This research examined the role of the cartilaginous end-plate (CEP) in ageing and degeneration of the human intervertebral disc (IVD). The matrix component affected primarily during degeneration of the IVD is proteoglycan (PG) (Pearce et al., 1987). The CEP, a hyaline cartilage found between the nucleus pulposus (NP) and the anulus fibrosus (AF) and the vertebral body, has been proposed as the source of the PG of the AF and NP. This study was undertaken to: 1) assess the similarity of CEP PG to PG from articular cartilage and IVD, (2) compare the CEP PG from healthy young discs with those from older degenerate discs (3) distinguish the changes in CEP PG due to ageing from those due to degeneration. The combined effects of ageing and degeneration were studied using end-plates from three healthy young spines and three post-mature spines; those to degeneration alone by comparison of two healthy with one degenerate disc in each of three spines. Altogether 86 CEP from 10 lumbar spines were examined. The CEP PG were prepared from 4M guanidinium chloride tissue extracts by density gradient ultracentrifugation under associative conditions. PG were separated into high and low molecular weight (M) components by Sepharose CL-2B chromatography. The PG and the high M and low M fractions were analysed for hexose (hex) and hexuronate (hexA) as measures of keratan sulphate and chondroitin sulphate, respectively. Also, the two fractions were analysed by composite agarose-polyacrylamide gel electrophoresis. The CEP PG resembled the IVD PG more closely than those of articular cartilage PG: the fraction excluded from Sepharose CL-2B was low, the hex/hexA ratio was high, and five electrophoretically distinct subspecies were seen. With degeneration, several properties of the CEP PG altered irrespective of age: the extractable .total proteoglycan fell, the ratio hex/hexA rose and number of electrophoretically distinct PG subspecies declined. With age, the sizes of the high M and low M fractions fell and the electrophoretic mobilities of the subspecies changed. These results suggested that degeneration involves both a conversion of aggregating to non-aggregating PG and the preferential biosynthesis of a keratan sulphate-rich over a chondroitin sulphate-rich PG. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Low back pain is also a vast socioeconomic issue which costing American taxpayers more than $50 billion yearly. Estimates state that up to 75% of low back pain is caused by lumbar degenerative disc disease. The nucleus seems plays a critical role in pain related to disc degeneration; it is the starting point of the degenerative cascade. All of these factors make it the focus of novel treatment options. The goal of this study is to create idealized models to determine the shape of nuclear implant best suited to resist the standard shear and torsional stresses that are generated in the lumbar spine. Thus, five nuclear intervertebral disc prosthetics (Implant designs 1-5) were designed. Shear testing was conducted using an Instron, and torsion testing was conducted using the LabVIEW in conjunction with a torsional pneumatic cylinder. Implant design 4 was determined to be the implant design best suited to resist shear stresses. Implant design 3 was determined to be the implant design best suited to allow normal torsion of the spine. Therefore, it was determined that a combination of implant design 3 and implant design 4 might be optimal in terms of shear, torsion, wear, and stability.

published_or_final_version / abstract / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

El documento digital no refiere asesor / Demuestra que la técnica quirúrgica de hemilaminectomía permite un adecuado abordaje para la exploración del canal medular y para la descompresión medular, logrando la remisión de los signos clínicos. Todos los perros que llegaron a la Clínica de Animales Menores de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos (FMV-UNMSM) con sospecha de presentar una compresión medular y diagnosticados con una hernia discal por radiología y tomografía durante un periodo de 2 años (Junio del 2005 – Julio del 2007) fueron incluidos en el estudio. La tomografía confirmó la compresión medular por una hernia discal hansen tipo I en 12 animales en la región toracolumbar (T11-L2). Estos animales fueron sometidos a una Hemilaminectomía en la Sala de Cirugía “Freddy Viera Raborg” de la Clínica de Animales Menores en la FMV - UNMSM. Dos animales fueron retirados del resultado quirúrgico, al primero por no regresar a los controles y el segundo por fallecer 2 días después de la cirugía presumiblemente debido a una mielomalacia hemorrágica ascendente. La técnica quirúrgica de hemilaminectomía permitió el adecuado abordaje al canal medular y el retiro de la masa compresora en el 100% de animales (12/12). El 90% (9/10) animales mostraron la remisión de los signos clínicos y retornaron a la ambulación en un promedio de 19.3 días teniendo como rangos 2 y 46 días. En 2 casos fue necesaria una doble hemilaminectomía unilateral. Estos resultados confirman el que la técnica de hemilaminectomía es eficiente para la exploración del canal medular y el tratamiento quirúrgico de la hernia discal hansen1. / Tesis

