Femoroacetabular impingement syndrome (FAIS) is a disorder characterized by specific morphology of the femur and/or acetabulum, which may lead to hip pain during gait. Compared to individuals without pain, people with FAIS walk with more anterior pelvic tilt, and their pain may result from excessive anteriorly-directed hip joint forces. Previous approaches using musculoskeletal modelling to calculate joint forces, however, may inaccurately assume that each individual stands in an entirely neutral position when determining static joint angles. Consequently, information on parameters that affect joint forces (such as pelvic tilt) is lost in kinematic data used to estimate joint loading. To observe the effect of computationally altered pelvic tilt on joint forces, gait data of six healthy individuals were processed using Vicon and Visual3D. Each participant’s pelvic tilt was adjusted by ±5 degrees and ±10 degrees of tilt at all time points. Five analyses were performed per individual: no change in tilt, two posterior (positive) tilts, and two anterior (negative) tilts. The resulting data were imported into OpenSim to estimate forces from the femur onto the acetabulum in the anterior, superior, and medial directions. Data for each participant were normalized for gait cycle and body weight in MATLAB. Statistical parametric mapping software was used to determine if the differences in joint loads were significant. A more anterior pelvic tilt led to a reduction in anteriorly-directed joint forces, and an increase in the superior and medial directions. Based on these results, each individual’s pelvic tilt (obtained from their stationary kinematic data) was accounted for when modeling FAIS and healthy individuals. Using the same methods as above, the hip joint forces of 22 people with FAIS were compared to those of 22 healthy individuals as both groups walked at a prescribed speed. Although there were reductions in joint forces in both FAIS limbs compared to those of the control group, the differences were not significant, possibly due to the high variability of joint forces. Despite the significant effects of pelvic tilt on hip joint force, other underlying assumptions need to be addressed in musculoskeletal modeling software in order to compare different conditions, such as the use of the same generic model despite differences in sex and hip morphology. Future studies comparing pathological and healthy joint loads can inform researchers on gait alteration strategies and the design of assistive devices to manage the symptoms and onset of conditions such as FAIS. / 2022-05-15T00:00:00Z

<p>Type 1 diabetes mellitus (T1DM) is a disease defined by its complications as much as its central pathology. One such complication, diabetic myopathy, has received more attention in recent years as it has become clear that by maintaining a healthy skeletal muscle mass, diabetic individuals are more likely to maintain metabolic control and avoid the health consequences associated with hyperglycemia. While only a limited number of studies have been performed on diabetic human skeletal muscle, the research clearly indicates that a loss of muscular strength and alterations in muscle phenotype are a result of T1DM, occurring within weeks of disease inception. Studies employing rodent models of T1DM have identified several key changes underlying the loss of contractile capacity and the changes to muscle phenotype. The research to date, however, has yet to thoroughly elucidate the mechanisms underlying diabetic myopathy. The goal of the following studies is to gain a more thorough understanding of the effects of T1DM on skeletal muscle contractile capacity, morphology, and regenerative capacity using the C57BL/6J-<em>Ins2^Akita</em> (<em>Ins2</em>^WT/C96Y) diabetic mouse model. Given the crucial role of muscle repair in maintaining a healthy muscle mass, any deficit observed here could have important implications in the pathophysiology of diabetic myopathy. The results of the following studies indicate that the <em>Ins2</em>^WT/C96Y mouse undergoes a loss of glycolytic muscle mass and other morphological/phenotypic alterations concomitant with loss of peak contractile force. Furthermore, the regenerative capacity of the muscle following injury is impaired in glycolytic muscle groups, particularly the tibialis anterior (TA). This impairment in regeneration can be, at least partly, attributed to chronic elevation in plasminogen activator inhibitor-1 (PAI-1). Pharmacological inhibition of this hormone improves regeneration of the TA in the <em>Ins2</em>^WT/C96Y mouse. These data have improved our mechanistic understanding of diabetic myopathy and have clinical implications for the treatment of T1DM.</p> / Doctor of Philosophy (PhD)

