Background: Knee osteoarthritis is responsible for more chronic disability than any other medical condition. Quadriceps femoris muscle weakness has long been associated with disuse atrophy in symptomatic knee osteoarthritis but more recently implicated in the aetiology of this condition. The purpose of this study was to assess the benefits of two interventions aimed at increasing quadriceps strength in subjects with moderate to severe knee osteoarthritis.

Methods: Twenty-eight patients, aged 55–75 years, diagnosed with moderate to severe knee osteoarthritis were recruited and randomised to either a six-week home resistance-training exercise program or a six-week home neuromuscular electrical stimulation (NMES) program. An additional eleven patients matched for age, gender and osteoarthritis severity formed a control group, receiving standard care. The resistance-training group performed six exercises three times per week, while the NMES group used the garment stimulator at the maximum intensity tolerated for twenty minutes five times per week. Outcome measures included isometric and isokinetic quadriceps strength, functional capacity (25m walk test, chair rise test, stair climb test), Western Ontario and McMaster Osteoarthritis Index (WOMAC) and Short Form 36 (SF-36) health surveys. These measures were assessed at baseline, pre-intervention (after familiarisation), post-intervention and at 6-weeks post-intervention. Additionally, quadriceps cross-sectional area (via MRI) and muscle atrophy/hypertrophy gene expression (via vastus lateralis biopsy) were assessed pre- and post-intervention.

Results: Both intervention groups showed significant improvements in all functional tests (e.g. in the stair test, a 22% improvement in the exercise group versus 17% for the NMES group), in the SF36 health survey (25% & 22% respectively), and in quadriceps cross-sectional area (4.3% & 5.4%) immediately post-intervention. An increase in isokinetic strength was seen in the exercise group only (11%). WOMAC score improved only for the NMES group (19%). With the exception of isokinetic strength, all benefits were maintained six weeks post-intervention.

Conclusions: Both a six-week home resistance-training program and a six-week home NMES program produced significant improvements in functional performance as well as physical and mental health for patients with moderate to severe knee osteoarthritis. Home-based NMES is an acceptable alternative to physical therapy for patients with knee osteoarthritis, and is especially appropriate for patients who have difficulty complying with an exercise program.

Abduction braces are commonly prescribed following the closed reduction of a dislocated prosthetic hip joint. Their use is controversial with limited evidence to support their use. We have conducted a retrospective review of dislocations in primary total hip replacements over a nine year period and report redislocation rates in patients braced, compared to those who were not. 67 patients were identified. 69% of those patients who were braced had a subsequent dislocation. Likewise 69% of those who did not receive a brace re-dislocated. 33% of patients that were braced dislocated whilst wearing the brace. Bracing was associated with patient discomfort, sleep disturbance, skin irritation and breakdown. Small femoral head size, monoblock femoral components and poor biomechanical reconstruction was prevalent amongst dislocators. Abduction bracing following closed reduction of a total hip replacement does not prevent redislocation and may be the cause of considerable morbidity to the patient.

Introduction: Quadriceps femoris (QF) atrophy has been associated with the development of knee OA and is a major cause of functional limitations in affected individuals. TKA reliably reduces pain but improvements in function are less predictable and deficits may persist for up to 2 years post-operatively. Patients undergoing elective surgery are routinely optimized medically but we hypothesized that pre-operative strength and fitness improvements would also enhance outcome.

Objectives: To determine the effect of a 6 week lower limb strengthening programme on post-operative QF strength and CSA, pain and functional scores.

To determine changes in Myosin Heavy Chain (MHC) isoform, hypertrophy marker IGF-1 and atrophy markers MuRF-1 and MAFbx.

Methods: 20 volunteers currently awaiting TKA were randomly assigned to a control [C] or intervention [I] group. [I] completed a 6 week home based, supervised exercise programme. Post-operatively all patients completed a standard inpatient physiotherapy routine.

Assessments were completed at baseline (T=0), T=6 weeks (just prior to operation) and 3 months post-operatively (T=18 weeks). Assessments included isokinetic dynamometry; MRI QF CSA and American Knee Society scores. A percutaneous muscle biopsy of the vastus lateralis muscle was also performed at T=0 and T=6 under local anaesthesia.

Results: At baseline there were no significant differences in parameters between groups. At T=18, [I] showed an 86% difference in QF peak torque above controls (P=0.003). CSA also improved by 6% versus a drop of 2.5% in [C] (P=0.041). Both groups showed improvements in Knee society function scores but [I] improved by 13 points more than [C] (P=0.044).

MHC IIa mRNA expression increased by 40% whilst IIx decreased by 60% representing a shift to a less fatigable fibre type (P=0.05 and 0.028 respectively). IGF-1, MuRF-1 and MAFbx mRNA levels did not change significantly in either group.

Conclusion: To our knowledge we have documented for the first time post-operative benefits by using a pre-operative training programme in TKA. This was manifest by continued rise in quadriceps peak torque, CSA and improved Knee society functional scores. We have also demonstrated the preservation of muscle plasticity in knee OA and suggest that factors other than known hypertrophy and atrophy pathways may be responsible.

Introduction: Despite a resurgence in cobalt-chromium metal-on-metal arthroplasty and hip resurfacing, the potential toxicity of cobalt ions in the periprosthetic area remains a cause for concern. Cytotoxic effects have been demonstrated in macrophages with cobalt ions inducing apoptosis and TNF-α secretion. A similar cytotoxic effect has been demonstrated in osteoblast-like cells. However, these studies assessed the acute cellular response to cobalt ions over 48 hours. To date, the effect on osteoblasts of chronic exposure to cobalt ions is unknown.

Aim: In this study we investigated the effect on osteoblasts of chronic exposure to cobalt ions. Specifically we investigated the chemokine response and effect on osteoblast function. We also investigated for a change in osteoblast phenotype to a less differentiated mesenchymal cell type.

Methods. Primary human osteoblasts were cultured and treated with cobalt (10ppm) over 21 days. Secreted chemokines (IL-8, MCP-1, TNF-α) were assayed using enzyme-linked immunosorbent assays (ELISA). Osteoblast function was assessed via alkaline phosphatase activity and calcium deposition. For a change in osteoblast phenotype, osteoblast gene expression was assessed using real time PCR. Immunoflourescent cell staining of actin filaments was used to examine for a change in osteoblast morphology.

Results: Chemokine (IL-8) secretion by osteoblasts was significantly increased after 7 days of stimulation with cobalt ions. In parallel with this, osteoblast function was also significantly inhibited as demonstrated by reduced alkaline phosphatase activity and calcium deposition. Regarding osteoblast phenotype, FSP-1, CTGF and TGF-β gene expression were upregulated after 7 days exposure indicating a transition in osteoblast phenotype to a less differentiated mesenchymal cell type. Immunoflourescent staining of actin filaments also showed a change in osteoblast morphology. Taken together, these data demonstrate cobalt ions induce a change in the osteoblast phenotype to that of a mesenchymal cell type. This is the first study to investigate osteoblast plasticity in the context of periprosthetic osteolysis.

Conclusion: After prolonged exposure to cobalt ions, IL-8 chemokine secretion is increased which attracts neutrophils to the periprosthetic area. Furthermore, osteoblasts no longer function as osteogenic cells as demonstrated by a decrease in osteoblast alkaline phosphatase activity and calcium deposition. Instead, they undergo transition to a mesenchymal cell type as demonstrated by an increase in the expression of genes associated with a mesenchymal cell lineage. Instead of secreting osteoid matrix the new cell type secretes unmineralized collagen. Cobalt ions are not benign and may play an important role in periprosthetic osteolysis by inducing osteoblasts to undergo transition to a less differentiated mesenchymal cell type.

Osteoporosis is a common skeletal disorder characterised by a reduced bone mass and a progressive microarchitectural deterioration in bone tissue leading to bone fragility and susceptibility to fracture. The Wnt/β-catenin pathway is a major signaling cascade in bone biology, playing a key role in regulating bone development and remodeling, with aberrations in signalling resulting in disturbances in bone mass.

Our objectives were to assess the gene expression profile of primary human osteoblasts (HOBs) exposed to dexamethasone with a view to identifying key genes driving bone mass regulation and to assess the effects of the Wnt antagonist Dickkopf-1 (Dkk1) on the bone profile of primary human osteoblasts exposed in vitro to dexamethasone.

HOBs were cultured in vitro and exposed to 10–8M dexamethasone over a time course of 4hr, 12hr and 24hr. RNA isolation, cDNA synthesis, in vitro transcription and microarray analysis were performed. Microarray data was validated by quantitative real time RT-PCR. Dkk1 expression was silenced using small interfering RNA (siRNA). Quantitative RT-PCR was performed to confirm gene knockdown. Control and Dex-treated HOBs were compared with respect to bone turnover. Markers of bone turnover analyzed included alkaline phosphatase activity, calcium deposition, osteocalcin expression, along with cell proliferation and cellular apoptosis.

Global changes in HOB gene expression were elicited by dexamethasone.

Development associated gene pathways were co-ordinately dysregulated with the expression profile of key genes of the Wnt Pathway significantly altered. Dkk1 expression in HOBs was increased in response to dexamethasone exposure with an associated reduction in alkaline phosphatase activity, calcium deposition and osteocalcin expression. Silencing of Dkk1 expression, as confirmed by quantitative RT-PCR, was associated with an increase in alkaline phosphatase activity and calcium deposition, along with increased cell proliferation and reduced cellular apoptosis.

Dkk1 is an antagonist of Wnt/β-catenin signalling and plays a key role in regulating bone development and remodeling. Silencing the expression of Dkk1 in primary human osteoblasts has been shown to rescue the effects of dexamethasone-induced bone loss in vitro. The pharmacological targeting of the Wnt/β-catenin signaling pathway offers an exciting opportunity for the development of novel anabolic bone agents to treat osteoporosis and disorders of bone mass.

