Title: Bone density in people after spinal cord injury Objective: The purpose of this paper is to determine the levels of bone mineral density in people following a spinal cord injury. The levels are measured using a DXA device and the results are subsequently evaluated. Methods: The thesis is composed of eight independent case studies. A non-standardized 14 open and closed question survey was used for quantifying purposes. Answering the questions was a necessary prerequisite for participation in the survey. The measured results of bone density and body composition were used for data analysis, together with the survey, in comparison with other studies. Results: Eight probands (four women and four men) participated in the research. Based on the obtained data, we can state that all probands (n=8) record a decrease in bone mineral density to the level of Osteopenia. Better bone mineral density measurements have not been confirmed in individuals with lower spinal cord lesions. Probands who regularly engaged in sports and daily training before spinal injuries have better results in densitometric measurements. Furthermore, it can be confirmed that probands with a past compression fracture have worse measurement results than probands without a past fracture. However, due to the low number of measured...

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Dual energy X-ray absorptiometry (DXA) has been well established in both clinical and research settings for measurement of bone mineral density (BMD), and is becoming more widely utilized for assessment of body composition. Reliability and validity are essential factors in both applications of this technique; however, neither have been confirmed for the QDR-4500A DXA at Virginia Tech. Therefore, measurements of the whole body (WB), lumbar spine (LS), total proximal femur (TPF) and total forearm (TF) were made in a group of young-adult males and females at two time-points, 5-7 days apart. Significant differences were not found in BMD (g/cm2) at these body sites with repeated measurements by DXA. Furthermore, measures of percent body fat (%BF), lean body mass (LBM), and fat mass (FM) by DXA were reliable. Validity of %BF by DXA was assessed from comparison to single-frequency bioelectrical impedance analysis (BIA). Significant differences were not found in measures of %BF by DXA and BIA. A second study investigated the reliability and validity of the QDR-4500A DXA in measurements of distal tibia (DT) BMD. Significant differences were not found between repeated measurements. Validity was established by a significant correlation between WB BMD and DT BMD. A third study examined the influence of navel jewelry on the accuracy of LS DXA measurements. Repeated measurements with a spine phantom revealed that both a navel ring and a barbell produced significantly greater measures of LS BMD compared to the spine phantom alone. Manual correction of navel jewelry did not eliminate BMD inaccuracies. Data from these studies confirmed that the QDR-4500A DXA at Virginia Tech was a reliable and valid device in measurement of WB, LS, TPF, TF and DT BMD, as well as %BF, LBM, and FM. In addition, effects of navel jewelry on LS BMD have been recognized. Further studies investigating the reliability and validity of DT BMD measures as well as effects of different types, gauges, and shapes of body jewelry on BMD measures in human subjects are warranted. / Master of Science

Turner Syndrome (TS) is a chromosomal disorder from conception characterized by the partial or complete absence of the second X chromosome in females. Chromosomal abnormalities, both numerical and structural, contribute to a significantly higher prevalence of fractures (30.5-32.2%) compared to non-TS postmenopausal women (14.9%). This highlights the intrinsic bone abnormalities associated with TS and increased fracture risk. Peripheral quantitative computed tomography (pQCT) is commonly used to assess bone mineral density (BMD). However, its accuracy in individuals with TS is limited due to the partial volume effect, highlighting the need for further clinical research to understand bone density changes compared to healthy controls. Osteoporosis is a significant comorbidity in TS, characterized by reduced bone quality and altered microstructure. Factors directly contributing to osteoporosis in TS include X chromosome abnormalities, hormonal imbalances, metabolic syndrome, and autoimmune disease. Current management strategies involve estrogen and growth hormone replacement, along with progastrin and bisphosphonates. Therapies targeting the inhibitors of the Wnt/β-catenin pathway could improve BMD and bone quality and reduce fracture risk. However, more clinical research is needed to understand the bone density compositional changes that occur to optimize therapeutic approaches for individuals with TS.

Bone drilling is a major part of orthopaedic surgery performed during the internal fixation of fractured bones. At present, information related to drilling force, drilling torque, rate of drill bit penetration and drill bit rotational speed is not available to orthopaedic surgeons, clinicians and researchers as bone drilling is performed manually. This research demonstrates that bone drilling force data if recorded in-vivo, during the repair of bone fractures, can provide information about the strength/quality of the bone. Drilling force does not give a direct measure of bone strength; therefore it has been correlated with the shear strength and screw pullout strength to determine the efficacy in estimating the bone strength. Various synthetic bone material densities and animal bones have been tested to demonstrate the use of drilling force data. A novel automated experimental test rig, which enables drilling tests, screw insertion and screw pullout tests to be carried out in a controlled environment, has been developed. Both drilling and screw pullout tests have been carried out in a single setting of the specimen to reduce the experimental errors and increase repeatability of the results. A significantly high value of correlation (r² > 0.99) between drilling force & shear strength and also between drilling force & normalised screw pullout strength in synthetic bone material was found. Furthermore, a high value of correlation (r² = 0.958 for pig bones and r² = 0.901 for lamb bones) between maximum drilling force & normalised screw pullout strength was also found. The result shows that drilling data can be used to predict material strength. Bone screws are extensively used during the internal fixation of fractured bones. The amount of screw been tightened is one of the main factor which affects the bone-screw fixation quality. Over tightening of screw can result into the loss of bone-screw fixation strength, whereas under tightening can result in the screw loosening. Therefore, optimum tightening of the screw is important to achieve the maximum bone-screw fixation strength. At present, optimum tightening of the screw is entirely dependent upon the skill and judgment of the surgeon, which is predominantly based on the feel of the screw tightening torque. Various studies have been reported in the literature to develop an algorithm to set an optimum tightening torque value to be used in surgery. A method which is based on the use of rotation angle of the screw while tightening, rather than using screw insertion/tightening torque, to optimise the bone-screw fixation strength is proposed in this research. The effectiveness of the proposed method has been successfully demonstrated on the synthetic bone material using the designed test rig. The optimum angle for the tested screw was found to be 120° which is equivalent to 33% of the screw pitch.