<p><strong>Background and Objectives: </strong>There are methodological challenges with research in osteoporosis. The first is to predict the lifetime risk of hip fracture incorporating trends in the rates of hip fracture and mortality. The second is to identify optimum pharmacotherapy to reduce fractures in the absence of active-comparator trials. A third is to isolate the costs for incident and prevalent fractures. The objective of this thesis is to investigate these issues.</p> <p><strong> </strong><strong>Methods: </strong></p> <p>Project 1: From national administrative data, we estimated the lifetime risk of hip fracture for age 50 years to end of life using life tables.</p> <p>Project 2: A literature review identified randomized placebo-controlled trials with nine drugs for post-menopausal women to estimate odds ratios between drugs for fractures.</p> <p>Project 3: From provincial administrative data from Manitoba excess costs relative to matched controls were estimated for incident fractures, prevalent fractures and non-fracture osteoporosis. .</p> <p><strong>Results and Conclusions:</strong></p> <p>Project 1:<strong> </strong>For women and men, the crude lifetime risks of hip fracture was 12.1% and 4.6% respectively, and lower after incorporating trends, 8.9% and 6.7%. The risk is expected to continue to fall for both women and men.</p> <p>Project 2: Three drugs, zoledronic acid, teriparatide and denosumab, had the highest odds of reducing fractures and the largest effect sizes. Estimates were consistent between Bayesian and classical approaches.</p> <p>Project 3: All incident fracture types and most prevalent fractures had significant excess costs, and the results were robust to assessment of missing variances. Excluding prevalent fractures underestimates the cost of illness of fractures.</p> / Doctor of Philosophy (PhD)

Submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic, Department of Chiropractic, Durban University of Technology, Durban, South Africa, 2016. / Background: Tennis is one of the most popular sports globally with over 75 million players around the world. Most studies have focused on junior or elite level players although the majority of players around the world are presumed to be recreational/non-professional players. To date, limited research is available pertaining to the epidemiology of tennis related musculoskeletal in non-professional league tennis players in South Africa. This study aimed to determine the profile of musculoskeletal injuries amongst league tennis players in the northern eThekwini region. Methods: This was a quantitative, cross-sectional, descriptive study utilizing a self-administered questionnaire, developed specifically for this research utilizing an expert group and pilot study. The questionnaire contained sections on demographics, tennis history, training and nutrition, court surface and equipment as well as a section on tennis related musculoskeletal injuries. Risk factors for injury were first tested using chi square tests in the case of categorical variables, and t-tests in the case of continuous variables. In order to assess the relationship between injury and potential risk factors for injury, a binary logistic regression using backward selection based on likelihood ratios was used. Odds ratios and 95% confidence intervals of the variables remaining in the model at the end were reported. A p value <0.05 was used to indicate statistical significance. Results: Eighty league tennis players responded giving a response rate of 70.16%. The period prevalence, and the point prevalence of tennis related musculoskeletal injury was 68.75% and 36.25% respectively. A predominance of injuries to the upper extremity were recorded (49%) compared to the lower extremity (27.5%) and the back and trunk (23.5%). The elbow was the most common anatomical site of injury (21.4%) followed by the shoulder (19.4%), the lumbar spine (17.3%) and the knee (8.2%). Age was considered to be a risk factor for injury (p=0.049) as older players in the study (49.32 (17.547) years of age) were less likely to contract an injury than younger players (48.38 (13.210) years of age). The likelihood of injury decreased with a higher Body Mass Index (p=0.042). The relationship between consumption of spirit alcohol and injury was significant (p=0.043). Ex-smokers had a higher chance of contracting an injury (p=0.013). It was also found that those who cycled weekly were less likely to contract an injury (p=0.040). Conclusion: The results concur with other studies on recreational/non-professional tennis players and add insight into risk factors predisposing this population to injury. Health care practitioners need to understand the risk factors for injury in this population so that players can be better managed. Using the results of the study, an injury prevention strategy such as a strength and conditioning program, needs to be implemented with the goal to reduce or prevent common injuries in this population of players. / M

