Dissertations / Theses: 'Bone strength'

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Jain, Atul. "The evaluation of bone strength." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/12989.

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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.

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Tassani, Simone <1979&gt. "Evaluation of bone strength: microtomographic tecniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1695/.

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This thesis is a part of a larger study about the characterization of mechanical and histomorphometrical properties of bone. The main objects of this study were the bone tissue properties and its resistance to mechanical loads. Moreover, the knowledge about the equipment selected to carry out the analyses, the micro-computed tomography (micro-CT), was improved. Particular attention was given to the reliability over time of the measuring instrument. In order to understand the main characteristics of bone mechanical properties a study of the skeletal, the bones of which it is composed and biological principles that drive their formation and remodelling, was necessary. This study has led to the definition of two macro-classes describing the main components responsible for the resistance to fracture of bone: quantity and quality of bone. The study of bone quantity is the current clinical standard measure for so-called bone densitometry, and research studies have amply demonstrated that the amount of tissue is correlated with its mechanical properties of elasticity and fracture. However, the models presented in the literature, including information on the mere quantity of tissue, have often been limited in describing the mechanical behaviour. Recent investigations have underlined that also the bone-structure and the tissue-mineralization play an important role in the mechanical characterization of bone tissue. For this reason in this thesis the class defined as bone quality was mainly studied, splitting it into two sub-classes of bone structure and tissue quality. A study on bone structure was designed to identify which structural parameters, among the several presented in the literature, could be integrated with the information about quantity, in order to better describe the mechanical properties of bone. In this way, it was also possible to analyse the iteration between structure and function. It has been known for long that bone tissue is capable of remodeling and changing its internal structure according to loads, but the dynamics of these changes are still being analysed. This part of the study was aimed to identify the parameters that could quantify the structural changes of bone tissue during the development of a given disease: osteoarthritis. A study on tissue quality would have to be divided into different classes, which would require a scale of analysis not suitable for the micro-CT. For this reason the study was focused only on the mineralization of the tissue, highlighting the difference between bone density and tissue density, working in a context where there is still an ongoing scientific debate.

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Kamimura, Masaki. "Interfacial tensile strength between polymethylmethacrylate-based bioactive bone cements and bone." Kyoto University, 2003. http://hdl.handle.net/2433/148752.

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Vallet, Quentin. "Predicting bone strength with ultrasonic guided waves." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066626.

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Cette thèse s'inscrit dans le cadre du développement d'une sonde ultrasonore afin d'obtenir des nouveaux biomarqueurs de l'os cortical et améliorer la prédiction du risque de fracture. Notre approche se base sur la mesure des ondes guidées ultrasonores dans l'os cortical. La technique de transmission axiale bidirectionelle a été utilisée pour mesurer les modes guidées se propageant dans l'enveloppe corticale des os longs (i.e., le radius). Les propriétés matérielles et structurelles liées à la résistance osseuse ont été obtenues à partir des courbes de dispersion en utilisant un schéma d'inversion. Ainsi, un problème inverse totalement automatique, basé sur une optimisation par algorithmes génétiques et un modèle 2D de plaque libre transverse isotrope, a été développé. Cette procédure d'inversion a d'abord été testée sur des matériaux contrôlés avec des propriétés connues. Puis, la faisabilité d'obtenir des propriétés corticales sur des radii ex vivo a été montrée. Ces estimations ont été validées par comparaison avec des valeurs de référence obtenues avec des techniques indépendantes telles que la micro-tomodensitométrie par rayons X (épaisseur, porosité) et la spectroscopie par résonance ultrasonore (élasticité). Un bon accord a été trouvé entre les valeurs de référence et les estimations d'épaisseur, de porosité et d'élasticité. Enfin, la méthode a été étendue à des mesures in vivo. La validité du modèle en présence de tissus mous a d'abord été démontrée. Puis, les propriétés osseuses ont été obtenues sur des sujets sains. Un bon accord a été trouvé entre l'épaisseur estimée et les valeurs de référence obtenues par tomodensitométrie périphérique haute résolution
We aimed at developing new ultrasound-based biomarkers of cortical bone to enhance fracture risk prediction in osteoporosis. Our approach was based on the original concept of measuring ultrasonic guided waves in cortical bone. The bi-directional axial transmission technique was used to measure the guided modes propagating in the cortical envelope of long bones (i.e., the radius). Strength-related structural and material properties of bone were recovered from the dispersion curves through an inversion scheme. To this goal, a fully automatic inverse problem based on genetic algorithms optimization, using a 2-D transverse isotropic free plate waveguide model was developed. The proposed inverse procedure was first tested on laboratory-controlled measurements performed on academic samples with known properties. Then, the feasibility of estimating cortical properties of ex vivo radius specimens was assessed. The inferred bone properties were validated by face-to-face comparison with reference values determined by a set of independent state-of-the art technologies, including X-ray micro-computed tomography (thickness, porosity) and resonance ultrasound spectroscopy (stiffness). A good agreement was found between reference values and estimates of thickness, porosity and stiffness. Lastly, the method was extended to in vivo measurements, first, by ensuring the validity of the waveguide model in presence of soft tissues to demonstrate the feasibility of measuring experimental dispersion curves in vivo and infer from them bone properties. Estimated cortical thickness values were consistent with actual values derived from high resolution peripheral computed tomography

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Varghese, Bino Abel. "Quantitative Computed-Tomography Based Bone-Strength Indicators for the Identification of Low Bone-Strength Individuals in a Clinical Environment." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1300389623.

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Hilal, M. K. "Development of a high strength bioactive bone substitute." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267175.

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Jin, Andi. "The effect of bisphosphonates on bone microstructure and strength." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/49791.

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Osteoporosis (OP) is a common disease, especially among postmenopausal women. OP is regarded as the main cause of fragility fractures. Bisphosphonate (BP) medications, approved by the FDA in 1995, have been adopted as the most common and frontline treatment to OP. The most obvious positive effect of BP is their ability to improve bone mineral density (BMD). However, lots of concerns have been raised after BP medications coming into market for about ten years. A new type of hip fractures (atypical fractures) has been reported and linked with long-term BP treatment. It is still debatable on the effect of BP on bone health. Previous studies have evaluated BP’s effect either by measuring BMD quantitatively or following up fracture cases. There are very limit studies from an engineering background investigating BP’s effect on bone strength and microstructure, especially on those bones sustaining fractures despite BP treatment. The femoral heads from trauma patients’ hip replacement operations were collected and worked as a BP study group (10 femoral heads) and fracture control group (13 femoral heads) depending on whether or not the patient had been treated with BP before fractures. Cadaver samples were collected from an elderly control group (5 femoral heads). Five cylindrical sub-samples were cored from the same location of each femoral head. All the five cylinder sub-samples were micro-CT scanned for microstructure measurements. Two of the five cylinder sub-samples were selected randomly and compressively mechanically tested for apparent strength. Another two sub-samples were further synchrotron radiation scanned for a sub-micro features study, especially focusing on the trabecular microcracks and fully broken trabeculae. The apparent strength for BP treated samples is 29% and 48% lower than that of non-treated fracture controls and elderly controls, respectively. The density and microstructure parameters for the BP study group are slightly higher than or at a similar level as those of non-treated fracture controls. However, there are 24% and 55% more microcracks existing in BP treated samples than that of non-treated fracture controls and elderly controls, respectively. There are a sub-group of patients with whom BP treatment does not work very well, as they still fractured even with BP treatment for years. The bone mass density and trabecular microstructure may not be the cause of lower apparent strength. Microcracks and fully broken trabeculae can partly explain the lower strength, but further studies at the sub-micro and fibrillar levels are highly suggested.

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Saxon, Leanne, and mikewood@deakin edu au. "The role of exercise in the development of bone strength during growth." Deakin University. School of Health Sciences, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051125.095337.