Introduction: After total knee arthroplasty (TKA) patients develop marked asymmetrical quadriceps femoris (QFM) weakness due to neurological activation deficits and muscle atrophy; this is associated with a slow (type I) to fast (type II) shift in myosin heavy chain (MHC) expression. Preoperative resistance training (prehabilitation) has been shown to improve strength and function after TKA however is considered costly and labour intensive. Neuromuscular electrical stimulation (NMES) offers the potential for unsupervised training, although its role in prehabilitation has not been investigated.

Aims: Determine changes in myosin heavy chain (MHC) mRNA expression following preoperative NMES.

Evaluate the ability of NMES prehabilitation to improve strength and functional recovery post-TKA.

Methods: Randomised control efficacy study applying NMES to the affected QFM for 20 min, 5 days/week, for 8 weeks pre-TKA. Isometric QFM strength was determined dynametrically and muscle cross-sectional area (CSA) calculated from MRI axial images. Function was assessed with a walk test, stair-climb test, and chair-rise test. Real-time PCR analysed MHC mRNA expression. All evaluations were performed at baseline and preoperatively with strength, CSA and function also tested at 6 and 12 weeks post-TKA.

Results: Patients scheduled for TKA were recruited and randomised into control (n=9) or NMES (n=5) groups. Only the NMES group increased strength (27.8%; p=0.05) and CSA (7.4%; p=0.013) preoperatively. MHC type II mRNA decreased by 42% (p=0.078) indicating a fast to slow fibre shift. Function also improved in the NMES group (stair climb [p=0.006]; chair rise [p=0.018]). While all patients deteriorated after surgery, only the NMES group had notable strength gain from 6 to 12 weeks (53%; p=0.011) with associated functional recovery (stair-climb, p=0.017; chair-rise, p=0.01; walking speed, p=0.014). There were differences seen between the groups at 3 months post-TKA: stair climb (61.6%, p=0.04) and chair rise (28.4%, p=0.013). There was greater muscle atrophy seen in the controls than the NMES group post-TKA when compared to baseline (12.1% [p=0.034] versus 3.7% [ns]).

Conclusions: This study has shown that 8 weeks preoperative quadriceps strengthening using home-based NMES can safely and effectively attenuate the extent and duration of QFM weakness and atrophy after primary TKA. This translates into significantly faster functional recovery thereby expediting a return to normal activities.

Introduction: Despite the documented benefits, some countries have yet to agree on the establishment of a national arthroplasty registry.

Aim: The objective of this study was to determine the opinions regarding the establishment of an Irish National register from the Consultant Orthopaedic Surgeons and Senior Orthopaedic trainees in Ireland. We also aim to find the possible reasons why a national joint register has not been established in Ireland.

Method: We have undertaken a questionnaire study to sample the opinions of the Consultant orthopaedic surgeons and Specialist registrars(SR), regarding establishment of an Irish national joint register. The questions asked related to opinions about the setting up, purpose and maintenance of an Irish National Joint Register.

Results: A total of 79 responses were received of 114 questionnaires distributed (a 69% first response rate). 97% believe it is time we set up a registry, 94% will contribute and 81% say it should be made compulsory for unwilling Surgeons and Hospitals to participate. 82% of respondents felt the set up cost should be borne by the government (Health Service Executive). Only10% of consultants agreed that the IOA should be involved in the cost bearing. Despite the overwhelming support for a national register, privacy and liability issues were major concern. 58% of the total respondents strongly agree/agree that access to registry report by the general public can expose surgeons and Hospitals to a medicolegal loophole; hence access to database should be restricted. 78% strongly agree/agree that the registry data may be used as benchmarking tools by the administrators of health-care systems to discriminate methods, implants, surgeons and hospitals, which are found to be underperforming.

Conclusion: There are considerable logistical challenges involved in the establishment of any registry. Other countries have done it successfully, and the benefits are well documented. This subject has endorsement from the Professionals as demonstrated by this study. In a litigious society such as ours, legislation may be required to further protect the integrity of a national joint replacement registry to ensure that the data are used as intended—to serve as an early warning system for premature device failure and to improve outcomes for our patients.

Background: The mechanism of tissue removal and residual tissue damage for ultrasonic ablation instruments have not been adequately investigated. In particular, the relationship between applied force and amplitude of distal tip displacement as determinants of cutting effect and residual tissue damage has not been clearly defined. Recent clinical studies have highlighted the potentially deleterious thermal and mechanical effect of ultrasonic energy in residual tissue.

Aims: To evaluate the role of ultrasonic tissue resection as an alternative to mechanical shaver and electrosurgical resection for orthopaedic applications. We aim to investigate factors influencing material removal rate (MRR), cutting rate (CR) and thermal damage for meniscus tissue resection using an experimental 20kHz ultrasonic ablation device.

Methods: An experimental force controlled testing rig was constructed using a 20kHz ultrasonic probe suspended vertically from a load cell. Ex-vivo bovine meniscus samples were harvested from knee joints and cut into uniform 16mm discs. Effect of variation in force (2.5–4.5N) and amplitude of distal tip displacement (242–494μm peak-peak) settings on material removal rate (MRR) and cutting (CR) was analyzed. Time-discrete temperature elevation in the meniscus was measured by embedded thermocouples and infrared thermography. Statistical analysis was conducted using SPSS v.11.0 (SPSS Inc., Chicago, IL). The experiment was designed using a response surface quadratic model with both input variables treated as continuous, using Design-Expert v.7.1.3 (Stat-Ease Inc., Minneapolis, MN).

Results: As either force or amplitude increases, there is a linear increase in MRR (Mean±SD: 0.9±0.4 to 11.2±4.9mg/s). A corresponding increase is observed in CR for increases in force and amplitude (Mean±SD: 0.08±0.04 to 0.73±0.18mm/s). Conversely, there is an inverse relationship between both force and amplitude, and temperature elevation, with higher force and amplitude settings resulting in less thermal damage. Maximum mean temperatures of 84.6±12.1°C and 52.3±10.9°C were recorded in residual tissue at 2mm and 4mm from the ultrasound probe-tissue interface respectively.

Conclusions: Although high power low frequency ultrasound is capable of meniscal resection, key limitations of this technology are low MRR rate and thermal damage. The mechanism of removal is primarily thermal, with tissue temperatures reaching potentially dangerous levels. Control of user force and amplitude of tip displacement settings in ultrasonic instrument design can maintain temperature peaks below critical temperatures of thermal necrosis during operation.

Introduction: Despite a resurgence in cobalt-chromium metal-on-metal arthroplasty, the potential toxicity of metal ions in the periprosthetic area remains a cause for concern. Studies to date have assessed the acute effect of cobalt ions on osteoblasts over 48 hours. The aim of our study was to determine the response of osteoblasts to cobalt ions over a prolonged period of exposure.

Methods. Primary human osteoblasts were cultured and treated with cobalt (10ppm) over 21 days. Osteoblast function was assessed via alkaline phosphatase activity and calcium deposition. ELISA were used to assess chemokine (IL-8, MCP-1 and TNF-α) secretion. Osteoblast gene expression was assessed using microarray analysis and real time PCR. Immunoflourescent cell staining of actin filaments was used to examine osteoblast morphology.

Results: Chemokine (IL-8) secretion by osteoblasts was significantly increased after 10 days of stimulation with cobalt ions. In parallel with this, osteoblast function was also significantly inhibited as demonstrated by reduced alkaline phosphatase activity and calcium deposition. Regarding osteoblast phenotype, FSP-1, CTGF and TGF-β gene expression were upregulated indicating a transition in osteoblast phenotype. Immunoflourescent staining of actin filaments also showed a change in osteoblast morphology. Taken together, these data show cobalt ions induce a change in the osteoblast phenotype to that of a mesenchymal cell type.

Conclusion: After 10 days of treatment with cobalt ions, osteoblasts no longer function as osteogenic cells. they undergo transition to a mesenchymal cell type. Furthermore, IL-8 secretion is increased which attracts neutrophils to the periprosthetic area thereby contributing to the inflammatory response that characterises osteolysis.

Introduction: Quadriceps femoris muscle (QFM) weakness has been associated with the development and progression of knee osteoarthritis, primarily due to arthrogenic muscle inhibition. Neuromuscular electrical stimulation (NMES) devices cause muscle contraction by circumventing these neural inhibitory feedback pathways. While it has been proposed this occurs in a reversed pattern of muscle fibre recruitment, the molecular mechanisms have not been clearly elucidated.

Methods: This randomised control efficacy study applied NMES to the affected QFM for 20 min, 5 days a week, for 8 weeks. Strength was assessed dynometrically and function determined using validated measures (timed stair climb, chair rise and 25 metre walk tests). A quantitative polymerase chain reaction (PCR) method measured quantities of types I, IIa, and IIx myosin heavy chain (MHC) mRNA of muscle specimens taken from vastus lateralis of the affected QFM. Expression of genetic markers associated with muscle wasting (MAFbx and MURF-1; E3 muscle specific ligases of the ubiquitin proteasome pathway) and muscle anabolic states (IGF-1) were also determined. Statistical analysis was performed using ANOVA’s and independent t-test’s where appropriate.

Results: Sixteen patients (10 women and 6 men) with radiologically severe knee OA were recruited and randomised into a control (n=6) or intervention (n=10) group. Groups were similar in terms of age (64.8 ± 11.0 vs. 64.6 ± 7.6; mean ± SD) and BMI (31.8 ± 6.1 vs.30.7 ± 2.9). There were significant improvements in function (stair climb [p< 0.01]; chair rise [p< 0.01]) and QFM strength (isokinetic [p< 0.01]; isometric [p< 0.01]) in the NMES group at week 8 compared to week 0. At the genetic level, IGF1 expression significantly increased two-fold in the NMES group (p< 0.05); Despite a 17% decrease in MAFbx expression, neither it nor MURF-1 changed significantly. MHC-I and MHC-IIa mRNA expression did not change in either group; MHC-IIx decreased by 42% in the NMES group only but was not statistically significant.

