291 research outputs found

    Biomechanical, muscle activation and clinical characteristics of chronic exertional compartment syndrome

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    Chronic exertional compartment syndrome (CECS) is a common problem within both military and athletic populations that can be difficult to diagnose. Furthermore, it is unclear what causes the development of CECS, particularly in the military population, as personnel undertake a variety of activities that can cause pain with CECS such as fast walking, marching and running. Chronic exertional compartment syndrome has been hypothesised to develop due to excessive muscle activity, foot pronation and abnormal biomechanics predominantly at the ankle. Treatment of CECS through running re-education to correct these abnormalities has been reported to improve symptoms. However no primary research has been carried out to investigate the biomechanical, muscle activation and clinical characteristics of military patients with CECS. The purpose of this thesis was to provide an original contribution to the knowledge through the exploration of these characteristics; and the development of insights into the development of CECS, with implications for prevention and treatment. Study one investigated the clinical characteristics of 93 service personnel with CECS. Plantar pressure variables, related to foot type and anterior compartment muscle activity, and ankle joint mobility were compared during walking between 70 cases and 70 controls in study two. Study three compared three-dimensional whole body kinematics, kinetics and lower limb muscle activity during walking and marching between 20 cases and 20 controls. Study four compared kinematics and lower limb muscle activity during running in a separate case-control cohort (n=40). Differences in electromyography (EMG) intensity during the gait cycle were compared in the frequency and time domain using wavelet analysis. All studies investigated subject anthropometry. Cases typically presented with bilateral, ‘tight’ or ‘burning’ pain in the anterior and lateral compartments of the lower leg that occurred within 10 minutes of exercise. This pain stopped all cases from exercising during marching and/or running. As such subsequent studies investigated the biomechanics of both ambulatory and running gaits. Cases in all case-control studies were 2-10 cm shorter; and were typically overweight resulting in a higher body mass index (BMI) than controls. There was strong evidence from study 3 that cases had greater relative stride lengths than controls during marching gait. This was achieved through an increase in ankle plantarflexion during late stance and a concomitant increase in the gastrocnemius medialis contraction intensity within the medium-high frequency wavelets. Given the differences in height observed, this may reflect ingrained alterations in gait resulting from military training; whereby all personnel are required to move at an even cadence and speed. These differences in stride length were also observed in walking and running gaits although to a lesser extent. There was no evidence from the EMG data that cases had greater tibialis anterior activation than controls during any activity tested, at any point in the gait cycle or in any frequency band. In agreement, there was also no evidence of differences between groups in plantar pressure derived measures of foot type, which modulate TA activity. Toe extensor - related plantar pressure variables also did not differ between groups. In summary, contrary to earlier theories, increased muscle activity of the anterior compartment musculature does not appear to be associated with CECS. The kinematic differences observed during running only partially matched the clinical observations previously described in the literature. Cases displayed less anterior trunk lean and less anterior pelvic tilt throughout the whole gait cycle and a more upright shank inclination angle during late swing (peak mean difference 3.5°, 4.1° and 7.3° respectively). However, no consistent differences were found at the ankle joint suggesting that running is unlikely to be the cause of CECS in the military; and that the reported success of biomechanical interventions may be due to reasons other than modifying pathological aspects of gait. In summary, the data presented in the thesis suggest that CECS is more likely to develop in subjects of shorter stature and that this is associated with marching at a constant speed and cadence. Biomechanical interventions for CECS, such as a change in foot strike or the use of foot orthotics, are unlikely to be efficacious for the military as personnel will continue to be required to march at prescribed speeds to satisfy occupational requirements. Preventative strategies that allow marching with a natural gait and/or at slower speeds may help reduce the incidence of CECS. The lack of association with foot type or muscle activity suggests that foot orthoses would not be a useful prevention strategy or treatment option for this condition.Headley Court Trustees - funding of student fee

    Biomechanical evaluation of a novel fiberglass reinforced polyamide custom ankle-foot orthosis: gait analysis and energy assessment in a population of mild foot-drop patients