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Exercise during growth may increase peak bone mass; if the benefits are maintained it may reduce the risk of fracture later in life (1). It is hypothesised that exercise will preferentially enhance bone formation on the surface of cortical bone that is undergoing bone modeling at the time (2). Therefore, exercise may increase bone mass accrual on the outer periosteal surface during the pre- and peri-pubertal years, and on the inner endocortical surface during puberty (3). An increase in bone formation on the periosteal surface is, however, more effective for increasing bone strength than medullary contraction (4). While exercise may have a role in osteoporosis prevention, there is little evidential basis to support this notion. It is generally accepted that weight-bearing exercise is important, but it is not known how much, how often, what magnitude or how long children need to exercise before a clinically important increase in bone density is obtained. In this thesis, the effect of exercise on the growing skeleton is investigated in two projects. The first quantifies the magnitude and number of loads associated with and in a moderate and low impact exercise program and non-structured play. The second project examines how exercise affects bone size and shape during different stages of growth. Study One: The Assessment of the Magnitude of Exercise Loading and the Skeletal Response in Girls Questions: 1) Does moderate impact exercise lead to a greater increase in BMC than low impact exercise? 2) Does loading history influence the osteogenic response to moderate impact exercise? 3) What is the magnitude and number of loads that are associated with a moderate and low impact exercise program? Methods: Sixty-eight pre-and early-pubertal girls (aged 8.9±0.2 years) were randomised to either a moderate or low impact exercise regime for 8.5-months. In each exercise group the girls received either calcium fortified (-2000 mg/week) or non-fortified foods for the duration of the study. The magnitude and number of loads associated with the exercise programs and non-structured play were assessed using a Pedar in-sole mobile system and video footage, respectively. Findings: After adjusting for baseline BMC, change in length and calcium intake, the girls in the moderate exercise intervention showed greater increases in BMC at the tibia (2.7%) and total body (1.3%) (p ≤0.05). Girl's who participated in moderate impact sports outside of school, showed greater gains in BMC in response to the moderate impact exercise program compared to the low impact exercise program (2.5 to 4.5%, p ≤0.06 to 0.01). The moderate exercise program included -400 impacts per class, that were applied in a dynamic manner and the magnitude of impact was up to 4 times body weight. Conclusion: Moderate-impact exercise may be sufficient to enhance BMC accrual during the pre-pubertal years. However, loading history is likely to influence the osteogenic response to additional moderate impact exercise. These findings contribute towards the development of school-based exercise programs aimed at improving bone health of children. Study Two: Exercise Effect on Cortical Bone Morphology During Different Stages of Maturation in Tennis Players Questions: 1) How does exercise affect bone mass (BMC) bone geometry and bone strength during different stages of growth? 2) Is there an optimal stage during growth when exercise has the greatest affect on bone strength? Methods: MRI was used to measure average total bone, cortical and medullary areas at the mid- and distal-regions of the playing and non-playing humerii in 47 pre-, peri- and post-pubertal competitive female tennis players aged 8 to 17 years. To assess bone rigidity, each image was imported into Scion Image 4.0.2 and the maximum, minimum and polar second moments of area were calculated using a custom macro. DXA was used to measure BMC of the whole humerus. Longitudinal data was collected on 37 of the original cohort. Findings: Analysis of the entire cohort showed that exercise was associated with increased BMC and cortical area (8 to 14%), and bone rigidity (11 to 23%) (all p ≤0.05). The increase in cortical bone area was associated with periosteal expansion in the pre-pubertal years and endocortical contraction in the post-pubertal years (p ≤0.05). The exercise-related gains in bone mass that were accrued at the periosteum during the pre-pubertal years, did not increase with advanced maturation and/or additional training. Conclusion: Exercise increased cortical BMC by enhancing bone formation on the periosteal surface during the pre-pubertal years and on the endocortical surface in the post-pubertal years. However, bone strength only increased in response to bone acquisition on the periosteal surface. Therefore the pre-pubertal years appear to be the most opportune time for exercise to enhance BMC accrual and bone strength

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Laudermilk, Monica J. "Influences of Select Dietary Components on Bone Volumetric Density, Bone Geometry and Indices of Bone Strength in Young Girls." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/201500.

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Osteoporosis, a major public health problem, likely has its origins in childhood. During periods of rapid skeletal growth, diet may influence accrual of bone mineral density (BMD) and adult bone health. This study used novel approaches in bone imaging to further characterize optimal skeletal development and enhance our understanding of key dietary components that influence attainment of peak bone mass (PBM) and contribute to determinants of peak bone strength in peri-pubertal females. The use of a validated food-frequency questionnaire (FFQ) enabled the influence of usual dietary intake on bone parameters to be examined.This study examined the relationship of dietary intake of micronutrients and bone macro-architectural structure in peri-pubertal girls. This study suggested that vitamin C and zinc intake are associated with objective measures of bone status in 4th, but not 6th grade girls. This indicates potential differences in micronutrient and bone associations at various age-associated stages of bone maturation.The impact of dietary fat on peri-pubertal skeletal growth is not well characterized. This study examined relationships of select dietary fatty acid (FA) intakes and measures of bone status in peri-pubertal girls. This study suggested that MUFA, total PUFA, n-6 and linoleic acid (LA) are inversely associated with bone status prior to menarche, but composition of dietary fat may be more important during the early-pubertal years. Decreased intakes of n-6 PUFA may benefit bone health in young girls.The impact of a dietary protein on volumetric bone mineral density (vBMD), bone mineral content (BMC) and bone strength throughout maturation remains controversial. Given evidence of both anabolic and catabolic affects of protein on bone health, this study examined relations of dietary protein from different sources with bone parameters in peri-pubertal girls. This study showed that dietary protein intake is related to higher trabecular but not cortical vBMD, BMC and BSI, and accounts for 2-4% of their variability in peri-pubertal girls. The relationship seems to vary by the source of dietary protein and calcium intake. However, a negative impact of animal protein on bone health is not supported. Large scale observational and intervention studies are needed to establish causality.

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Ward, Ryan C. "Contribution of high school sport participation to young adult bone strength." Thesis, University of Iowa, 2018. https://ir.uiowa.edu/etd/6333.

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Nearly 8 million American adolescents participate in sports. Many sports (e.g. basketball, volleyball) require powerful muscle movements. Normally, participation declines in young adulthood. The purpose of this study was to assess longitudinal effects of interscholastic high school sport participation and muscle power on young adult bone strength. 295 young adults from the Iowa Bone Development Study participated in this study. Participants were classified into sport participation groups based on an interscholastic sport participation history questionnaire. Groups included Power Sport Participant (PSP), Other Sport Participant (OSP), and Nonparticipant (NP). Current physical activity (PA) behaviors were assessed via questionnaire. Dual x-ray absorptiometry (DXA) assessed hip areal bone mineral density (aBMD) and was used with hip structure analysis (HSA) to estimate femoral neck section modulus (FN Z) and hip cross-sectional area (CSA). Peripheral quantitative computed tomography (pQCT) provided stress-strain index (SSI) and bone strength index (BSI) at 38% and 4% cross-sectional tibial sites respectively. Vertical jump estimated muscle power at age 19. Gender-specific multiple linear regression predicted young adult bone outcomes based on sport participation groups. Mediation analysis analyzed effects of muscle power on relationships between sport participation and bone outcomes. All analyses were adjusted for current PA. For both males and females, bone outcomes for PSPs were greater than bone outcomes for NPs (P < 0.025). Bone outcomes for PSPs were also greater than OSPs in females (P < 0.025). Mean differences for PSPs and NPs differed between 6.5% to 15.7%. 14.2% to 27.5% of the effect of sport participation on bone outcomes was mediated by muscle power. These results provide evidence to say that former male power sport participants and other sport participants and female power sport participants have stronger bones than peers even when adjusting for current PA. Muscle power did not fully explain differences in all bone outcomes suggesting that sport participation has additional bone health benefits.

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Ong, Fook Rhu. "Analysis of bone drilling characteristics for the enhancement of safety and the evaluation of bone strength." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/13900.

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Bone drilling is a major part of modern orthopaedic surgery associated with the principles of internal fixation of fractured bones. At present, information related to drilling forces, 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 orthopaedic surgery involving the drilling of bone can greatly benefit from the technology of automation/ mechatronics, which allows the collection and storage of the drilling data for analysis as well as for the improvement of the drilling procedure. The research also represents a significant contribution to the development of a drilling system for the enhancement of safety and/or as a diagnostic tool for the evaluation of bone strength. A novel automated experimental rig, which enables drilling tests to be carried out in a controlled environment, has been developed. The investigation for the enhancement of safety involves the detection of drill bit break-through on a femoral shaft in the presence of system compliance and inherent fluctuation of drilling forces. Since these two factors affect the detection of drill bit break-through, a robust and reliable method based on a modified Kalman filter has been developed. When applied to the force difference between successive samples and the rotational speed, the modified Kalman filter has been found to be very effective in establishing trends and ironing out major fluctuations caused by the system compliance and inherent drilling force fluctuation. The evaluation of bone strength related to the cancellous bone at the proximal femur has resulted in the establishment of a positive relationship between the average drilling force and bone mineral density (BMD), obtained from bone densitometry, which is used to estimate bone strength in clinical practice. The correlation has been found to depend on the direction of drilling. This is indicated by a linear relationship obtained in the anterior-posterior direction (perpendicular to the cervical axis), which is not interchangeable with the relationship in the direction of the cervical axis. Findings of this research have indicated that analysis of bone drilling forces has the potential to provide additional information about the strength of bone.

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Armstrong, Alison L. "Hormone replacement therapy - effects on strength, balance and bone density." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284686.

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Raikar, Sajal Vijay. "Cement Augmentation Enhanced Pullout Strength Of Fatigue Loaded Bone Screws." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226240822.

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Battula, Suneel Ranga Sai. "Experimental and Numerical Evaluation of the Pullout Strength of Self-tapping Bone Screws in Normal and Osteoporotic Bone." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194988102.

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Ensminger, Alyssa M. "Prediction of Radial Bending Strength by Cortical Porosity and Diameter." Ohio University Honors Tutorial College / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors149278795178393.

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Keene, Beth E. "Identifying a non-invasive measure of bone status in dairy cattle." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9599.