Title: The Use of Vibration in Sports and Health Care Objectives: The aim of this study is to confirm or refute established hypotheses. Hypotheses: 1. The use of vibration loading improves muscle strength. 2. The use of vibration loading improves bone mineral density. 3. The use of vibration loading can influence balance. Methods: This diploma thesis is elaborated as search form. It is based on exploration of available literary sources, clinical trials accessible through electronic databases of medical and sports, and library catalogs. The resources from sport, physiology, biomechanics, and various medical disciplines (osteology, physiotherapy, kinesiology) were used also. Results: Due to retrieval process of whole body vibration training it was found out that this method can improve muscle strength, bone mineral density, balance and mobility. The effect depends on chosen parameters of whole-body vibrations. Under certain conditions whole-body vibration training could represent an alternative or a supplement to conventional training in order to increase muscle strength and bone mineral density or improve balance and mobility of elderly. The selection of right vibration parameters could support ordinary physical therapy of some neurological disorders. Keywords: vibration, whole-body vibration...

Title: The Use of Vibration in Sports and Health Care Objectives: The aim of this study is to determine whole-body vibration training as potential training method in sport and health area. The usage of vibration training should increase strength, bone mineral density, and balance. Methods: This diploma thesis is solely theoretical. It is based on review of available literary sources, clinical trials accessible through electronic databases of medical and sports, and library catalogs. The resources from sport, physiology, biomechanics, and various medical disciplines (osteology, physiotherapy, kinesiology) were used also. Results: The research concluded that the usage of whole-body vibration of an appropriate frequency or acceleration respectively could represent an alternative or a supplement to conventional training in order to increase muscle strength and bone mineral density or improve balance and mobility of elderly. The selection of right vibration parameters could support ordinary physical therapy of some neurological disorders. Keywords: vibration, whole-body vibration training, muscle strength, balance, bone mineral density, neurological disorders, physical therapy

La microarchitecture osseuse est un des déterminants de la qualité osseuse qui peut maintenant être évaluée in vivo au radius et au tibia distaux avec une résolution isotropique de 82μm par un nouveau scanner à haute résolution (XtremeCT, SCANCO Medical AG). Par ailleurs, l’utilisation d’analyse en éléments finis sur les volumes 3D obtenus permet d’évaluer les propriétés biomécaniques de l’os comme la résistance osseuse. Nous avons montré qu’il s’agissait d’une technique prometteuse pour évaluer la densité, la microarchitecture et les propriétés biomécaniques osseuses au niveau des sites périphériques, notamment parce que ces mesures étaient associées chez la femme avec des fractures ostéoporotiques de toutes sortes. Nous avons également montré que les mêmes mesures étaient tout aussi pertinentes chez l’homme, alors qu’il est moins sujet à l’ostéoporose. Les résultats étaient associés aux fractures ostéoporotiques de toutes sortes, notamment les fractures vertébrales. L’analyse en éléments finis permet donc la mesure in vivo de la résistance osseuse, ce qui pourrait fournir des informations sur la fragilité osseuse et le risque de fracture non accessible par les seules mesures de densité ou de microarchitecture osseuse. / Bone microarchitecture is one of the determinants of bone quality that can now be evaluated in vivo at the distal radius and tibia with an isotropic resolution of 82μm with a new high-resolution peripheral scanner (XtremeCT, SCANCO Medical AG). Moreover, the use of finite element analysis on the 3D bone volume acquired allows the assessment of bone biomechanical properties such as bone strength. Our studies show that this technique is promising to assess bone density, microarchitecture and strength at peripheral skeletal sites. Indeed those measures were associated with osteoporotic fractures of all kinds in women. We also demonstrated that those same measures were associated with osteoporotic fractures of all kinds, including vertebral fractures, in men, who are less prone to be affected by osteoporosis. Finite element analysis allows in vivo measurement of bone strength, which might provide additional information about bone fragility and fracture risk that are not assessed by measures of density or microarchitecture.

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