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Background:Approximately 15% of the world’s population are affected bysome kind of disability where over 150 conditions may affect the human gaitpattern. The ability to ambulate with ease is important for overall well-being.Various assistive devices have been developed to improve mobility of theirusers. A lot of research is currently focused on ankle exoskeletons, showingpromising results in providing important assistance during stance phase of gait. Objective:To investigate how different combinations of active and passiveelements in an ankle exoskeleton affects the metabolic cost of walking. Methods:Musculoskeletal simulations were carried out in OpenSim Moco.Different assistive configurations were tested over one gait cycle using a pas-sive element, an active element, and a parallel connection of the both. Parame-ter values were modified to find the most optimal setup for reducing metaboliccost. Results:All assistive configurations were found successful in reducing bothwhole-body metabolic cost and the metabolic cost of the plantarflexors whencompared to the unassisted gait. Most whole-body metabolic cost reductionwas found when using a passive spring with resting length of 0.28 m and stiff-ness of 6 kN/m in parallel with an active motor capable of providing forceequal to 150% of body weight. The most reduction in metabolic cost of theplantarflexors was also found for a parallel connection of elements, but herewith a 100% body weight motor and spring with rest length of 0.19 m andstiffness of 10 kN/m. With higher assistance, more reduction in ankle mo-ment generated by the muscles was observed. Conclusion:Powered ankle exoskeletons are promising in terms of minimiz-ing metabolic cost during walking due to assistance during late stance phaseof gait for ambulators requiring plantarflexor assistance. Keywords:Simulation, exoskeleton, ankle, moco.

Ankle arthritis is a debilitating condition that causes severe pain and decreased function in the affected limb on the order of end-stage hip arthrosis, end-stage kidney disease, and congestive heart failure. Total ankle replacement is a viable surgical option for treating end-stage ankle arthritis, but few have studied its effects on balance over time. Therefore, the purpose of this study was to test the accuracy of a single-marker method of tracking center of mass, evaluate center of pressure measurements in total ankle replacement patients, and analyze lower extremity joint contributions over a two-year recovery period. Subjects stood on two force platforms for ten seconds in different conditions, and relevant variables were calculated from the force platform and 3D motion capture data. Results showed that increasing recovery time restored partial symmetry between the surgical and non-surgical limbs in ground reaction force, ankle range of motion, and ankle and hip moment contribution in static balance tasks. Furthermore, the ankle and hip may have different roles in postural stability. The results of the studies suggest that total ankle replacement is an effective treatment for end-stage ankle arthritis in terms of restoring postural stability. While patients may not have returned to the level of healthy control subjects, they are more functional and more stable after a two-year recovery period. While further work is needed, the results are encouraging for the outlook of ankle arthritis patients who may need total ankle replacement surgery. / Master of Science / Ankle arthritis is a debilitating condition that causes severe pain and decreased function in the affected limb on the order of end-stage hip arthrosis, end-stage kidney disease, and congestive heart failure. Total ankle replacement is a viable surgical option for treating end-stage ankle arthritis, but few have studied its effects on balance over time. Therefore, the purpose of this study was to test the accuracy a simplified method to track the center of gravity of the human body, evaluate center of pressure (the point where the force of body weight acts) measurements in total ankle replacement patients, and analyze lower extremity joint contributions to balance over a two-year recovery period. Subjects stood on two force measurement platforms for ten seconds in different conditions, and relevant variables were calculated from the force platform and 3D motion capture data. Results showed that increasing recovery time restored partial symmetry between the surgical and non-surgical limbs in weight-bearing force, center of pressure excursion, and ankle and hip contributions to stability. The results of the study suggest that total ankle replacement is an effective treatment for end-stage ankle arthritis in terms of restoring balance. While patients may not have returned to the level of healthy people, the results suggest they are more stable after a two-year recovery period. While further work is needed, the results are encouraging for the outlook of ankle arthritis patients who may need total ankle replacement surgery.