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The objectives of this research were to evaluate non-invasive measures of bone mineral content (BMC) and bone mineral density (BMD) as rapid, on-farm tools to assess phosphorus (P) status in dairy cows. In addition, the effects of parity and stage of lactation on measures of BMC of the fused 3rd and 4th metacarpal bone and of caudal vertebrae 14 and 15 were assessed. The caudal vertebrae and right front metacarpal (sample pairs) were excised from 107 Holstein cull cows following slaughter. Parity, age, and days in milk (DIM) of the donor animal were obtained for 43 pairs of samples. Samples were grouped by parity (1, 2, 3, and >4) and stage of lactation (Stage 1 = < 90 DIM, Stage 2 = > 90 and < 150 DIM, Stage 3 = >150 and < 250 DIM and Stage 4 = > 250 DIM). Samples were analyzed for BMC and BMD with dual energy X-ray absorptiometry (DXA), BMC with radiographic photometry (RP), breaking strength with mechanical methods, and mineral content with chemical procedures. Estimates of BMC obtained with RP and DXA were poorly related to chemical measures of actual BMC and to measures of breaking strength. In caudal vertebrae 14 and 15, increasing stage of lactation decreased energy to peak load with the lowest values observed in late lactation. Stage of lactation had no effect on BMC measured chemically in the caudal vertebrae or metacarpal. Parity did not affect breaking strength of the metacarpal or caudal vertebrae or total ash or P content of any bone. Results indicated that imaging techniques are not useful measures of BMC in mature dairy cattle.
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Bell, Penelope Jane. "Bone strength of students in the UAE : an investigation into lifestyle, bone quality and bone density of students in the United Arab Emirates (UAE)." Thesis, City University London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433679.

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Glass, Natalie Ann. "The relationship between adiposity and bone development." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/5938.

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The objective of this research was to evaluate the relationships between greater adiposity and bone development during adolescence. Bone was evaluated from age 11 to 17 years in the Iowa Bone Development Study using peripheral quantitative computed tomography (pQCT). Body composition (fat and lean mass) was estimated by dual energy x-ray absorptiometry (DXA). The first research aim evaluated the associations between greater overall adiposity and subsequent maturation and bone strength in 135 girls and 123 boys. Greater adiposity was defined according to age 8 Body Mass Index (BMI) to categorize participants as overweight (OW) or healthy-weight (HW). Maturation was defined as the age of peak height velocity (PHV). Bone strength was assessed at the radius and tibia (bone strength index, BSI, and strength-strain index, SSI). Differences in bone strength between OW and HW were evaluated with sex-specific multi-level regression models to account for individual growth and correlation between repeated measurements. Analyses were adjusted for centered age (measurement visit age - grand mean age of cohort), change in fat mass, and limb length in Model 1, with additional adjustment for lean mass in Model 2. Analyses were repeated using biological age (visit age - age PHV). BMI was positively associated with age of maturation in girls and boys (p< 0.05). HW versus OW girls had significantly lower BSI and SSI at the radius and tibia (p< 0.05) in Model 1. Results remained significant except for radial BSI in Model 2. HW versus OW boys had significantly lower BSI and SSI (all p< 0.05) at the tibia, but not radius, in Model 1. Significant differences were sustained in Model 2. Analyses were repeated using biological age, which yielded similar results for boys, but reduced parameter estimates were observed in girls, with only tibial SSI significant in Model 2 (p< 0.05). These findings support a stronger role for greater adiposity in the occurrence of earlier maturation and greater bone strength in girls than boys while greater lean mass appeared to play a greater role in boys. The second research aim evaluated associations between abdominal adiposity and bone in 132 girls and 122 boys. Visceral adipose tissue area (VAT, cm2) and subcutaneous adipose tissue area (SAT, cm2) were estimated from DXA scans. Sex-specific analyses evaluated the fat-bone relationship with growth models using biological age as the time variable adjusted for limb length and lean mass. There were no significant associations between bone parameters and VAT or SAT in girls. In boys, greater VAT was associated with lower trabecular bone density (tBMD) and BSI (all p< 0.05) at the tibia, but not radius. Greater VAT and SAT were associated with smaller cortical bone size and thickness (all p< 0.01) at the radius, but not tibia. Analyses limited to overweight participants showed VAT was negatively associated with periosteal circumference at the radius and tibia, cortical bone thickness at the tibia and SSI (all p< 0.05) at the radius in girls. In boys, the results were relatively unchanged for VAT, while SAT was only significantly associated with lower tBMD (p< 0.05) at the tibia. These results suggest the bone-fat relationship may vary depending on adiposity and bone site. The third research aim evaluated the longitudinal association between intramuscular fat and cortical bone at the tibia from age 11 to 17 years in 153 girls and 143 boys. Muscle density (MD) was used to estimate intramuscular fat (IMF). Lower MD indicates greater IMF. The relationships between muscle density and cortical bone parameters were modeled using multi-level regression models adjusted for biological age, limb length and muscle cross-sectional area measured by pQCT. In the adjusted multi-level regression models, MD was positively associated with cortical bone parameters, but only reached statistical significance for BMD, bone mineral content (BMC), bone cross-sectional area, cortical thickness and SSI in girls, while only SSI was significant in boys (all p< 0.05). These results suggest that greater fat content within muscle may be harmful to weight-bearing cortical bone during adolescence. In conclusion, findings from the first aim suggest there are sex- and site-specific differences in the relationship between adiposity and bone during adolescence. Findings from the second and third aims indicate these differences could be explained, in part, by the existence of specific fat depots (abdominal more so than intramuscular fat) that could be harmful to bone and that may be more apparent in boys due to a sex-specific fat distribution pattern that favors accumulation of abdominal rather than peripheral fat.

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Farr, Joshua Nicholas. "Influences of Soft Tissue Composition and Physical Activity on Bone Volumetric Density, Bone Geometry, and Fracture Prevalence in Young Girls." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145283.

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Fractures are a major public health concern and there is an urgent need to identify high-risk individuals. This study used novel approaches in bone imaging to characterize optimal skeletal development in girls and enhance our understanding of the structural and functional deficits that contribute to skeletal fragility and fracture risk during growth. The findings indicate that fracture in girls is associated with lower trabecular bone density, but not bone macro-architecture at metaphyseal regions of weight-bearing bones, which is consistent with findings reported in children at the distal radius. These findings suggest that lower trabecular density at metaphyseal regions of long bones track throughout the appendicular skeleton and may be an early marker of skeletal fragility.Obese children are overrepresented in childhood fracture cases. Nevertheless, the effects of fat on bone during growth remain unclear. This study showed that skeletal muscle was a stronger determinant of bone parameters in girls than total body adiposity, although fat mass had a persistent, albeit weak association with bone parameters. Furthermore, fatty infiltration of skeletal muscle, which is associated with type 2 diabetes mellitus, was inversely associated with bone strength in girls. These findings are consistent with the proposed functional model of bone development which posits that forces from muscle contractions are the main mechanical challenges to which bones adapt.Physical activity during growth is critical for optimal bone development. The findings from this study support this premise and suggest that regular physical activity enhances bone strength in girls. Nevertheless, for exercise to be accepted as an important public health osteoporosis prevention strategy, lasting adaptations must be shown. Plausible biological explanations have been offered in support of the peri-pubertal years as a "window of opportunity" for maximizing the response to exercise. Findings from this study suggest that a two year school-based high-impact jumping intervention was not an effective means to enhance bone parameters in girls. Controlled dose-response trials will be necessary to test questions regarding the types, bouts, and durations of exercise required to define the "dose" of exercise needed to elicit meaningful skeletal adaptations during growth.

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Bediz, Bekir. "Human Tibial Bone Strength Prediction By Vibration Analysis For Diagnosing Progressing Osteoporosis." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610694/index.pdf.

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Osteoporosis is a metabolic bone disease that needs to be properly diagnosed. The current diagnosing procedure of osteoporosis is based on the mineral density of bones measured by common methods such as dual energy X-ray absorptiometry (DXA). However, due to the deficiencies and limitations of these common methods, investigations on the utilization of other non-invasive diagnosing methods have been executed. For instance, using vibration measurements seems to be a promising technique in diagnosing metabolic bone diseases such as osteoporosis and also in monitoring fracture healing. Throughout this study, bone structural modal parameters obtained from vibrations experiments with decreasing mineral density are examined and therefore, it is aimed to find a new approach to detect osteoporosis or progressing osteoporosis by investigating a relation between structural dynamic properties and mineral density of bone. The main advantage of this study is that loss factor, which is an inherit property of bone, is investigated since in the previous studies mainly the changes in natural frequency of bones with the state of osteoporosis is examined. In this thesis, both in vitro and in vivo experiments are carried out on human tibia specimens. The measured frequency response functions (FRFs) are analyzed using modal identification techniques to extract the modal parameters of the human tibia. The results obtained from in vitro experiments show that loss factor may be a powerful tool in diagnosing osteoporosis, however due to the difficulties encountered in the case of in vivo experiments makes the use of this parameter as a diagnosing tool difficult. It is also seen from in vivo experiments that there is a weak correlation between the natural frequencies of tibia and BMD measurements of patients. Therefore, in order to investigate the parameters affecting the natural frequencies of tibia, finite element (FE) model of human tibial bone is constructed. Using this FE model tibia, the effect of boundary conditions of experiments and geometry of the bone on natural frequencies of bone is examined. These analyses show that the effect of both boundary conditions and geometry of tibia is very high. Therefore, it is concluded that if the necessary conditions are satisfied, the using natural frequency information of tibia seems to be a possible and practical method that can be used to detect progressing osteoporosis. Also, using the FE model of tibia, the changes of natural frequencies of tibia with the variation in elastic modulus are investigated.

