No description available.

The aim of the original work presented in this thesis was to investigate morphological and functional differences in clinical and control populations, which may negatively impact the experience of pain. Firstly, morphological differences were investigated between groups of healthy controls and chronic low back pain (CLBP) patients. Included in the latter were subgroups of patients not previously investigated in the current morphological literature, those with and without pain behaviour. We investigated differences in gray matter (GM) volume between groups using an automated whole brain technique, and a manual method applied to two regions of interest, namely prefrontal cortex and insular cortex. A deficit in GM volume of right dorsal prefrontal cortex between CLBP patients and controls was found, with a further deficit in left insular cortex for CLBP patients with concomitant pain behaviour. Secondly, we conducted two studies using functional magnetic resonance imaging (fMRI) and a task of selective attention. Our initial investigation provided a proof of principle regarding the suitability of a semantic dot probe task within the fMRI environment. Pain-free participants were grouped based upon fear of pain scores. The results indicated differential behavioural and functional results between the groups. The thesis culminates with an fMRl study investigating selective attention in CLBP patients with pain behaviour. The clinical group were tested prior to and on completion of an intensive multidisciplinary pain management programme (PMP), with the aim of assessing if selective attention is sensitive to cognitive interventions. Selective attentional bias was demonstrated in the clinical group for pain-related trials at both testing sessions, although the direction of attention differed. Similarly, fMRI results showed differences in neural correlates for task performance between groups, with pre-PMP results demonstrating a reliance on semantic and memory processes. The fmdings suggest that fear of pain may be a vulnerability factor in the transition from acute to chronic pain and furthermore, CLBP patients with pain behaviour have structural, functional and behavioural differences which may negatively impact their ability to cope with their pain condition.

'Background: Back pain is strongly (but variably) associated with degeneration of intervertebral discs. Mechanical loading has long been considered one of the causes of disc pathology and pain, but its precise role is poorly understood. In particular the spatial relation between load distribution inside the disc, the disc matrix changes as a result of load and their relationship with pain has not been researched. Methods: Distribution of compressive stress inside intervertebral discs from all regions of the spine was studied using stress profilometry in cadaveric motion segments. Matrix pathological changes were studied using simple histology and light microscopy in two groups of surgically removed discs: 'painful' discs from patients undergoing surgery for suspected discogenic pain, and 'control' discs from patients undergoing surgery for scoliosis or spondylolisthesis reduction. Ingrowth of nerves and blood vessels into the annulus was studied by immunohistochemistry with an endothelial and a general neuronal marker. Stress reduction inside annulus fissures were investigated using stress profilometry. Proteoglycan reduction within annulus fissures was studied by means of a novel, semi-quantitative method involving simple histology and image analysis. Although semi-quantitative, the technique had great spatial resolution and allowed integration with the results from the mechanical experiments. Results: High stress concentrations were localised in the middle annulus and increased with disc degeneration. Associated stress gradients appeared early in the degeneration process and were not diminished in late stage degeneration when substantial compressive loading is transferred to the neural arch. Nerve and blood vessel ingrowth increased with degeneration, but were confined to the outermost 4mm of the annulus. Other cellular changes such as apoptosis, cellular infiltration and proliferation were mostly confined to the annulus. Annulus fissures were found to represent focal regions of low proteoglycan content, and also of low compressive stress, especially when the nucleus was also decompressed. Conclusions: Results suggest that high stress gradients play an important role in progressive annulus disruption, and that annulus fissures provide a microenvironment that is mechanically and chemically conducive to the ingrowth of nerves and blood vessels. Co-localisation of nerves, blood vessels and stress concentrations in the middle-outer annulus suggest that this is the most likely site of discogenic pain. Pain is associated with annulus disruption and the attempted healing rather than age-related degenerative changes in the nucleus.

No description available.

Mechanical low back pain is a common and costly medical problem. Most treatment options for low back pain have been reported to provide only short-term improvements in symptoms. Increasing the endurance of the local abdominal muscles, particularly transversus abdominis, by means of the so-called hollowing manoeuvre is a recommended method for long-term improvement in spinal stability and ultimately for prevention and alleviation of low back pain.

No description available.

No description available.

