294 research outputs found

    Biomechanics

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    Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse dynamics, finite element analysis, and musculoskeletal modeling are used to simulate and investigate human situations in regard to movement and injury. Biomechanical technologies are progressing to answer contemporary medical questions. The future of biomechanics is dependent on interdisciplinary research efforts and the education of tomorrow’s scientists

    Master of Science

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    thesisMusculoskeletal disorders, fatigue and other problems associated with the use of traditional, hand-rim wheelchairs have been documented in several studies. In response to these problems students in the Mechanical Engineering program at the University of Utah have created three alternative propulsion wheelchair prototypes. The three designs are the hand-lever, track-ball, and four-bar design. These wheelchair prototypes were designed to reduce injuries and fatigue, while maintaining safe, ergonomic function. This study tested and compared these prototypes, as well as a traditional hand-rim wheelchair. Each wheelchair propulsion system was evaluated using a wide spectrum of tests. This allowed the evaluation of each system's strengths and weaknesses. These tests included metabolic evaluation, maneuverability, usability and biomechanical modeling. The metabolic testing revealed that the upper body propulsion systems had lower energy demands than the lower body propulsion systems. Maneuverability testing found that the arm lever and hand-rim systems were the two systems which were most maneuverable. Biomechanical modeling noted that the hand-lever had lower force requirements and lowest joint moments than the hand-rim design and the four-bar had lower force requirements and lower joint moments than the trackball

    Quantitative Evaluation of Geared Manual Wheelchair Mobility in Individuals with Spinal Cord Injury: An Integrative Approach

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    The purpose of this dissertation is to quantify the effects of using geared wheelchair wheels on upper extremity biomechanics and energy expenditure during functional mobility tasks in individuals with spinal cord injury (SCI). The effects of using geared wheels on hand-rim biomechanics, glenohumeral joint dynamics, and shoulder muscle activity were investigated during manual wheelchair propulsion over tiled and carpeted level-floors and up a ramp in low gear (1.5:1) and standard gear (1:1) conditions. The results for the hand-rim biomechanics indicated that regardless of the terrain, using the geared wheels in the low gear condition significantly decreased the propulsion speed, stroke distance, and hand-rim kinetics, including the peak hand-rim resultant force, propulsive moment, and rate of the rise of the resultant force. The significant decrease in the normalized integrated hand-rim propulsive moment suggests that the low gear condition is less demanding than the standard gear condition, in spite of the higher repetition during propulsion in low gear. Analysis of the glenohumeral joint dynamics and shoulder muscle activity during geared manual wheelchair propulsion over carpeted floor showed that the peak glenohumeral joint inferior force and flexion moment, as well as the shoulder flexors muscle activity, decreased significantly during the low gear condition. Manual wheelchair users with SCI were tested during the six-minute push tests on passive wheelchair rollers to evaluate the effects of using geared wheels on energy expenditure. The results indicated that using geared wheels in the low gear condition significantly increased the energy cost of propulsion and decreased the intensity of wheelchair propulsion. The findings of this dissertation demonstrate that using geared wheels in comparison to standard wheels decreases the demands on the upper extremity of manual wheelchair users, which may ultimately help preserve upper limb function leading to higher levels of activity, independence and quality of life

    EFFECT OF SEATING CUSHIONS ON PRESSURE DISTRIBUTION IN WHEELCHAIR RACING

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    This study investigated the efficacy of pressure mapping technology in quantifying athlete-wheelchair interaction at the seating interface, and the influence of foam inserts on pressure (peak and average), and contact area. An XSENSOR LX100 pressure mat was located at the seating interface of six nationally ranked wheelchair racing athletes, who performed regular propulsion on treadmill. Substantial inter-athlete variation was observed on resulting pressure distribution (area and magnitude) for all athletes. Implementation of a foam insert did not impede recording ability, however did alter seating characteristics, lowering seating pressure (peak and average), and increasing contact area. This increase may enhance athlete-wheelchair interaction, which will likely result in a more powerful technique, and increased probability of winning races

    Walker-Assisted Gait in Rehabilitation: A Study of Biomechanics and Instrumentation

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    While walkers are commonly prescribed to improve patient stability and ambulatory ability, quantitative study of the biomechanical and functional requirements for effective walker use is limited. To date no one has addressed the changes in upper extremity kinetics that occur with the use of a standard walker, which was the objective of this study. A strain gauge-based walker instrumentation system was developed for the six degree-of-freedom measurement of resultant subject hand loads. The walker dynamometer was integrated with an upper extremity biomechanical model. Preliminary system data were collected for seven healthy, right-handed young adults following informed consent. Bilateral upper extremity kinematic data were acquired with a six camera Vicon motion analysis system using a Micro-VAX workstation. Internal joint moments at the wrist, elbow, and shoulder were determined in the three clinical planes using the inverse dynamics method. The walker dynamometer system allowed characterization of upper extremity loading demands. Significantly differing upper extremity loading patterns were Identified for three walker usage methods. Complete description of upper extremity kinetics and kinematics during walker-assisted gait may provide insight into walker design parameters and rehabilitative strategies

    Effects of Stroke Patterns on Shoulder Joint Kinematics and Electromyography in Wheelchair Propulsion

