The objective of this thesis is to develop design approaches and models for prosthetic ankle joints using kinematic models of the human ankle and compliant mechanisms technology. Compliant mechanisms offer several potential design advantages over traditional rigid-body designs including high reliability and low cost. These design advantages are ideal for use in prosthetics. Some prosthetic ankle/foot systems currently on the market have multiple degrees of freedom yet are expensive. Additionally, even though these systems have multiple degrees of freedom, none of them are designed after the actual movements of the biological ankle. In this thesis a two, single degree-of-freedom hinge joint model, which is a kinematic model based on the biological ankle during walking, is used to develop compliant prosthetic ankle joints. The use of the model together with compliant mechanisms may provide the ability to develop highly functional prosthetic ankle joints at a lower cost than current high-performance prosthetic systems. Finally, a design approach for ankles may facilitate future development for knees, hips or other biological joints.

Context: Abdominal training may decrease the risk of lower extremity injuries through improved balance and postural control. Objective: To determine the effect of an eight-week abdominal-training program on center of pressure, lower extremity joint angles, and abdominal muscle activation during a single-leg drop landing. The effects of abdominal training on abdominal muscle thickness was assessed. Design: A cohort research design. Setting: Research laboratory. Other Participants: Sixty healthy physically active college-aged students participated. They were divided into three groups: Control, Chronic ankle instability (CAI), and Healthy. Nineteen Control (age = 22.0 ± 2.72 yrs, mass = 74.1 ± 13.8 kg, height = 172.6 ± 11.3 cm, BMI = 24.8 ± 3.1 %), 21 CAI (age = 22.1 ± 2.3 yrs, mass = 77.6 ± 14.0 kg, height = 175.4 ± 12.3 cm, BMI = 25.1 ± 2.6 %), and 20 healthy (age = 22.9 ± 3.4 yrs, mass = 70.9 ± 15.6 kg, height = 172.2 ± 8.9 cm, BMI = 23.7 ± 3.3 %). Subjects in the CAI group had a history of CAI and functional ankle instability (FAI). The Ankle Instability Index and the Functional Ankle Ability Measure were used to self-report CAI and FAI respectively. Interventions: The CAI and Healthy groups participated in an eight-week abdominal-training program while the Control group maintained their normal activities of daily living and level of physical activity. Main Outcome Measures: Abdominal muscle thickness was measured biweekly throughout the study. Center of pressure excursion, muscle activation, vertical ground reaction force, and lower extremity joint angles were measured during a single-leg drop landing, pre- and postabdominal training. Results: Muscle thickness at rest increased in the rectus abdominis and external oblique muscles follow training. Eight weeks of abdominal training decreased vertical ground reaction forces and muscle activation down the lower kinetic chain. Center of pressure excursion and velocity were increased following training. Conclusions: Eight-weeks of abdominal training increased abdominal muscle thickness. Training improved neuromuscular efficiency throughout the kinetic chain and may have improved dynamic postural control. Our data also suggest CAI subjects may utilize both feedforward and feedback mechanisms to maintain postural control.

Ramp descent is a demanding task for trans-tibial amputees, due to the difficulty in controlling body weight progression over the prosthetic foot. A deeper understanding of the impact of foot function on ramp descent biomechanics is required to make recommendations for rehabilitation programs and prosthetic developments for lower-limb amputees. The thesis aim was to determine the biomechanical adaptations made by active unilateral trans-tibial amputees (TT) using a microprocessor-controlled ankle-foot prosthesis in active (MC-AF) compared to non-active mode (nonMC-AF) or elastically articulated ankle-foot device. A secondary aim was to determine the biomechanical adaptation made by able-bodied individuals when ankle motion was restricted using a custom made ankle-foot-orthosis and provide further insight into the importance of ankle dynamics when walking on ramps. Kinetic and kinematic data were recorded from nine TT’s and twenty able-bodied individuals. Able-bodied participants, ankle restriction, led to an increase in involved limb loading response knee flexion that is accompanied by the increased knee power generation during the single-limb-support phase that correlates to TTs results. TT’s use of an MC-AF reduced the ‘plantar-flexion’ resistance following foot contact allowing foot-flat to be attained more quickly. Followed by the increased ‘dorsi-flexion’ resistance which reduced the shank/pylon rotation velocity over the support foot, leading to an increase in negative work done by the prosthesis. These findings highlight the importance of having controlled ankle motion in ramp descent. Use of an MC-AF can provide TTs controlled motion for descending ramps and hence provide biomechanical benefits over using more conventional types of ankle-foot devices. / Engineering and Physical Science Research Council (EPSRC) via Doctoral Training Account (DTA) (EP/P504821/1) Chas. A. Blatchford and Sons Ltd., Basingstoke, UK provided the prosthetic hardware, prosthetist support, and facilitated the attendance of the TT participants for this study

