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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.


Assari, Soroush January 2011 (has links)
Background: Comminuted supracondylar femur fractures in the elderly are often treated with either retrograde femoral nailing or locked plating. Early weight-bearing is typically restricted after fixing supracondylar fractures, thereby impairing the patient's mobilization. In general, surgeons are more comfortable allowing early weight-bearing of long bone fractures after nailing rather than plating, but early studies of retrograde nails for supracondylar fractures using standard distal locking showed poor fixation compared with locked plating. Newer generation distal locking techniques, such as the spiral blade, may demonstrate improved fixation, potentially allowing early weight bearing. The purpose of this study is to biomechanically compare locked plating with retrograde nailing of osteoporotic supracondylar femur fractures with simulated physiologic weight-bearing in the post-operative period. Methods: The Locking Condylar Plate (LCP) and Retrograde/Antegrade EX Femoral Nail (RAFN) with spiral blade locking were tested using 10 paired elderly cadaveric femurs, divided into normal and low BMD groups, with a simulated AO/OTA type 33-A3 supracondylar femur fracture. Each specimen was subjected to 200,000 loading cycles simulating six weeks of postoperative recovery with full weight-bearing for an average individual and the construct subsidence and axial stiffness were measured. Results: LCP fixation compared to RAFN showed higher axial stiffness for normal and low BMD groups (80% and 57% respectively). After cyclic loading, axial stiffness of both constructs decreased by 20% and RAFN fixation resulted in twice as much subsidence (1.9±0.6 mm). Two RAFN constructs with low BMD failed after a few cycles whereas the matched pairs fixed with LCP failed after 68,000 and 100,000 cycles. Conclusions: The LCP construct was stiffer than RAFN construct. Early weight bearing may cause 3-4 mm of subsidence in elderly patients with low BMD. However, because of the observed failures in two of the samples treated with RAFN in the low BMD group, early weight bearing is not recommended in osteoporotic bones treated with RAFN. / Mechanical Engineering


Man, Yuncheng 25 January 2022 (has links)
No description available.

A Breathing Intervention to Enhance Cardiac Regulation and Mitigate Stress in Police Cadets

Napier, Samantha 01 January 2021 (has links) (PDF)
Maintaining effective performance under stress can be challenging, especially in the dangerous environments encountered by the police and military personnel. This document reviews the impact of stress on performance, discusses breath interventions as a means of stress mitigation, suggests an approach for exploring the value of a breath intervention in police cadets, tests, analyzes, and discusses a test of this method and results. Biofeedback training can be used to produce resonance breathing that is synchronized with heart rate and optimizes heart rate variability (HRV). This intervention was expected to alleviate physiological and subjective stress responses. Studies reviewed confirm that higher HRV is associated with lower stress and better cognitive performance. Training resonance breathing produces similar results when studies are well-designed. Relative to controls, resonance breathing training should improve the performance of police cadets on a series of cognitive and physical tests included in their curriculum, and on a simulated operational scenario given at the end of training. Research also tested whether personality traits associated with resilience predict higher baseline HRV and better performance during training.

Lateral wedges and the biomechanical risk for knee osteoarthritis

Russell, Elizabeth M 01 January 2011 (has links)
Obesity is the primary risk factor for the development and progression of medial compartment knee osteoarthritis. Laterally-wedged insoles reduce many of the biomechanical risk factors for disease development and progression in osteoarthritis patients and lean individuals but it is unknown how efficacious they may be for asymptomatic, but at-risk, obese women. 14 Obese and 14 Control women participated. The purpose of the first study was to examine how an 8° laterally-wedged insole affected the kinetics and kinematics of the lower extremity. The results of a gait analysis indicated that the insole reduced the peak external knee adduction moment and the impulse of the moment in both groups while minimally affecting the kinematics of surrounding joints. A second study examined the benefits of the wedge on the mediolateral shift in the center of pressure on the tibial plateau. A musculoskeletal modeling analysis estimated muscle forces and joint contact forces. The results showed that the wedge laterally shifted the center of pressure of the joint contact force and redistributed a portion of the mechanical load off the medial compartment of the knee joint. This partial unloading of the medial compartment has critical implications for medial knee osteoarthritis prevention. The final study quantified the coordination patterns between articulating segments of the lower extremity. The purpose of this study was to determine if the insole detrimentally affected the coupled rotations. The results of a vector coding analysis indicated similar coupled transverse rotations of the leg and thigh segments and of the transverse rotations of the leg and frontal plane rotations of the foot. In conclusion, the insole may be used to relieve a biomechanical problem at the knee joint without detrimentally affecting the coordinated rotations of the lower extremity segments. The results of these studies suggest that biomechanical benefits may be achieved through the use of laterally-wedged insoles in obese populations. Thus, obese individuals who are at risk for medial compartment knee osteoarthritis may be able to use the wedged insole to delay or prevent disease onset.

