Introduction. The PACE trial was the first randomized controlled trial (RCT) investigating the efficacy of paracetamol in acute low back pain. Non-compliance to study medication was considered to be a limitation of this RCT. In contrast to conventional statistical methods, complier average causal effects (CACE) analysis may provide unbiased estimates of the effects for participants compliant to paracetamol. Methods. Intention to treat (ITT), as-treated, propensity weighted CACE and joint modeling CACE estimates were calculated for pain intensity, disability, global perceived effect and function at two weeks of follow up with compliance defined as an average of at least four tablets per day during the first two weeks of the trial. For pain intensity, exploratory analyses were conducted using additional time points and definitions of compliance. Results. 547 participants had been randomized to placebo and 550 to regular paracetamol; of the latter group, 72% of patients was classified as compliers. Mean differences in pain intensity between paracetamol and placebo using the main time point and definition of compliance were non-significant (ITT 0.11, p = 0.49; as-treated 0.29, p = 0.12; propensity weighed CACE −0.12, p = 0.51; joint modeling CACE 0.28, p = 0.13); similar results were obtained for disability, global perceived effect and function and for additional time points and definitions of compliance. Conclusion. In compliers, paracetamol had no significant effect on pain intensity when compared to placebo; this supports the conclusions from the original analysis. However, these calculations are based on patient-reported compliance, which may not perfectly represent actual medication consumption. Conflicts of interest: AM has received funding for a postgraduate research scholarship from GlaxoSmithKline. CM has received funding to review teaching materials prepared by GlaxoSmithKline. The other authors declare no competing interests. Sources of funding: The PACE trial was an investigator-initiated study funded by a project grant from National Health and Medical Research Council of Australia. GlaxoSmithKline Australia provided subsequent supplementary funding and the paracetamol and matched placebo. CM is supported by Australian Research Council Future Fellowships FT-100100603. CL is supported by a Career Development Fellowship from the National Health and Medical Research Council, Australia (APP1061400). This secondary analysis of the PACE data has been supported by a program grant of the Dutch Arthritis Foundation and by the Foundation “De Drie Lichten” in The Netherlands

Objectives. Understanding lumbar facet joint involvement and biomechanical changes post spinal fusion is limited. This study aimed to establish an in vitro model assessing mechanical effects of fusion on human lumbar facet joints, employing synchronized motion, pressure, and stiffness analysis. Methods and Results. Seven human lumbar spinal units (age 54 to 92, ethics 15/YH/0096) underwent fusion via a partial nucleotomy model mimicking a lateral cage approach with PMMA cement injection. Mechanical testing pre and post-fusion included measuring compressive displacement and load, local motion capture, and pressure mapping at the facet joints. pQCT imaging (82 microns isotropic) was carried out at each stage to assess the integrity of the vertebral endplates and quantify the amount of cement injected. Before fusion, relative facet joint displacement (6.5 ± 4.1 mm) at maximum load (1.1 kN) exceeded crosshead displacement (3.9 ± 1.5 mm), with loads transferred across both facet joints. After fusion, facet displacement (2.0 ± 1.2 mm) reduced compared to pre-fusion, as was the crosshead displacement (2.2 ± 0.6 mm). Post-fusion loads (71.4 ± 73.2 N) transferred were reduced compared to pre-fusion levels (194.5 ± 125.4 N). Analysis of CT images showed no endplate damage post-fusion, whilst the IVD tissue: cement volume ratio did not correlate with the post-fusion behaviour of the specimens. Conclusion. An in vitro model showed significant facet movement reduction with stand-alone interbody cage placement. This technique identifies changes in facet movement post-fusion, potentially contributing to subsequent spinal degeneration, highlighting its utility in biomechanical assessment. Conflicts of interest. None. Sources of funding. This work was funded by EPSRC, under grant EP/W015617/1