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Resumo: A desidratação do núcleo pulposo que, juntamente com o anulus fibroso, compõe o disco intervertebral, participa do processo de degeneração da coluna vertebral. Torna-se importante entender como este processo de desidratação e a consequente alteração das propriedades mecânicas influenciam na biomecânica dessa articulação. O principal objetivo deste estudo é analisar a influência da desidratação no coeficiente de amortecimento viscoso e como esta variação pode alterar o comportamento mecânico do disco intervertebral lombar. Este estudo é composto de duas etapas: na primeira, o coeficiente de amortecimento viscoso foi obtido experimentalmente de unidades funcionais de colunas lombares suínas antes e após o processo de desidratação das mesmas; na segunda, foi simulado em modelo computacional a resposta harmônica, utilizando-se dados da literatura e do coeficiente de amortecimento viscoso, analisando as diferenças entre uma simulação com o disco intervertebral hidratado e desidratado. O coeficiente de amortecimento viscoso hidratado (4,7) e desidratado (2,7) apresentou diferença estatisticamente significante (p<0,001). Na simulação computacional podese evidenciar uma menor influência da variação do coeficiente de amortecimento viscoso quando analisado de forma isolada do que quando analisado em conjunto com variações nos dados referentes à rigidez, principalmente nas frequências de ressonância e nas amplitudes de pressão intradiscal e deformação do disco intervertebral. Concluiu-se que discos intervertebrais desidratados respondem de forma diferente à vibração, o que pode contribuir para os processos lesivos da coluna vertebral / Abstract: The dehydration of the nucleus pulposus which, with the anulus fibrosus, composes the intervertebral disc, participates in the process of degeneration of the spine. It is important to understand how this process and the consequent alteration of dehydration of the mechanical properties influence the biomechanics of this joint. The aim of this study is to analyze the influence of dehydration in the viscous damping coefficient and how this variation can change the mechanical behavior of lumbar intervertebral disc. This study consists of two stages: first, the viscous damping coefficient was obtained experimentally in functional units of porcine lumbar spine before and after the dehydration process of them; second, an harmonic response was simulated in a computer model, using literature data and the viscous damping coefficient, analyzing the differences between a simulation with the hydrated and dehydrated intervertebral disc. The hydrated (4.7) and dehydrated (2.7) viscous damping coefficient showed a statistically significant difference (p <0.001). In the computer simulation, a lower influence of variation of the viscous damping coefficient can be detected when analyzed separately than when analyzed together with variation on stiffness data, especially in the resonance frequencies and in the amplitudes of the intradiscal pressure and deformation of the intervertebral disc. We conclude that dehydrated intervertebral discs respond differently to vibration, what can contribute to the damaging processes of the spine / Orientador: José Elias Tomazini / Coorientador: Mauro Hugo Mathias / Banca: Fernando de Azevedo Silva / Banca: José Geraldo Trani Brandão / Banca: Valdeci Donizete Gonçalves / Banca: Magda Francisca Gonçalves Rocha / Doutor