Conclusions: The use of an 8 week NMES program produces significant quadriceps strength gain with associated functional improvements in subjects with severe knee OA. Expression of muscle atrophy markers did not change significantly; however increased IGF-1 expression could potentially inhibit further muscle atrophy. Of the 3 MHC mRNA isoforms, only MHC-IIx demonstrated a change in response to NMES. These results would indicate NMES induces early quadriceps strength gain by a predominantly neurological adaptation.

Background: The Wrightington Frusto-Conical 2 (FC2) hip is a tapered stem with derotation flutes designed to withstand physiological loads in normal gait. There is a paucity of literature with regard to the outcome of this stem. This study was designed to determine the medium term outcome of the FC2 hip

Methods: We identified 217 consecutive patients who underwent total hip arthroplasty using the FC2 stem in one institution. Patients were recalled for clinical review. Pain, function and movement were assessed using the Harris Hip Score (HHS) and the D’Aubigne Postel Score. General quality of life and hip specific assessed were made using the WOMAC and SF-36 self directed questionnaires. Statistical analysis was performed.

Results: 86 patients were assessed with a mean follow-up of 7.3 years. Objective clinical outcomes were judged to be good or excellent according to the HHS and the D’Aubigne Postel scores. WOMAC assessment of disease specific outcome demonstrated excellent results particularly in relation to pain and stiffness. SF-36 demonstrated a quality of life score in keeping with an aging study population. There was a 95% survival at 7.3 years.

Conclusions: The FC2 hip has demonstrated a good outcome in the medium term. It shows outcomes that are similar to the Exeter and Charnley hips at this length of followup. Longitudinal follow-up studies are necessary to determine the results of hip implants

Background: Unicondylar knee arthroplasty (UKA) are being expanded to include younger patients with more active lifestyles because of its minimally invasive nature. Prior to expanding this role, it is important to examine mode of failure and implication of conversion to TKA in the low demand elderly patients.

Aim: To ascertain the modes of early failure of unicondylar knee Arthroplasty and assess whether the conversion to TKA improved the functional scores, range of motion, pain, and patient satisfaction.

Method: A retrospective study to evaluate the results of 14 revision procedures after failed unicompartmental knee arthroplasty (UKA). Patients’ operative charts were reviewed. Details of modes of failure, technical difficulty of revision including exposure, component removal, and management of bone loss were noted. Post operative functional outcome was assessed using WOMAC osteoarthritis index and SF-36.

Result: Total of 106 primary unicondylar knee arthroplasty procedures was performed between 2003 and 2007 in our institution. Oxford unicondylar implant was used in all patients. 13.21% of these were revised to total knee replacement. Revisions were performed 4 months to 36 months after the primary procedure; 86% of these were required within the first 12 months. The average time to failure was 15.6 months.

The modes of failure were aseptic loosening (4), progression of osteoarthritis (2), instability (3), infection (2), dislocated insert (1) and persistent pain after UKA (2). Tibia insert exchange was done in one patient and the rest were converted to primary Scorpio and PFC components. Three of the patients had significant defect in femoral condyle. Fourteen percent of cases required femoral stem extension or metal wedge augmentation.

Nine of the 14 knees (64%) were followed up for an average of 15 months. The mean WOMAC and SF-36 scores at latest follow up were 33.33 and 63.79 respectively.

Conclusion: Despite the advantage of minimally invasive UKA, early failure can occur in the face of good surgical technique. The higher long-term success rate claimed by implant manufacturer is challengeable and patient should be informed during consent.

Introduction: At the time of revision hip surgery, large bony defects are often encountered. The traditional method of replacing this lost bone is by the impaction bone grafting technique. Vibration is commonly used in civil engineering to improve compaction of aggregate particles and to increase the compressive and shear strengths of the aggregate. Studies on soil mechanics have established that vibration applied to an aggregate results in more efficient alignment of particles and reduces the energy required to impact the aggregate. In this in-vitro study we have developed a novel method of applying vibration to the bone impaction process.

Methods: 60 Bovine femoral heads were cut into quarters and then milled using the Noviomagnus manual bone mill. Fat and blood were then removed using a pulsed lavage normal saline system over a sieve tower. A vibration impaction device was developed which housed two 15V DC motors with eccentric weights attached inside a metal cylinder. A weight was dropped onto this from a set height 72 times so as to replicate the bone impaction process. The bone graft underlying this was thus impacted into a pellet, with or without the aid of vibration. A range of frequencies of vibration were tested, as measured using an accelerometer housed in the vibration chamber.

Each shear test was then repeated at four different normal loads so as to generate a family of stress-strain graphs. The Mohr-Coulomb failure envelope from which the shear strength and interlocking vales are derived was plotted for each test.

Results: Graft impacted with the addition of vibration at 60Hz was significantly more resistant to shearing force than graft impacted without vibration (p< 0.03). Testing at 20 and 40 Hz showed no statistical difference (p=0.62, p=0.42).

Conclusion: Civil engineering principles hold true for the impaction bone grafting procedure. The best frequency of vibration to enhance the mechanical properties of the aggregate is in the region of 60Hz.

Patients with spinal cord injuries have been seen to have increased healing of attendant fractures. While the benefits are obvious, this excessive bone growth also causes unwanted side effects, such as decreased movement around joints, joint fusion and renal tract calculi. However, the cause for this phenomenon remains unclear.

This paper evaluates two groups with spinal column fractures – those with neurological compromise (n=10) and those without (n=15), and compares them with a control group with isolated long bone fractures (n=12). Serum was taken from these patients at five specific time intervals post injury (1 day, 5 days, 10 days, 42 days (6 weeks) and 84 days(12 weeks)). These samples were then analysed for levels of Transforming Growth Factor-Beta (TGF-.) using the ELISA technique. This cytokine has been shown to stimulate bone formation after both topical and systemic administration.

Results show TGF-.; levels of 142.79±29.51 ng/ml in the neurology group at 84 days post injury. This is higher than any of the other time points within this group (.0.009 vs. all other time points, ANOVA). Furthermore, this level is also higher than the levels recorded in the no neurology (103.51±36.81 ng/ml) and long bone (102.28±47.58 ng/ml) groups at 84 days post injury (p=0.009 and p=0.04 respectively, ANOVA).

In conclusion, the results of this work, carried out for the first time in humans, offers strong evidence of the causative role of TGF-.; in the increased bone turnover and attendant complications seen in patients with acute spinal cord injuries.

Background: Quadriceps femoris muscle (QFM) weakness has been implicated in the development of knee osteoarthritis (OA) as well as predicting functional ability after TKA. Preoperative strengthening (prehabilitation) may be facilitated by applying neuromuscular electrical stimulation (NMES) to the affected QFM using a garment-based portable stimulator.

Methods: Single blind, randomised control efficacy study with NMES applied to the affected QFM for 20 min, 5 days a week, for 8 weeks pre-TKA. Isokinetic and isometric strength was assessed at baseline, week 2, week 5 and immediately pre-op. Function was assessed using a 25 metre timed walk test (TWT), timed stair-climb test (SCT), and timed chair-rise test (CRT) at baseline and pre-op.

Results: 13 patients (8 women and 5 men) scheduled for TKA for knee OA were recruited and randomised into a control (n=5) or intervention (n=8) group. Groups were similar in terms of age (65.5 ± 6.8 vs. 61.8 ± 9.0; mean ± SD) and BMI (29.7 ± 2.1 vs.33.2 ± 5.6). There was an improvement in SCT (p< 0.01) and CRT (p< 0.01) in the NMES group at week 8 compared to week 0. Isokinetic hamstring strength and isometric QFM strength increased significantly at weeks 2, 5 and 8 compared to baseline whereas isokinetic QFM strength only increased at week 5 (p< 0.05) and week 8 (p< 0.01) compared to baseline.

Conclusion: The use of a portable home-based NMES program for 8 weeks results in significant strength gains with associated improvements in function in patients scheduled for TKA for knee OA.

Aims: A retrospective review of all periacetabular osteotomies (PAO) performed at a general elective orthopaedic Hospital over a 7-year period. To assess the clinical, functional and radiographic outcome associated with PAO when introduced as a new procedure to a non-super-specialised regional centre.

Methods: A retrospective review of 85 PAOs performed on 79 patients at Cappagh Hospital between 1/4/1998 and 1/4/2005. The medical records and radiographic images of all patients were reviewed. Clinical follow-up evaluations were also performed.

Results: 85 PAOs were performed on 79 patients. Mean age at time of surgery was 22.9 years (range, 14–41 years) with an increased preponderance of females (F:M=10:1) and right sided hip involvement (R:L=1.1:1). The mean Merle D’Aubigne and Postel hip score increased from 12.4 (range 9–14) preoperatively to 16 (range 11–18) postoperatively (P< 0.0001). The average lateral center edge angle increased from 5° preoperatively to 26° postoperatively (P< 0.0001). The anterior center edge angle averaged 6.6° preoperatively and improved to 34.4° postoperatively (P < 0.0001). The acetabular index angle decreased from an average of 24.8° preoperatively to 8.4° postoperatively (P< 0.0001). At clinical follow-up, 77% of patients had no/mild pain, 30% of patients had a limp and 64% of patients were unlimited in physical activity.

Conclusions: The short term results in this group of patients treated with PAO show reliable radiographic correction of deformity and improved clinical scores. We suggest that PAO may safely be carried out at a non-super-specialized institution provided the surgeons have sufficient experience and patients are selected appropriately.

