No description available.

No description available.

This thesis describes the development of artificial disc technology for the replacement of intervertebral discs in the human lumbar spine. The clinical problem is back pain. There may be a relationship between certain forms of back pain and disc degeneration. The mechanical properties of human intervertebral discs are examined in detail. The genetic basis of disc degeneration is presented. The hypothesis is that such degeneration leads to a loss of normal stiffness in the segments affected leading to abnormal mechanical behaviour which in turn leads to pain. The evidence for this is presented. The development of surgical solutions to relieve back pain, from fusion through first generation mechanical artificial discs to elastomeric designs, is traced. The author‘s personal contributions to this area of knowledge are set out. The appreciation of the requirement for a restoration of physiological stiffness is argued throughout, showing where fusion and first generation discs have not met the clinical aim of pain relief, because they have not restored physiological stiffness. The path to an elastomeric, viscoelastic, polyhydrocarbon, rubber solution in the form of the “Freedom“ disc has filled 17 years of the author‘s academic pursuits. It will be shown that this technology may represent a possible solution to the clinical problem. Failure is part of all new advancement and this too is presented, to show how that has influenced thinking, producing original ideas to overcome these failures. Providing lessons are learned from these failures then our patients in the future will benefit.

Abstract Musculoskeletal diseases, such as osteoarthritis (OA), lumbar disc degeneration (LDD) and osteoporosis (OP), are common complex disorders affected by both environmental and genetic factors. OA and LDD are degenerative diseases affecting joints and spine and Modic changes (MC) are a specific phenotype of LDD. OP is a disorder causing bone fragility. There are families with a history of early onset cartilage degradation, disc disorders and bone fragility as well as rare, more severe disorders with these traits as part of the phenotype. The aim of this study was to identify predisposing genetic factors in Finnish families with three different musculoskeletal phenotypes and to investigate the use of whole exome sequencing (WES) as a tool. Six families were studied here, three diagnosed with hip and knee OA, two with MC and one with primary OP. Using WES together with in silico and in vitro analyses we identified new candidate genes. In the two OA families we identified family specific variants, c.-127G>T in the 5’UTR of FIP1L1 and p.Arg210Gly in OLIG3. We observed expression of these genes in human bone and cartilage. Both FIP1L1 and OLIG3 participate in the regulation of transcription. Family specific variants were also found in both families with MC: p.Gln1611fs in HSPG2 and p.Glu553Lys in MAML1. HSPG2 encodes for an important structural protein in the disc and MAML1 is a transcription factor. The family with primary OP had previously been reported to carry a heterozygous COL1A2 deletion leading to nonsense-mediated mRNA decay. In the WES we identified an additional change that may contribute to the phenotype: p.Arg428* in ZNF528. We showed experimentally that the variant leads to expression of a truncated form of ZNF528 in the nucleus. ZNF528 binding sites are located near genes associated with bone phenotypes. We identified twelve potential target genes for ZNF528 that were differentially expressed in patients’ cells compared to controls. Altogether, we identified five new candidate genes for the studied phenotypes demonstrating that WES can be used as a tool in studying complex musculoskeletal phenotypes in families. One of the identified candidate genes, HSPG2, encodes a structural protein, whereas, OLIG3, FIP1L1, MAML1 and ZNF528, participate in the regulation of transcription supporting the importance of regulatory mechanisms in the pathogenesis of musculoskeletal diseases. / Tiivistelmä Tuki- ja liikuntaelinsairaudet, kuten nivelrikko, välilevyrappeuma ja osteoporoosi, ovat yleisiä, monitekijäisiä sairauksia. Nivelrikko ja välilevynrappeuma ovat eteneviä nivelten ja selkärangan sairauksia. Modic muutokset ovat välilevyn ja nikaman välisten päätelevyjen muutoksia. Osteoporoosi on luuta haurastuttava sairaus. Varhaisessa iässä ilmenevää ruston haurastumista, välilevyn sairauksia tai luun haurautta tavataan myös suvuittain esiintyvinä sairauksina tai vakavien harvinaisten sairauksien oireina. Tutkimuksen tarkoitus oli tunnistaa altistavia geneettisiä tekijöitä kolmelle tuki- ja liikuntaelimistön sairaudelle suomalaisissa perheissä käyttäen eksomisekvensointi-menetelmää. Aineisto koostui kuudesta perheestä: kolmessa oli diagnosoitu lonkan ja polven nivelrikko, kahdessa selän välilevyjen Modic muutoksia ja yhdessä primaarinen vaikea selän osteoporoosi. Tunnistimme uusia ehdokasgeenejä käyttäen eksomisekvensointi-menetelmää sekä in silico ja in vitro analyysejä. Kahdessa nivelrikkoperheessä tunnistimme perhekohtaiset variantit kahdessa geenissä: c.-127G>T variantin FIP1L1 geenin säätelyalueella ja p.Arg210Gly variantin OLIG3 geenissä. Osoitimme, että nämä traskription säätelyyn osallistuvat geenit ilmenevät ihmisen luu- ja rustokudoksessa. Perhekohtaiset variantit havaittiin myös perheissä, joilla oli todettu Modic muutoksia: p.Gln1611fs HSPG2 -geenissä ja p.Glu553Lys MAML1 -geenissä. HSPG2 koodaa välilevylle tärkeää rakenneproteiinia ja MAML1 on transkriptiota säätelevä tekijä. Primaarista osteoporoosia sairastavalla perheellä oli aiemmin havaittu heterotsygootti, geenituotteen hajottamiseen johtava deleetio, COL1A2 -geenissä. Eksomisekvensoinnlla havaitsimme mahdollisesti taudin ilmiasuun lisäksi vaikuttavan muutoksen ZNF528 -geenissä. Osoitimme kokeellisesti, että havaittu variantti johtaa lyhentyneen proteiinin tuottoon solussa. ZNF528 on transkriptiotekijä, jolle tunnistimme kaksitoista mahdollista kohdegeeniä ja havaitsimme että niiden tuotto oli muuttunut potilaiden soluissa kontrollisoluihin verrattuna. Tunnistimme viisi uutta ehdokasgeeniä kolmessa eri sairaudessa eksomisekvensointi-menetelmän avulla. Yksi tunnistetuista geeneistä, HSPG2, koodaa rakenneproteiinia, ja muut osallistuvat transkription säätelyyn. Tämä tukee käsitystä säätelytekijöiden tärkeydestä TULE sairauksien synnyssä.