The pathogenesis of low back pain is complex but likely involves the intervertebral disc (Nachemson, 1976). Direct evidence for its importance is lacking because an accurate in vivo method of imaging the lumbar intervertebral disc has not been established. The objective of this research was to develop classifications of gross morphologic appearance and magnetic resonance image (MRI) of the disc that describe the changes associated with aging and degeneration, thereby permitting interpretation of the MRI in terms of gross morphology and allowing correlation of morphologic, chemical, mechanical, radiologic and epidemiologic data with a standard reference of disc aging and degeneration. The classifications were developed on the basis of literature review, detailed examination of 55 discs and expert advice. Two sets of three observers, one for the morphologic classification and one for the MRI classification evaluated 68 life size randomized duplicates of discs making detailed observations about overall category and 17 regional morphologic parameters and 11 regional MRI parameters. The data was tested to demonstrate the validity of the classifications using established criteria (Tugwell & Bombardier, 1982; Guyatt 4 Kirschner, 1985; Feinstein, 1985). The consistency with which the classifications could be applied was evaluated by calculating weighted kappa, a statistical test of agreement that corrects for agreement by chance; the ability of the classifications to distinguish stages in the process of ageing and degeneration by stepwise discriminant analysis; their conformity with other measures by comparisons within and between classifications and, comparisons with histologic and chemical data. The degree of agreement for all six intra-observer pairs was 'almost perfect' (weighted kappa > 0.80); for 5 interobserver pairs 'substantial' (weighted kappa > 0.60) and for one MRI interobserver pair 'moderate' (weighted kappa > 0.50). This represented a satisfactory level of agreement and indicated the classifications could be applied consistently (Feinstein, 1981). The linear regression model developed by stepwise discriminant analysis clearly demonstrated the ability of the classifications to distinguish distinct stages in disc aging and degeneration. Wilk's lambda, a likelihood ratio statistic reflecting discriminatory function, approached zero in both the morphologic (0.0408) and MRI (0.0H80) classifications. In both models, parameters pertaining to the nucleus pulposus of the disc accounted for the majority of the variance (morphologic partial R² 0.8598 and MRI partial R² 0.8811) suggesting nuclear parameters are the most important in distinguishing overall category. The correlation table generated by principal component analysis demonstrated that the categories assigned to regional parameters correlated significantly (p > 0.0001) with each other and with the overall category. From the linear combinations of parameters (principal components) generated the weighting of the nucleus pulposus behaved independently attesting to its importance. Comparisons of the morphologic and MRI classifications yielded high indices of trend (Pearson correlation coefficient of 0.81) and concordance (kappa of 0.62). Trends in the histologic and chemical data were consistent with the classifications but could not be evaluated statistically because only 15 specimens were studied. This research suggests that the classifications are valid and will form a basis for the interpretation of MRI. Preliminary evidence suggested MRI is sensitive to early changes in extracellular matrix composition not apparent in gross morphology. / Medicine, Faculty of / Graduate