The role of the upper body in human locomotion

Baird, Jennifer L 01 January 2012 (has links)
The arms and thorax are integral parts of the human body for locomotion. However, the legs have been the focus of study in a majority of research on human walking and running. The human body functions best when all the parts work together as a cohesive unit. The overall aim of these studies was to analyze changes in arm, thorax and pelvis interactions under various manipulations, and to relate those findings to angular momentum control. Manipulations used were: gait speed, arm and thorax kinematics (removal of arm swing and reduction of axial rotation), age and mode of locomotion (walking and running). In the first study, manipulating arm swing and axial rotation led to changes in thorax-pelvis coordination and upper and lower body angular momentum that were designed to maintain angular momentum control through adapted arm swing. Walking without arm swing resulted in an increase in the range of whole-body angular momentum. This increase in angular momentum could potentially lead to problems in maintaining balance. In the second study, older adults demonstrated a smaller change than young adults did in thorax-pelvis coordination with increasing speed. However angular momentum differences were apparent at slower speeds but not faster, indicating that older adults regulate angular momentum independently of coordination, and do so differently than young adults. In the third study, walking and running locomotion modes led to a different organization of thorax-pelvis coordination and arm swing. This resulted in an inverse relationship between coordination and angular momentum regulation. The more out-of-phase coordination pattern in walking had smaller arm swing, while a more in-phase coordination pattern in running was associated with greater arm swing. In both modes of locomotion, arm swing was used to generate angular momentum to counter that of the legs. The general finding from these studies is that angular momentum is a factor of human locomotion that is regulated regardless of the degree of thorax-pelvis coordination in order to allow the momentum of the arms to counter that of the legs. This balance of angular momentum is likely important for the energetics and control of walking, and is an indirect result of the linking of upper and lower body movements. Arm swing is important for regulating angular momentum and plays a key role in countering the momentum generated by the legs.

Effects of Dual Tasking on Anticipated and Unanticipated Cutting Maneuvers on Knee Biomechanics in Collegiate Male Athletes

Frendt, Taylor Renee 19 October 2017 (has links)
No description available.

Biomechanical Comparison of Various Posterior Dynamic Stabilization Systems for Different Grades of Facetectomy and Decompression Surgery

Parikh, Rachit D. January 2010 (has links)
No description available.

