Low back pain is an ailment that affects a significant portion of the community. However, due to the complexity of the spine, which is a series of interconnected joints, and the loading conditions applied to these joints the causes for back pain are not well understood. Investigations of damage or failure of the spinal structures from a mechanical viewpoint may be viewed as a way of providing valuable information for the causes of back pain. Low back pain is commonly associated with injury to, or degeneration of, the intervertebral discs and involves the presence of tears or lesions in the anular disc material. The aim of the study presented in this thesis was to investigate the biomechanical effect of anular lesions on disc function using a finite element model of the L4/5 lumbar intervertebral disc. The intervertebral disc consists of three main components - the anulus fibrosus, the nucleus pulposus and the cartilaginous endplates. The anulus fibrosus is comprised of collagen fibres embedded in a ground substance while the nucleus is a gelatinous material. The components of the intervertebral disc were represented in the model together with the longitudinal ligaments that are attached to the anterior and posterior surface of the disc. All other bony and ligamentous structures were simulated through the loading and boundary conditions. A high level of both geometric and material accuracy was required to produce a physically realistic finite element model. The geometry of the model was derived from images of cadaveric human discs and published data on the in vivo configuration of the L4/5 disc. Material properties for the components were extracted from the existing literature. The anulus ground substance was represented as a Mooney-Rivlin hyperelastic material, the nucleus pulposus was modelled as a hydrostatic fluid in the healthy disc models and the cartilaginous endplates, collagen fibres and longitudinal ligaments were represented as linear elastic materials. A preliminary model was developed to assess the accuracy of the geometry and material properties of the disc components. It was found that the material parameters defined for the anulus ground substance did not accurately describe the nonlinear shear behaviour of the tissue. Accurate representation this nonlinear behaviour was thought to be important in ensuring the deformations observed in the anulus fibrosus of the finite element model were correct. There was no information found in the literature on the mechanical properties of the anulus ground substance. Experimentation was, therefore, carried out on specimens of sheep anulus fibrosus in order to quantify the mechanical response of the ground substance. Two testing protocols were employed. The first series of tests were undertaken to provide information on the strain required to initiate permanent damage in the ground substance. The second series of tests resulted in the acquisition of data on the mechanical response of the tissue to repeated loading. The results of the experimentation carried out to determine the strain necessary to initiate permanent damage suggested that during daily loading some derangement might be caused in the anulus ground substance. The results for the mechanical response of the tissue were used to determine hyperelastic constants which were incorporated in the finite element model. A second order Polynomial and a third order Ogden strain energy equation were used to define the anulus ground substance. Both these strain energy equations incorporated the nonlinear mechanical response of the tissue during shear loading conditions. Using these geometric data and material properties a finite element model of a representative L4/5 intervertebral disc was developed. When the measured material parameters for the anulus ground substance were implemented in the finite element model, large deformations were observed in the anulus fibrosus and excessive nucleus pressures were found. This suggested that the material parameters defining the anulus ground substance were overly compliant and in turn, implied the possibility that the stiffness of the sheep anulus ground substance was lower than the stiffness of the human tissue. Even so, the mechanical properties of the sheep joints had been shown to be similar to those of the human joint and it was concluded that the results of analyses using these parameters would provide valuable qualitative information on the disc mechanics. To represent the degeneration of the anulus fibrosus, the models included simulations of anular lesions - rim, radial and circumferential lesions. Degeneration of the nucleus may be characterised by a significant reduction in the hydrostatic nucleus pressure and a loss of hydration. This was simulated by removal of the hydrostatic nucleus pressure. Analyses were carried out using rotational loading conditions that were comparable to the ranges of motion observed physiologically. The results of these analyses showed that the removal of the hydrostatic nucleus pressure from an otherwise healthy disc resulted in a significant reduction in the stiffness of the disc. This indicated that when the nucleus pulposus is extremely degenerate, it offers no resistance to the deformation of the anulus and the mechanics of the disc are significantly changed. Specifically, the resistance to rotation offered by the intervertebral disc is reduced, which may affect the stability of the joint. When anular lesions were simulated in the finite element model they caused minimal changes in the peak moments resisted by the disc under rotational loading. This suggested that the removal of the nucleus pressure had a greater effect on the mechanics of the disc than the simulation of anular lesions. The results of the finite element model reproduced trends observed in both the healthy and degenerate intervertebral disc in terms of variations in nucleus pressure with loading conditions, axial displacement of the superior surface and bulge of the peripheral anulus. It was hypothesised that the reduced rotational stiffness of the degenerate disc may result in overload of the surrounding innervated osseoligamentous anatomy which may in turn cause back pain. Similarly back pain may result from the abnormal deformation of the innervated peripheral anulus in the vicinity of anular lesions. Furthermore, it was hypothesised that biochemical changes may result in the degeneration of the nucleus, which in turn may cause excessive strains in the anulus ground substance and lead to the initiation of permanent damage in the form of anular lesions. With further refinement of the components of the model and the methods used to define the anular lesions it was considered that this model would provide a powerful analysis tool for the investigation of the mechanics of intervertebral discs with and without significant degeneration.