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21

Taymouri, Farid. "Reference data for bone material strength index (BMSI) measured by impact microindentation." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/666868.

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Objetivo: La microindentación de impacto (MII) es una técnica que permite medir in vivo la resistencia tisular mecánica ósea. Se ha demostrado que la MII proporciona información útil sobre la evaluación de enfermedades esqueléticas, pero se desconoce el efecto que la edad puede ejercer sobre la propiedad ósea medida. El objetivo del estudio es analizar la relación entre la edad y la MII. Material y métodos: El índice de Resistencia Mineral Ósea (BMSi), la variable de medición de MII, se midió en 69 mujeres (mediana de edad: 49 años; rango: 30-81 años) y 19 varones (mediana de edad: 34 años; rango: 24-98 años) sanos. La correlación entre BMSi y la edad se analizó mediante regresión lineal. La asociación entre BMSi y edad se evaluó mediante ANOVA tras ajustar por el índice de masa corporal. El posible efecto de depleción estrogénica postmenopáusica sobre el BMSi se estudió comparando el subgrupo de mujeres más jóvenes con las más mayores mediante la prueba t de Student. Resultados: Los análisis de regresión lineal mostraron que la BMSi no se correlaciona con la edad en varones (R2=0,0016, p=0,74) ni en mujeres (R'=0,076, p=0,25). Asimismo, el análisis ajustado de ANOVA no demostró asociación entre la BMSi y la edad ni en varones (p=0,78) ni en mujeres (p=0,73). Finalmente, no se encontraron diferencias entre la BMSi entre las mujeres más jóvenes y las mayores (p=0,8). Conclusiones: La resistencia tisular mecánica ósea en individuos sanos es independiente a la edad y a la depleción estrogénica postmenopáusica.
Objective: Impact microindentation (IMI) is a technique that allows the measurement of mechanicalbone tissue resistance in vivo. IMI has proven to provide useful information on the evaluation of skeletal diseases, but the effect of age on the bone property that is measured by this technique is unknown. This study aims to analyzethe relationship between age and MIH. Material and methods: Bone Material Strength index (BMSi), IMI's output variable, was measured in 69 healthy women (median age: 49 years, range: 30-81 years) and 19 healthy men (median age: 34 years, range: 24-98 years). The correlation between BMSi and age was analyzed by linear regression. The association between BMSi and age was evaluated by ANOVA after adjusting for body mass index. The potential effect of postmenopausal estrogenic depletion on BMSi was studied by comparing the younger vs the older subset of women through a t-student test. Results: Linear regression analysis showed that BMSi was not correlated with age in either men (R'=0.0016, p=0.74) or women (R'=0.076, p=0.25). Similarly, the BMI-adjusted ANOVA model revealed a lack of association of BMSi with age in men (p=0.78) and women (p=0.73). Finally, there were not significant differences on BMSi detected between the younger and the older subset of women (p=0.8). Conclusions: Bone tissue mechanical resistance in healthy individuals is independent of age and postmenopausal estrogenic depletion.

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Wilks, Desiree Cristin. "Effects of age and athletic specialisation upon bone strength in master athletes." Thesis, Manchester Metropolitan University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484821.

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Bones are a fundamental element of the musculoskeletal system with complex tasks. They need to be lightweight to allow effective locomotion, but also strong enough to resist external forces of often several times body weight. This is possible due to the combination of unique material characteristics and a structure that adjusts to changing requirements. However, bone mass is generally proposed to decrease with age, contributing to an enhanced fracture incidence, which is strongly associated with morbidity, mortality and rising health care costs. The understanding of the bones' adaptation to mechanical forces is vital to preserve good bone health into old age and thus to prevent Osteoporosis the most common skeletal disorder. The objectives of this thesis were to investigate the adaptation of the middle aged and the elderly skeleton to various types of mechanical loading of differing magnitudes, and to evaluate the etiology of the age-related loss of bone mass and strength in the context of strenuous long-term exercise. Altogether 448 participants were involved in the study. The cross-sectional comparisons of bone mass and strength between athletes of differing disciplines and controls showed that differences at the mechanically loaded tibia increased systematically as the discipline specific speed decreased, i.e. greatest differences were found between sprinters and controls amounting to -12% in males and to -20% in females. In the radius no group differences of bone measures were observed, except for sprint cyclists,who had larger bone mass and strength than the controls. Age dependencies considered primarily structural shaft measures of both the radius and the tibia of track and field athletes, whereas fewer correlations were found in either the controls or the cyclists. The correlations appeared to be stronger if the values were larger at young age (40 yrs), i.e. in the tibia of sprint runners. Also, they were stronger and more systematic in females than in males. In co~clusion, mechanical loading was positively associated with bone strength in the middle aged and elderly study participants. The reduction in athletic performance with age may be associated with the observed loss in tibial bone strength in the athletes but not the controls, because maintenance of bone strength 'is dependent on the exposure to mechanical loading in both athletes and non-athletes. The stronger age correlations in the radius compared to the tibia imply a protective effect of exercise against an age related loss in bone mass and strength. Larger athlete vs. control group differences along with stronger age correlations in females as opposed to males suggest a gender specific response to mechanical loading.

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Whittington, J. M., E. J. Shoen, L. L. Labounty, Jeremy A. Gentles, Jenna M. Kraska, Ann Marie Swisher, J. E. Keller, et al. "Bone Mineral Density and Content of Collegiate Throwers: Influence of Maximum Strength." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4094.

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Bone is a plastic tissue, changing in density and size with different levels of stress. Furthermore, it appears that BMD is altered in a site specific manner. However, BMD has not been studied extensively in all types of athletes, particularly well trained strengthpower athletes, such as throwers. The pwpose of this study was to examine the BMD of USA Division I collegiate throwers (shot put, discus, etc.). BMD was compared to normative data and to different athletes. Measures of whole body maximum strength and throwing performance were correlated with BMDs. Potential right/left side and sex differences were examined. Athletes were 4 males, 3 females age 19.9 ± 0.9 years. BMD was measured with a DEXA Maximum isometric strength was measured using a midthigh pull standing on a force plate. Force time-curves were generated during the strength tests. Peale force (PF) and normalized pealc force (PFa) were correlated with BMDs. Comparison indicates throwers have denser bones compared to normative data and compared to other types of athletes. Male throwers tend to have greater total body BMD than female throwers (p < 0.05). Dominant arm showed slightly greater BMD compared to non-dominant (p < 0.05). Furthermore, BMD is related to PF (r = 0.68) and PFa (r = 0.56). Throwers have greater BMD's than non-athletes or most other types of athletes. However, throwers showed only a small indication of sidedness. These observations likely stem from their training program (whole body heavy loading).

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Whittington, J. M., E. J. Schoen, L. L. Labounty, R. Hamdy, Michael W. Ramsey, Margaret E. Stone, William A. Sands, G. Gregory Haff, and Michael H. Stone. "Bone Mineral Density and Contet of Collegiate Throwers: Influence of Maximum Strength." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/4128.

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AIM: Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.). METHODS: Seven throwers (4 males; 3 females) who were 19.0 ± 0.9 years had their BMD compared to an age matched control group (n=14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs. RESULTS: Generally, throwers had denser bones with male throwers tending to have a greater total BMD (P≤0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P≤0.05). Furthermore, total body BMD was related to PF (r=0.68, r2 =0.46) and PFa (r=0.56, r2=0.31). CONCLUSIONS: Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.

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25

Vasireddy, Sreekanth. "Metacarpal radiographic indices in the assessment of bone strength and fracture risk." Thesis, University of Sheffield, 2010. http://etheses.whiterose.ac.uk/14584/.

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Osteoporotic fractures are associated with morbidity and increased mortality, and treating fractures is an increasing expenditure for national health systems. Targeting fracture preventative measures appropriately starts with finding those at risk of fracture, services for which can be expensive and poorly available. Metacarpal morphometry can potentially be an inexpensive and widely available method of skeletal strength assessment. In this study a semi-automated metacarpal morphometry (SMCM) technique and a fully automated digital x-ray radiogrammetry (OXR) technique were studied for fracture prediction ability. 9 OXR was studied in a nested case-control setting with hip fracture patients and controls (Hip fracture Prevention Study, HIPS), and OXR bone mineral density (BMO) and OXR metacarpal index (MCI) were found to predict hip fracture risk (odds ratio, OR 1.79 and 1.72 respectively for 1 standard deviation (SO) decrease in measurement). OXR was also studied in a prospective setting for vertebral fracture prediction (Vertebral Osteoporosis Trial), and OXR-BMO and OXR-MCI were found to predict vertebral fracture risk (OR 1.56 and 1.81 respectively). SMCM was studied in a prospective setting (HIPS), and average MCI of 6 metacarpals (AMCI) was found to predict all fracture risk and hip fracture risk (OR 1.30 and 1.42 respectively), but not clinical vertebral fracture risk. In all these settings however, hip, spinal and forearm OXA measures had similar or higher point estimates for the respective fracture risk predictions. There was a trend for disproportionately greater bone loss with age at the metacarpals by MCM measures, compared to hip or forearm OXA measures, especially when associated with other medical conditions such as rheumatoid arthritis. Although MCM measures were not superior to OXA measures in fracture risk prediction, there may be a useful role for them in epidemiological studies or providing a clinical service where access to OXA is limited.