Purpose and Background. Work-related musculoskeletal disorders (WRMSD) can affect 56–80% of physiotherapists. Patient handling is reported as a significant risk factor for developing WRMSD with the back most frequently injured. Physiotherapists perform therapeutic handling to manually assist and facilitate patients’ movement to aid rehabilitation, which can increase physiotherapists risk of experiencing high forces during patient handling. Methods and Results. A descriptive cross-sectional study was completed to explore and quantitatively measure the movement of ten physiotherapists during patient handling, over one working day, in a neurological setting. A wearable 3-dimensional motion analysis system, Xsens (Movella, Henderson, NV), was used to measure physiotherapist movement and postures in the ward setting during patient treatment sessions. The resulting joint angles were reported descriptively and compared against a frequently used ergonomic assessment tool, the Rapid Upper Limb Assessment (RULA). Physiotherapists adopted four main positions during patient handling tasks: 1) kneeling; 2) half-kneeling; 3) standing; and 4) sitting. Eight patient handling tasks were identified and described: 1) Lie-to-sit; 2) sit-to-lie; 3) sit-to-stand; facilitation of 4) upper limb; 5) lower limb; 6) trunk; and 7) standing treatments; and 8) walking facilitation. Kneeling and sitting positions demonstrated greater neck extension and greater lumbosacral flexion during treatments which scores highly with the RULA. Conclusion. This research identified that patient treatment tasks were more often performed in kneeling or sitting positions than standing. Current moving and handling guidance teaches moving and handling in a standing position; loading and stresses experienced by the physiotherapists may differ in sitting or kneeling positions. Conflicts of interest. None. Sources of funding. None. This work has been presented as a poster at the CSP conference Glasgow 2023

Microdiscectomy is the most commonly performed spine surgery in the world. Due to its technical simplicity and low complication rate, this was the first spine surgical procedure transitioning for one-day surgery. However, the economic assessment of this outpatient transition was never performed and the question on the real impact in the burden of spine care remains. This economic study aims to access the cost-utility of outpatient lumbar microdiscectomy when compared with the inpatient procedure. To do so, a cost-utility study was performed, adopting the hospital perspective. Direct medical costs were retrieved from the assessment of 20 patients undergoing outpatient lumbar microdiscectomy and 20 undergoing inpatient lumbar microdiscectomy, from a in a Portuguese NHS hospital. Utilities were calculated with quality-adjusted life-years were derived from Oswestry Disability Index values (ODI). ODI was assessed prospectively in outpatients in pre and 3- and 6-month post-operative evaluations. Inpatient ODI data were estimated from a meta-analysis. both probabilistic and deterministic sensitivity analyses were performed and incremental cost-effectiveness ratio (ICER) calculated. A willingness to pay (WTP) threshold of €60000/QALY gained with inpatient procedure was defined. Out results showed that inpatient procedure was cost-saving in all models tested. At 3-month assessment ICER ranged from €135753 to €345755/QALY, higher than the predefined WTP. At 6-month costs were lower and utilities were higher in outpatient, overpowering the inpatient procedure. Probabilistic sensitivity analysis showed that in 65% to 73% of simulations outpatient was the better option. The savings with outpatient were about 55% of inpatient values, with similar utility scores. No 30-day readmissions were recorded in either group. The mean admission time in inpatient group was 2.5 days. Since there is an overall agreement among spine surgeons that an uncomplicated inpatient MD would only need a one-day admission, an analysis reducing inpatient admission time for one day was also performed and outpatient remained cost-effective. In conclusion, as the first economic study on cost-utility of outpatient lumbar microdiscectomy, this study showed a significant reduction in costs, with a similar clinical outcome, proving this outpatient transition as cost-effective

Study purpose and background. Kinematic variables have been identified as potential biomarkers for low back pain patients; however, an in-depth comparison between chronic (n=22), acute (n=15), and healthy controls (n=136) has not been done. This retrospective data analysis compared intervertebral lumbar motion parameters, angular range of motion, translation, maximum disc height, motion share inequality (MSI) and variability (MSV), and laxity, between these groups. Methods and results. Kinematic parameters were determined using video tracking techniques utilising quantitative fluoroscopy (QF), during both weight-bearing and recumbent controlled sagittal bending tasks. Data was analysed for normality, and appropriate statistical tests were applied to determine differences between groups. There were no significant differences between the groups for age, height, weight and sex. Whilst few differences were found between acute and healthy groups, differences were shown between both chronic and healthy, and acute and chronic groups for all six parameters. Of particular note were examples of differences in the motion share parameters between the acute and chronic populations, with an increased MSI in the chronic group during recumbent flexion, and MSV during recumbent extension, and inversely an increase in MSV in the acute group during weight-bearing flexion. Conclusion. Analysis of intervertebral lumbar motion provides valuable insights into kinematic differences between chronic, acute, and healthy control populations. These findings suggest that there is variation between the groups which is knowledge that may benefit management strategies. Further exploration of the time varying data is warranted to explore how such differences may relate to the motion share inequalities and variability shown. Conflicts of Interest. No conflicts of interest. Sources of Funding. No funding obtained