Wear debris is a key factor in the pathophysiology of aseptic loosening of orthopaedic endoprostheses. Cobalt-chromium-molybdenum (Co-CrMo) alloys are used for metal-metal hip implants due to their enhanced wear resistance profiles. Whilst these alloys have widespread clinical application, little is known about their direct effect on osteoblast biology. To address this issue, in this study we have investigated particle-mediated inflammation, as a putative mechanism of aseptic loosening. The effects of Co2+ ions on the bone cellular milieu were assessed in vitro by profiling of classical inflammatory mediators. The inflammatory driver PGE2 was quantified and found to be increased, following osteoblast stimulation with metal ions, suggesting the initiation of a local inflammatory response to metal particle exposure. To determine the biological import of this molecular event, the role of metal ions in recruiting inflammatory cells by chemokine production was assessed. These data demonstrated significant induction of the chemokines, IL-8 and MCP-1 following both 12 and 24 hour exposure to 10ppm of Co2+. In this study, we demonstrate that Co2+ particles can rapidly induce chemotactic cytokines, IL-8 and MCP-1 early stress-responsive chemokines that function in activation and chemotaxis of monocytes, and PGE2, which stimulates bone resorption. We have shown that this induction occurs at a transcriptional level with significantly increased mRNA levels. These data lend further weight to the hypothesis that wear mediated osteolysis, is due, at least in part, to underlying chronic inflammation.

The purpose of this study was to review the early results of a consecutive series of patients undergoing periac-etabular osteotomy (PAO) at Cappagh National Orthopaedic Hospital. The procedure was first carried out in 1998, and a total of 85 PAOs have been performed in 79 patients. The mean follow-up was 42 months (range 6-84 months). There were 72 females and 7 males with a mean age at the time of the operation of 22.9 years (range, 14-41 years). The preoperative diagnosis was developmental hip dysplasia in 80 hips, Legg-Calve-Perthes disease in one hip, congenital coxa vara in three hips, and slipped capital femoral epiphysis in one hip. The average Merle d’Aubigne score increased from 12.4 points preoperatively to 16 points at latest followup. The lateral center edge angle of Wiberg was between – 20 and +28 before surgery and was improved from 12 to 48 (average 30 degrees) following PAO. While, the anterior center edge angle of Lequesne and de Seze was between – 22 and +35 preoperatively and was improved by an average of 28 degrees (range, 17 – 40) postoperatively. The acetabular index angle decreased from an average of 24.8 preoperatively to 8.4 postoperatively. Clinical follow-up revealed that 77% of patients had no or mild pain, 33% of patients had a limp and 64% of patients were unlimited in physical activity, representing a markedly improved clinical outcome. Four patients underwent subsequent total hip arthroplasty. The short term results in this group of patients treated with PAO show reliable radiographic correction of deformity and improved clinical scores. The study reflects the learning curve associated with performing this procedure and the results that can be expected with a smaller clinical case-load than described in previous studies. We suggest that PAO may safely be carried out at a non-super-specialized institution provided the surgeons have sufficient experience and patients are selected appropriately.

Introduction: Total knee replacement (TKR) is an established and successful treatment option for symptomatic osteoarthritis of the knee. Arthroplasty surgeons, however, continue to debate the merits of posterior cruciate ligament (PCL) preservation or resection. Published literature on this subject has not demonstrated a significant clinical difference in outcome in matched subjects. Deliberate PCL resection during non-posterior stabilised TKR has also been shown to have similar outcomes.

The aims of this study were to map the tibial PCL footplate using MRI in patients undergoing TKR and more importantly, to document the percentage disruption of this footplate as a result of the tibial cut.

Patients and Methods: Patients awaiting TKR were prospectively enrolled into this study. Plain radiographs and an MRI scan of the knee were performed. Using coronal and sagittal images and the available software, the cross sectional area of the tibial PCL footplate was determined along with its location relative to the tip of the fibular head. Plain x-rays of the knee were performed postoperatively. Using a number of pre-determined markers we estimated the impact of the operative tibial cut on the PCL footplate.

Results: Twenty-five patients were enrolled into this study. There were 7 male and 18 female patients, mean age: 69 years. The vast majority of implants were AMK (80%), with a mean posterior slope cut of 3.6 degrees (range 0–7) and mean spacer height 11.4 mm (range 8–16).

From MRI analysis, the tibial PCL footplate had a mean surface area of 83 mm² (range: 49 – 142), and there was a significant difference between male and female patients [Male: 104 mm²versus Females: 75 mm²; t-test, p < 0.005]. The inferior most aspect of the PCL footplate was located on average 1 mm above the superior most aspect of the fibular head (range: 10 mm below to 7 mm above).

Analysis of post-operative radiographs showed that the average tibial cut extended to 4 mm above the tip of the fibular head (range 2 mm below to 14 mm above). Over one third of patients had tibial cuts extending below the inferior most aspect of their PCL footplate (complete removal) and a further one third had cuts which extended into their PCL footplate (partial removal).

Conclusions We have found a wide variation in the size and location of the tibial PCL footplate when referenced against the fibular head.

Proximal tibial cuts using conventional jigs resulted in the removal of a significant portion if not all of the PCL footplate in the majority of patients.

Our findings suggest that when performing PCL retaining TKR’s, we commonly do not actually preserve the PCL.

Introduction: Despite exhaustive prophylactic measures, intra-operative contamination still occurs following cemented arthroplasty. We undertook a prospective study to identify the incidence of intra-operative deep wound contamination in cemented joint arthroplasty. Furthermore, we assessed the medium term incidence (at 4 years) of wound contamination in this patient cohort.

Materials & Methods: A total of 82 consecutive patients admitted for elective cemented arthroplasty were enrolled in the study over a 6 month period. Standard medical and dental work up was performed prior to admission to assess fitness for surgery. Pre-operative wound site preparation included Hibitane showers and painting and draping of the operative site in both the anaesthetic room and theatre. All cases were undertaken in an ultra-clean laminar airflow theatre and the surgical team wore isolation suits in all cases. Standard swabs from skin incision and deep in the wound were sent in addition to the blades and suction tip used. Cultures were typed by morphology and identified by standard techniques. A control swab was sent from all cases to exclude contamination occurring in the laboratory setting.

Results: A total of 82 patients were included in the study. Mean patient age was 67.4 years (36–85 years). Of the 82 procedures performed, 59 were total hip replacements and 23 total knee replacements. Five procedures were performed for revision arthroplasty (1 knee and 4 hips). 19 of the 82 cases (23%) examined grew contamination organisms with S. epidermidis being the commonest organism (16). In 16 cases a single specimen demonstrated contamination. 2 patients had 2 contaminated specimens and 1 had 3 contaminated specimens. No significant correlation between the duration of the case, number of personnel in theatre, or the seniority of the operating surgeon was demonstrated. On medium term follow up (mean 49.6 months, 95% CI 3.2 months) no patient had developed clinical evidence of infection.

Conclusion: We noted a high incidence of intra-operative contamination of cemented arthroplasties despite standard prophylaxis. However, this was not reflected by a similar rate of post-operative infection. This may be due to a small bacterial innoculum in each case or possibly may be due to the therapeutic effect of peri-operative intra-venous antibiotic prophylaxis.

Introduction: Haematogenous pyogenic spinal infection encompasses spondylodiskitis, septic discitis, vertebral osteomyelitis and epidural abscess. Management of pyogenic spinal infection can involve conservative methods and surgical intervention. We carried out a retrospective review of 48 cases of pyogenic vertebral osteomyelitis presenting over a twelve-year period to the National Spinal Injuries Unit of the Republic Of Ireland. Our objective was to analyze the presentation, aetiology, management and outcome of 48 cases of non-tuberculous pyogenic spinal infection.

Methods: Both the Hospital Inpatient Enquiry (HIPE) System and the National Spinal Injuries Unit Database were used to identify our study cohort. The medical records, blood results, radiologic imaging and bacteriology results of all patients identified were reviewed.

Results: The average age of presentation was 59 years with an almost even distribution between males and females. Most patients took between three and six weeks to present to hospital. Diagnosis was confirmed by serological testing of inflammatory markers and radiological imaging. The most frequently isolated pathogen was Staph. aureus (75% of cases). 94% of cases were managed by conservative measures alone, including antibiotic therapy and spinal bracing. However, in 6% of cases surgical intervention was required due to neurological compromise or mechanical instability.

Conclusions: With this large cohort of non-tuberculous, pyogenic spinal infections from the NSIU, we conclude that Staph. aureus is the predominent pathogen. In the vast majority, conservative management with antibiotic therapy and spinal bracing is very successful. However in 6% of cases surgical intervention is warranted and referral to a specialist centre is appropriate.

Aims: Rugby is a popular sport in Ireland, with over 100,000 players registered with the Irish Rugby Football Union (IRFU) at all levels. We report a 10 year series of spinal injuries presenting to the National Spinal Injuries Unit (NSIU) at the Mater Misericordiae University Hospital.

Methods: A large series of spinal injuries in rugby players was isolated utilizing the NSIU database, HIPE and data from the IRFU. An extensive chart review and telephone interview was performed in all cases to determine age, mechanism of injury, possible aetiological factors, anatomic location of injury, American Spinal Injuries Association (ASIA) scores, current level of activity and response to rehabilitation.

Results: From 1994 to 2004, 22 rugby players with spinal injuries necessitated admission to the NSIU. Twelve patients (54%) presented with neurology. The average age at time of injury was 21.1 years (range 14 – 44 years) and all patients were male. The average length of hospital stay was 10.1 days (range 1 – 45 days). Twenty patients had cervical spine injuries. The most common mechanism of injury was hyperflexion of the cervical spine, with C5/C6 most commonly injured. Fifteen injuries occurred at adult level, the remainder at schoolboy level. Seventeen (77%) players were injured whilst playing First Team rugby. Eleven (50%) players were injured in the Backs, the remainder in the Forwards. 68% of injuries occurred in the tackle situation and 32% in the scrums, rucks and mauls. Winger, Full Back and Hooker were the playing positions at greatest risk.