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Joshi, Rupali Narayan. "IDENTIFICATION OF MECHANISMS OF DELAYED PUBERTY ON BONE STRENGTH DEFICITS DURING DEVELOPMENT." Diss., Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/55431.

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Kinesiology
Ph.D.
Osteoporosis which is frequently referred to as a pediatric disease with geriatric consequences (Golden, 2000) can result from a lack of optimal bone accrual during the development (NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy, 2001). Pubertal timing is a key factor that contributes to optimal bone accrual and strength (Bonjour et al., 1994; 21 Warren et al., 2002). Bone mass doubles during the onset of puberty and young adulthood (Katzman et al., 1991) with more than 90% of peak bone mass being accrued at the end of second decade of life (Schneider & Wade, 2000). The rate of periosteal expansion is elevated during the pubertal period (Specker et al., 1987; Bradney et al., 2000) and this expansion parallels longitudinal growth (Parfitt, 1994). Irrespective of other changes, periosteal expansion lowers fracture risk by improving the strength of long bones by increasing the moment of inertia (Orwoll, 2003). Therefore, a delay in puberty may actually increase the time available for periosteal development and positively affect bone strength. Previous animal studies have shown decreases in strength, endocortical bone formation and increases in periosteal bone formation with delayed puberty. Clinical studies report negative effects of delayed puberty on bone mass accrual suggesting that delayed puberty is a multifactorial problem affecting bone strength development. The purpose of this study was to determine the effect of delayed puberty on mechanical strength and endocortical bone marrow cells in two models: female rats treated with gonadatropin releasing hormone antagonists (GnRH-a) and energy restriction (30%). Thirty-two female Sprague Dawley rats (21 to 22 days-of-age) were received from (Charles Rivers Laboratories, Wilmington, MA, USA) and housed individually at the Temple University Central Animal Facility (Temple University Weiss Hall). Animals were randomly assigned to one of three groups; control (n=10), GnRH-a (n=10) and energy restriction (ER) (n=12). The GnRH-a group was injected with gonadotropin releasing antagonist injections (GnRH-a) (Antide, Bachem, Torrance, Ca. USA) at a dose of 2.5 mg/kg/BW. The ER group received a 30% energy restricted diet (0pen Source diet (D07100606)(Research Diets, New Brunswick, NJ). All animals were sacrificed on Day 51. One way analysis of variance testing (ANOVA) with a significance level of 0.05 was used to assess group differences. Following the two protocols the uterine weight in the GnRH-a group was 80.6% lower than control; no change in the ER group. Ovarian weight was significantly lower in the GnRH-a group (83.3%) and in the ER group (33.3%) as compared to controls. A 22.7% lower muscle weight was found in the ER group but was equal to control and GnRH-a when normalized by body weight (BW). The retro-peritoneal fat pad weight was significantly decreased by 64.95% in the ER group as compared to controls. Energy restriction did not result in any deficit in bone strength when normalized by body weight however the GnRH-a group had a 26.2% lower bone strength compared to control. Histomorphometric changes were not significantly different between groups, but the ratio for periosteal versus endocortical bone formation rates for the control group was 1.38, GnRH-a was significantly higher with a ratio of 5.54 and for ER was 3.02 indicating that periosteal BFR are almost twice endocortical BFR in the experimental groups. There was a significant decrease in the trabecular percent bone volume (BV/TV) of the lumbar vertebra in the GnRH-a group (20.2%) compared to control. However BV/TV was significantly higher in the ER (18.4%) compared to the control group. Proliferation was suppressed to 59.6% of control in the GnRH-a group but only 85.5% of control in the ER group. The alkaline phosphatase activity was 31.2% lower in the GnRH-a group and 63.9% lower in the ER group. The relative quantification (RQ) of RUNX2 gene expression was lowest in control followed by GnRH-a and highest in ER group although no statistical significance was observed between any groups. Thus our data infers that 30% energy restriction does not negatively impact bone health. Thirty percent food restriction with no deficits in micronutrients or hormone suppression may just suppress growth as indicated by the maintenance of bone strength per body weight and equivalent muscle mass per body weight in the ER group compared to control. The GnRH-a injections resulted in decreased bone strength and trabecular bone volume. Female Athlete Triad or Anorexia Nervosa are the two clinical conditions hypothesized to result from a combination of ER and estrogen deficient environment. Studies replacing estrogen in hypothalamic amenorrhea or IGF-1 in anorexia alone have failed to improve bone mineral density (BMD), but a combination of IGF-1 and estrogen has been successful in improving BMD. This suggests that estrogen dependant and independent mechanisms work in combination to protect bone. Our study investigated both mechanisms separately and indicates that ER at 30% may be protective for bone health. Since estrogen deficiency may be the extreme end of the spectrum affecting trabecular bone, treatment therapies may have to be based on age, magnitude and severity of energy restriction and presence or absence of menstrual status.
Temple University--Theses

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27

Yamanaka, Atsushi. "Biomechanical Investigation of Anthropoid Limb Bone Morphology in Terms of Bending Strength." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149551.

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28

Burt, Lauren A. "Upper body bone strength and muscle function in non-elite artistic gymnasts." Thesis, Australian Catholic University, 2011. https://acuresearchbank.acu.edu.au/download/285f3fb7c88a999d12b83b71701c682999d6d8f0bb8cf51abb8134e482e0afa3/8793736/Burt_2011_Upper_body_bone_strength_and_muscle.pdf.

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Musculoskeletal development in the upper limbs of non-elite female gymnasts during pre and early pubescent growth is under researched. Most studies have focussed on elite rather than non-elite gymnasts, via dual-energy X-ray absorptiometry (DXA). The purpose of this thesis was to longitudinally characterise the effects of non-elite female artistic gymnastics participation on upper limb musculoskeletal parameters using peripheral Quantitative Computed Tomography (pQCT), DXA and muscle function assessments. Three major studies were designed. Study one compared the upper limb of two groups of gymnasts (high-training gymnasts (HGYM), participating in 6-16 hr/wk, low-training gymnasts (LGYM), participating in 1-5 hr/wk) and an age matched control group (NONGYM) for differences in bone mass, size and strength. Difference in upper limb muscle size, structure and function were also compared. Study two pooled both HGYM and LGYM to compare traditional pQCT skeletal parameters at the radius (4% and 66% sites) with NONGYM. To advance the understanding of site and bone specificity in young gymnastics, similar measures were also undertaken at the ulna. Study three combined variables in studies one and two in a longitudinal (6-month) comparison of the upper limb musculoskeletal changes in two groups of gymnasts (HGYM, LGYM) and a NONGYM group. Benefits beyond growth associated with gymnastics participation during pre- and early pubertal years were examined.

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Speed, Catherine A. "Grip strength, forearm muscle fatigue and the response to handgrip exercise in rheumatoid arthritis." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4871/.

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Weakness and subjective fatigue are common features of rheumatoid arthritis (RA). However, whether there is a true increase in the fatigability of rheumatoid skeletal muscle, in which fibre atrophy has been frequently reported, is unclear. Such factors may influence the ability to respond to exercise programmes. In this work, a reliable and sensitive technique for the objective measurement of forearm muscle fatigue during sustained grip was developed, using power spectral analysis of the surface myoelectric signal (SMES).The inter-relationships between grip force (hand function) and the activity and severity of the rheumatoid disease process with muscle fatigue (defined as the decline in the median frequency of the SMES with work, (MDFG)) and the initial median frequency of the SMES (IMF) were examined. It has been previously suggested that the IMF of the SMES may reflect the fibre type of the underlying muscle. The response to a 12-week progressive right hand grip strengthening programme in healthy females and those with RA was also evaluated. Potential predictors of outcome and the mechanisms of strength gain were examined. Forearm muscle fatigue in RA was not significantly greater than in healthy controls. However, higher levels of fatigue were associated with greater systemic disease activity and greater disease severity. The IMF of the SMES was shown to be stable over a wide range of grip forces for a given individual. It was significantly elevated in rheumatoid subjects, and showed a direct association with greater disease severity. Handgrip exercise was highly effective in improving hand function in females with RA. Strength gains were also demonstrated in healthy controls. Subjects with more severe disease and greater IMF of the SMES showed the greatest improvement in hand function. Greater systemic and local disease activity during the 12-week programme were limiting factors to improvement in grip. Local (right hand) disease activity remained stable or improved in the RA group overall, in spite of a trend towards deteriorating systemic and left handed disease activity. The two main potential mechanisms of strength gain (neural adaptation and gains in muscle mass) were assessed in both rheumatoid and healthy groups. The former was assessed by evaluation of the neuromuscular efficiency, derived from the relationship of the root mean square of the SMES at a given grip force. Gains in muscle mass were also assessed using this technique and by volumetric analysis of forearm musculature using magnetic resonance imaging. Although significant gains in muscle mass were demonstrated in the control group, no such gains were seen in the rheumatoid subjects. This indicates that neural adaptation was an effective method of strength gain in the rheumatoid group.

