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: 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.

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.

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: 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.