Nine (41%) patients underwent surgery and 11 (50%) required rehabilitation in the National Rehabilitation Centre, Dun Laoghaire, with an average length of inpatient stay of 9.22 months (range 5 – 14 months). Eight (36%) patients felt that their injury was preventable. Of those patients without neurology, 60% have returned to playing rugby.

Conclusion: Rugby as a sporting pastime is not without risk. During the ten year period under review, 8 players suffered permanent disability as a direct result of participation in competitive rugby. Serious spinal injuries continue to occur and recent rule changes have had little effect in reducing their incidence.

Urinary retention following total hip and knee arthroplasty is a common problem frequently requiring catheterisation in the immediate post-operative period. The direct relationship between urinary tract instrumentation and deep sepsis in total hip replacements is well documented.

Method: This prospective study analysed 164 male patients who underwent primary arthroplasty between September 2004 and March 2005 inclusive. Patients who had previous urological intervention for obstructive symptoms were excluded from the study. Upon admission and prior to surgery, all patients answered an 8-point urinary symptom questionnaire and were tested on their ability to micturate while supine.

Result: 34 patients required urinary catheterisation – 130 did not. The average age of the catheterised group was 69.5+/−10.7 years (range 45–90) and the non catheterised group was 65.2+/−10.5 years (range 33–85). There was no difference between these groups (p=0.134, ANOVA). Similarly, there was not difference (p=0.919, ANOVA) between the blood loss in the 2 groups, 880.6+/−455.5 mls and 895+/−533.7 mls respectively. With regards to the symptom questionnaire, the average score in the catheter group was 3.1+/−2.4 and the non-catheter group was 2.0+/−1.8 (p=0.034, ANOVA). The ability to micturate in a supine position was of no predictive value with 22 patients in the catheter group able to do so.

Conclusion: These results show the value of a urinary symptom questionnaire used pre-operatively in predicting those who may require post-operative urinary catheterisation. By appropriate use of this tool, patients with potential for post-operative retention may be identified before surgery. Consequently, this group should be catheterised pre-operatively thus reducing their risk of infection.

Introduction: Total hip arthroplasty for osteoarthritis secondary to developmental dysplasia of the hip (DDH) is technically difficult due to the abnormal anatomy involved. The use of a modular hip replacement system is advantageous in that its versatility allows for intra-operative adjustment to accommodate for final acetabular position and version.

Aim: The aim of this study was to assess our early results with the S-ROM hip (DePuy), a cementless modular femoral implant.

Methods and materials: We performed 22 total hip replacements on 20 patients with DDH over a three and a half year period. Nineteen patients were female and one was male. Ages ranged from 30 to 59 years (average 38.3 years). Ten patients had had previous osteotomies performed, including two of whom had Ganz periace-tabular osteotomies performed in our centre.

Nine patients had additional acetabular bone grafting with autologous femoral head, two patients had subtrochanteric osteotomy, and another patient had an adductor tenotomy performed at the time of their surgery. Follow-up ranged from 6 to 44 (mean 19.6) months.

Results: Harris hip scores improved from an average of 42 points pre-operatively to 90 points post-operatively. No radiographic evidence of osteolysis was seen around the femoral implant. Two patients required revision of their acetabular components. Both had satisfactory outcomes.

Conclusion: Our early results with the S-ROM femoral prosthesis correlate well with those from other studies involving arthroplasty for DDH. There were no complications related to the use of uncemented prostheses. Modularity makes this implant extremely versatile and easy to use in this complex patient population.

Aims: Rugby is a popular sport in Ireland, with over 90,000 players registered with the Irish Rugby Football Union (IRFU) at all levels. We report a 10 year series of spinal injuries presenting to the National Spinal Injuries Unit (NSIU) at the Mater Misericordiae University Hospital.

Methods: A large series of spinal injuries in rugby players was isolated utilizing the NSIU database, HIPE and data from the IRFU. An extensive chart review and telephone interview was performed in all cases to determine age, mechanism of injury, possible aetiological factors, anatomic location of injury, American Spinal Injuries Association (ASIA) scores, current level of activity and response to rehabilitation.

Results: From 1994 to 2004, 22 rugby players with spinal injuries necessitated admission to the NSIU. Twelve patients (54%) presented with neurology. The average age at time of injury was 21.1 years (range 14 – 44 years) and all patients were male. The average length of hospital stay was 10.1 days (range 1 – 45 days). Twenty patients had cervical spine injuries. The most common mechanism of injury was hyperflexion of the cervical spine, with C5/C6 most commonly injured. Fifteen injuries occurred at adult level, the remainder at schoolboy level. Seventeen (77%) players were injured whilst playing First Team rugby. Eleven (50%) players were injured in the Backs, the remainder in the Forwards. 68% of injuries occurred in the tackle situation and 32% in the scrums, rucks and mauls. Winger, Full Back and Hooker were the playing positions at greatest risk.

Nine (41%) patients underwent surgery and 11 (50%) required rehabilitation in the National Rehabilitation Centre, Dun Laoghaire, with an average length of inpatient stay of 9.22 months (range 5 – 14 months). Eight (36%) patients felt that their injury was preventable. Of those patients without neurology, 60% have returned to playing rugby.

Conclusion: Rugby as a sporting pastime is not without risk. During the ten year period under review, 8 players suffered permanent disability as a direct result of participation in competitive rugby. Serious spinal injuries continue to occur and recent rule changes have had little effect in reducing their incidence.

Introduction: An arthroplasty database, such as the Swedish Hip Registry, provides a crude means of quality control over the sizable number of prosthetic implants available on the market today. It provides relatively rapid feedback on the performance of orthopaedic devices and surgical techniques, allowing inferior devices and methods to be discontinued. The maintenance of an arthroplasty register is inexpensive and of enormous benefit to the patient. At present, there is no nationwide arthroplasty register in operation in the Republic of Ireland.

Aim: To develop an arthroplasty register which prospectively captures all clinical, radiographic and medical outcome data on patients undergoing surgery in our unit

Materials and methods We are using an existing computer software programme (Bluespier Patient Manager) to capture our information, although our database is stored independently of this.

Data recorded includes medical outcome scores (WOMAC and MOS SF-36), patient data, operative details (including type of prostheses used and operative technique employed), inpatient course, and any postoperative events. For revision procedures, additional data such as location of bony defects (Gruen zones) and acetabular bone loss (Paprosky classification) are also recorded. Follow up in a special Joint Register Clinic is at six months, two years and every five years thereafter for primary procedures. This is reduced to every two years in the case of revision procedures.

To date, a pilot study involving four surgeons has prospectively captured data on 82 patients undergoing both primary and revision procedures in our unit. We aim to enrol all our patients in the register from July 2005, increasing the amount of data collected, which we hope will subsequently benefit patients undergoing hip and knee arthroplasty in the future.

To date the principal focus of the mechanism of cervical spine fracture has been directed towards head/neck circumference and vertebral geometric dimensions. However the role of other measurements, including chest circumference and neck length, in a standard cervical fracture population has not yet been studied in detail. Cervical fractures often involve flexion/extension type mechanisms of injury, with the head and cervical spine flexing/extending, using the thorax as an end point of contact. Thus, the thorax may play an important role in neck injuries.

Study design: We prospectively studied all patients with cervical spine fractures who were admitted to the National Spinal Injuries Unit from 1 July 2000 to 1 March 2001. Anthropometrical measurement of head circumference, neck circumference, chest circumference, and neck length were analysed. Ages ranged from 18 to 55 years, and all patients with concomitant cervical pathology were excluded from the study. Mechanism of injury involved flexion/extension type injuries in all cases; those with direct axial loading were excluded. A control group of 40 patients (age 18–50 years) involved in high velocity trauma with associated long bone fractures, in whom cervical injury was suspected, but who were without any cervical fracture, or associated pathology, were similarly measured.

Results: Our analysis revealed a statistically significant increase in chest size in the male control group versus the male fracture group (97.89 cm versus 94.19 cm, P < 0.05, Student’s t-test). There was a correspondingly significant increase in chest circumference between the female controls versus the female fracture group (92.33 cm versus 88.88 cm, P < 0.05, Student’s t-test). Our results revealed no statistical difference in head circumference, neck circumference, or neck length between each of the groupings. These results indicate a proportionately larger chest may be a protective factor in cervical spine fractures.

Management of symptomatic residual acetabular dysplasia in adolescence and early adulthood remains a major therapeutic challenge. At our unit the two senior authors review all patients preoperatively and simultaneously perform each procedure. In the four years from 1998 forty-three Bernese osteotomies were performed in 40 patients with residual acetabular dysplasia. The mean average age at surgery was 21 years (range 12 – 43 years) and there were 34 female patients. The indication for surgery was symptomatic hip dysplasia (all idiopathic but for one male with a history of slipped capital femoral epiphysis) presenting with pain and restricted ambulation. 4 patients had previous surgery on the affected hip (2 Salter’s osteotomy, one Shelf procedure and one proximal femoral osteotomy). 27.5% of patients had symptomatic bilateral disease. 42% of patients had Severin class IV or V dysplasia at presentation. 100% of patients had preservation of the hip joint at last follow-up evaluation (mean 2.4 years), with excellent results in 82%, an average post-operative Harris hip score of 96, and an average d’Aubigne hip score of 16.1. The mean post-operative improvements in radiographic measures were as follows: Anterior centre edge angle +19.4°, Lateral centre angle +25.8°, Acetabular Index – 10.7°. Head to Ischial distance – 7.3mm. Surgical operative time decreased from 128 minutes to 43 minutes from the first to the most recent case. Average blood loss has reduced from 1850mls to 420mls over the four years experience. Predonation of 2 units of blood requested from all patients with baseline hemoglobin of > 12g/dl. When combined with intraopera-tive cell salvage the need for transfusion of homologous blood has been eliminated. All complications occurred in the first 9 patients: (one major – iliac vein injury requiring no further treatment; four moderate – lateral cutaneous nerve injuries; four minor – asymptomatic heterotopic ossification). Our experience confirms that the Ganz periacetabular osteotomy is an efficacious procedure for the treatment of the residually dysplastic hip, providing excellent clinical results, where early intervention is the key to improved outcome. It is a technically demanding procedure with a significant early learning curve and we believe that a two

Between 1994 and 2002, 42 patients aged over 65 years were admitted to the spinal injuries unit with odontoid fractures. Data was retrospectively collected by analysis of the national spinal unit database, hospital inpatient enquiry (HIPE) system, chart and x-ray review. Mean age of patients was 79 years (66–88). Mean following-up with 4.4 years (1–9 yrs). Male to female ratio was 1:1.2 (M=19, F=23). Among the mechanism of injury, simple fall (low-energy) was the commonest underlying cause in 76% of the odontoid fracture, whereas 23% fractures were sustained as a result of motor vehicle accident.