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Wilkerson, Lucas T. "FINITE ELEMENT ANALYSIS OF CANCELLOUS BONE." UKnowledge, 2012. http://uknowledge.uky.edu/me_etds/17.

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A variety of pathologies exist which increase the likelihood of bone fracture. Present methods for determining the fracture risk of a specific patient are based exclusively on the amount of bone present. While the quantity of bone tissue is correlated with strength, it neglects to account for bone’s intricate microarchitecture. To assess the effect of bone quality on strength, a methodology was developed for the structural analysis of cancellous bone biopsies. Thirty biopsies were selected from a pre-existing biopsy bank, and scanned using a SCANCO µCT-40 at a resolution of 30 microns. Cortical bone was removed from the resulting three-dimensional geometry, and the remaining cancellous bone was meshed with solid tetrahedral elements. A linear static uniaxial compression test was performed using ANSYS v14.0 to determine the apparent-level Young’s modulus. The maximum von Mises stress was also investigated, but showed poor convergence with increased mesh density. Consistent with the methodology of Pistoia et al., the failure load was assumed to occur when 2% of the bone volume exceeded 7000 µstrain. The results of the finite element analysis compared favorably with known values for cancellous bone strength.

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Suhr, Stephanie Marie. "A Fractal-Based Mathematical Model for Cancellous Bone Growth Considering the Hierarchical Nature of Bone." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright148467307435565.

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Custer, Erica M. "Cortical Bone Mechanics Technology and Quasi-static Mechanical Testing Sensitivity to Bone Collagen Degradation." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556281791006274.

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33

Radloff, Stefan E. "The effects of trabecular architecture, strength, and bone mineral density on calcaneal ultrasound." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11756.

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34

Dean, Maureen A. "Predictions of Distal Radius Compressive Strength by Measurements of Bone Mineral and Stiffness." Ohio University Art and Sciences Honors Theses / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1461595642.

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35

Furukawa, Taizo. "High-strength hydroxyapatite/poly (L-lactide) composites for internal fixation of bone fractures." Kyoto University, 2000. http://hdl.handle.net/2433/180873.

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36

Butler, Tiffiny A. "THE EFFECTS OF POST PUBERTAL FOOD RESTRICTION ON BONE ARCHITECTURE, STRENGTH, AND MEDULLARY ADIPOSE COMPOSITION." Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/244901.

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Kinesiology
Ph.D.
The purpose of this investigation was to determine the effects of post pubertal caloric restriction on bone architecture, strength, and medullary adipose quantity. A randomized control comparison design was utilized and the study was conducted in a laboratory setting. All procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at Temple University (protocol number 3396). Female Sprague Dawley rats (23days-of-age, n=120) were randomly assigned into seven groups, baseline (BL) (n=18), control (C) (n=17), caloric restriction (FR) (n=17), control recovery (RC) (n=17), caloric restriction recovery (RFR) (n=17), control ovariectomy (COVX) (n=17) and food restricted ovariectomy (FROVX) (n=17). On day 65, a 6 week 30% caloric restriction protocol was administered. Following food restriction, a subset of the control and food restricted groups were sacrificed (n=34) and the remaining animals (n=68) control recovery (RC) and food restricted recovery (RFR) groups had a 10 week recovery with ad lib food. Recovery groups, RC and RFR: were sacrificed after the 10 week recovery period at 183 days of age (n=34). The remaining animals were ovariectomized (OVX) and grouped into control ovariectomy (COVX) and food restricted ovariectomy (FROVX). Six weeks post OVX the animals were sacrificed at 270 days of age. After sacrifice blood was taken by cardiac puncture, bones were harvested, cleaned of soft tissue, fixed and prepared for analysis. Anthropometric measurements were taken including retroperitineal and gonadal fat pad weights as well as adrenal glands, ovaries, uteri, and tricep surae muscle group weights. Main Outcome Measures: The outcome variables for this study were bone mechanical competence, trabecular and cortical bone mass and architecture, marrow adipocyte number as well as serum markers of bone formation and resorption. Insulin - like growth factor - 1 (IGF-1) and C- terminal telopeptide (CTX) was measured to determine bone formation and resorption. Statistical Analysis: One-way Analysis of Variance (ANOVA) was performed to determine differences between all groups. Tukey's honestly significant difference (HSD) post hoc analysis was conducted to determine differences between groups. Student's t - tests were used to detect differences between age groups (acute, recovery, post-OVX) A p value was set at less than or equal to 0.05 for all statistical tests. All statistical analysis was performed using (GraphPad Prism version 5.00 for Windows, GraphPad Software, San Diego California USA). Variables were normalized with a linear regression-based correction using body weight. All variables with an R2 level greater than 0 were normalized to avoid choosing an arbitrary R2 value as a cut-off for normalization. Results: Body weight was 18% lower than control animals following caloric restriction. Weight loss was due to fat mass predominately; muscle mass was maintained relative to body weight. Bone length and growth rates were diminished however no differences were found following refeeding. No differences were found in bone strength at any time point. However relative to body weight peak moment and stiffness were significantly higher following caloric restriction. Cortical bones mass and cross sectional moment of inertia were enhanced in the femoral diaphysis with bone mass greater post OVX in the calorically restricted group (FR-OVX). No significant differences were found in ash percent in the femur was found between any groups at any time point however vertebral bone mineral density in acute FR and post OVX time points in FROVX was significantly greater indicating an enhanced bone quality in the restricted. No change in trabecular quantity or quality were observed in the distal femur between groups however vertebral trabecular architecture was enhanced in number and thickness in acute FR and post OVX time points in FROVX. No significant difference in number of marrow adipocytes were found at any time point. Serum CTX decreased significantly in acute in FR and increased at recovery in RFR and post OVX in FROVX. Serum IGF - 1 decreased in the acute FR with IGF - 1 significantly greater after recovery in RFR. Conclusions: Evidence was found to suggest that moderate caloric restriction (nutrient replete) post puberty was positive for bone. Bone quantity was increased with relative cortical area and bone area relative to body weight increased in the FR group. Significant increases in FROVX bone quantity post OVX suggests that bone mass gains during caloric restriction attenuated cortical bone loss at maturity post OVX. Bone quality increases in cross sectional moment of inertia relative to body weight may have accounted for the transient increase in FR bone strength in the femur. Decreases in acute CTX and IGF- 1 levels indicates that bone formation and resorption were decreased during development that may have been the mechanism for bone loss attenuated post OVX in calorically restricted. Growth rate slowing during caloric restriction may have decreased the rate of formation and resorption during a crucial time of peak bone mass accrual and bone modeling. This decrease in one modeling may have been mechanism that preserved bone quantity during acute caloric restriction. Increases in femur quality in polar moment of inertia coupled with a decrease in bone length changed the shape of the bone making it more robust. A shorter bone with a thicker cortex with no change in mineral content may have been the mechanism in the transient increase in bone strength in the femur. Quality changes in mineral density in vertebrae acting as a mineral storage back up as a last resort if quantity and quality changes were not sufficient in maintain bone strength. Moderate caloric restriction transiently increased strength, by increasing bone mass relative to body, altering bone geometry and increased vertebral mineral density.
Temple University--Theses

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Ahamed, Yasmin. "Sex-specific changes in bone structure and strength during growth: pQCT analysis of the mid-tibia." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/387.

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Introduction: The process by which children's bones grow has not been fully charcterised. The current dogma is that girls fill in their medullary canal area by forming bone at the endosteum. It has been argued that the sex difference in how bone strength is conferred -- favouring boys -- may contribute to the relative protection that aging men have over aging women with respect to fracture incidence and the prevalence of osteoporosis. Primary Objectives: 1)To compare bone surface changes at the periosteal and endosteal surface of the tibial midshaft in boys and girls. 2)To compare how bone density at the tibial midshaft is accrued in boys and girls. 3) To compare sex differences in bone strength accrual. Methods: Design and Participants: Participants were obtained from a 20-month randomized, controlled school-based physical activity intervention. As we found no difference in the effect of the intervention on pQCT bone outcome variables, both groups were combined for our current study. A total of 183 participants (93 boys, 89 girls) received a pQCT scan at baseline. Results: Sex-specific comparisons of the pQCT bone outcome variables showed significantly greater rates of change (slope) for boys for the total area (ToA), cortical area (CoA), medullary canal area (MedA) and strength-strain index (SSI) measures, p<0.001. No significant differences were observed for CoD, p=0.904. The magnitude of these differences is 60.8% for ToA, 55.7% for CoA, 75.6% for MedA, 1.3% for CoD, and 54.7% for SSI. Examination of differences between the sexes (intercept) revealed significant differences with greater gains observed for boys for all measures p<0.001 except for CoD where girls exhibited greater gains p<0.001. Conclusion: Girls showed a similar pattern of cortical bone growth at the tibial midshaft- periosteal apposition dominated over endosteal resorption. Boys' increased changes and pattern of growth were of a greater magnitude at both surfaces compared to girls. This resulted in a greater increase in strength as measured by SSI in boys which can partly be explained by their larger size. Girls exhibited greater increases in CoD; however, no significant difference in the change in CoD was observed between the two.