Background. Trunk muscles play an important role in supporting the spinal column. A decline in trunk muscle mass, as measured by bioelectrical impedance analysis (TMM–BIA), is associated with low back pain and poor quality of life. Purpose. The purpose of this study was to determine whether TMM–BIA correlates with quantitative and functional assessments traditionally used for the trunk muscles. Methods. We included 380 participants (aged ≥ 65 years; 152 males, 228 females) from the Shiraniwa Elderly Cohort (Shiraniwa) study, for whom the following data were available: TMM–BIA, lumbar magnetic resonance imaging (MRI), and back muscle strength (BMS). We measured the cross-sectional area (CSA) and fat-free CSA of the paravertebral muscles (PVM), including the erector spinae (ES), multifidus (MF), and psoas major (PM), on an axial lumbar MRI at L3/4. The correlation between TMM–BIA and the CSA of PVM, fat-free CSA of PVM, and BMS was investigated. Results. TMMBIA correlated with the CSA of total PVM and each individual PVM. A stronger correlation between TMM–BIA and fat-free CSA of PVM was observed. The TMM–BIA also strongly correlated with BMS. Conclusion. TMM–BIA is an easy and reliable way to evaluate the trunk muscle mass in a clinical setting. Conflict of interest. None. Sources of funding. None

Background

Intervertebral disc degeneration (DD) is a complex age-related condition that constitutes the main risk factor for disabling back pain. DD is assessed using different traits extracted from MR imaging (MRI), normally combined to give summary measures (e.g. Pfirmann score). The aetiology of DD is poorly understood and despite its high heritability (75%), the precise genetic predisposition is yet to be defined. Genome wide association study (GWAS) is used to discover genetic variants associated with a disease or phenotype. It tests variants across the whole genome. It requires large samples to provide adequate but unfortunately there is poor availability of spine imaging data due to the high cost of MRI. We have adopted new methods to examine different MRI traits independently and use the information of those traits to boost GWAS power using specialized statistical software for jointly analyse correlated traits.

Purpose and Background

Clinical practice guidelines (CPGs) recommend self-management for low back pain (LBP). Our recent narrative review on self-management needs revealed a consensus with respect to the critical components of self-management interventions. With mobile health advancements, apps offer innovative support for LBP management. This study aims to identify current apps for the self-management of LBP, assessing them for their quality, intervention content, theoretical approaches, and risk management approaches.

Aims. This study, using a surgeon-maintained database, aimed to explore the risk factors for surgery-related complications in patients undergoing primary cervical spine surgery for degenerative diseases. Methods. We studied 5,015 patients with degenerative cervical diseases who underwent primary cervical spine surgery from 2012 to 2018. We investigated the effects of diseases, surgical procedures, and patient demographics on surgery-related complications. As subcategories, the presence of cervical kyphosis ≥ 10°, the presence of ossification of the posterior longitudinal ligament (OPLL) with a canal-occupying ratio ≥ 50%, and foraminotomy were selected. The surgery-related complications examined were postoperative upper limb palsy (ULP) with a manual muscle test (MMT) grade of 0 to 2 or a reduction of two grade or more in the MMT, neurological deficit except ULP, dural tear, dural leakage, surgical-site infection (SSI), and postoperative haematoma. Multivariate logistic regression analysis was performed. Results. The significant risk factors (p < 0.050) for ULP were OPLL (odds ratio (OR) 1.88, 95% confidence interval (CI) 1.29 to 2.75), foraminotomy (OR 5.38, 95% CI 3.28 to 8.82), old age (per ten years, OR 1.18, 95% CI 1.03 to 1.36), anterior spinal fusion (OR 2.85, 95% CI 1.53 to 5.34), and the number of operated levels (OR 1.25, 95% CI 1.11 to 1.40). OPLL was also a risk factor for neurological deficit except ULP (OR 5.84, 95% CI 2.80 to 12.8), dural tear (OR 1.94, 95% CI 1.11 to 3.39), and dural leakage (OR 3.15, 95% CI 1.48 to 6.68). Among OPLL patients, dural tear and dural leakage were frequently observed in those with a canal-occupying ratio ≥ 50%. Cervical rheumatoid arthritis (RA) was a risk factor for SSI (OR 10.1, 95% CI 2.66 to 38.4). Conclusion. The high risk of ULP, neurological deficit except ULP, dural tear, and dural leak should be acknowledged by clinicians and OPLL patients, especially in those patients with a canal-occupying ratio ≥ 50%. Foraminotomy and RA were dominant risk factors for ULP and SSI, respectively. An awareness of these risks may help surgeons to avoid surgery-related complications in these conditions. Cite this article: Bone Joint J 2021;103-B(1):157–163