<p>Dedicated to the memory of Dr. Colin E. Webber</p> / <p>This comparative study of peripheral (p) QCT, high-resolution pQCT (hr-pQCT) and 1.0 Tesla pMRI technologies quantified short-term test-retest reproducibility, validity, one-year detection limit and clinical sensitivity of each modality’s derived bone measures. Select bone outcomes were evaluated from scans performed on Hamiltonian women above 50 years old and externally validated in a population-based cohort. In the local cohort (age: 74 ± 9 years and BMI 27.65 ± 5.74 kg/m²), Tb.Sp measured on pMRI, Ct.Th and vBMD from pQCT showed significant correlations (r²=0.52-0.85) with hr-pQCT, yielding slopes near unity. Bland-Altman analyses revealed significant relationships between pQCT and pMRI bone outcome values (Tb.Th(-), Tb.N(+), BV/TV(-)) and agreement with hr-pQCT. Short-term reproducibility was < 5% for pQCT but only BV/TV was < 5% for pMRI. Co-registration and excluding individuals with fractures mildly reduced precision error and one-year change. In the local cohort, only Ct.Th and cortical vBMD associated with fractures (OR: 1.09-3.28) using hr-pQCT, which was externally validated in the national cohort. Certain trabecular measures on pMRI and pQCT erred towards increased odds for fractures locally. For pQCT, these became significant in the national cohort (OR:1.04-3.81). This Canadian reference dataset for hr-pQCT showed larger Tb.Sp and smaller Tb.N compared to Americans but age-related decline in Ct.Th and BV/TV was faster in Europeans. This study demonstrated validity of pMRI and pQCT-derived volumetric bone outcomes and reasonable short- and long-term precision error for pQCT but not 1.0T pMRI. A single CT slice from pQCT was comparable to 110 slices from hr-pQCT in associations with fractures.</p> / Doctor of Philosophy (Medical Science)

Hairdressers’ exposure to work-related musculoskeletal disorders (WMSDs) appears to be insufficiently described in the literature. Knowledge regarding musculoskeletal disorders in this group is also sparse. The purpose of the research was to investigate the status of work-related musculoskeletal disorder cases found in Taiwanese hairdressers and to develop user-centred, strategic solutions to prevent the accumulation of musculoskeletal disorders in this group, especially newcomers to the industry. The study involved a series of investigations into the status of WMSDs for hairdressers in Taiwan as a first step towards their prevention. A hairdresser-oriented, musculoskeletal questionnaire was used to discover the risk factors associated with WMSDs and a validated, on-line, rapid, upper-limb assessment tool was used to identify critical hairdressing working postures. Improvements to the main critical hairdressing working postures identified by the first stage of the research have been addressed by an ergonomics training programme. The effectiveness of this is validated using 3D-motion analysis based on a pre- and post-test evaluation of awkward movements. A scientific approach to 3D-motion analysis has been achieved specifically by the study of the awkward working postures of the upper extremity during hair-blow-waving and hair-straightening activities. The relationship between working postures and WMSDs in various body regions is discussed. In this regard, poor posture and movement can lead to local mechanical stress on the muscles, ligaments and joints, resulting in discomfort in the musculoskeletal system, particularly the neck, back, shoulder and wrist. This research has provided a WMSDs prevention framework as a strategic method of securing a continuous improvement in the awkward working postures adopted during various hairdressing activities. Topics for further studies are suggested.

Bisphosphonates (BPs) are used for the treatment of osteoporosis. This study evaluated changes in bone microdamage with BP treatment duration. Fifty-one iliac crest biopsies were obtained from Caucasian women, ages 41 to 87 years, who were previously diagnosed and treated for osteoporosis with oral BPs for 1-16 years duration. Patients diagnosed with any disease, drug, or substance abuse that may affect bone metabolism were excluded. Bone samples were sectioned, stained, and histologically examined using light and fluorescence microscopy. Bone area, number and length of microcracks were quantified. Following adjustment for age, BMD, BV/TV, trabecular thickness, and turnover, regression analysis revealed a relationship between microcrack density and treatment duration (p=0.018). No significant relationship was observed between microcrack length and treatment duration. This study provides novel data relating microdamage with varying BP treatment duration in human bone. Given information from other studies showing that microdamage amounts are related to changes in bone biomechanics, the BP treatment duration related changes in microdamage shown offer new information that may help optimize osteoporosis treatment.