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38

Warnock, Sarah M. "Cortical Bone Mechanics Technology (CBMT) and Dual X-Ray Absorptiometry (DXA) Sensitivity to Bone Collagen Degradation in Human Ulna Bone." Ohio University Honors Tutorial College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1556305540256918.

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39

Ozdurak, Rabia Hurrem. "Vibration Analysis In The Diagnosis Of Bone Mineral Density In Healthy And Osteopenic Radius Bone And Its Correlation To Muscle Strength." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/12605109/index.pdf.

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Muscle strength is assumed to be closely related with BMD, the so called determinant of bone strength, however, new methods for bone strength measurement are arising. The purpose of this study was to determine the relationship between bone mineral density (BMD), muscle strength and natural frequency of the radius in the dominant and non-dominant arm in healthy and osteopenic individuals aged between 50-70 years. Sixty sedentary male (thirty healthy and thirty osteopenic) participated this study. Bone mineral density assessment was performed by dual x-ray absorbtiometry (DEXA) and quantitative computed tomography (QCT), whereas muscle strength was measured by an isokinetic dynamometer quantitatively. Natural frequency of the radius was determined by a dual channel frequency analyzer. Differences between BMD, muscle strength and natural frequency in healthy and osteopenic participants according to dominancy were examined by Analysis of Variance (ANOVA). Pearson Product Correlation Coefficient test was conducted to determine the magnitude of the correlation between cortical, trabecular and average BMD, muscle strength and natural frequency. Results demonstrated a statistically significant difference between BMD, natural frequency and muscle strength in the dominant arm of both groups. There was also a significant difference in the non-dominant arm in terms of BMD, natural frequency and muscle strength, except in total work in the non-dominant arms. Moreover, there was a moderate positive correlation between BMD measured by DEXA and natural frequency in the dominant arm (r = ,59
p <
.001) and non-dominant arm (r = 0,64
p <
0.001), whereas the muscle strength was correlated to BMD with a low positive correlation in terms of peak torque in extension (r = ,36
p = ,005), peak torque in flexion (r = ,31
p = ,016), total work in extension (r = ,28
p = ,030) and total work in flexion (r = ,27
p = ,041) in the dominant arms. The correlation between muscle strength and BMD was not significant in the non-dominant arm. The highest correlation between natural frequency and bone geometry parameters was observed in cortical thickness (r = ,82
p = ,02). A statistically significant positive correlation (r = ,81
p = ,04) was also observed between average BMD measured by QCT and by DEXA. In summary, according to the findings of this study, it can be concluded that vibration analysis is a precise method in predicting bone strength that depends highly on its size, shape and the distribution of its trabecular and cortical components.

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40

Zhang, Qilei. "Preparation of high-strength and high-modulus HA/UHMWPE nanocomposites for cortical bone replacement /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CBME%202008%20ZHANG.

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41

Altai, Zainab. "Prediction of the strength of human long bone using CT based finite element method." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21636/.

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42

Selmon, Serah Elizabeth. "Influence of Oral Contraceptives on Bone Adaptations to Isokinetic Strength Training in Young Women." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9852.

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Osteoporosis is a debilitating and costly disease of the skeleton characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Current data suggest that at present time, 7.8 and 21.8 million women have osteoporosis and osteopenia respectively. The development of osteoporosis and related fracture in later life depends not only on the rate of bone loss in adulthood, but also on the amount of bone present at skeletal maturity. Oral contraceptives (OC), because of their capacity to diminish concentrations of free testosterone and estrogen, have been purported to affect bone mass in young adult women, but results have proven inconsistent. Further, positive skeletal effects of exercise training are thought to be compromised by use of OCs in skeletally immature females. PURPOSE: To assess the independent and synergistic effects of OC use on bone mineral density (BMD) and long bone mechanical bending stiffness (EI) in college-aged females after unilateral isokinetic resistance training. METHODS: Forty six females (age 20 +/- 1.4 yr, height 163.8 +/- 6.2cm, weight 58.9 +/- 8.6kg, fat 27.9 +/- 4.8%) were categorized as OC users (OC, N=22) or non-users (NOC, N=24). Subjects participated in 32 weeks (3 d/wk) of unilateral arm and leg training at an angular velocity of 60 degrees/s using isokinetic dynamometers. BMD and EIMRTA were assessed using dual-energy x-ray absorptiometry (DXA) and mechanical response tissue analysis (MRTA), respectively. RESULTS: Total leg and arm muscular strength of the trained limb increased by 16% and 15%, respectively (p < 0.001), beyond changes observed in the control limbs. Total body BMD increased from baseline for NOC subjects (p < 0.05), but not for OC users. This difference failed to show significance (p = 0.069) when comparisons were run between NOC and OC groups. Increases in ulnar BMD (p < 0.01 for all limbs) and BMD of the trained total hip (OC, p < 0.001; NOC, p < 0.05) occurred irrespective of contraceptive status. Positive changes in EI were conflicting, occurring in the trained ulna for the NOC group (p < 0.05), and trained tibia for OC users (p < 0.05). Tibial BMD increased only for the untrained leg in NOC subjects (p < 0.01). No between group differences were found to be significant, nor were differences between trained vs. untrained, and weight bearing (tibia) vs. non-weight-bearing (ulna) limbs found to be significant. CONCLUSION: These results suggest that oral contraceptives may limit attainment of total body peak bone mass in young adult females. Skeletal maturation in the ulna appeared to be unaffected by exercise training and OC use. Positive effects of exercise training on the total hip were seen in both groups, irrespective of OC status. Conversely, exercise training and use of OCs use may limit the attainment of bone mass in the tibia. Further studies are needed to determine the interactive effects of OC use and isokinetic resistance training on measures of total body and site-specific bone status.
Master of Science

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43

Ljunggren, Ribom Eva. "Muscles, Estrogen, and Bone." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3779.

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44

Nelson, McKenzie Louise. "Predictions of Radius Bending Strength by Radius Stiffness, Mineral, and Ulna Mechanical Properties." Ohio University Art and Sciences Honors Theses / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1492615282195033.

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45

Wright, Nicole C. "The Association between Rheumatoid Arthritis, Bone Strength, and Body Composition within the Women's Health Initiative." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195197.

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Introduction: Osteoporotic fractures, a major public health problem in aging populations, can lead to increased disability and mortality. Though rheumatoid arthritis (RA) patients have a higher risk for fractures than healthy populations, it is not known how hip structural geometry and body composition, two factors associated with bone strength, affect fracture risk in this population. The overall goal of this dissertation is to examine the association between RA, fracture, hip structural geometry, and body composition, in the participants of the Women's Health Initiative (WHI).Methods: The association between probable RA and fracture risk was tested using the entire WHI cohort (n=161,808). The association between probable RA and hip structural geometry was tested, both cross-sectionally and longitudinally, in a smaller sample (n=11,020) of participants from the WHI Bone Density Centers (WHI-BMD). The last study, testing the association between probable RA and body composition was also conducted in the WHI-BMD cohort.Results: In comparison to the non-arthritic group, the probable RA group had a significant 50%, 2-fold, and 3-fold increase in any, spine, and hip fracture, respectively. The association was not mot modified by age or ethnicity, but glucocorticoid use altered the association between RA and spine fractures. In terms of geometry, the probable RA had a significantly lower (p<0.05) mean hip BMD, outer diameter, cross-sectional area, and section modulus at the narrow neck region compared to control groups, indicating reduced bone strength. Body composition changes were present between the probable RA and the control group, with the probable RA group having statistically lower estimate of lean mass and statistically higher estimates of fat mass compared to the non-arthritic control group cross-sectionally and over the study.Conclusion: These studies confirm the increased risk for fracture among RA patients, while providing evidence that RA alters bone strength, especially at the hip, and negatively effects body composition by reducing lean mass and increasing fat mass. Additional research is needed link structural geometry and body composition to bone strength to lead to tailored interventions to minimize decreases in bone strength in this high fracture risk population.

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46

Mardock, Michelle Anne. "Muscular Strength Training Modifies Regulation of Bone Remodeling: Inferences From Serum Biomarkers in Young Women." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34631.

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Biochemical markers of bone turnover allow inference of the events occurring at the bone tissue level and may detect changes in bone cell activity earlier than densitometric technologies. Serum concentrations of receptor activator for nuclear factor kappa-beta ligand (RANKL), osteoprotegerin (OPG), osteocalcin, and N-telopeptide (NTx) were measured in women aged 20 + 1.5 years (mean + SD) who underwent 32 weeks of unilateral isokinetic concentric or eccentric muscular strength training. Changes in serum biomarkers were compared with changes in arm and leg flexor and extensor muscle strength. Dual X-ray absorptiometry (DXA) measures of bone mineral density (BMD) and bone mineral content (BMC) of the total forearm, total tibia, and total body also were assessed. The mean serum OPG concentration increased from 4.6 + 1.9 pmol/L to 5.2 + 2.1 pmol/L (â 14.9 %, mean + SD; p = 0.05, n = 20) following long-term isokinetic exercise training that also increased elbow extensor and knee flexor muscular strength (p < 0.05) and total forearm BMD (p = 0.04). The ratio of OPG/RANKL also increased over the course of the study (p = 0.045). Serum concentrations of other measured bone biomarkers did not change during training. Serum concentrations of OPG, a suppressor of osteoclastogenesis, increased with high-load muscular strength training that led to local increases in muscle strength and BMD. These adaptations may represent an exercise-mediated suppression of osteoclast differentiation and activity. The central role of the RANKL-OPG cytokine system in the regulation of bone cell biology is well established. Further research is needed to confirm the efficacy of using serum OPG and RANKL as biomarkers of bone cell metabolism in healthy populations undergoing long-term exercise interventions.
Master of Science

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47

Mitchell, Kathryn Ann. "The Effect of Hypothalamic Suppression and Caloric Restriction on Bone Strength and Geometry during Puberty." Master's thesis, Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/175721.