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    Ankle foot orthoses (AFOs) are medical devices used to stabilize the ankle following traumatic injuries, or lesion to the central or peripheral nervous systems leading to foot-drop. This represents the inability to lift the foot during the swing phase of walking, due to neuro-muscular impairments of the ankle dorsiflexor muscles. Mild foot-drop patients may need a comfortable AFO that provides support to the ankle and that can bend seamlessly with the physiological ankle motion in common daily motor tasks. While off-the-shelf AFOs are cost-effective solutions, they may not fully comply with the foot and leg shape and the patient-specific functional requirements. Over the last 20 years, advancements in additive manufacturing technologies have allowed to manufacture custom orthotic devices that better fit the affected anatomical segment. This thesis aimed at evaluating the functional and biomechanical outcome of a novel fiberglass-reinforced polyamide passive-dynamic custom AFO, manufactured via Selective Laser Sintering, in a population of foot-drop patients (n = 10; age = 64.9 ± 11.4 years, BMI = 26.2 ± 2.1 kg/m2). The energy absorbed and released by the custom AFO during the stance phase of walking has been estimated from its experimentally-measured stiffness and motion tracked via a 8-camera motion analysis system. The functional evaluation was assessed via gait analysis in the three conditions: shod (no-AFO), wearing an off-the-shelf AFO (a Codivilla spring) and wearing the custom AFO. Kinematics and kinetics of the hip, knee and ankle joints were estimated via skin-markers attached to relevant bony landmarks according to the IOR-gait kinematic protocol. Both AFOs resulted in decreased sagittal-plane range of motion of the ankle in the swing phase of gait, as well as in reduced plantarflexion angle. Spatiotemporal parameters analysis showed a significant increased stance time (63.7 ± 1.5 vs 63.7 ± 2.1 vs 61.0 ± 2.7 [% stride time]), normalized speed of walking (52.3 ± 12.9 vs 51.8 ± 14.1 vs 49.3 ± 13.9 [% height/s]) and normalized stride length (64.7 ± 11.0 vs 64.2 ± 11.6 vs 63.3 ± 11.3 [% height]) for the custom AFO with respect to the off-the-shelf one and to the shod condition. The energetic evaluation highlighted that the custom AFO releases part of the stored energy at foot-off thus contributing to the propulsive phase. Moreover, patients perceived the custom AFO more comfortable than the Codivilla spring (VAS score: 8.6 ± 1.2 vs 5.3 ± 1.3). This study provides evidence for the beneficial functional outcomes of AFO personalization, especially for mild foot-drop patients not satisfied with standard orthotics.Ankle foot orthoses (AFOs) are medical devices used to stabilize the ankle following traumatic injuries, or lesion to the central or peripheral nervous systems leading to foot-drop. This represents the inability to lift the foot during the swing phase of walking, due to neuro-muscular impairments of the ankle dorsiflexor muscles. Mild foot-drop patients may need a comfortable AFO that provides support to the ankle and that can bend seamlessly with the physiological ankle motion in common daily motor tasks. While off-the-shelf AFOs are cost-effective solutions, they may not fully comply with the foot and leg shape and the patient-specific functional requirements. Over the last 20 years, advancements in additive manufacturing technologies have allowed to manufacture custom orthotic devices that better fit the affected anatomical segment. This thesis aimed at evaluating the functional and biomechanical outcome of a novel fiberglass-reinforced polyamide passive-dynamic custom AFO, manufactured via Selective Laser Sintering, in a population of foot-drop patients (n = 10; age = 64.9 ± 11.4 years, BMI = 26.2 ± 2.1 kg/m2). The energy absorbed and released by the custom AFO during the stance phase of walking has been estimated from its experimentally-measured stiffness and motion tracked via a 8-camera motion analysis system. The functional evaluation was assessed via gait analysis in the three conditions: shod (no-AFO), wearing an off-the-shelf AFO (a Codivilla spring) and wearing the custom AFO. Kinematics and kinetics of the hip, knee and ankle joints were estimated via skin-markers attached to relevant bony landmarks according to the IOR-gait kinematic protocol. Both AFOs resulted in decreased sagittal-plane range of motion of the ankle in the swing phase of gait, as well as in reduced plantarflexion angle. Spatiotemporal parameters analysis showed a significant increased stance time (63.7 ± 1.5 vs 63.7 ± 2.1 vs 61.0 ± 2.7 [% stride time]), normalized speed of walking (52.3 ± 12.9 vs 51.8 ± 14.1 vs 49.3 ± 13.9 [% height/s]) and normalized stride length (64.7 ± 11.0 vs 64.2 ± 11.6 vs 63.3 ± 11.3 [% height]) for the custom AFO with respect to the off-the-shelf one and to the shod condition. The energetic evaluation highlighted that the custom AFO releases part of the stored energy at foot-off thus contributing to the propulsive phase. Moreover, patients perceived the custom AFO more comfortable than the Codivilla spring (VAS score: 8.6 ± 1.2 vs 5.3 ± 1.3). This study provides evidence for the beneficial functional outcomes of AFO personalization, especially for mild foot-drop patients not satisfied with standard orthotics