Injuries to the lower extremity are frequent and severe in frontal automotive collisions, often leading to pain and long-term impairment. Most injury criteria developed for the lower extremity are conducted with the foot and ankle in a neutral posture, do not take into account footwear, and assess injury risk to the entire lower extremity at the tibia. An instrumented boot, designed to address some of these challenges, was calibrated over a range of impact energies expected in frontal automotive collisions. A dynamic calibration method was developed to convert changes in voltage across a piezoresistive polymer to the applied axial force. The instrumented boot was then used to examine the axial impact response of two commonly used Anthropomorphic Test Device (ATD) lower legs, under altered ankle postures. Both posture and ATD model were found to affect the load distribution on the foot, highlighting the need to establish injury limits for non-neutral postures as well as selecting the appropriate ATD model. The instrumented boot provided regional loading information that was not reflected in standard industry metrics, emphasizing the importance of increased instrumentation in this area. A technique was developed for mounting cadaveric feet to ATD tibia shafts, in order to gather industry-relevant load data while examining the impact characteristics of the foot. Load data were collected at the plantar surface of the foot using the instrumented boot, as well as the tibia load cells in the ATD shaft, that highlighted differences in load transmission through cadaveric and ATD feet. Understanding the impact characteristics of ATDs under non-standard ankle postures as well as examining the load transmission through cadaveric feet highlighted some shortcomings with current injury assessment techniques. The results of this work can be used to improve future collision testing practices, in order to reduce the incidence of lower extremity injuries. / Thesis / Master of Applied Science (MASc) / Foot and ankle injuries are common in automotive collisions and often lead to pain and long-term impairment. Experimental work on these types of injuries is traditionally conducted with the foot and ankle positioned in a neutral ankle posture, which does not reflect the range of ankle postures individuals may assume in a car crash. The purpose of this work was to use biomechanical tools to assess foot/ankle injury risk. Impact testing was performed on two commonly used crash test dummy lower legs in conditions relevant to those experienced in car crashes. A technique was developed to mount cadaveric feet to crash test dummy tibias to gather injury information of the foot, while also collecting load data in the tibia shaft – relevant metrics for industry crash testing. The results of this work outline the shortcomings of traditional injury assessment methods and may be used to improve future practices.

An estimated 23,000 ankle injuries occur every day in the U.S. Ankle sprains account for 85% of all ankle injuries and inversion ankle sprains account for 85% of all ankle sprains. There is growing evidence that suggests gender and fatigue may increase the risk for inversion ankle sprains. Investigating the effects of fatigue and gender on peroneal reflex response after ankle inversion may help explain the differences in sprain rates with fatigue and gender. Therefore, the purpose of this study was to investigate the effects of fatigue and gender on peroneus brevis and peroneus longus reflexes after ankle inversion. A "trap-door" platform was used to elicit peroneal reflexes from sixteen males and fifteen females by suddenly inverting the ankle to 20°. Five unfatigued peroneal reflex measurements were performed before and after a fatigue protocol that attempted to fatigue the ankle evertors over 12 minutes to 75% of the unfatigued MVC torque. Results showed that reflex delay was not affected by fatigue, gender, or their interaction. PL reflex amplitude was not affected by fatigue or gender but was affected by their interaction. Results showed that PL reflex amplitude decreased by 11.3% in males and increased 22.1% in females with fatigue. A secondary analysis attempted to rule out extraneous factors that could have contributed to the differences in reflex response, but no experimental explanations were found. The differences in PL reflex amplitude were attributed to biomechanical, physiological, and anatomical differences between males and females. / Master of Science

No description available.