Fractures were classified according to Anderson and D’Alonzo method. There were 29 (69%) type 11 fractures, 13 (30%) were type 111 fractures and there was no type 1 fracture. Anterior and posterior displacements were recorded with almost equal frequency. Seven fractures displaced anteriorly and six fractures posteriorly. Primary union occurred in 59% of fractures. Forty (95.3%) fractures were treated non-operatively. Two fractures were stabilized primarily with C1/C2 posterior interspinous fusion. These fractures were odontoid type 11, anteriorly displaced. Three fractures (7.1%) failed to unite and another three fractures (7.1%) united with prolonged interval (9–11 months). Neurological compromise was mainly related to displacement of the fracture. The overall complication rate was significant (48%) with an associated in-hospital mortality of 11.1%. Loss of reduction, non-union after non operative treatment, pin site problems and complication due to associated injuries accounted primarily for this significant complication rate. Most fractures can be managed in orthosis but unstable fractures require rigid external immobilization or surgical fixation.

Outcome was assessed using a cervical spine outcome questionnaire from Johns Hopkins School of Medicine. Questionnaires were sent by post to all patients identified. Non responders were subsequently contacted by phone, if possible, to complete the questionnaire.

In the follow-up, additional 6(14.2%) patients were found deceased, 4 patients were unavailable for review and the remaining 69% had significant recovery. Functional outcome scores approached pre-morbid level in all patients. Outcome of these patients are related to increasing age, co-morbidity and the severity of neurological deficit.

Study Design: A retrospective review of the functional outcome of neurologically intact patients with burst fractures of the first lumbar vertebra.

Objective: To assess the functional outcome of patients treated either surgically or conservatively following burst fractures of L1.

Methods: A retrospective review of 38 neurologically intact patients with burst fractures of L1 was performed. Follow-up clinical evaluation was obtained from 26 patients, eleven of whom were treated surgically and fifteen of whom were managed conservatively. Patients were assessed with regard to pain, employment status, ability to partake in recreational activities and their overall satisfaction with treatment. Radiographic evaluation of anterior body compression and vertebral kyphosis was performed at the time of injury. Computed tomography scanning of spinal canal compromise was also recorded at the time of injury. Subsequent recordings of vertebral kyphosis were assessed at the time of remobilisation and at 3-month follow-up evaluation.

Results: Mean follow-up time for the 26 patients was 43.02 months. At final clinical follow-up of the fifteen patients managed conservatively, 6 patients (40%) had little or no pain; 12 patients (80%) had returned to work with 6 (40%) stating that they had little or no restrictions in their ability to work; 8 patients (53%) had returned to the same level of recreational activity as prior to their injury with 7 (47%) stating they had little or no restrictions in their ability to participate in recreational activities. One patient (9%) reported being very dissatisfied with the operative treatment of their spine fracture.

No correlation was found between kyphotic deformity, extent of canal compromise and clinical outcome.

Conclusions: Non-operative management of burst fractures of the first lumbar vertebra is a very safe and effective method of treatment. It reduces hospitalisation time and avoids the costs and risk of surgery. Patients return to the functional activities of daily living quickly and have a better clinical outcome when compared with operative management.

Percutaneous Radiofrequency Ablation (RFA) has become the method of choice in the treatment of a wide spectrum of disorders. It was introduced for the treatment of Trigeminal Neuralgia and has since been used both extensively and successfully in the treatment of this disorder. Over the past two decades it has been advocated in the treatment of hepatic metastases, lung tumours and cerebral tumours. In 1992 Rosenthal et al reported using this procedure for the treatment of Osteoid Osteomas with good outcome. Further case series have supported this modality of treatment. However, the biomechanical effects of RFA on cortical bone have not been reported to date.

The study comprised of 16 large white land-raised male pigs. All were between 70–80kg in weight at the time of treatment. RFA was performed on the femur, tibia and humerus of each animal 24 hours, 1 week and 4 weeks before euthanisation. RFA was carried out via a percutaneous technique under fluoroscopic guidance. The fibula was not treated in each case and used as an intrinsic control to account for inter-group variability. The Modulus of Rigidity, Maximum Torsional Strength of all bones were determined and compared.

There were three pathological fractures, all occurring in the hemerii and all occurring at 4 weeks post treatment. The Modulus of Rigidity and Maximum Torsional strength were significantly reduced at 24 hours and 1 week when compared with the control. However in the 4 weeks group the biomechanical strength of cortical bone was not significantly different and had almost returned to normal which is contradictory to the clinical setting. There was no significant difference at 24 hours and 1 week.

RFA has become well established as the method of choice for the treatment of Osteoid Osteomas, however the biomechanical consequences of this procedure have not been reported to date. The torsional strength of RF ablated cortical bone is severely attenuated after 1 week, 40% reduction in torsional strength when compared with the control group. This study demonstrated that RFA of cortical bone is an effective treatment for cortical lesions however the biomechanical weakness promotes the need for weight-bearing restrictions when managing these patients postoperatively.

Management of symptomatic residual acetabular dysplasia in adolescence and early adulthood remains a major therapeutic challenge. At our unit the two senior authors review all patients preoperatively and simultaneously perform each procedure. In the four years from 1998 forty-three Bernese osteotomies were performed in 40 patients with residual acetabular dysplasia. The mean average age at surgery was 21 years (range 12 – 43 years) and there were 34 female patients. The indication for surgery was symptomatic hip dysplasia (all idiopathic but for one male with a history of slipped capital femoral epiphysis) presenting with pain and restricted ambulation. 4 patients had previous surgery on the affected hip (2 Salter’s osteotomy, one Shelf procedure and one proximal femoral osteotomy). 27.5% of patients had symptomatic bilateral disease. 42% of patients had Severin class IV or V dysplasia at presentation. 100% of patients had preservation of the hip joint at last follow-up evaluation (mean 2.4 years), with excellent results in 82%, an average post-operative Harris hip score of 96, and an average d’Aubigne hip score of 16.1. The mean post-operative improvements in radiographic measures were as follows: Anterior centre edge angle +19.4°, Lateral centre angle +25.8°, Acetabular Index – 10.7°. Head to Ischial distance – 7.3mm. Surgical operative time decreased from 128 minutes to 43 minutes from the first to the most recent case. Average blood loss has reduced from 1850mls to 420mls over the four years experience. Predonation of 2 units of blood requested from all patients with baseline hemoglobin of > 12g/dl. When combined with intraoperative cell salvage the need for transfusion of homologous blood has been eliminated. All complications occurred in the first 9 patients: (one major – iliac vein injury requiring no further treatment; four moderate – lateral cutaneous nerve injuries; four minor – asymptomatic heterotopic ossification). Our experience confirms that the Ganz peri-acetabular osteotomy is an efficacious procedure for the treatment of the residually dysplastic hip, providing excellent clinical results, where early intervention is the key to improved outcome. It is a technically demanding procedure with a significant early learning curve and we believe that a two-surgeon approach is invaluable to the management of these difficult cases.

Introduction: Fractures of the sternum result from a direct blow or from an indirect mechanism with hyperflexion of the spine. The association between spinal injury and sternal fractures has been reported but is commonly overlooked and underestimated.

Aims: Our aim was to study the clinical and radiological effects of an attendant sternal fracture on vertebral fractures. Berg first described the extra stability afforded to the thoracic spine by the sternal-rib complex and the adverse effects of damage to this “4th column” apropos of 2 cases.

Materials and Methods: None patients were admitted to our unit from October 1996 to August 2001 suffering from vertebral fractures and concomitant sternal fractures. The clinical notes and plain film radiographs of these patients were studied.

Results: The average age of the 9 patients (5 males and 4 females) was 33 years (range 21–73). Seven had been involved in road traffic accidents and 2 had fallen from a height. Four patients had injuries to their cervical spine, 4 to their thoracic spine and one had a lumbar spine fracture. In terms of neurological compromise, only one of the cervical groups had a neurological deficit compared to all 4 in the thoracic group (2 complete and 2 incomplete). The patient with the lumbar spine fracture suffered incomplete neurological compromise. All 6 of the patients with neurological compromise underwent surgical management. The other 3 patients were treated conservatively.

Conclusion: It has been traditionally accepted that the sternum is injured only in association with upper thoracic spine. Our findings suggest that spinal injury at lower thoracic, upper lumbar or cervical level may also be associated with sternal injuries. However, the relative severity of the vertebral injury and neurological compromise in the thoracic spine subgroup offers clear support of Berg’s “4th column” theory of thoracic spine fractures when compared to fractures of the cervical or lumbar spine with sternal injuries.

The thoracic spine has always been associated with a stability that is considerably augmented by the rib cage and associated ligaments. Fractures of the thoracic spine require great forces to be applied, causing high levels of other injuries. In addition, the narrow spinal canal dimensions result in high levels of neurological compromise when fractures occur.

Between February 2nd 1995 and March 21st 2001, 1249 patients were admitted to our spinal tertiary referral unit. Of these, 77 had suffered fractures to some part of their upper thoracic spine (T1–T6), of which, 32 required surgical procedures. Using patient case notes, we retrospectively studied this series.