[Truncated abstract] There have been few studies into the effects of rehabilitation following lumbar microdiscectomy and consequently little evidence of its effect, if any, on outcome. Most studies cited fall into one of two categories: research involving a spinal surgery procedure without rehabilitation, or research involving spinal surgery with a nonspecific generic 'rehabilitation' or 'physical therapy'. In an era of evidence based medicine the efficacy of specific rehabilitation protocols following defined lumbar spine surgical procedures needs to be established for surgeons, therapists and patients to have confidence that the rehabilitation is appropriate and effective. The study was proposed to investigate the outcome of a specific and novel rehabilitation protocol commenced immediately after lumbar microdiscectomy. Data collected from the research cohort were compared to data collected from a contrast group who underwent standard rehabilitation at a distant site. A retrospective study (Phase One) was carried out with a cohort of post-operative microdiscectomy patients between February 2000 and December 2002. The outcome of surgery followed by the rehabilitation protocol was assessed using validated outcome instruments. A contrast or control group was not included. After reviewing the data limitations with the design and implementation of the study were identified. A prospective study (Phase Two) was proposed and changes made in the principal outcome measure used, in the demographic data to be retrieved, the addition of pain scales, and in the exclusion of compensable patients. A contrast group was included for the prospective study. ... The study group commenced exercise and posture correction the day following surgery. There were restrictions placed on activity involving bending. The contrast group followed the advice of the surgeon in Queensland and attended rehabilitation at local physiotherapy facilities. Both groups were followed for 12 months using outcome instruments. Strict comparison between WA and QLD cohorts were limited due to sample size, however trends were observed. Data of the prospective study showed that there was greater reduction in back pain with the early rehabilitation protocol (P<.0001) compared to standard rehabilitation (P=.09), while there was no difference between groups in leg pain. There was a significant improvement in the level of functional disability between time-points for the WA cohort, and overall change from pre-operative RMQ measures to 12 months in both groups were statistically significant. The WA group was less reliant on pain medication and was more satisfied with the results of their surgery. The primary hypothesis of this study that there would be a difference in outcome following lumbar microdiscectomy in patients who receive early specific rehabilitation compared to those who receive standard rehabilitation at another centre, was supported in both primary and secondary outcome data. The key finding of this study was that commencing the early exercise protocol resulted in significantly less back pain over the 12 month time period of the study. Other major findings were that the WA cohort demonstrated significant improvement in function at all time-points and between all time-points except six to 12 months, took less pain medication and were more satisfied with the outcome of their surgery than the QLD cohort.

Bibliography: leaves 102-116. / 116, [43] leaves, [51] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Analyses the characteristics and relative incidence of annular defects in the human lumbar spine and investigates their role in the pathogenesis of invertebral disc degeneration. / Thesis (Ph.D.)--University of Adelaide, Dept. of Pathology, 1992

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

The association between age-related vertebral fractures (VFx) and disc degeneration (DD) is not clear, despite the high prevalence of both conditions. Load is transferred to the vertebra by the adjacent intervertebral discs, and degenerative changes within the disc alter how the net force is distributed over the interface between vertebra and disc, known as the vertebral endplate (EP). The ability of the vertebra to resist fracture depends not only on the magnitude of the net force, but also on the distribution. Multiple lines of evidence suggest that the ability of the vertebra to withstand the distribution of applied force depends on the spatial distribution of bone mineral density (BMD) within the vertebra. First, the strength and stiffness of a region of bone in the vertebra are highly correlated with the BMD of that region. Second, changes in the spatial distribution of regional BMD have been associated with aging and DD. Thirdly, some of these observed changes have been replicated in computer models bone adaption with in the presence of progressive DD, suggesting that bone adaption is occurring in response to the altered force distribution associated with DD, and that maladaptation could elevate the risk of fracture. Notably, the current clinical method of identifying patients at risk of fracture is to use an average measure of BMD for the entire vertebra. The lack of consideration of the spatial distribution of BMD may explain why the clinical method used at present does not adequately identify those at risk of fracture. The possible relationship among spatial distribution of BMD, DD, force distribution across the endplate, and vertebral strength suggests that characterizing the spatial distribution of BMD within a vertebra could add to the understanding of why some vertebra are more likely to fracture. This project sought to determine if an association exists between the spatial distribution of vertebral BMD and disc health in order to provide an improved perspective of the clinical sequelae of DD and to improve the ability of clinicians to identify those who would benefit most from intervention. This study found evidence that the distribution of bone in the vertebral body and EP depend on the health of the adjacent disc. The distribution of pressure in discs favors the anterior most portion of the disc in anteriorly flexed postures and the density in the anterior most portion of the EP appears to respond to this shift, suggesting that bone is adapting to loading patterns associated with certain postures more than others. This study also found association between reduced regional disc height and altered distribution of trabecular density which was positive in the nuclear region and negative in the annular region. In some cases there was a lack of association between disc height and density distribution that may indicate maladaptation and thus increased risk of fracture. This study, being cross-sectional could not identify whether the observed alterations in density and degeneration initiated in the vertebra or the disc. However, this study contributes to the understanding of the relationship between the distribution of vertebral density and the functional properties of the adjacent disc that may ultimately improve the clinician's ability to predict VFx. / 2017-06-21T00:00:00Z