As alterações de sinal no osso subcondral dos corpos vertebrais foram descritas primeiramente por Modic, correlacionando o espectro das alterações da medula óssea no corpo vertebral relacionadas a discopatias degenerativas. O Modic tipo I representa a alteração de sinal do tipo edema, já o Modic II representa a alteração de sinal com padrão de lipossubstituição e o Modic III representa alteração de sinal relacionada a esclerose óssea. O objetivo primário deste estudo foi avaliar se há alteração na detecção dos padrões da classificação Modic na coluna lombar comparando a técnica Dixon com o protocolo tradicional. Como objetivo secundário avaliamos a correlação intra-observador e interobservador. O estudo foi realizado de forma retrospectiva com a inclusão de pacientes cujas ressonâncias magnéticas (RM) foram realizadas na Central de Diagnóstico Ribeirão Preto (CEDIRP). Dois médicos radiologistas de forma independente classificaram as alterações do tipo Modic permitindo uma avaliação interobservador e um dos radiologistas realizou uma segunda análise dos exames possibilitando uma avaliação intra-observador. Os resultados evidenciaram que a técnica Dixon apresentou superioridade na detecção do Modic I em todas as análises e também apresentou médias mais altas da espessura das alterações no osso subcondral. Houve correlações intra-observador moderadas e substanciais no protocolo tradicional e substanciais a altas com a técnica Dixon. A correlação interobservador demonstrou uma correlação moderada na avaliação deste tipo de alteração nos platôs superior e inferior de L3 e correlação inversa e não significativa para a o platô superior de L5 utilizando o protocolo tradicional. Já a correlação interobservador com a técnica Dixon evidenciou concordância perfeita entre os observadores na avaliação de tipo de alteração de sinal no osso subcondral do platô inferior de L1, correlação inversa para o platô inferior de L3 e superior de L4, correlação substancial entre o platô inferior de L2, platô inferior de L5 e superior de L5. Concluímos que a técnica Dixon apresentou superioridade na detecção do Modic I em relação ao protocolo tradicional, assim como permitiu detectar médias mais altas da espessura das alterações no osso subcondral. Também conclui-se que houve boa reprodutibilidade intra-observador e correlação interobservador variável entre os platôs vertebrais analisados / Signal changes in the subchondral bone of the vertebral bodies were first described by Modic, correlating the spectrum of bone marrow changes in the vertebral body to degenerative disc diseases. Modic type I represents the change of edema type signal, while Modic II represents the change of signal with liposubstitution pattern and Modic III represents signal change related to bone sclerosis. The main objective of this study was to evaluate if there is difference in the detection of Modic classification in the lumbar spine comparing the Dixon technique with the traditional protocol. We evaluated the intraobserver and interobserver correlation as a secondary objective. The study was performed retrospectively, including patients whose magnetic resonance imaging (MRI) was performed at the Ribeirão Preto Diagnostic Center (CEDIRP). Two radiologist physicians independently classified the Modic type endplate changes allowing an interobserver evaluation and one of the radiologists performed a second analysis of the exams making possible an intraobserver evaluation. The results showed that the Dixon technique presented superiority in the detection of Modic I in all the analyzes and also presented higher averages of the thickness of the alterations in the subchondral bone. There were moderate and substantial intraobserver correlations in the traditional protocol and substantial to high Dixon technique. The interobserver correlation was moderate in the evaluation of this type of alteration for the upper and lower plateau of L3 and inverse and nonsignificant for the upper plateau of L5 using the traditional protocol. On the other hand, the interobserver correlation with the Dixon technique showed perfect agreement among the observers in the evaluation of type of signal change in the subchondral bone of the lower plateau of L1, an inverse correlation for the lower plateau of L3 and higher of L4, a substantial correlation between the lower plateau of L2, lower of L5 and higher of L5. We conclude that the Dixon technique presented superiority in the detection of Modic I compared with the traditional protocol, as well as allowed the detection higher averages of the thickness of alterations in the subchondral bone. It was also concluded that there was good intraobserver reproducibility and a variable interobserver correlation between the vertebral plateaus analyzed

No description available.

Low back pain is a costly financial and loss of productivity societal issue. Although its aetiology is unclear, it has been associated with the intervertebral disc and its degeneration which has been thought to be caused in part by poor nutrition. In this thesis the caudal disc of skeletally mature equines is utilised as an animal model. Techniques such as x-ray, light imaging, histology and magnetic resonance imaging were employed to investigate the vascular and structural anatomy of the disc and its surroundings and the uptake of tracers within the disc tissue. A detailed study of the anatomy revealed similarities with the human disc. The equine disc consists of two distinct structural areas; a nucleus and annulus. The surrounding vascularisation is similar; a main anteriorly positioned artery, the median caudal artery splits and encircles the centre of the vertebral body providing nutrition to the vertebral body. Smaller vessels anastomose over the surface of the vertebral body. Within the vertebral body the vessels end in capillary terminations at the edge of the vertebral cartilage endplate. As in humans these terminations were seen to vary along the endplate with shape and density; the capillaries are densest and larger in the area next to the nucleus. The cartilage endplate itself was found to have a variable width; of between 0.16 mm and 0.33 mm being widest at the nucleus. The annulus was seen to consist of lamellar rings which had high collagen content. A marked difference between equines and humans found was the number and width of lamellae present; equines were found to have on average 5 lamellae with a width range of 140 10 1110 microns. The shape of the discs was also found to be different with equines having almost circular coccygeal discs which have a concave superior and inferior surface. The nucleus of the disc, unlike current literature was found to have local order. An important contribution to knowledge which this thesis has made is data collected on diffusion time and partition coefficient on many regions within the disc. It was found that to reach equilibrium it took up to 22 hours in the outer anterior annulus but only 5 ½ hours in the central nucleus. Diffusion was found to be fastest with the neutral ring-shaped molecule Gadovist and slowest in the positive ion, manganese. Partition coefficients between the tracers were also found to vary. The highest partition coefficient was 6 in the central nucleus with manganese and the lowest was 0.5 with Magnevist at 0.5 in the nucleus area. This information will be useful in aiding drug delivery clinically and performing contrast enhanced imaging for pathology detection.