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Kinesiology
M.S.
INTRODUCTION: Low energy availability and hypothalamic amenorrhea are both risk factors for developing insufficient bone mineral density (BMD) in young physically active women. The prevalence of osteopenia in women athletes is estimated to be between 22-50%. PURPOSE: Determine the effect of calorie restriction and hypothalamic suppression on bone strength and geometrical measures. METHODS: 30 female Sprague-Dawley rats, age day 23, were randomly assigned to a control (C, n=8) group that received daily saline injections (0.2cc) for 27 days and sacrificed at age day 50, or two experimental groups; delayed puberty (GnRH-a, n=14) that received daily injections of gonadotropin releasing hormone antagonist (GnRH-a, 0.2cc, dosage 0.2mg*kg-1) or food restricted and delayed puberty (FR-G, n=8) that received daily injections of gonadotropin releasing hormone antagonist and had a 30% caloric restriction (no deficit in micronutrients) based on the C group's average daily food consumption. All animals were sacrificed at age day of 50. RESULTS: Body weight on day of sacrifice of the FR-G was significantly lower than C (15%, p < 0.001) while GnRH-a was significantly higher than C (8%, p=0.013). The GnRH-a treatment was successful indicated by significantly lower uterine and ovary weights in both the FR-G and GnRH-a groups (p < 0.001). The percent muscle to fat ratio of the FR-G group was significantly higher than control (64%, p=0.038). There was no difference in absolute femoral peak moment, however when normalized for body weight the FR-G and GnRH-a groups were significantly higher than control (19%, p = 0.004 and 20%, p < 0.001 respectively). Cortical bone total area was significantly less in the FR-G group as compared to control (10%, p = 0.043) however, FR-G had a larger cortical thickness compared to control (15%, p = 0.036). In the trabecular both the GnRH-a and FR-G groups had a significantly lower percent bone volume per total volume (BV/TV) compared to control (p < 0.001). However, when normalized for body weight, the percent bone volume of the FR-G group was higher than both control (p = 0.046) and GnRH-a (p < 0.001). The structure was also affected, GnRH-a and FR-G had a higher structural model index (SMI) values than control (p = 0.002, p = 0.007). CONCLUSION: Hypothalamic suppression and caloric restriction before puberty reduced body weight, body fat, and muscle weight while increasing femoral peak moment relative to body weight and increasing cortical thickness in the femur while maintaining trabecular volume per body weight. These results could suggest bone strength is more correlated with body composition than hypothalamic function.
Temple University--Theses

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48

Gabel, Leigh Elizabeth Christine. "Bone strength accrual across adolescent growth and the influences of physical activity and sedentary time." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61281.

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With recent advances in imaging technologies, we are acquiring a better understanding of the complex hierarchy of bone and how bone adapts its geometry, microarchitecture and ultimately, its strength to withstand the loads imposed upon it during adolescent growth. Thus, in this thesis, I examine the influence of physical activity (PA), sedentary time, maturity and sex on estimated bone strength and its determinants (i.e., microarchitecture, geometry and density) across adolescence. This thesis is based on the UBC Healthy Bones III Study (HBSIII), a mixed longitudinal cohort of healthy girls and boys age 8-12 years at study entry. We assessed bone strength, geometry and density at the tibial shaft using peripheral quantitative computed tomography (pQCT) and bone strength, microarchitecture, geometry and density at the distal tibia and radius using high-resolution pQCT (HR-pQCT). We assessed PA and sedentary time using accelerometry. Four studies comprise this thesis. First, I investigated cross-sectional associations between sedentary time and bone strength and its determinants at the distal tibia by HR-pQCT. I found no associations between sedentary time and bone parameters. Second, I examined maturity- and sex-related adaptations of bone geometry and strength at the tibial shaft using pQCT. I found that larger bone area in boys provided them a greater bone strength advantage compared with girls across adolescence. Third, I examined maturity- and sex-related adaptations of bone strength and its determinants by HR-pQCT at the distal tibia and radius. I found greater bone strength in boys across adolescence was underpinned by greater trabecular bone volume and total bone area. Fourth, I examined prospective associations between PA, sedentary time and bone strength and its determinants at the distal tibia and radius using HR-pQCT. I observed greater bone strength and trabecular bone volume in participants engaging in more PA and lower total bone area in participants engaging in more sedentary time. Collectively, these studies enhance our understanding of how bone is gained during adolescence and add a unique perspective to the benefits of PA for bone strength and its determinants.
Medicine, Faculty of
Experimental Medicine, Division of
Medicine, Department of
Graduate

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49

Tan, Vina Phei Sean. "Effects of a school-based physical activity intervention on adolescent bone strength, structure and density : the Health Promoting Secondary Schools (HPSS) bone health study." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53717.

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Physical activity (PA) benefits bone strength in children but little is known of the effects of PA on bone strength in adolescents. In this thesis, my primary aim was to determine the effect of a secondary school based PA intervention on bone strength, structure and density in adolescents. This 8-month cluster, randomized-controlled, whole school-based intervention study had four intervention and five control schools. Participants were 210 Grade 10 students who were 15.3 years old, on average, at baseline. The Health Promoting Secondary Schools (HPSS) intervention was a choice-based model based on self-determination theory that aimed to increase PA, promote healthy eating and reduce screen time in adolescents. I used peripheral quantitative computed tomography (pQCT) to assess bone strength, structure and density at the distal and shaft sites of the tibia and radius. I assessed PA using a validated PA self-report questionnaire and I measured a sub-set of participants’ PA objectively using accelerometry. Part I is a systematic review and narrative synthesis of PA and pediatric bone literature. High-quality randomized-controlled trials (RCTs) with weight-bearing PA increased bone strength in children. Bone structure adaptations in response to PA were more common than adaptations in bone density (RCTs and observational studies). Only one RCT involved adolescents (average age 13.8 years) and studies often overlooked the influence of muscle on bone responses to PA. In Part II, moderate-to-vigorous PA (MVPA), vigorous PA (VPA) and grip strength positively influenced bone strength in boys and girls after controlling for ethnicity, maturity, limb length and muscle mass. Sedentary time (SED) negated the positive influence of MVPA, but not VPA, on bone strength in girls. In Part III, the HPSS intervention did not lead to significant gains in bone strength, structure or density in adolescents. The external factor of a province-wide teacher job action possibly hindered the execution of the HPSS intervention. In summary, MVPA and VPA benefit bone strength in adolescents but further investigations are warranted to determine the effects of SED on bone strength. It remains to be determined the effects of a choice-based intervention on bone strength adaptations in adolescent boys and girls.
Medicine, Faculty of
Medicine, Department of
Experimental Medicine, Division of
Graduate

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50

Ajaxon, Ingrid. "Can Bone Void Fillers Carry Load? : Behaviour of Calcium Phosphate Cements Under Different Loading Scenarios." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316656.

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Calcium phosphate cements (CPCs) are used as bone void fillers and as complements to hardware in fracture fixation. The aim of this thesis was to investigate the possibilities and limitations of the CPCs’ mechanical properties, and find out if these ceramic bone cements can carry application-specific loads, alone or as part of a construct. Recently developed experimental brushite and apatite cements were found to have a significantly higher strength in compression, tension and flexion compared to the commercially available CPCs chronOS™ Inject and Norian® SRS®. By using a high-resolution measurement technique the elastic moduli of the CPCs were determined and found to be at least twice as high compared to earlier measurements, and closer to cortical bone than trabecular bone. Using the same method, Poisson's ratio for pure CPCs was determined for the first time. A non-destructive porosity measurement method for wet brushite cements was developed, and subsequently used to study the porosity increase during in vitro degradation. The compressive strength of the experimental brushite cement was still higher than that of trabecular bone after 25 weeks of degradation, showing that the cement can carry high loads over a time span sufficiently long for a fracture to heal. This thesis also presents the first ever fatigue results for acidic CPCs, and confirms the importance of testing the materials under cyclic loading as the cements may fail at stress levels much lower than the material’s quasi-static compressive strength. A decrease in fatigue life was found for brushite cements containing higher amounts of monetite. Increasing porosity and testing in a physiological buffer solution (PBS), rather than air, also decreased the fatigue life. However, the experimental brushite cement had a high probability of surviving loads found in the spine when tested in PBS, which has previously never been accomplished for acidic CPCs. In conclusion, available brushite cements may be able to carry the load alone in scenarios where the cortical shell is intact, the loading is mainly compressive, and the expected maximum stress is below 10 MPa. Under such circumstances this CPC may be the preferred choice over less biocompatible and non-degradable materials.

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Dissertations / Theses on the topic 'Bone strength'

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