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Neck pain and injuries remain prevalent in many occupational categories. Risk factors include non-neutral neck postures and head loads. Most ergonomic tools do not account for the changes associated with these risk factors, or the effects that head position and load can have on the upper extremities. The purpose of this study was to investigate the effects of different neck postures and head loads on cervical discomfort and upper extremity functional integrity. Participants maintained flexed, extended, protracted, and neutral neck postures for a total of 4 minutes each. These trials were done both with and without a 3.68 kg head load. After each trial, measures of cervical discomfort, changes in hand sensation, hand and pinch grip strength, and holding forces were recorded. Cervical discomfort was found to increase in non-neutral postures and with the addition of a head load. Extension resulted in the greatest levels of discomfort, followed by flexion and protraction, with similar levels of discomfort, and neutral, which caused the least discomfort. Sternocleidomastoid activity increased in a loaded, non-neutral posture compared to an unloaded, neutral posture. These data could be implemented into current ergonomic tools to more comprehensively assess task demands and reduce the risk of injury. / Thesis / Master of Science in Kinesiology

Symptomatic spinal disorders affect a large proportion of the population and are associated with substantial morbidity, social burden, and economic impact. Spine surgery interventions can provide excellent results in carefully selected patients whose symptoms fail to improve with non-operative management, but an evidence-based approach is paramount to optimize outcomes and rigorous standards of health research methodology are critical to avoid misleading conclusions. This thesis aimed to investigate and apply modern innovations in health research methodology to the field of spine surgery. It consists of seven chapters divided between three sections: randomized controlled trials, observational studies, and systematic reviews and meta-analyses. By applying the findings of each chapter, clinicians, researchers, and other evidence users can advance the credibility of future research and enhance the care of patients with spinal disorders. / Thesis / Doctor of Philosophy (PhD)

Диссертационное исследование посвящено определению эффективности разработанной методики формирования нейтрального положения позвоночника в фитнесе. Результаты исследования подтвердили выдвинутую гипотезу о том, что тренировка абдоминальных мышц при нейтральном положении позвоночника наиболее эффективна и безопасна, чем использование в тренировочном процессе классических упражнений для пресса. / The dissertation research is devoted to determining the effectiveness of the developed method of forming the neutral position of the spine in fitness. The results of the study confirmed the hypothesis that training the abdominal muscles in a neutral position of the spine is more effective and safer than using classical exercises for the press in the training process.

Hydropower plays an important role in the Swedish power system and is a valuable renewable energy source with great ability for regulation. It is, therefore, crucial to plan and optimize hydropower in a way that is effective. In this project, the Skellefte River is modeled with the software Spine. The focus is on applying a piece-wise linear function to describe the electricity production, instead of a simpler linear one, and optimizing the profit. The results of the optimization indicate that the piece-wise linear function gives accurate values on the electricity production. This work has also further contributed to the development of Spine. / Vattenkraft spelar en viktig roll i det svenska elsystemet och är en värdefull förnybar energikälla med stor regleringsförmåga. Det är därför avgörande att planera och optimera vattenkraft på ett effektivt sätt. I detta projekt modelleras Skellefteälven med programvaran Spine. Fokus ligger på att tillämpa en styckvis linjär funktion för att beskriva elproduktionen istället för att använda en enklare linjär funktion. Modellen optimeras efter pris. Resultaten av optimeringen indikerar att den styckvis linjära funktionen ger korrekta värden på elproduktionen. Detta arbete har också bidragit till den fortsatta utvecklingen av Spine. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

