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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.

Aggregating proteoglycans (PG) bearing chondroitin sulfate (CS) side chains are well-known inhibitors of neural plasticity and associate with hyaluronan and tenascin-R to form a complex of extracellular matrix (ECM) in the central nervous system (CNS). Little is known about whether proteolytic cleavage of the core protein affects neural plasticity. Several members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family of metalloproteinases are glutamyl-endopeptidases that cleave aggregating PGs. Our initial studies determined that neural cultures secrete a brevican-containing matrix, and that these neural cultures also produced ADAMTS4, a protease that cleaves brevican. Furthermore, this brevican-containing matrix in astrocytes could be modulated by treatment with transforming growth factor beta (TGFbeta) through the inhibition of the activity of the ADAMTSs.Once it was established that neural cultures produce a brevican-rich matrix, we s ought to utilize this matrix to determine whether cleavage of aggregating PGs, especially brevican, by the ADAMTSs influences neurite outgrowth in cultured neurons. Transfection of rat neurons with ADAMTS4 cDNA induced longer neurites, and interestingly, this effect proved to be independent of the proteolytic action of the ADAMTSs. Addition of recombinant ADAMTS4 or ADAMTS5 protein to immature neuronal cultures similarly enhanced neurite extension, an action dependent on the activation of extracellular signal-related kinase (ERK)1/2 (MAP kinase 42/44), resulting in the first evidence that ADAMTSs may induce intracellular signaling events. Studies of dendritic spine morphology and levels of synaptic proteins in response to ADAMTS4 treatment were also undertaken. Neuronal cultures treated with ADAMTS4 showed increased length of dendritic spines and increased percent of immature spines detected. A concurrent decrease in post-synaptic protein staining was detected on the neurites of yo ung neurons overexpressing ADAMTS4 or expressing proteolytically-inactive mutant ADAMTS4 protein. Thus, ADAMTS4 may promote plasticity in neurons in vitro by preventing the formation, maturation, and/or stabilization of synapses. Overall, these experiments provide evidence that implicate the ADAMTSs as mediators of neural plasticity, and while primarily known only as proteases, these studies demonstrate that the ADAMTSs exert actions distinct from these proteolytic properties that require the induction of intracellular signaling events.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

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1. INTRODUCTION Injuries of the lower cervical spine can be among the most devastating injuries of the musculoskeletal system because of the increased risk of the injury to the spinal cord, and also because they so often occur to the younger members of the population (Jones A.A.M. et al., 2003; Sekhon H.S.L. et al., 2001; Ball P.A., 2001). The cervical spine is the most vulnerable spinal segment (Sekhon H.S.L. et al., 2001). The mechanism of cervical spine trauma is defined by the direction and magnitude of the forces that have been applied externally to the head and neck complex resulting in injury (Allen B.L.Jr., 1982). Common injury vectors include flexion, compression, rotation and extension (Allen B.L.Jr., 1982). The pattern of injury is related not only to the external applied force, but also to the initial position or posture of the head and neck at the time of injury (Allen B.L.Jr., 1982). One pattern of these injuries of the lower cervical spine is a facet dislocations (Allen B.L.Jr., 1982). The facet dislocation of the cervical spine result from a hyperflexion injury of the neck (Allen B.L.Jr., 1982). These injuries are characterized radiographically by anterolisthesis of one cervical vertebrae over the other and include the slide anteriorly of the inferior facet of the upper dislocated vertebra over the superior facet of the vertebra below (Allen B.L.Jr., 1982; Razack N. et al., 2000). The facet dislocations of the lower cervical spine represent from 4% to 50% of... [to full text]

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XXI amžiuje skausmas yra rimta problema. Vis daugiau jaunų žmonių skundžiasi nugaros skausmais. Nugaros skausmai dėl mažo fizinio aktyvumo, netaisyklingos laikysenos yra viena labiausiai paplitusių ligų. Iškėlėm hipotezę, kad pratimai vandenyje pagerins vaikų stuburo paslankumą ir laikyseną. Tyrimas buvo atliktas LKKA baseine. Tyrime dalyvavo 12 vaikų, iš jų 10 berniukų ir 2 mergaitės. Tiriamųjų amžiaus vidurkis buvo 10,88 ± 2,10 metų, svorio - 46,2 ± 1,54 kg, ūgio vidurkis 156,9 ± 2,04 cm. Tiriamiesiems 8 mėnesius 2 kartus per savaitę po 1 valandą buvo taikoma KT vandenyje. KT pagrindą sudarė tempimo, atsipalaidavimo, liemens raumenų pratimai bei pratimai laikysenai gerinti. Buvo vertinama tiriamųjų laikysena, stuburo paslankumas, liemens raumenų statinė ištvermė bei gyvensenos ypatumai. Visi minėti rodikliai registruoti 3 kartus ( KT pradžioje, KT viduryje ir KT pabaigoje). Darbo tikslas – nustatyti vaikų, kuriems buvo taikyta KT vandenyje, stuburo paslankumo, raumenų ištvermės ir laikysenos pokyčius. Iškelti uždaviniai: nustatyti ir palyginti vaikų liemens raumenų ištvermę, stuburo paslankumą, laikyseną prieš ir po kineziterapijos vandenyje, bei nustatyti ir įvertinti vaikų gyvensenos ypatumus. Tyrimo rezultatai parodė, kad pratimai vandenyje patikimai (p<0,05) padidino liemens raumenų (pilvo, nugaros, kairės bei dešinės pusės) ištvermę, stuburo paslankumą, pagerino pečių, liemens ir pilvo laikyseną. Taip pat nustatėme, jog vaikų fizinis aktyvumas nėra pakankamas, nes... [toliau žr. visą tekstą] / Pain is a very serious problem in the 21st century. More and more young people complain of backache. Because of reducing amount of physical activities, incorrect posture, backache is one of the most common diseases. A hipothesy is that exercises in water will improve spine flexibility and children posture will improve as well. A research was made in LKKA swimming pool. 12 children – 10 boys and 2 girls – took part in this research. The average age of those who were researched was 10,88 ± 2,10 years, the average weight 46,2 ± 1,54 kg and height 156,9 ± 2,04 cm. They were in physiotherapy in water for 8 months 1 hour twise a week. Aquatic therapy consisted of posture, stretch, relaxing exercises and exercises for waist muscles. Posture, spine flexibility, waist muscles static endurance and particularities of lifestyle of the researched people was evaluated. All indicators are mentioned three times (in the beginning, in the middle and at the end of physiotherapy in water). The purpose is to find spine flexibility, muscle endurance and posture changes of kids who were in physiotherapy in water. Targets: to measure and assess children‘s trunk muscle endurance, back mobility and posture before and after aquatic therapy; to assess the lifestyle of the participants. The research results showed that exercises in the water increased waist muscles (stomach, back, left and right side) endurance, spine flexibility, improved shoulder, waist and stomach posture. Moreover, we realised that... [to full text]

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