In this experiment, average calcaneal fracture force is measured across male and female groups. The purpose of this experiment is an analysis of alternatives exploring the importance of sex-based criteria in models representing injuries typical in underbody blast environments. Seventeen (17) right legs were harvested at the knee from cadavers representing three anthropometries: 50th percentile male (6), 75th percentile female (6), and 5th percentile female (5). Care was taken to preserve anatomically correct geometry as the legs were cut to equal lengths, the tibia and fibula were potted in Dyna-Cast®, flesh and ligaments were excised from the inferior surface of the calcaneus, and a small Dyna-Cast® pad was poured and sanded flat – interfacing with the exposed calcaneal surface. Each test specimen was mounted in a custom fixture and exposed once to high-rate axial loading characterized by a constant acceleration and 25.4mm intrusion, achieving an average speed of 4.7m/s (σ = 0.3m/s) in 10ms. Input acceleration was measured by an Endevco 7264c accelerometer and a Denton 2513 six-axis load cell measured reaction force proximal to the specimen. A VR Phantom v9.1 camera recorded x-ray imagery at 2k frames per second. Data were collected by a TDAS Pro data acquisition system at 20k samples per second and filtered in accordance with SAE J211. Time of fracture, established through x-ray imagery, was used to determined fracture force from the electronically synchronized load-cell data. 100% injury was recorded. Average calcaneus fracture forces were reported as follows: 5406N (σ = 780N) for 50th percentile males, 4130N (σ = 1061N) for 75th percentile females, and 2873N (σ = 1293N) for 5th percentile females. Statistical significance was established between the reported averages according to three ANOVA tests: One-way (p = 0.0054), Brown-Forsythe (p = 0.0091), and Welch's (p = 0.0156). Unpaired Student's t-test confirmed significant differences between 50th percentile male vs 75th percentile female (p = 0.0469) and 50th percentile male vs 5th percentile female (p = 0.0030); the t-test did not show significance between the two female groups (p = 0.1315). Average impulse-to-fracture was calculated for each group and found to be not statistically significant. / Master of Science / A marked shift can be found in combat wound epidemiology towards a predominance of extremity injuries sustained from explosives. The Warrior Injury Assessment Mannequin (WIAMan) Project sought to develop a baseline dataset of post-mortem human surrogate responses to realistic explosive loading and correlate it to a highly instrumented mannequin for the further development of combat vehicles and personal protective gear. The following experiment exists within the WIAMan paradigm as an analysis of alternatives exploring the adequacy of the above mentioned baseline dataset in directly representing both male and female injuries. More specifically, this experiment interrogates the differences in average fracture forces between male and female calcanei across three anthropometries: 50th percentile male, 75th percentile female, and 5th percentile female. Testing was carried out on 17 right cadaver legs cut to equal lengths, potted proximally in Dyna-Cast®, with the inferior surface of their calcanei exposed; a small Dyna-Cast® pad was poured for each calcaneus and sanded flat. Each test specimen was fixed to a Denton 2513 six-axis load cell proximally and exposed to a high-rate, constant acceleration, 25.4mm displacement aligned with the calcaneus along the long axis of the leg bones. Fracture time, established through x-ray images recorded at 2k frames per second with a VR Phantom V9.1 camera, was used to determine load cell force measurement at fracture. Average calcaneus fracture forces were reported as follows: 5406N (σ = 780N) for 50th percentile males, 4130N (σ = 1061N) for 75th percentile females, and 2873N (σ = 1293N) for 5th percentile females. Statistical significance was established between the reported averages according to three ANOVA tests: One-way (p = 0.0054), Brown-Forsythe (p = 0.0091), and Welch's (p = 0.0156). Unpaired Student's t-test confirmed significant differences between 50th percentile male vs 75th percentile female (p = 0.0469) and 50th percentile male vs 5th percentile female (p = 0.0030); the t-test did not show significance between the two female groups (p = 0.1315). Average impulse-to-fracture was calculated for each group and found to be not statistically significant.