Background. The rate of subsidence for lumbar fusion surgery is variable from 7- 89%. Subsidance can affect the outcome of surgery by compramising alignment, foraminal height and stability. Modic changes have been shown to affect the stiffness and strength of the vertebral end plate and shown to affect both fusion rates and clinical outcome. Ongoing laboratory investigations into the material properties of the degenerate lumbar spine show modic changes affect the end plate and trabecular bone mechanics. This study aims to bridge this basic science research into clinical practice. Methods. A retrospective analysis of all patients in two tertiary spinal centres who have undergone lumbar interbody fusion with the implantation of a ‘cage’ over the past 6 years were analysed by two independent spinal surgeons. Pre-operative MRI findings were correlated with post-operative interbody cage subsidence after 1 year. Results. A total of 108 Interbody cages were included. Comparison of demographics did not reveal and significant between group variations. Comparison made between those displaying no modic changes and those displaying any of the three modic change types revealed a significantly higher subsidence rate in those displaying modic changes (p=0.003). Subgroup analysis showed that Type 2 modic changes (n=27) had a significantly higher subsidence rate (p=0.002). Those displaying type 3 modic changes (n=7) did not have any incidents of subsidence. Conclusions. Type 2 modic changes are associated with a higher rate of Lumbar interbody cage subsidence in this study. Those displaying type 3 changes seem to be protected from interbody cage subsidence. No Conflict of Interest. Funding: Produced as part of a research grant from the Gwen Fish Trust and Action Arthritis

Background and Purpose. The STarT Back approach comprises subgrouping of LBP patients according to risk of persistent LBP-related disability, and matches patients to appropriate treatments. In a clinical trial and implementation study, this stratified care approach was clinically and cost-effective compared to usual non-stratified care. However, the long-term cost- effectiveness is unknown, and could be established with decision modelling. A systematic review of model-based economic evaluations in LBP found shortcomings with existing models, including inadequate characterisation of the condition in health states and absence of long-term modelling. This study conceptualises the first decision model of this stratified care approach for LBP management, and assesses long-term cost-effectiveness. Methods. A cost-utility analysis from the NHS perspective compared stratified care with usual care, in patients consulting in primary care with non-specific LBP. A Markov state-transition model was constructed where long-term patient prognosis over ten years was dependent upon physical function achieved at twelve months. Consultation with experts helped define condition health states, inform the long-term modelling, and choice of sensitivity analyses. Results. Preliminary base-case results indicate this model of stratified care is cost-effective over a ten-year time horizon, delivering 0.10 additional quality-adjusted life years (QALYs) at a cost-saving of £100.27 per patient. Sensitivity analyses indicate the approach is likely to be cost-effective in all scenarios, and cost-saving in most, although sensitive to assumptions regarding long-term patient prognosis. Analysis from the societal perspective improved the associated cost-savings. Conclusion. It is likely that implementation of this stratified care model will help reduce unnecessary healthcare usage, whilst improving patient quality of life. No conflicts of interest. Funding: Research stipend for JAH by the Institute for Primary Care & Health Sciences, Keele University