    An investigation into the relationship between rocker sole designs and alteration to lower limb kinetics, kinematics and muscle function during adult gait

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    Introduction Intermittent claudication (IC) is a condition which affects people with peripheral arterial disease in the lower limbs and causes calf muscle pain and limping due to the lack of blood supply to the gastrocnemius muscle in particular. This limits the distance people with IC (known as claudicants) can walk before having to stop because of the pain. The accepted best treatment currently is enrolment onto supervised exercise regimes, but these provide limited improvement and do not alter their antalgic gait. This study aims to investigate the effect of specific footwear designs on gait and lower limb muscle function with the intention of identifying which features would be recommended for inclusion in footwear designed to relieve their painful symptoms by offloading the calf muscles. Method Fifteen volunteer healthy subjects, age range 20-29 years (mean 25.3 ± 2.73) undertook a series of gait laboratory trials with shoes adapted with specifically-chosen outsole features. High street shoes were adapted with the test conditions which included shoes with five different heel heights (varying from a 1.5cm to 5.5cm heels), two heel profile conditions (curved and semi curved heels), three traditional (angled) rocker soles with varying apex positions (55%, 62.5% and 70% of shoe length) and three with varying apex angles (10, 15, and 20 deg.), plus three with different forepart sole stiffness (solid, semi-flexible and flexible). The baseline shoe was taken as being one with no heel curve, a heel height of 3.5mm, an apex position of 62.5% of shoe length, and apex angle of 15 deg. and a stiff forepart to the shoe. Measurement and comparisons were taken of lower limb kinetics and kinematics (Qualysis, Sweden) plus electromyographical (EMG) activity (Noraxon USA) of medial gastrocnemius, soleus, tibialis anterior, rectus femoris and biceps femoris during walking trials where the walking speed was controlled using timing gaits. Data were analysed using Visual3D and OpenSim software to enable interpretation of EMG activity to enable calculation of lower limb muscle function during gait. Results Changes from the baseline shoe were taken as being at a level of significance of p<0.05. The most effective footwear test condition in regards to offloading of the calf muscles compared to the control shoe was that with a 4.5cm heel, a 55% of shoe length apex position, and a 20° rocker apex angle; which demonstrated significant offloading to the calf muscles. The 55% apex position had a significant offloading influence on the calf muscles whilst at the same time not significantly altering knee and hip kinematics. Conclusion This study demonstrates that a potentially useful shoe design was identified for treatment of claudicant calf pain which did not adversely affect more proximal joint kinetics and kinematics

    The Role of the Subtalar Joint and the Influence of Footwear Characteristics during Slip Perturbations

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    Slips are considered one of the most common causes of major accidental injuries. The objective of this thesis is two-fold. The first objective is to determine the role of the subtalar joint during a slipping perturbation. The second is to determine if certain footwear characteristics, that may restrict the normal function of the subtalar joint (i.e., insole stiffness and heel counter stiffness), will change the response to unexpected heel contact slipping perturbations. Forty-two participants (30 females, 12 males) were recruited from a university aged population (21.19 years ± 2.7 years). Trials were performed over a 10 m walkway with rectangular sheets of sandpaper placed at each foot contact. Ten participants performed walking trials barefoot while the other 32 participants were randomly assigned to one of four footwear conditions (n=8) (condition 1: flexible insole, soft heel counter; condition 2: flexible insole, stiff heel counter; condition 3: rigid insole, soft heel counter; condition 4: rigid insole, stiff heel counter). Electromyography (EMG) signals were collected from eight lower limb muscles (tibialis anterior, peroneus longus, medial gastrocnemius, rectus femoris and medial hamstring). Kinematic data was collected using a 20 marker set-up. Marker triads were placed on the tibia, calcaneous and mid-foot to determine subtalar joint motion. Kinetic data was collected using forces plates embedded in the walkway. Unexpected slips were presented after a predetermined number of normal walking trials. Wax paper adhered to the underside of a sandpaper sheet was exchanged on the second force plate to cause an unexpected heel contact slip perturbation. Overall, 20 participants experienced a slip. Within the barefoot condition, 80% of the participants experienced an unexpected slip perturbation. The prevalence of slips was not as great within all of the footwear conditions (25%–50%). During slip trials the average onset of eversion occurred slightly later than in normal walking trials, but was not statistically significant.The tibialis anterior elicited a burst of activity during the middle phase of stance that is typically not seen during normal walking. The average onset of tibialis anterior activity was earlier with the similar durations and relatively higher magnitudes than normal walking. During slip trials, the peroneus longus did not have significantly different onsets or durations and the magnitudes were slightly higher compared to normal walking trials. During slip trials, the medial gastrocnemius onset was not found to be significantly different when compared to normal walking trails, but the magnitudes were significantly lower. A higher rate of vertical loading was the only significant finding that would have indicated an increased risk of slipping within the barefoot condition; while lower stance durations, gait velocities, heel velocities, and smaller shank and foot-floor angles indicated an increased risk of slipping within the shod conditions. These finding would suggest that individuals who were in the shod conditions would have been at a higher risk of slipping than the barefoot condition, which should have resulted in higher incidences and severities; when in fact, the severity and incidences of slips was much lower. Therefore, the footwear, along with decreasing loading rate, must offer a level of stability to the foot and ankle during heel contact that controls foot motion. In particular, decreasing the rate of pronation or eversion at the time the slip was detected, which would likely decrease the severity of the slip; evident due to diminished recovery times.The peroneus longus does contribute to controlling subtalar motion alongside the tibialis anterior and finally, footwear characteristics that restrict normal subtalar joint motion seen in barefoot individuals will help decrease the risk of slipping and decrease the severity, improving chances for recovery