Vertebral fractures affect at least 12-20% of men and women over the age of 50, and the risk of fracture increases exponentially with age. Despite their high prevalence, the failure mechanisms leading to these fractures are not well understood. For example, clinical observations of fractured vertebra often note that one or both vertebral endplates have collapsed, but the precise involvement of the endplates in the initiation and progression of failure has not yet been defined. The mechanisms of failure may also relate to spatial variations in the density and microstructure of the porous trabecular bone within the vertebra as well as to the health of the adjacent intervertebral discs (IVDs) which transfer loads directly to the vertebral endplates. Delineating the contributions of these factors would shed light on the etiology of vertebral fractures and would aid in development of clinically feasible, patient-specific finite element (FE) models of the vertebra. These models are built from a patient's quantitative computed tomography (QCT) scan and have shown tremendous promise for accurate, patient-specific estimates of bone strength and fracture risk. Further validation studies are required to assess the impact of the choices of material properties and boundary conditions, as a prerequisite for broad implementation of these FE models in clinical care. The overall goal of this work was to define the failure processes involved in vertebral fractures and to evaluate the accuracy of patient-specific FE models in simulating these processes. Mechanical testing of human spine segments, in conjunction with micro-computed tomography, enabled the assessment of deformation at the vertebral endplate and deformation throughout the entire bone, as the vertebra was loaded to failure under both axial compression and anterior flexion. These data were compared against predictions of vertebral deformation obtained from QCT-based FE models. The impact of the choice of boundary conditions was specifically examined by comparing the accuracy of the FE predictions between models that simulated applied loads based on measured distributions of pressure within IVDs and models that used highly idealized boundary conditions. The results of these studies demonstrated that sudden and non-recoverable endplate deflection is a defining feature of biomechanical failure of the vertebra, for both compression and flexion loading. The locations of endplate collapse as vertebral failure progressed were associated with the porosity of the endplate and the microstructure of the underlying trabecular bone. FE analyses incorporating the experimentally observed endplate deflections as boundary conditions provided more accurate predictions of displacements throughout the rest of the vertebra when compared to FE models with highly idealized boundary conditions. Under anterior flexion, the use of boundary conditions informed by measurements of IVD pressure mitigated, but did not eliminate, the inaccuracy of the idealized boundary conditions. No further improvement in accuracy was found when using boundary conditions based on pressure measurements corresponding only to IVDs whose level of degeneration matched that observed in the IVDs adjacent to the vertebra being modeled. Overall, the accuracy of the FE predictions of vertebral deformation was only moderate, particularly near the locations of endplate collapse. The outcomes of this work indicate that the vertebral endplate is principally involved in vertebral fractures and that current methods for QCT-based FE models do not adequately capture this failure mechanism. These outcomes provide a biomechanical rationale for clinical diagnoses of vertebral fracture based on endplate collapse. These outcomes also emphasize that future studies of patient-specific FE models should incorporate physiologically relevant loading conditions and also material properties that more accurately represent the vertebral endplate in order to obtain higher fidelity predictions of vertebral failure.

Le rôle de l’inflammation dans la discopathie dégénérative a pu être étudié dans certains modèles animaux, de tissus post-mortem ou parfois dans des tissus chirurgicaux mais ce phénomène reste encore mal compris. La dégénérescence des disques intervertébraux peuvent être à l’origine de diverses pathologies rachidiennes telles que la hernie discale, la radiculopathie et la myélopathie. Le disque subit un déséquilibre homéostasique, une néoinnervation et une néovascularisation laissant pénétrer les cellules immunitaires au sein du disque. Nous avons analysé 78 échantillons de plasma de patients atteints de pathologie du rachis ayant eu recours à la chirurgie. Les patients ont été stratifié en quatre groupes selon la présence ou l’abscence de myélopathie, hernie discale, radiculopathie, spondylolisthésis, lésions nerveuses et canal étroit. Nous avons identifié un profil de biomarqueurs plasmatiques propre à chacun des groupes. Un profil pro-inflammatoire (augmentation de la protéine C-ractive (CRP), du facteur de nécrose tumorale (TNFα)) semble s’apparié aux patients souffrant de myélopathie, avec une augmentation significative de neurofilament à chaine légère (NfL), confirmant une atteinte de la moelle épinière et une dégradation axonale. Les patients atteints de radiculopathie, ont de faibles niveaux de cytokines pro-inflammatoires. Les patients souffrant de spondylolisthésis semblent être caractérisés par l’augmentation de la chimiokine 22 à motif CC (CCL22) et de la molécule soluble d’adhésion intercellulaire (sICAM-1). La concentration en adiponectine est diminuée chez tous les patients. Des niveaux élevés des biomarqueurs de CD40-ligand soluble (sCD40L), de lipocalin-2 (LCN2) et du sérum amyloïde A (SAA) étaient associés à la dégénérescence des disques intervertébraux. / The role of inflammation in degenerative disc disease has been studied in animal models, in post-mortem tissue and surgical tissue, but the phenomenon remains poorly understood. Degeneration of the intervertebral discs contributes to various spinal pathologies such as disc herniation, radiculopathy, and myelopathy. The disc undergoes homeostatic imbalance, neoinnervation, and neovascularization, allowing immune cells to penetrate the disc tissue. We analyzed blood samples from patients with spinal pathology who had undergone surgery. We stratified patients according to their clinical criteria, and measured inflammatory, antiinflammatory, and trophic biomarkers in samples and compared them with healthy donor samples. We develop a plasma biomarker profile specific to subgroups of patients. A pro-inflammatory profile (increased CRP, TNFα) appears to be associated with patients suffering from myelopathy, with a significant increase in NfL, confirming damage to the spinal cord and axonal degradation compared with other patients and healthy donors. Patients with radiculopathy had low levels of pro-inflammatory cytokines. Patients suffering from spondylolisthesis seem to be characterized by an increase in CCL22 and sICAM-1, which may allow macrophages to penetrate the damaged disc. Adiponectin concentration was lower in all patient subgroups compared to healthy donors. The elevated levels of the biomarkers sCD40L, LCN2 and SAA, were linked to intervertebral degeneration.

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