It has been deduced from indirect evidence that significant adjustments of vascular resistance take place in the venous network when blood flow changes in a organ. In the following experiments, we attempted to test the hypotheses that changes in postcapillary resistance in skeletal muscle may be due to changes in venous diameter, changes in the number of venules with blood flow, and/or changes in the apparent viscosity of blood in venules. The hypotheses were tested by observing the response of cat sartorius muscle venules (7-200 μm diameter) during arterial pressure reduction and muscle contraction. There was no observable change in venular diameter during any of the above perturbations. There was a significant decrease in the already low normalized velocity of blood in venules from a mean of 13 sec⁻¹ under control conditions to 5 sec⁻¹ during arterial pressure reduction to 20 mm Hg. At very low pressures, the number of venules with blood flow decreased. Combining our findings with Lipowsky's (1975) in vivo viscometry data, it was predicted that resistance in venules would increase 100% as a result of increases in blood viscosity when blood flow was reduced 60%. During post-contraction hyperemia the normalized velocity of blood in venules increased from 16 sec⁻¹ to 38 sec⁻¹ and the number of venules with blood flow increased a modest amount. Combining our observations with Lipowsky's data, we predict that venular resistance would fall 54% when blood flow increased 250% If shear rate changes cause substantial changes in blood viscosity in venules as suggested by the findings cited above, hydrostatic pressure in the small venules should tend to remain relatively constant as flow is altered. To determine whether this is the case, pressures of venules were measured using the servo-null technique during arterial pressure reduction. Pressures in the larger venules were a linear function of blood pressure and blood flow with an intercept not significantly different from the systemic venous pressure. Pressures in the smallest venules studied (24 μm), however, were somewhat insensitive to alterations in blood pressure (intercept of 10.4 mm Hg) and blood flow (intercept of 13.2 mm Hg). The stability of pressure in 40 venules supports the hypothesis that variable blood viscosity maintains the pressure drop in the venous network and the capillary hydrostatic pressure somewhat constant during changes in blood flow.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Objectives: The overall aim of this thesis was to investigate the precision error, annual changes, and monitoring time intervals of muscle and fat outcomes measured by peripheral quantitative computed tomography (pQCT), as well as explore the strength of their associations with fall status in older adults. Methods: Participants aged >60 years old (N=190) were recruited from the Saskatoon Cohort of the Canadian Multicentre Osteoporosis Study (CaMOs). The precision error (Root Mean Squared Co-efficient of Variation, CV%RMS) of soft-tissue outcomes from previously reported pQCT image analysis protocols (n=6) were calculated and compared using repeat forearm and lower leg scans collected from a random sub-sample of women (n=35). Prospective scans were collected with 1 and/or 2 years of follow-up (n=97) to estimate annual changes and monitoring time intervals for pQCT-derived muscle and fat outcomes in women. Imaging data and responses from a retrospective fall status questionnaire were analyzed to investigate the associations of muscle density, functional mobility, and health- related factors to fall status for both men and women (n=183). Results: Precision errors of muscle and fat outcomes ranged from 0.7 to 6.4% in older women, however not all protocols were equally precise. Muscle cross-sectional area decreased by 0.8 to 1.2% per year, with greater losses in the lower limb. Biological changes in muscle area and density may be detected with 80 and 95% certainty within monitoring time intervals of 4 to 9 years. The odds of having reported a fall increased by 17% for every unit decrease in muscle density (mean 70.2, SD 2.6mg/cm3) after adjusting for age, sex, body mass index, general health status, diabetes, the number of comorbidities, and functional mobility. Discussion: This dissertation demonstrated the potential for pQCT to study changes in muscle and fat outcomes in older adults. Both muscle area and density can be precisely measured. Observed annual changes in soft-tissue outcomes were small in older adults; highlighting the importance of precise measurements to detect changes beyond measurement error. Together with the estimated monitoring time intervals, these findings can assist the planning of prospective investigations of musculoskeletal health in aging. Furthermore, based on the observed independent association between muscle density and fall status, monitoring muscle density may further complement the study of musculoskeletal health and fall risk in community-dwelling older adults.