    THE EFFECTS OF PROLONGED RUNNING ON THE BIOMECHANICS AND FUNCTION OF THE FOOT AND ANKLE

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    Running injuries have been linked to morphology and lower limb function, and changes in foot and ankle biomechanics and function within a run may contribute to the predisposition to injury. This thesis investigates the effects of prolonged running on the foot and ankle, and potential mechanisms underlying changes in foot posture. Methods: A series of studies were undertaken from field to laboratory, measuring foot posture changes after prolonged running of different durations. Further measures of ankle invertor strength and medial ankle stiffness were taken in the laboratory studies as well as kinematic and plantar pressure data captured every ten minutes to enable repeated measures analysis of pedal movement to be conducted. Reliability across the foot posture, strength and stiffness measures was also determined. The latter studies involved the development and mechanical testing of a novel foot orthosis component which was compared to a standard open cell orthotic foam. A double blind randomised controlled trial then compared how the novel and standard foam components affected foot posture, ankle invertor strength and medial and plantar soft tissue stiffness after a 30-minute run. Results: A mean drop in NH and increase in FPI-6 following the half marathon, hour long and 30-minute treadmill runs was seen, with changes decreasing as running duration reduced. Ankle invertor strength and medial ankle stiffness reduced but did not correlate to the change in foot posture. Changes in foot and ankle kinematics were seen within 30 minutes of running. Mechanical testing of the novel orthotic component and standard foam revealed characteristic differences in response to loading, and changes in foot posture measures after 30 minutes of running in the randomised controlled trial were almost identical across both conditions. Further comparison of invertor strength and medial foot and ankle stiffness revealed no significant differences, but a large difference between exertion measures was seen. Conclusion: There was an overall effect of duration of running on changes in foot posture in this thesis, and the foot posture change was moderated by two different foot orthosis conditions although the mechanism remains unclear.University of Plymout

    Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking

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    Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p \u3c 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p \u3c 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p \u3c 0.001) and reduced fascicle shortening speed (p \u3c 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p \u3c 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage

    Kinematics, Kinetics, and Modeling of Fatigue in Young Distance Runners

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    In recent years, organized distance races have reported increases in children and young adult participants. In addition, female high school athletes generally experience higher rates of injury, including those due to overuse and specialization. These early injuries can lead to a higher likelihood of future injuries, growth plate disruption, and psychological outcomes like burnout. However, there is no general consensus among coaches, physicians, or athletic bodies about safe cumulative running loads at younger ages. The purpose of this study was to investigate how kinematics, kinetics, and muscle activations changed with fatigue in a group of young female distance runners. Motion and ground reaction force data was collected before and after a 5-kilometer run at the subjects’ personal best pace for eleven healthy girls aged 8-17. The resultant data was processed and characteristics such as joint angles, moments, and powers, ground reaction forces, and muscle forces were compared for pre and post run, as well as for the younger runners compared to the older runners. Ankle joint mechanics were most significantly altered by fatigue, and knee kinetic changes were most dependent on the runners’ age. In addition, knee flexor forces increased and extensor forces decreased with fatigue, while changes to muscle forces around the hip and ankle were more dependent on the age of the runner. These results suggest that performance and injury avoidance in these young runners can be aided by strength programs including the involved muscles to avoid imbalances

    Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking

    Get PDF
    Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p < 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p < 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p < 0.001) and reduced fascicle shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage
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