Dissertation submitted in partial compliance with the requirements for the Masters Degree in Technology: Chiropractic, Durban University of Technology, 2010. / The aim of this study was to determine the inter-examiner reliability of motion palpation to detect joint dysfunction in hindfoot and midfoot joints of asymptomatic feet and feet with chronic ankle instability syndrome. The rationale for this study was that motion palpation is a commonly used assessment tool that is used by the chiropractic profession to detect the need for manipulation of the spine and extremities. Also until the reliability of motion palpation is known, other studies using motion palpation as an assessment tool to detect the need for manipulation in the hindfoot and midfoot are questionable. The study was conducted at Durban University of Technology (DUT). Patients that responded to the adverts were then screened via telephonic interview. The researcher performed a case history, physical examination and a foot and ankle regional examination on each patient. Three masters chiropractic students then independently assessed both the symptomatic and asymptomatic feet of each patient and recorded their results. The data was then statistically analysed using SPSS version 15. It was found that the inter-examiner reliability of motion palpation for detecting restrictions in feet with chronic ankle instability syndrome was fair and for detecting instability, there was moderate reliability. In the asymptomatic group the examiners showed to have poor reliability in detecting restrictions and moderate reliability in detecting instability. Inter-examiner reliability was better in the symptomatic group and in this group examiners had more agreement on detecting instability as opposed to restrictions. This study has showed that inter-examiner reliability ranged from poor to moderate in the symptomatic and asymptomatic group with the reliability ranging from poor to moderate. Therefore, one can conclude that motion palpation can be used as an assessment tool to detect joint dysfunction in hindfoot and midfoot joints. However, further studies are warranted to address other subjective and objective measurements such as tenderness and range of motion together with motion palpation.

The ankle sprain is a common injury in basketball. A mechanism for this injury occurs when landing improperly from a jump. The concept of wedge and flare designs in shoes is (1) to offer benefit in reducing the potential for an ankle sprain while (2) not hindering performance or usability concerning basketball movements that are needed for successful play. The purpose was to take conceptual designs of the wedge and flare through an iterative design process. Therefore, the objectives were to fabricate shoe prototypes with these conceptual designs, to test the performance of these prototypes, and to develop the next iteration of design based upon the results of testing. The results of this design process are discussed.

Thesis (M.Tech.: Chiropractic)-Dept. of Chiropractic, Durban Institute of Technology, 2005 xiii, 81 leaves ; 30 cm / Damage to the proprioceptive organs, as well as lack of proprioceptive retraining, after an inversion ankle sprain, has been shown to contribute to the problem of recurring ankle joint injuries, which has the highest incidence of sports related injuries. The proprioceptive organs are important as afferent pathways in reflexes and for the adjustment of posture and muscle tone (Miller and Narson, 1995 and Jerosch and Bischof, 1996). Manipulation is thought to cause a change in the afferent pathways of the manipulated joints and it is proposed that this change may restore normal proprioceptive input, in a previously injured joint (Wyke, 1981 and Slosberg 1988). This however is unproven as indicated in a study by Lephart and Fu, (1995), where techniques to improve proprioception remain untested and according to Brynin and Farrar (1995), screening for proprioceptive and neuromuscular co-ordination should be carried out as part of a chiropractor’s physical examination and injury evaluation. This was a qualitative pre-post clinical study. Forty (40) subjects between the ages of 25 and 45, who had been diagnosed with chronic ankle instability syndrome, were recruited.

Thesis (M.Tech.: Chiropractic) - Dept. of Chiropractic, Durban Institute of Technology, 2005 221 leaves ; 30 cm / Previously the focus has been on the improvement of strength prior to proprioception (Calliet, 1997; Flemister et al. 1998 and Buhler et al. 2002). However according to Oloff (1994); Vegso (1995); Calliet (1997); Kawaguchi (1999); Buhler et al. (2002) and McGrew et al. (2003), focus should lie in obtaining a functional range of motion (increased flexibility) and proprioceptive ability and strength will follow with normalization of the relationship of the anatomical structures. All research in this regard has never assessed the assumption that the strength of the relevant musculature would return (Blokker et al.1992 and Klaue et al.1998). The objectives of this study were: to determine the relative effectiveness of Proprioceptive Neuromuscular Facilitation as compared to the Active Rocker-Board Exercises in the rehabilitation of chronic ankle sprains; as well as to determine the best sequence of applying these techniques to chronic ankle sprains in terms of objective clinical findings.