This dissertation has two major parts; Analytical and Experimental. The analytical section contains a study using Finite Element Analysis of dynamic instrumentation to demonstrate stress reduction in adjacent level discs. The experimental section contains biomechanical testing of facet fusion allograft technique and finally a comparison between In Vivo and In Vitro intradiscal pressures to determine forces acting on Lumbar spine segment L4-L5. A comprehensive study of available data, technology and literature was done. Conventional fusion instrumentation is believed to accelerate the degeneration of adjacent discs due to the increased stresses caused by motion discontinuity. A three dimensional finite element model of the lumbar spine was obtained which simulated flexion and extension. Reduced stiffness and increased axial motion of dynamic posterior lumbar fusion instrumentation designs results in a ~10% cumulative stress reduction for each flexion cycle. The cumulative effect of this reduced amplitude and distribution of peak stresses in the adjacent disc may partially alleviate the problem of adjacent level disc degeneration. Traditionally a pedicle screw system has been used for fixation of the lumbar spine and this involves major surgery and recovery time. Facet fixation is a technique that has been used for stabilization of the lumbar spine. The cadaver segments were tested in axial rotation, combined flexion/extension and lateral bending. Implantation of the allograft dowel resulted in a significant increase in stiffness compared to control. Facet fusion allograft provides an effective minimally invasive method of treating debilitating pain caused by deteriorated facet joints by permanently fusing them. An In Vitro biomechanical study was conducted to determine the intradiscal pressure during spinal loading. The intradiscal pressures in flexion/extension, lateral bending and axial rotation was compared to In Vivo published data. There is no data that explains the actual forces acting on the spine during flexion, extension, lateral bending or axial rotation. The functional spinal units were tested in combined axial compression and flexion/extension, combined axial compression and lateral bending and combined axial compression and axial rotation using a nondestructive testing method. Overall, this study found a good correlation between In Vivo and In Vitro data. This can essentially be used to make physiological relation from experimental and analytical evaluations of the lumbar spine. It is important to know how much load needs to be controlled by an implant.

