by the activity of tissue myeloperoxidase (MPO) and tissue oedema by the wet-to-dry ratio. Neutrophil respiratory burst activity was measured in control animals and groups pretreated with vitamin C.

IRI significantly decreased muscle function and increased muscle neutrophil MPO activity and muscle oedema. Pretreatment with vitamin C preserved muscle function and reduced tissue oedema and neutrophil infiltration. Neutrophil respiratory burst activity was reduced in the group treated with vitamin C compared with the control group.

We conclude that pretreatment with oral vitamin C protects against acute muscle IRI, possibly by attenuating neutrophil respiratory burst activity.

Recent reports have suggested an association between Perthes’ disease and an underlying thrombophilic or hypofibrinolytic tendency. In Northern Ireland there is a high incidence of Perthes’ disease (11.7 per 100 000 or 1 in 607 children) in a stable paediatric population.

We reviewed 139 children with Perthes’ disease and compared them with a control group of 220 aged- and gender-matched healthy primary schoolchildren with similar racial and ethnic backgrounds.

There were no significant deficiencies of antithrombotic factors protein C, protein S, antithrombin III or resistance to activated protein C. A total of 53 (38.1%) of the children with Perthes’ disease had a prolonged activated partial thromboplastin time (> 38) compared with 13 (5.9%) of the control group (p < 0.001). Our findings have shown that using standard assays, thrombophilia secondary to antithrombotic factor deficiency or resistance to activated protein does not appear to be an aetiological factor for Perthes’ disease. The cause of the prolonged activated partial thromboplastin time, usually associated with a clotting factor deficiency, is under further investigation.

Compression foot pumps are widely used for the prevention of postoperative venous thrombosis. We tested the efficiency of the pump in ten healthy subjects; the velocity of venous blood flow in the common femoral vein was measured in the horizontal, Trendelenberg (foot-up) and reverse-Trendelenberg (foot-down) positions.

Application of the foot pump produced an increase in the venous velocity in all subjects. The mean increase in the horizontal position was 27.2% and in the Trendelenberg position 15.4%. In the reverse-Trendelenberg position, the foot pump produced a mean increase of 102.8%.

The efficiency of the compression foot pump in increasing venous return is improved by adopting the reverse-Trendelenberg position. This may increase its thromboprophylactic effect.

We have reviewed 59 patients with injury to the spinal cord to assess the predictive value of the sparing of sensation to pin prick in determining motor recovery in segments which initially had MRC grade-0 power.

There were 35 tetraplegics (18 complete, 17 incomplete) and 24 paraplegics (19 complete, 5 incomplete), and the mean follow-up was 29.6 months. A total of 114 motor segments initially had grade-0 power but sparing of sensation to pin prick in the corresponding dermatome. Of these, 97 (85%) had return of functional power (≥ grade 3) at follow-up. There were 479 motor segments with grade-0 power but no sparing of sensation to pin prick and of these only six (1.3%) had return of functional power. Both of the above associations were statistically significant (chi-squared test, p < 0.0001).

After injury to the spinal cord, the preservation of sensation to pin prick in a motor segment with grade-0 power indicated an 85% chance of motor recovery to at least grade 3.