Funding. This report presents independent research commissioned by the National Institute for Health Research (NIHR) (NIHR HTA project number 12/201/09). NEF is a Senior NIHR Investigator and was supported through an NIHR Research Professorship (NIHR-RP-011-015). KK was supported by a HEFCE Senior Clinical Lectureship award. The views and opinions expressed by authors in this publication are those of the authors and do not necessarily reflect those of the NHS, the NIHR, MRC, CCF, NETSCC, the Health Technology Assessment programme or the Department of Health. Background and Purpose. Stratified care (SC) has previously been found to be a cost-effective approach for primary care LBP patients. The SCOPiC trial compared the clinical and cost-effectiveness of a modified SC model combining prognostic and clinical characteristics to allocate sciatica patients into one of three groups (with matched care pathways) versus non-stratified, usual care (UC). Methods. Cost-utility analysis was undertaken over 12-months. Resource use and quality of life (EQ-5D-5L) data were obtained from postal questionnaires, mean costs and QALYs were calculated for each trial arm along with cost-effectiveness acceptability curves. The base case analysis was by intention-to-treat, and performed from NHS and personal social services (PSS) perspective. Sensitivity analyses included healthcare provider and societal perspectives, as well as analyses for each of the three patient groups. Results. 476 patients were randomised (238 per arm). Mean NHS/PSS costs (SD) recorded were £663.58 for SC and £617.37 for UC. Mean QALYs (SD) were 0.659 (0.173) for SC and 0.671 (0.168) for UC; the adjusted mean difference in QALYs was −0.011 (−0.035, 0.013). In this base-case analysis, the chance of SC being cost-effective at a threshold of £30,000 per QALY was only 19%. Similarly, low probabilities of effectiveness were observed in all sensitivity analyses. The chance of SC being cost-effective at a threshold of £30,000 ranged from 18% to 52% for each of the three patient groups. Conclusions. Overall, the SC model that we tested for sciatica in primary care was not a cost-effective option compared to usual, non-stratified care. No sources of funding. No conflicts of interest

Purpose and background. Identifying features in nonspecific low back pain (NSLBP) subjects that distinguish them from controls, or for elucidating subgroups, has proved elusive. Yet these would be helpful to monitor progress, improve management, and understand the nature of the condition. Previous work using quantitative videofluoroscopy (QF) has indicated that the distribution of motion between lumbar intervertebral joints is more uneven in those with a history of NSLBP. However, there maybe other features of these complex motion patterns yet to be revealed. A multivariate analysis was therefore carried out to explore other possible differences. Methods and results. Intervertebral motion data of L2/3 to L4/5, from a previously published study was used. This examined 40 patients with NSLBP and 40 healthy controls, matched for gender, age and body mass index, who underwent passive recumbent QF in the coronal and sagittal planes. For each motion direction, principal components analysis was carried out and salient dimensions selected. Using a lower dimensional principal components (PC) representation, groups were compared using Hoteling's T test. Linear and quadratic discriminant analysis (LDA and QDA) was carried out using PC representations to examine group differences. The features most clearly distinguishing groups from the LDA was examined graphically. An analysis of the sensitivity of the results to the number of PC dimensions was carried out. The performance of the LDA and QDA classifiers were examined using leave-one-out cross-validation. Conclusions. Hotelling tests revealed significant differences between groups for right and left side-bending. This was confirmed by LDA and QDA. There was no clear difference in the performance of these classifiers and performance did not improve by including more than 4 PC dimensions. Visualisation of the LDA indicated that patients had relatively lower amplitude motion at L4/5, compensated by higher amplitude at L2/3/4. These results point to additional features of lumbar motion that differentiates NSLBP. No conflicts of interest. No funding obtained (however, the original study was funded by NIHR - CATCDRF09)