Biomechanical Comparison of Meniscal Repair Systems in Shear Loading

Kaufmann, Alan January 2013 (has links)
A meniscal tear is an injury that often occurs as a result of a varus or valgus rotation of the femur on the tibia coupled with axial rotation while the knee is partially flexed, thus creating preferential loading of the posterior horn and shear forces on the meniscus. Such injuries can be repaired surgically, either with standard suturing techniques or with commercially available all-inside meniscal repair devices, which are designed to make the repair surgery faster, easier, and potentially safer. Many prior biomechanical studies have loaded an excised, repaired meniscus in tension and found that the repaired meniscus performs similarly to an uninjured sample. However, it is more appropriate to apply shear forces to the tissue in order to simulate the mechanism of injury. To date, three prior studies have investigated the biomechanical properties of meniscal repairs in shear, all of which used isolated meniscal tissue samples. The present study used an in situ bovine model to investigate the strength of commercially available meniscal repair systems under a shear loading regime. Medial menisci were torn and subsequently repaired using one of three techniques: standard inside-out vertical mattress sutures, Depuy Mitek Omnispan, or Smith & Nephew Fast-Fix. A control group was left unrepaired. Samples were subjected to a battery of cyclic side loading to create shear forces within the knee. Statistical analysis (ANOVA) demonstrated no significant difference in the stiffness, shear force, or subsidence between groups. The conclusion that the repair techniques perform similarly is consistent with tensile and in situ testing. Pathological observations showed no significant differences between repair devices, but all repaired samples demonstrated less wear than unrepaired samples, indicating that the experimental model is an effective method for creating wear within the knee. This result indicates that the flexible all-inside devices are mechanically comparable to the more commonly performed conventional suturing techniques. It is concluded that the mechanical performance may not be the best indicator of success of the surgical repair, as long as the device is able to anatomically reduce the tear. / Bioengineering

Design and Analysis of a Biomechanical Model of the Rat Hindlimb with a Complete Musculature

Young, Fletcher 23 May 2022 (has links)
No description available.

Advancing the delivery of aerobically intense walking training for walking recovery after stroke

Cataldo, Anna Virginia Roto 17 January 2023 (has links)
Stroke survivors define the recovery of safe, efficient, and independent walking as a top research priority after stroke. Eighty percent of stroke survivors experience significant and lasting walking challenges with approximately 1/4 of survivors unable to achieve independent walking by three months after stroke. The heterogeneous nature of post stroke recovery presents a significant challenge in developing more targeted, personalized walking interventions after stroke. The effectiveness of neurorehabilitation to facilitate motor recovery is predicated on the ability of the nervous system to reorganize and remodel (i.e., neuroplasticity) in response to an intervention. Aerobic exercise generates neuroplastic potential meaningful for motor learning; this is largely evidenced by improvements in motor skill acquisition, accuracy, and retention in neurologically-intact individuals following an acute bout of high intensity exercise. The beneficial priming effect of high intensity aerobic exercise suggested by these results is exciting, especially in the context of stroke motor recovery, yet the exact mechanisms contributing to the beneficial priming effect of exercise on learning are not well defined. In contrast, it is well-recognized that, along with task-specificity and amount of practice, aerobic intensity is a critical training parameter for walking recovery interventions after stroke. Indeed, higher aerobic training intensities have generally contributed to greater improvements in walking function, as measured by improvements in functional measures of walking speed and endurance, in addition to cardiovascular fitness. Given the evidence, recent clinical practice guidelines for stroke gait rehabilitation emphasize training intensity to not only drive cardiovascular benefits but to also promote neuroplastic changes that maximize the potential for motor learning after stroke. That is, beyond the amount of practice, the intensity of practice is considered a critical component of the “dose” of training. However, strategies to optimize the dosage of training parameters for a given stroke survivor remain largely undefined. Taken together, there is a recognized need to (i) expand the evidence-base of performance measures that may aid in optimizing training dose, including the (ii) use of biomarkers, and to (iii) explore promising interventions focused on optimizing the intensity of practice. Study 1 of this dissertation is meant to expand the evidence-base of performance measures that may aid in optimizing training dose by improving the ability to monitor training intensity—a critical component of training dose—during walking after stroke. To that end, I developed and validated five equations that can be used by clinicians at point-of-care to more accurately and reliably measure training intensity compared to the current standard proxy measure, heart rate monitoring. Study 2 of this dissertation is meant to evaluate the effects of a novel soft robotic exosuit-assisted walking intervention focused on optimizing training intensity, as well as the value of an intensity-dependent molecule, brain-derived neurotrophic factor (BDNF), as a biomarker of treatment efficacy. Results suggest that exosuit-assistance may promote high intensity walking training, at a level that elicits an increase in serum BDNF levels, and in a manner that may reduce the reliance on propulsion-based compensatory walking mechanics that worsen peak propulsion symmetry. / 2024-01-17T00:00:00Z

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