Twenty-six of the 32 patients were male, with an average age of the group of 24.4 +/− 11.3 years and an average impatient stay of 17.5 +/− 10.5 days. 29 patients suffered fractures at more than one level and 23 patients suffered complete neurological compromise. Only 2 patients were neurologically intact. 90.7% sustained their injuries in road traffic accidents, with 53.9% of the male group being involved in motorcycle accidents. Multiple imaging (in addition to plain film radiography) was required in 30 cases with 20 patients suffering injuries apart from their spinal fracture. Of these, 15 had associated chest injuries. Cardiothoracic surgical consultants were required in 56.3% of cases, and from the general surgeons in 37.5% of patients. 59.4% of patients required intensive care unit therapy, with another 4 patients going to the high dependency unit.

Fractures to the upper thoracic spine are injuries with devastating consequences, both due to high levels of neurological compromise and concomitant injuries. This series would suggest that patients suffering from these injuries are best treated in a multi-disciplinary approach within a general setting, rather that in a specialist orthopaedic unit, where other medical and surgical services may not be readily available.

Introduction: The Ganz periacetabular osteotomy aims to improve femoral head coverage in dysplastic hips. It is joint preserving procedure and therefore is ideally preformed before significant articular cartilage degeneration. One proposed advantage of this procedure is that it partially preserves the posterior column and does not disrupt the vascular supply of the main fragment. This study aims to 1) assess the role of MR imaging in the perioperative evaluation of articular cartilage and labrial tissues prior to Ganz osteotomies and 2) to document any alteration in the vascularity of the acetabular fragment post operatively.

Patient and Methods: Twenty patients (all female, average age 18.2 years) under consideration for peracetabular osteotomy for hip dysplasia and MR Studies of the pelvis as part of the perioperative assessment. Sixteen patients had follow-up imaging at 4, 12 and 26 weeks post surgery, at which time evidence of healing, oedema, vascularity and femoral head coverage were assessed.

Discussion: MR imaging has proven to be a reliable method of assessing articular cartilage health before considering pelvic osteotomy. Hopefully this will allow more appropriate selection of patients likely to benefit from this procedure. In addition MRI scanning allows clearer assessment of other articular elements, such as labium and ligamentum teres, that are difficult to visualize with plain radiographs and CT scans. A further benefit of MR scanning is that, as this study has shown the vast majority of patients who are potential candidates are female of childbearing age and it voids the use of ionizing radiation in this sensitive group of patients. This study has shown that despite some early alterations in osteotomy fragment vascularity the ultimate outcome is that vascularity is substantively unharmed by periacetabular osteotomy.

Conclusion: MR imaging is extremely useful in the perioperative workup and postoperative follow-up in patients undergoing Ganz periacetabular osteotomies.

The Mater Hospital is Ireland’s primary referral centre for spinal injuries receiving 80–90% of all spinal cases annually. In today’s society the number of people competing at more competitive and professional levels is also increasing. Over the years, a lot of work has gone into safety precautions in sport. However despite those improvements our impression was that the incidence of both minor and serious sporting injuries is increasing.

The purpose of this study was to determine the incidence, pattern and mechanism of sports-related spinal injuries in Ireland over the last decade.

Data was collected by performing an audit of the National Spinal Injuries Database from 1994–2001. This database is a prospective computerized database. Data entered relates to the initial presentation, mechanism, level of injury and their acute in-hospital management.

On average 200–220 patients are admitted annually to the National Injuries Spinal Unit. 173 of these were related to sport, which represented 13% of total spinal injuries. 80% are male under 40 years. 29% sustained neurological deficit. The sports responsible for most spinal injuries in Ireland were equestrian (43.8%), followed by rugby (16.4%), diving (15%), GAA (13.6%) and skiing (3%). Rugby injuries were most likely to cause neurological damage. Equestrian accidents commonly caused thoracolumbar fractures while injuries sustained in diving, rugby and GAA were mostly to the cervical spine.

Sport is an important cause of spinal injuries in Ire-land. Coaches and team doctors must be educated about safe practices and emergency management of these terrible injuries and for those unfortunately affected in the prime of their lives adequate rehabilitation resources need to be implemented so as to lessen their economic burden.

Introduction: Increased levels of IL-6 and IL-8 have been found in intervertebral disc (IVD) tissue from patients undergoing fusion for discogenic low back pain. The stimuli that induce these mediators in degenerate discs remain unknown. Impaired diffusion of nutrients and wastes to and from the nucleus pulposus (NP) is believed to be an important factor in the degenerative process. The oxygen tension and pH in the NP of degenerating discs are significantly decreased.

Aims: The aims of this study were to (1) demonstrate the ability of porcine NP to respond to a proinflamma-tory stimulus (lipopolysaccharride) in vitro, (2) investigate the effects of pH, pO₂ and glucose concentration on NP proinflammatory mediator secretion and (3) determine if methylprednisolone or indomethacin can block NP proinflammatory mediator secretion.

Methods: IVDs were harvested from 6-month old pigs and dissected under sterile conditions in the laboratory. 200mg samples of NP were cultured under optimal conditions (control), in a 1% O₂ environment, at pH6 and in culture medium without glucose for 72 hours. Blocking experiments were performed by culturing LPS-stimulated samples with either methylprednisolone or indomethacin for 24 hours. IL-6 and IL-8 levels were estimated by ELISA.

Results: Time and dose-response curves were generated for each experiment (results not shown). Results for the optimum dose and at 72 hours incubation were note.

Data = mean ± standard deviation. Statistical analysis was by students t test. A significant result between control and stimulated groups is indicated by: * p=0.024m, † p=0.0007 or ‡ p=0.012.

Methylprednisolone (2mg/ml) caused a significant (p=0.044) 30-fold reduction in IL-6 production and a significant (p=0.00004) 500-fold reduction in IL-8 levels as compared with nucleus pulposus cultured with 5 μg/ml LPS alone for 24 hours.

Addition of 500 μM indomethacin significantly (p=0.04) decreased IL-6 production by a factor of 120 and IL-8 levels by a factor of 50 (p=0.00004).

Necrotic cell death, as measured by lactate dehydrogenase (LDH) concentration, was not significant in any of the experiments.

Aims: To correlate clinical imaging and surgical finding in patients with knee arthritis. In an attempt to identify specific lesions that correlate with the location of clinical pain.

Methods: 26 patients and 32 knees were eligible for inclusion in the study. All patients had been admitted for total knee arthroplasty. In all patients an attempt was made to correlate symptoms with radiographic findings and then intraoperative findings. A senior orthopaedic registrar carried out standard knee scores and clinical examinations, radiographs and a radiologist blindly evaluated MRI scans. The integrity of the articular cartilage as well as the menisci and ligaments were all graded.

Results: At clinical examination all patients score 70 or higher on a visual analogue scale. In eighteen patients, the maximum site of clinical tenderness was referable to the medial joint line. In seven patients symptoms were on the lateral aspect. Pain was recorded on a line diagram of the knee for analysis. MR images confirmed advanced arthritis with meniscal derangement with extrusion and maceration. Note was made of osteophyte formation, medial collateral ligament laxity and oedema and discrete osteochondral defects. Bone marrow bruising and oedema was also recorded. In nine patients subchondral cysts were identified with extensive associated bone oedema. At surgery, meniscal degeneration was identified in fifteen of twenty-six, meniscal tears were identified in six; the menisci were normal in two patients.

Discussion: These results suggest that there is a direct correlation between clinical symptoms and meniscal derangement in severe osteoarthritis. Isolated articular defects and bone marrow oedema did not correlate well with location of pain. Presence of medial collateral oedema correlated well with severity of radiological arthritis and clinical findings.

In summary, this study suggests that patients with symptomatic knee arthritis are likely to have meniscal derangement and medial collateral oedema. A greater understanding of the origin of pain in the degenerate knee may assist in the choice of management options for these patients.

Standard protocol following total hip arthroplasty dictates that the hip is kept in a position of abduction until soft tissue healing is sufficient to provide stability. This is maintained by use of an abduction pillow while in bed, meaning that the patient must sleep on their back. Many patients find this position uncomfortable and have significant difficulty in sleeping.

Aims: To assess the impact of sleep deprivation on recovery of the patient and quality of life in the peri-operative period.

Methods: Patient cohort consisted of elective admissions for total hip replacement. All were assessed using the Epworth sleep scale, SF-36 as well as the Hospital Anxiety and depression score. Body mass index and history of insomnia or obstructive sleep apnoea were recorded. Baseline oxygen saturation was compared with postoperative overnight saturation and request for night sedation.

Results: 64 consecutive patients undergoing total hip arthroplasty surgery were eligible for inclusion in the study. Mean age 68 (43 to 85), 42 females, 22 males, 62 patients were satisfied with the result of surgery, 1 patient with hip dysplasia had a persistent leg length inequality and one complained of back pain. All patients were nursed according to standard protocol with abduction pillow while in hospital and instructions to sleep on their back while at home. 18 patients did not fully comply with this instruction while at home. There were no early dislocations with a mean follow up of 5.4 months. Mean hospital anxiety and depression scores were significantly increased following surgery mean pre-operatively (5.2), to highest level (3.4) at two weeks, (8.5) at six weeks, returning to normal levels after three months (4.2). Epworth sleep scores were similarly increased with sleep patterns returning to normal at the three month stage. Increasingly, body mass index correlated significantly with poor scores and low oxygen saturation readings. This group of patients had a predisposition to obstructive sleep apnoea, which was predicated by sleeping on their backs, they require more night sedation and analgesia.

Conclusions: Standard precautions following total hip arthroplasty are not without morbidity. Sleep deprivation leading to increased anxiety and decreased satisfaction. Increased demand for night sedation and analgesia with their resultant costs and dependence. Sleeping in the supine position may also precipitate obstructive sleep apnoea in at risk patients.