Aims. The aim of this study was a quantitative analysis of a surgeon’s learning curve for scoliosis surgery and the relationship between the surgeon’s experience and post-operative outcomes, which has not been previously well described. Patients and Methods. We have investigated the operating time as a function of the number of patients to determine a specific pattern; we analysed factors affecting the operating time and compared intra- and post-operative outcomes. We analysed 47 consecutive patients undergoing scoliosis surgery performed by a single, non-trained scoliosis surgeon. Operating time was recorded for each of the four parts of the procedures: dissection, placement of pedicle screws, reduction of the deformity and wound closure. Results. The median operating time was 310 minutes (interquartile range 277.5 to 432.5). The pattern showed a continuous decreasing trend in operating time until the patient number reached 23 to 25, after which it stabilised with fewer patient-dependent changes. The operating time was more affected by the patient number (r =- 0.75) than the number of levels fused (r = 0.59). Blood loss (p = 0.016) and length of stay in hospital (p = 0.012) were significantly less after the operating time stabilised. Post-operative functional outcome scores and the rate of complications showed no significant differences. Take home message: We describe a detailed learning curve for scoliosis surgery based on a single surgeon’s practise, providing useful information for novice scoliosis surgeons and for those responsible for training in spinal surgery. Cite this article: Bone Joint J 2016;98-B:679–85

Purpose and Background:. To identify treatment effect modifiers within the STarT Back Trial which demonstrated prognostic stratified care was effective in comparison to standard care for patients with low back pain. Methods:. Secondary analysis of the STarT Back Trial using 688 patients with available 4-month follow-up data. Disability (baseline and 4 months) was assessed using the Roland Morris Disability Questionnaire (RMDQ) using continuous and dichotomized (>7) outcome scores. Potential treatment effect modifiers were evaluated with group x predictor interaction terms using linear and logistic regression models. Modifiers included: age, gender, education, socio-economic status (SES), employment status, work satisfaction, episode duration, general health (SF-12), number of pain medications, and treatment expectations. Results:. No significant treatment effect modifiers were identified using linear regression, however logistic regression analysis identified SES as a treatment modifier (interaction: OR = 0.65; 95% confidence interval = 0.42 to 0.98). Comparing those receiving stratified care versus best current care, the proportion of patients with poor 4 month outcome was similar for lower SES patients (35.4% vs. 37.2%), yet different for high SES patients (19.3% vs. 38.9%). No other treatment effect modifiers were identified; however exploratory analyses indicated trends for worse outcomes with increased age, patients taking ≥3 medications, those with lower education, and those with poor treatment expectations as potential treatment effect modifiers. Conclusion:. SES was identified as a treatment effect modifier in the STarT Back Trial with patients with lower SES not benefiting from stratified care. The explanations for this finding need further exploration

Objective

Modic changes (MC) is a form of intervertebral disc degeneration visible as subchondral and vertebral bone marrow changes on spine magnetic resonance (MR). Their etiology is not understood, but microbial infection may be involved for some subtypes. This study set out to test for an association between MC and gut microbiome in a population sample.

Studies on recurrent disc herniation quote rates of recurrence without regard to the times of recurrence and the influence of longer follow-up. Our objective was to assess the use of survival analysis to measure the rate of revision after lumbar microdiscectomy. We undertook a retrospective analysis of the hospital records of 993 patients who underwent lumbar microdiscectomy over a period of ten years. After calculating the overall rate of revision for the mean length of follow-up, we carried out a survival analysis using the life-table method. During the study period 49 patients had a revision microdiscectomy. This gave an overall rate of revision of 4.9% at a mean follow-up of 5.25 years. Using survival analysis, the rate of revision was 7.9% at a follow-up of ten years when the number at risk was 84. Survival analysis gives a more accurate estimation of the true rate of recurrence for patients undergoing lumbar microdiscectomy. The method allows better comparison between different interventions for disc herniation