Thesis (M.Tech.:Chiropractic)-Dept. of Chiropractic, Durban University of Technology, 2007 121 leaves / Ankle sprains account for 85% of all injuries to the ankle (Garrick, 1997). Inversion sprains result from a twisting of a weight-bearing foot into a plantarflexed and inverted position leading to lateral ankle ligament injury. Louwerens and Snijders (1999) state that there are multiple factors involved in ankle sprains or lateral ankle instability. These include injury to the lateral ankle ligaments, proprioceptive dysfunction and decrease of central motor control. Other factors that still need further research include the role of the fibularis muscles, the influence of foot geometry and the role of subtalar instability in ankle sprains (Louwerens and Snijders, 1999). This study focused on the fibularis muscles. Fibularis longus and brevis muscles are found in the lateral compartment of the leg and function to evert/pronate the foot and plantarflex the ankle. Fibularis tertius is found in the anterior compartment and its function is to evert and dorsiflex the foot. Myofascial trigger points in these three muscles refer pain primarily over the lateral malleolus of the ankle, above, behind and below it (Travell and Simons, 1993 2: 371). This is the exact area where ankle sprain patients experience pain. Travel and Simons (1993 2:110) state that a once off traumatic occurrence can activate myofascial trigger points. When considering the mechanism of injury of a lateral ankle sprain, the importance of the fibularis muscles becomes obvious. When the ankle inverts during a lateral ankle sprain, these muscles are forcefully stretched whilst trying to contract to bring about their normal action. Therefore these muscles are often injured from traction when the foot inverts (Karageanes, 2004). It stands to reason that as a result of this mechanism of injury myofascial trigger points may develop in the fibularis muscles. It was hypothesised that fibularis muscle trigger points would prove to be more prevalent in the injured leg when compared to the uninjured leg. To further investigate this hypothesis, an analytical, cross sectional study (phase 1) was done on 44 participants between the ages of 15 and 50. Consecutive convenience sampling was used and participants were screened according to phase 1’s inclusion and exclusion criteria. According to Travel et al. (1999 1: 19) myofascial trigger points (whether active or latent) can cause significant motor dysfunction. Trevino, et al. (1994) stated that fibularis muscle weakness is thought to be a source of symptoms after an inversion sprain. Treatment for ankle sprains involves minimising swelling and bruising and encouraging adequate ankle protection in the acute phase. The patient is advised to rest for up to 72 hours to allow the ligaments to heal (Ivins, 2006). After the acute phase has passed, rehabilitation is focused on. This includes improving the ankle range of motion and proprioception. Attention is also given to strengthen the muscles, ligaments and tendons around the ankle joint. In the recommended treatment protocol however, no mention is made of evaluating the musculature around the ankle joint for myofascial trigger points and or treating these points. McGrew and Schenck (2003) noted that if the musculature and neural structures surrounding the ankle joint were affected during an ankle sprain injury, and were left unresolved, they would lead to chronic instability. It was hypothesised that lateral ankle pain due to inversion ankle sprain injuries may be due to referred pain from the fibularis muscle trigger points. Patients treated with dry needling of the fibularis muscle trigger points would therefore show a greater improvement in terms of subjective and objective clinical findings when compared to a placebo treatment (detuned ultrasound) applied to the fibularis muscle trigger points.

Thesis (M.Tech.: Chiropractic)-Dept of Chiropractic, Durban Institute of Technology, 2005 x, 58, Annextures A-L, 20 leaves / An inversion ankle sprain can be defined as an injury caused by landing forcefully on an inverted, plantarflexed and internally rotated foot. This results in the fibres of the surrounding ligaments to become ruptured without disturbing the continuity of the ligament. Chronic stable ankle sprains was defined as the recurrent giving way of the ankle and there may be residual pain and swelling with no mechanical instability. According to literature, mechanisms involved in the development of chronic ankle sprains are: the lack of appropriate and early immobilization in severe cases, the development of scar tissue, lack of strengthening exercises or the development of hypermobility. Many treatments have been suggested to address these factors and would include: peripheral manipulation of the ankle joint, Muscle Energy Technique, muscle strengthening and stretching, proprioceptive training and deep transverse friction massage. Of the above mentioned treatments, Muscle Energy Technique has not been researched in a clinical setting for the treatment of chronic stable ankle inversion sprains. Therefore the purpose of this study was to investigate the relative effectiveness of Muscle Energy Technique compared to Manipulation in the treatment of chronic stable ankle inversion sprains.