In several cases, current therapies available to treat a large number of musculoskeletal system diseases are unsatisfactory as they provide only temporary or partial restoration of the damaged or degenerated site. In an attempt to maintain a high standard of life quality and minimise the economic losses due to the treatments of these frequently occurring ailments and subsequent lost working days, alternative therapies are being explored. Contrary to the current treatments, tissue engineering aims to regenerate the impaired tissue rather than repair and alleviate the symptoms; thus offering a definitive solution. The annulus fibrosus (AF) of the intervertebral disc (IVD) is a musculoskeletal system component frequently subjected to degeneration and rupture, characterised by predominance of anisotropically arranged collagen fibres. In the present thesis, electrospinning technology is used to fabricate polycaprolactone (PCL) scaffolds intended to replicate the anisotropic structure of the AF.

Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2010 / Bibliografia: f. 64-68. / A hérnia de disco intervertebral cervical é uma doença de caráter degenerativo, com quadro clínico diverso e sendo comum sua ocorrência. Ela ocorre quando o disco se desloca do seu local anatômico em direção a medula ou às raízes nervosas, causando assim / A herniated cervical intervertebral disc is a degenerative disease with a clinical diverse and they commonly occur. It occurs when the disc moves from one anatomical site into the spinal cord or nerve roots, thus causin mechanical deformation or local irr

Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2008 / Bibliografia: f. 54-61 / Patologias relacionadas à coluna vertebral representam um problema socioeconômico importante, e estão diretamente relacionadas com os hábitos de vida, sobretudo pela permanência na posição sentada de maneira incorreta. Há grande interesse em estudar a sob / Pathologies related to the spine represent a major socioeconomic problem, and are directly related to the habits of life, particularly for permanence in the sitting position, frequently kept in an inadequate manner. There is great interest in studying the

Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2012 / Bibliografia: f. 79-84 / A compreensão da biomecânica da coluna cervical e as alterações em níveis adjacentes a isões (artrodeses) é de grande importância para o entendimento do desenvolvimento do que passou a ser denominado "doença do nível adjacente". Levando-se em consideração / A thorough comprehension of the biornechanics of the cervical spine as welI as alterations in adjacent leveis and fusions (arthrodesis) is crucial to understanding the deveiopment of what is now referred to as "Adjaceni-Level Disease". Given that interver

abstract: Introduction. Intervertebral disc degeneration (DD) is one of the most common diagnoses in patients with neck pain and contributes to worldwide disability. Despite the advances in diagnostic imaging today, little is known about functional status of cervical DD. The purpose of this research was to 1) develop and validate an ovine model of cervical spine DD, 2) to quantify and compare the effect of disc lesions on dynamic spinal stiffness, and 3) study the effect of disc lesions on spinal accelerations and displacements during two types of spinal manipulative therapy (SMT). Methods. Fifteen sheep received surgically induced disc injury to the mid-cervical spine via scalpel wound a minimum of five months earlier and 15 sheep served as controls. All animals were biomechanically assessed at the level of the lesion using swept-sine mechanical loads from 0-20 Hz under load control to quantify dynamic dorsoventral (DV) spine stiffness (load/deformation, N/mm). The effect of disc lesion on stiffness was assessed using a one-factor repeated measures ANOVA comparing 32 mechanical excitation frequencies. Tri-axial accelerometers rigidly attached to adjacent vertebrae across the target level further evaluated the effect of disc lesion on spinal motion response during two types of SMTs. A 2x6x2 repeated measures ANOVA examined the effect of disc lesion and SMT force-time profile on spine motion response. Postmortem histological analysis graded specimens at the target site and comparison was made with descriptive statistics. Results. Annular disc tears were only observed in the disc lesion group and the mild degeneration identified was localized to the injured annular tissue that did not progress to affect other areas of the disc. No difference in overall DD grading was found among the groups. DV stiffness was significantly increased in the disc lesion group by approximately 34% at 31 of 32 frequencies examined (p<.05). SMTs resulted in decreased displacements in the disc lesion group (p<.05), and SMT type significantly influenced spinal accelerations for both the DV and axial planes. Conclusion. Disc lesions in the ovine cervical spine produce localized annular degenerative changes that increase the cervical spine dynamic stiffness and reduce its spinal motion response during manual examination and treatment that is further augmented by the force-time profile administered by the clinician. / Dissertation/Thesis / Doctoral Dissertation Kinesiology 2015