Introduction: Non-specific low back pain is a common condition that continues to place a considerable burden on society. Various treatment approaches have emerged which are aimed at targeting non-specific low back pain and one of the most commonly recommended of these is spinal manipulative therapy, which is a central component of the chiropractic approach. However, despite observations in clinical practice in which some individuals respond well, results from clinical trials of treatment interventions for low back pain, such as chiropractic, are repeatedly seen to have small effect sizes. A plausible explanation for this is that low back pain may be considered a heterogeneous condition consisting of a number of subgroups of patients. Previously highlighted as a research priority, these subgroups and their predictive factors for outcome are beginning to be identified among low back pain patients receiving chiropractic treatment; however they are largely unstudied in the UK chiropractic patient population. The overall aim of this prospective cohort study was to attempt to identify predictors of outcomes in the short, medium and long term in low back pain patients undergoing chiropractic treatment in primary care settings throughout the UK. Methods: All practising members of the British Chiropractic Association were invited to participate in the study. Each chiropractor was required to recruit 10 consecutive low back pain patients. Patients were eligible for inclusion if they were between 18 and 60 years of age; presenting with a new episode of low back pain with or without leg pain; no treatment for low back pain within the previous 3 months; not pregnant; no contraindications to chiropractic care; a mobile phone user. All participating patients completed an informed consent form. Data were recorded utilising self report paper questionnaires by patients and chiropractors at baseline; and by patients only at the 4th visit, 3 months and 6 months follow-up. In addition, outcomes in the immediate short term were recorded from patients via text message on a daily basis for 7 days following the 1st visit. Baseline potential predictor variables encompassed demographics, clinical characteristic, clinical examination findings, work-related factors and psychosocial factors. The primary outcome was patient self-report global improvement. Patients were subgrouped according to the duration of the current episode of low back pain into acute (less than 2 weeks) and subacute/chronic (2 weeks or greater). Multivariate logistic regression analysis was used to construct prognostic models for baseline and change score variables at each follow-up. Results: Sixty-five chiropractors and 452 low back pain patients (222 acute; 230 subacute/chronic) participated in the study. The loss to follow-up at 6 months was approximately 65%. Almost 60% of patients participated in the text message study and the response rate was high (96%). The acute patients reported higher pain and disability at baseline; however a greater proportion of these patients were categorised as improved at each follow-up. The greatest drop in pain scores occurred in the 1st week in both subgroups. Several baseline predictor variables were independently associated with improvement at follow-up; however these differed between the subgroups with the exception of the patient-practitioner relationship. Early changes in pain were independently associated with improvement for the acute and subacute/chronic patients in the short and medium term. The discriminative ability of the baseline and change score prognostic models varied from weak to acceptable. Conclusion: The investigation presented here contributes to the body of research concerning prognostic factors, specifically those in the immediate short term, in the UK chiropractic LBP patient population and for being the largest study of its kind to date in the UK. Furthermore, this study highlights the potential impact of the patientpractitioner relationship on outcome in low back pain patients receiving chiropractic care. Although several baseline variables predicted improvement at follow-up, the importance of early change as a prognostic indicator is emphasised.

Findings from randomised controlled trials (RCTs) on primary care treatments for non-specific low back pain (NSLBP) often show modest or non-significant differences in responses to treatments. The overall response to treatment within arms, however, is often large. This raises the question of the non-specific effects associated with using the treatments and whether the size of these non-specific effects is much larger than the size of effects associated with the specific components of treatments. Non-specific effects in clinical trials, defined in this thesis as the effects on the overall improvement of symptoms (i.e. response to treatment) that is not attributed to the treatment itself, contribute to the clinical course of symptoms and can be related to the patient, the symptoms, the healthcare practitioner, the communication between the patient and practitioner, the nature of treatment provided and the setting and environment of the clinical encounter. The objectives of this study were examining: 1) the pattern of within-arm overall responses to treatments in RCTs on non-specific low back pain; 2) sources of variation in responses to treatments by investigating the association of non-specific factors with overall responses to treatments; 3) the influence of patient characteristics on responses to treatments using individual patient data from RCTs; and 4) whether merely participating in RCTs adds to the size of response to treatments (the ‘trial effect’). The findings suggest that responses to treatments for NSLBP follow a pattern of an early large improvement in symptoms within 13-27 weeks of starting treatment followed by a smaller further improvement. This pattern was common to arms of RCTs regardless of the type of treatment. There was evidence that participants who had back pain episodes of less than 13 weeks showed larger responses to treatments than those with longer duration. There was weak inconclusive evidence for the association with age, gender, history of back pain, overall trial quality, adequacy of patient blinding and adequate compliance. There was no evidence that participating in RCTs led to larger improvement in back pain symptoms compared with participating in cohort studies. In conclusion, there is some evidence for the association of factors that are not related to the treatments with responses to treatments for NSLBP. Insufficient data hindered the assessment of other non-specific factors that were considered to be important, such as practitioner-patient communication.

Lumbar back pain has considerable socio-economical impacts, motivating a recently increasing interest from the research community. Yet, mechanisms triggering pain are not fully understood and this considerably hinders the development of efficient treatments and therapies. The objective of this thesis is to participate to the general understanding of the biomechanics of the spine through the development of computational strategies for the intervertebral disc. The intervertebral disc is a complex structure mainly comprised of the nucleus pulposus and the annulus fibrosus. The nucleus pulposus is the gelatinous core of the disc, which consists of a charged and hydrated extra-cellular matrix and an ionised interstitial fluid. It is enclosed in the annulus fibrosus which is formed by concentric layers of aligned collagen fibre sheets, oriented in an alternating fashion. A biphasic swelling model has been derived using mixture theory for soft, hydrated and charged tissues in order to capture the salient characteristics of the disc's behaviour. The model fully couples the solid matrix under finite deformations with the ionised interstitial fluid. The nucleus is assumed to behave isotropically while the effects of the collagen fibres in the annulus fibrosus are accounted for with a transversely isotropic model. The fixed negative charges of the proteoglycans, which induce an osmotic pressure responsible for the swelling capabilities of the disc, are constitutively modelled under the simplifying Lanir hypothesis. A Newton-Raphson solver was specifically built to solve the resulting nonlinear system of equations, together with a verification procedure to ensure successful implementation of the code. This was first reduced to the one dimensional case in order to demonstrate the appropriateness of the biphasic swelling model. The three dimensional model exhibited numerical instabilities, manifesting in the form of non-physical oscillations in the pressure field near boundaries, when loads and free-draining boundary conditions are simultaneously applied. As an alternative to considerable mesh refinement, these spurious instabilities have been addressed using a Galerkin Least-Square formulation, which has been extended for finite deformations. The performance and limitations of the GLS framework, which drastically reduces the pressure discrepancies and prevents the oscillations from propagating through the continuum, are demonstrated on numerical examples. Finally, the current state of the model's development is assessed, and recommendations for further improvements are proposed.