No description available.

Low back pain is a common cause of disability and work inability, often associated with intervertebral disc degeneration. The current understanding of disc degeneration is limited and none of the available treatments is entirely effective. The work described herein investigates potential strategies for the biological herapeutic restoration of disc degeneration. Firstly, an in vitro study to investigate the effects of BMP-7 on human discal cellular viability was performed. Cultured cells were treated with TNF-a or H202 to induce apoptosis, resulting in the down regulation of extracellular matrix proteins, decreased cell viability, morphological changes and activation of caspase-3; however, addition of BMP-7 alone prevented the observed effects, demonstrating the ability of BMP-7 to prevent apoptosis of human disc cells in vitro. Secondly, the differentiation potential of stem cells towards disc-like cells was studied. Rodent mesenchymal stem cells (rMSCs) were cultured alone or co-cultured with rat disc tissue. Differentiation potential of rMSCs was evaluated by mRNA and protein expression, cellular function and morphological studies. The co-culture conditions led to the expression of chondrocytic markers in rMSCs, whereas rMSCs cultured alone did not express the chondrocytic markers. Cellular contact between the co-cultured rMSCs and the discal tissue were observed. This study demonstrated that rMSCs can differentiate into functional disc-like cells in a tissue influenced co-culture environment. Finally, the survival and differentiation of CD34+ or CD34?? bone marrow (hBM) cells, in an intra-discal xenogeneic transplantation rat model was investigated. Human CD34+ or CD34?? cells were isolated, fluorescent-labelled and injected into rat coccygeal discs. The survival of transplanted cells was confirmed by fluorescent positive cells as well as a human nuclear specific marker. Interestingly, CD34?? cells survived until day 42 in the injected discs, and differentiated into cells ex:pressing a chondrocytic phenotype. In contrast, CD34+ cells could not be detected by day 21. This data suggests that transplanted hBM CD34?? cells, in contrast to CD34+ cells, were able to survive and differentiate within the intervertebral disc. Together, the results of these studies can both encourage and contribute to the basis of potential biological therapies in the restoration of intervertebral disc degeneration.

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

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

abstract: Intervertebral Disc Degeneration (IVDD) is a complex phenomenon characterizing the desiccation and structural compromise of the primary joint in the human spine. The intervertebral disc (IVD) serves to connect vertebral bodies, cushion shock, and allow for flexion and extension of the vertebral column. Often presenting in the 4th or 5th decades of life as low back pain, this disease was originally believed to be the result of natural “wear and tear” coupled with repetitive mechanical insult, and as such most studies focus on patients between 40 and 50 years of age. Research over the past two decades, however, has demonstrated that environmental factors have only a modest effect on disc degeneration, with genetic influences playing a much more substantial role. Extensive research has focused on this process, though definitive risk factors and a clear pathophysiology have proven elusive. The aim of this study was to assemble a cohort of patients exhibiting definitive signs of degeneration who were well below the average age of presentation, with minimal or no exposure to suspected environmental risk factors and to conduct a targeted genome analysis in an attempt to elucidate a common genetic component. Through whole genome sequencing and analysis, the results corroborated findings in a previous study, as well as demonstrated a potential connection and influence between mutations found in IVD structural or functional genes, and the provocation of IVDD. Though the sample size was limited in scale and age, these findings suggest that further IVDD research into the association of variants in collagen, aggrecan and the insulin-like growth factor receptor genes of young patients with an early presentation of disc degeneration and minimal exposure to suspected risk factors is merited. / Dissertation/Thesis / Masters Thesis Biology 2016