The thoracic spine has always been associated with a stability that is considerably augmented by the rib cage and associated ligaments. Fractures of the thoracic spine require great forces to be applied, causing high levels of other injuries. In addition, the narrow spinal canal dimensions result in high levels of neurological compromise when fractures occur.

Between 2 February 1995 and 21 March 2001, 1249 patients were admitted to our spinal tertiary referral unit. Of these, 77 had suffered fractures to some part of their upper thoracic spine (T1-T6), of which 32 required surgical procedures. Using patient case notes, we retrospectively studied this series.

26 of the 32 patients were male, with an average age of the group of 24.4 ± 11.3 years and an average inpatient stay of 17.5 ± 10.5 days. 29 patients suffered fractures at more than one level and 23 patients suffered complete neurological compromise. Only 2 patients were neurologically intact. 90.7% sustained their injuries in road traffic accidents, with 53.9% of the male group being involved in motorcycle accidents. Multiple imaging (in addition to plain film radiography) was required in 30 cases with 20 patients suffering injuries apart from their spinal fracture. Of these, 15 had associated chest injuries. Cardiothoracic surgical consultations were required in 56.3% of cases, and from the general surgeons in 37.5% of patients. 59.4% of patients required intensive care unit therapy, with another 4 patients going to the high dependency unit.

Fractures to the upper thoracic spine are injuries with devastating consequences, both due to high levels of neurological compromise and concomitant injuries. This series would suggest that patients suffering from these injuries are best treated in a multi-disciplinary approach within a general setting, rather than in a specialist orthopaedic unit, where other medical and surgical services may not be readily available.

Degenerate disc disease is a major cause of low back pain, yet its aetiology is still poorly understood. The intervertebral disc is the largest avascular structure in the body. Cells of the nucleus pulposus, therefore, rely on diffusion of oxygen & nutrients down concentration gradients from peripheral vessels in the cartilage end-plates. Thus, there is a low oxygen tension and cellular respiration is largely anaerobic.

The purpose of this study was to examine the effects of inflammation, hypoxia and acidosis on degeneration and pro-inflammatory mediator production in virgin porcine nucleus pulposus cultures.

Intervertebral discs were harvested from normal 6-month old agricultural pigs slaughtered for other purposes. Nucleus pulposus was contained within the annulus until further dissection under sterile conditions in the laboratory was performed. Nucleus pulposus was harvested, diced and divided into 200mg samples. Samples were incubated under optimal conditions.

Discs were cultured in 5μg/ml E. coli lipopolysaccharide, in a hypoxic environment or at low pH. IL-6, IL-8 and LDH assays were performed by ELISA, in accordance with manufacturer’s instructions.

Time and dose-response curves were generated for each experiment (results not shown). Results at 72 hours incubation are tabulated below:

These results confirm that nucleus pulposus is a biochemically active tissue capable of producing pro-inflammatory mediators in response to environmental stresses. IL-6 and IL-8 are both involved in the inflammatory cascade, causing chemotaxis of neutrophils and macrophages to the area. IL-8 itself causes hyperalgesia. Acidotic and inflammatory conditions, but not hypoxia, stimulated cytokine release. This may indicate a protective reduction in cellular activity in reduced oxygen environments. Necrosis, as measured by LDH production, was negligible.

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.

Aseptic loosening has become the single most important long-term complication of total joint replacements. The pathophysiology of this loosening is multifactorial in origin ranging from mechanical wear, poor surgical technique, thermal damage and the inflammatory response to particulate wear debris. Cytokines are released in response to macrophage activation by particulate wear debris (PWD), the resultant inflammatory cascade stimulates osteoclastic resorption of bone. The failure of remodelling and repair mechanisms may be as a result of Osteonecrosis from cement (PMMA).

Hypothesis: That PMMA increases Osteoblast susceptibility to necrosis and apoptosis following inflammatory challenge.

Materials and Methods: Osteoblast cell cultures were grown on PMMA cement plates and assessed for apoptosis and necrosis by PI exclusion staining, morphological changes on light and electron microscopy and flow cytometry.

Results: PMMA induced osteonecrosis is highest at 1 hour (34.45) in comparison to control levels (4.55). There is no significant change in Apoptosis at 24 hours. Culture of the Osteoblasts on cement and delayed stimulation with TNF-α causes increased Apoptosis and Necrosis.

Conclusion: PMMA cement causes Osteoblast necrosis in the early stages of polymerisation, after 24 hours there is little increase in apoptosis/necrosis. However Osteoblasts that grow in contact with cement are more susceptible to apoptosis and necrosis following TNFα challenge. This may prove to be an important step in the pathogenesis of Aseptic loosening.

The management of type two odontoid peg fractures remains controversial. The policy in our unit is to initially manage all of these injuries non-operatively. Patients with displaced fractures (0.2mm translation, > 15° angulation) are placed in halo vests followed by fracture reduction under radiological control. Undisplaced or minimally displaced fractures are treated in either custom-made minerva orthoses or halo vests.

We report the results of 42 consecutive cases of type two odontoid peg fractures. There were 24 males and 18 females with a mean age of 53 (range 18–89) years. Twenty-one (50%) of patients were > 65 years of age. In 29 cases the fracture was undisplaced or minimally displaced and in the remaining 13 cases it was displaced (> 2mm translation, > 15° angulation) either posteriorly (extension-type)(6) or anteriorly (flexion type) (7). All displaced cases were treated in halo vests while the remainder were treated in minervas (14) or halo vests (15).

Loss of reduction occurred in nine cases necessitating adjustment in five and C1/2 posterior fusion in four. Of these cases five were displaced extension type-fractures, two required fusion. Pin site infection necessitated early removal of halo vest and conversion to minerva in three cases. In all of these cases fracture union was achieved.

Overall, union was achieved in 37 patients giving a non-union rate of 12%. The mean age of the five non-unions was 42 years with only one patient over 65 years of age. Four of these patients had C1/2 posterior fusions and the remaining patient refused surgery.

Of the 29 patients with displaced or minimally displaced fractures five (17%) required surgery for either non-union (3) or displacement (2), whereas three (23%) of the displaced group required surgery for non-union (1) or displacement (2). All of these were extension type fractures.

We conclude that a policy of non-operative management of these fractures resulted in union in a high proportion of patients of all age groups except for those with extension type fractures. This fracture pattern may warrant primary surgical intervention.

Aseptic loosening is currently the leading cause of failure of total hip arthroplasty. The aetiology of periprosthetic bone resorption is currently under intense investigation. Wear particles are produced from the articulating surface of the femoral and acetabular components. These particles gain access to the bone-cement interface where they are phagocytosed by macrophages. Particle stimulated macrophages differentiate into bone resorping osteoclasts. This leads to periprosthetic bone resorption and subsequent implant loosening.

Nuclear factor kappa B (NFκB) is a transcription factor known to be activated by pathogenic stimuli in a variety of cells. The activation of NFkB would appear to be the primary event in the activation of particle stimulated macrophages in the periprosthetic membrane. NFκB subsequently causes a cascade of events leading to the release of bone resorbing cytokines, namely interleukin-6 (IL-6) and tumour necrosis factor α (TNFα).

The aim of our study was to ascertain if bone resorption could be prevented in vitro by the addition of PDTC, an NFkB inhibitor to particle stimulated macrophages.

Human monocytes were isolated and cultured from healthy volunteers. The monocyte/macrophage cell line was differentiated into osteoclasts by the addition of alumina particles and allowed to adhere onto bone slices. The NFkB inhibitor, PDTC, has added to the cultured osteoclasts. Bone resorption was analysed by counting the number of resorption pits in each bone slice.

The addition of PDTC to stimulated macrophages reduced the number of resorption pits by greater than 40% compared to control.

This is a unique and promising finding that may offer a future therapeutic strategy for the prevention of periprosthetic bone resorption and therefore aseptic loosening in total hip arthoplasty.

This study examines patient characteristics, indications for conversion, surgical and anaesthetic technique, peri-operative management and complications of surgery in this small and challenging group of patients. In the six years from 1994 to 1999, 33 conversion arthroplasties were performed for failed femoral hemiarthroplasty. The average age at conversion surgery was 75.5 years (range 65–90). The female to male ratio was 6:1. Primary hemiarthroplasties comprised 24 Austin-Moore, 6 Thompson & 3 Bipolar prostheses. The average interval from primary to conversion surgery was 50 months (6 months to 17 years). The average age at primary surgery was 71.2 years (62–88) – AMP:71.4 years, Thompson’s: 74.2 years, Bipolar: 63.5 years. All hemiarthroplasties were performed for fractured femoral necks. 62% of patients came from the Eastern Health Board area, while 38% were tertiary are referrals from other Health Boards. The average length of stay was 17.5 days (3–24). Indications for conversion included gross loosening/acetabular erosion in 9 cases, suspected infection in 4 cases and abscess/septicaemia in 1 case. All but 3 patients had significant pain (night pain etc.) and/or severely impaired mobility.

We also looked at anaesthetic and analgesic practice, surgical technique and prostheses used.

Post-operatively, mean total blood loss was 1430 ml (420–2280) with an average of 1.4 units of blood transfused (0–5). Intraoperative complications included acetabular & femoral perforation, periprosthetic fracture and cement reactions. Complications post-op (in hospital) included cardiac arrhythmia’s, cerebrovascular accidents, pulmonary embolus, myocardial infarct, respiratory & urinary tract infections, constipation, nausea & vomiting.

The elderly nature of these patients and the physiological stress of what is major surgery allied with multiple co-morbidities make their care especially challenging. A conversion arthroplasty is a procedure with a significant risk of considerable morbidity. Primary total hip replacement or bipolar hemiarthroplasty are options which, therefore, should be seriously considered in the case of fractured femoral necks to minimise the need for further surgery in the future, with all its attendant risks.