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    The purpose of this dissertation was to analyze shoulder joint kinematics and electromyographic activities of wheelchair propulsion between two stroke patterns. Twenty physical therapy students (14 females and 6 males, age 27.4 ± 5.9 years, body mass 64.41 ± 9.37 Kg and body height 169.32 ± 9.12 cm) participated. Eleven reflective markers were placed on thorax and right scapula, humerus, third metacarpophalangeal joint and wheelchair axle. Surface electrodes were placed on right pectoralis major, anterior and posterior deltoids, infraspinatus, middle trapezius, biceps brachialis long head and triceps brachialis. Participants propelled a standard wheelchair on a stationary roller system at 0.9 m/s and 1.8 m/s with semicircular (SC) and single loop (SL) stroke patterns for 20 seconds. Three-dimensional body movement and muscle activities were recorded at 100 and 1000 Hz, respectively. All data were compared for differences between two patterns and two speeds using 2-way repeated measures ANOVA (α \u3c .05). Results showed longer drive phase and shorter recovery phase in SC when compared to SL, with no difference found on cycle time. Smaller release angles in SC caused longer angle ranges of hand contact on the pushrim while initial contact angles did not change. During drive phase, smaller scapular protraction range of motion (ROM) was found in SC. Shoulder abduction in drive phase was larger in terms of the maximal angle and ROM. In the recovery phase, minimal scapular tilting, protraction, and shoulder abduction and internal rotation were larger in SC when compared to SL pattern. Shoulder linear velocities and accelerations were higher in both phases for abduction/adduction and flexion/extension in SC. For SC pattern, pectorals major and middle trapezius showed lower activities during drive phase while posterior deltoid and triceps showed higher activities during both phases when compared to SL. Although posterior deltoid and triceps muscles work harder in SC pattern, longer drive phase and lower muscle activities in pectorals major and middle trapezius during the drive phase may make SC the better stroke pattern in wheelchair propulsion when compared to SL

    Markerless Kinematics of Pediatric Manual Wheelchair Mobility

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    Pediatric manual wheelchair users face substantial risk of orthopaedic injury to the upper extremities, particularly the shoulders, during transition to wheelchair use and during growth and development. Propulsion strategy can influence mobility efficiency, activity participation, and quality of life. The current forefront of wheelchair biomechanics research includes translating findings from adult to pediatric populations, improving the quality and efficiency of care under constrained clinical funding, and understanding injury mechanisms and risk factors. Typically, clinicians evaluate wheelchair mobility using marker-based motion capture and instrumentation systems that are precise and accurate but also time-consuming, inconvenient, and expensive for repeated assessments. There is a substantial need for technology that evaluates and improves wheelchair mobility outside of the laboratory to provide better outcomes for wheelchair users, enhancing clinical data. Advancement in this area gives physical therapists better tools and the supporting research necessary to improve treatment efficacy, mobility, and quality of life in pediatric wheelchair users. This dissertation reports on research studies that evaluate the effect of physiotherapeutic training on manual wheelchair mobility. In particular, these studies (1) develop and characterize a novel markerless motion capture-musculoskeletal model systems interface for kinematic assessment of manual wheelchair propulsion biomechanics, (2) conduct a longitudinal investigation of pediatric manual wheelchair users undergoing intensive community-based therapy to determine predictors of kinematic response, and (3) evaluate propulsion pattern-dependent training efficacy and musculoskeletal behavior using visual biofeedback.Results of the research studies show that taking a systems approach to the kinematic interface produces an effective and reliable system for kinematic assessment and training of manual wheelchair propulsion. The studies also show that the therapeutic outcomes and orthopaedic injury risk of pediatric manual wheelchair users are significantly related to the propulsion pattern employed. Further, these subjects can change their propulsion pattern in response to therapy even in the absence of wheelchair-based training, and have pattern-dependent differences in joint kinematics, musculotendon excursion, and training response. Further clinical research in this area is suggested, with a focus on refining physiotherapeutic training strategies for pediatric manual wheelchair users to develop safer and more effective propulsion patterns

    Manual Wheelchair Propulsion in Older Adults

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    Compared to individuals with spinal cord injury (SCI), propulsion by older adults is poorly defined. The goal of this project is to examine the impact of wheelchair, surface, and user characteristics on propulsion mechanics in older adults and individuals with SCI. All participants self-propelled over a series of surfaces at a self-selected velocity and kinetic data collection were provided by the SmartWheel. We described a standard clinical protocol (SCP) for objective assessment of manual wheelchair propulsion and defined reference values for individuals with SCI based this protocol (N=128). The SCP requires self-propulsion over tile, low pile carpet, and up an ADA ramp. In addition we provided a decision framework based on graphical reference data; guiding clinicians through an objective assessment of propulsion, identifying opportunities for intervention and follow-up. We then compared propulsion of individuals with paraplegia (IP, N=54) and older adults (OA, N=53). OA propelled slower than IP; used a greater push frequency and minimum Mz, shorter stroke length, and similar resultant force. When surface difficulty increased, the IP group responded with increased work. This may indicate a lack of capacity in OA to respond to increased resistance. For our cohort of older adults we defined the impact of surface type, wheelchair weight, and rear axle position (N=53). As surface difficulty or chair weight increased, velocity decreased. Controlling for velocity, push frequency, resultant and tangential force increased as surface difficulty increased; heavier chairs had decreased stroke length and increased resultant and tangential force; and posterior axle positions had increased velocity. Controlling for velocity, posterior axle positions had increased forces. Finally, we examined the impact of strength and gender. Body-weight normalized grip strength was collected. Stronger individuals propel faster than weaker individuals. On low pile carpet, both genders decreased velocity versus tile, but women decreased push frequency while men increased. Surface type has a substantial impact on propulsion velocity and force; magnifying any differences between users and wheelchair configurations. Wheelchair weight and axle position independently affect propulsion mechanics. Gender and strength appear to influence propulsion. Older adults are marginal self-propellers at best; powered mobility may be a more appropriate mobility solution
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