Background. Complex interventions, such as exercise for LBP, often have many treatment targets. Matching a primary outcome to the target(s) of exercise interventions may provide greater standardized mean differences (SMDs) than using an unmatched primary outcome. We aimed to explore whether the conclusions of exercise trials for LBP might differ with i) improved matching of outcomes to treatment targets and ii) the use of composite outcome measures. Methods and Results. We investigated i) matching in five trials (n=1033) that used an unmatched primary outcome but included some of their matched outcomes as secondary outcomes; ii) composite outcomes in four trials (n=864). The composite consisted of standardised averaged matched outcomes. All analyses replicated the primary outcome analysis, applied to the matched or composite outcome in each dataset. When not possible, SMDs were calculated for the primary and matched outcomes. i) Of five trials, three had greater SMDs and increased statistical significance with matched outcomes (pooled effect SMD 0.35 (95% CI 0.16, 0.54), p=0.0003) compared to an unmatched primary outcome (pooled effect SMD 0.13 (95% CI 0.04, 0.23) p=0.007). ii) Of four composite outcomes: two matched trials had greater SMDs and improved statistical precision in the primary outcome than the composite outcome; two unmatched trials had greater SMDs and improved statistical precision in the composite compared to the primary outcome. Conclusion. Using an outcome that matches exercise targets in LBP trials appears to produce greater SMDs than an unmatched primary outcome. Future trials should consider primary outcome selection aligned with exercise treatment targets. Sources of Funding: L Wood's PhD is funded by the Research Institute for Primary Care and Health Sciences, Keele University. Prof NE Foster is a UK National Institute for Health Research Senior Investigator, and was supported by a UK National Institute for Health Research Professorship (NIHR-RP-011-015). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. Conflicts of interest: No conflicts of interest

Background. Low back-related leg pain (LBLP) is clinically diagnosed as referred leg pain or sciatica. Within the spectrum of LBLP there may be unrecognised subgroups of patients. This study aimed to identify and describe clusters of LBLP patients using latent class analysis (LCA). Methods. The study population were 609 LBLP primary care consulters. Variables from clinical assessment were included in the LCA. Characteristics of the statistically identified clusters were described and compared to the clinically defined groups of LBLP patients. Results. A five cluster solution was optimal. Cluster one (n=104) had mild leg pain severity, no clinical signs suggestive of sciatica and more anxiety. Cluster two (n=122), three (n=188) and four (n=69) represented mild, moderate and severe sciatica in terms of response to clinical assessment items, pain severity and impact on function. Cluster five (n=126) was more difficult to define based on response to clinical assessment items (below knee pain and possible neural tension) and had a similar severe profile to cluster four in terms of high pain, disability, psychosocial factors, work impact and risk of poor outcome; but had longer duration pain and more comorbidities. Cluster three consistently mirrored the profile of the overall group of patients with a clinical diagnosis of sciatica. Cluster one mirrored the referred leg pain group. Conclusion. This is the first study that used LCA to classify LBLP patients, including sciatica. These clusters could represent more homogenous groups that may require different treatment approaches. Further work will describe the clinical course and longer term outcomes of these clusters. No conflicts of interest. S Stynes is supported by an NIHR/CNO Clinical Doctoral Research Fellowship (CDRF-2010-055). Dr Konstantinou is supported by a HEFCE/NIHR Senior Clinical Lectureship. Professor Hay is a NIHR Senior Investigator

Background. Fractures of the odontoid peg are one of the commonest spinal injuries in the elderly population. In this population there is a higher risk of morbidity and mortality as a result of the injury. The magnitude of this risk has not been quantified in the literature. Aim. To show a survivorship analysis in a cohort of elderly patients with odontoid peg fractures. Method and Materials. A 6-year retrospective analysis was performed on all patients >65 years old admitted to a spinal unit with an isolated odontoid peg fracture. Actuarial (Life-Table) analysis was used to estimate survivorship from the date of fracture. Results. A total of 32 patients > 65 years of age with isolated odontoid peg fractures were identified. There were 17 male and 15 female. A low velocity mechanical fall was the commonest cause for the injury. The average age for the females was 86.7 years and for the males 78 years. The age distribution was unimodal in both sex, the greatest number occurring for the females in the 85-94 year age group and 75-84 years for the males. Overall, it was estimated that only 62.5 % would be alive by one year. The period of greatest mortality was within the first 12 weeks, a lesser contribution from then to one year, and had no impact on mortality thereafter. Males appeared to suffer a heavier mortality than females within the first year. At one year the male survival rate had fallen to 58.8% compared with a female rate of 66.6%. Conclusion. We observed that odontoid peg fractures in the elderly are not benign injuries and are a cause of high mortality rates within the first three months of the injury. Patients who survived to one year following the injury were observed to have their risk return to age and sex matched rates for this population