Background: Diabetic peripheral neuropathy (DPN) is diagnosed clinically as a loss of sensation in the feet and affects over 2 million people in the UK. One of the functional effects of DPN is a decrease in standing stability giving rise to a risk of falls. In an attempt to stabilise in the mediolateral direction, people with DPN frequently walk with a wider base of support and stand with a larger stance width. This is often seen in the elderly and is not always beneficial for stability contributing to falls risk. Standing balance requires the integration of sensory information from somatosensory, vestibular and visual systems. Alterations in distal sensory input may result in a re-weighting of the effectiveness of remaining sensations in mediating a stabilising postural response; termed sensory re-weighting. Alterations in posture such as adopting a wider stance width and wearing Ankle Foot Orthoses (AFOs) may also affect sensory input as well as altering the mechanics of the ankle and hip joints. The impact of distal sensory loss on the sensory control of balance in people with DPN compared to the healthy population is unknown. Moreover, it is not known whether standing balance or the sensory control of balance is affected by the adoption of an increased stance width and wearing (AFOs) that restrict mediolateral ankle motion. A better understanding of the mechanisms underlying balance dysfunction in diabetic peripheral neuropathy and how it might be manipulated could inform the development of future interventions to improve balance. Aim: To explore the effects of ankle foot orthoses and stance width on standing balance and the sensory control of mediolateral balance in people with DPN and healthy controls. Objectives: To assess how mediolateral postural stability and the sensory control of balance is affected by (a) AFO use and alterations in stance width in healthy participants (study 1) (b) acute distal sensory loss in healthy participants (study 2) (c) chronic sensory loss in people with DPN and how this in turn is modulated by AFO use and alterations in stance width (study 3). Methods: Postural stability and the response to selective muscle vibration that stimulates muscle spindle afferents was measured by 3D motion analysis. Study 1 investigated the effects of stance width and AFOs on postural sway and the response to selective hip proprioception stimulation induced by vibration of the hip abductors in healthy participants. Study 2 investigated the effect of an acute reduction of somatosensory information induced by cooling in healthy participants on the response to ankle evertor and hip abductor vibration. This provided a model of the acute effects of sensory loss. Study 3 compared healthy people with people with chronic DPN. It investigated the impact on stance stability and whether there was a change in the postural response (gain) to ankle evertor and hip abductor vibration. It further explored the effect of altering the stance width and wearing an AFO on stability and the postural response to hip abductor vibration. Results: Study 1: In healthy controls postural sway was significantly reduced when wearing an ankle foot orthoses and when standing at wider stance widths. Whilst this was also seen during balance perturbation, trunk motion increased at larger stance widths. This could be the result of the AFO restricting ankle motion and affecting the interpretation of the hip vibratory input by the postural control system. Study 2: Experimental reduction in distal sensation by cooling resulted in a reduction in postural responses to ankle evertor muscle vibration. Conversely postural responses at the level of the hip, to proximal (hip) muscle vibration, significantly increased. Study 3: Baseline sway velocity was higher in people with DPN compared to healthy controls. Postural strategies were modified in the DPN group, with increased motion at more proximal segments of the shoulder and head. In both groups, AFO and stance width significantly reduced baseline sway velocity, and the size of postural responses (translations) to hip abductor muscle vibration. Conclusion: Alterations in stance width and the use of AFOs can affect postural sway and the response to selective proprioceptive stimulation. Whilst acute reductions in distal sensory loss are associated with sensory re-weighting of distal and proximal proprioceptive information this is not seen in people with chronic DPN, possibly resulting from long term adaptive changes in the multi-sensory control of balance. Novel differences were found in postural strategies between healthy and DPN groups. The increase in head and trunk motion in people with DPN may have a negative impact on visual acuity and therefore a risk factor for falls. In people with diabetic peripheral neuropathy AFOs and increased stance width led to a reduction in postural response size and postural sway. The effect of AFO on sway velocity was more pronounced in those with DPN at smaller stance widths. Clinically this suggests that an AFO could be used in those with diabetic peripheral neuropathy to slow down the velocity of sway and increase stability.

Ankle foot orthoses (AFOs) are used to improve walking in some lower extremity conditions but AFOs restrict ankle motion resulting in a trade-off in ankle and hip mechanics. While the use of AFOs have been well documented, there still remain gaps in the literature. The first study compared the differences in sagittal plane ankle and hip kinematics and kinetics across three conditions at two speeds in healthy individuals while the second study compared frontal plane kinetics at the hip and knee and vertical ground reaction forces between two conditions at two speeds in healthy individuals. This was studied by collecting and analyzing three-dimensional joint kinematics and ground reaction forces from twelve healthy adults. Participants walked in three conditions (shod; i.e. athletic shoes only and two reduced push-off conditions using solid ankle foot orthoses (SAFOs); i.e. unilateral brace and bilateral brace conditions) and at two speeds (1.25m/s and 1.5m/s). In the first study, generalized linear models with general estimating equations were used to compare ankle and hip angles, moments and power for the braced and unbraced sides separately in all three conditions. In the second study, frontal plane kinetics and vertical ground reaction forces in the unbraced limb in the unilateral brace condition were compared to the same side during shod walking using paired sample t-tests. From our first study we found that the reduced push-off from the use of SAFOs results in decreased peak plantarflexion angles and power generation at the ankle and increased peak flexion angles, and first and second peak power generation at the hip in the braced limbs in both unilateral (p≤0.05) and bilateral (p≤0.05) brace conditions at both speeds. On the unbraced side in the unilateral brace condition, there were decreased peak power generation at the ankle at 1.25m/s and increased peak extension moments, first and second peak power generation at the hip compared to the shod condition (p<0.05) at both speeds. In the comparison between the unilateral and bilateral brace conditions, the changes in ankle and hip mechanics were similar to the changes between the shod condition and the bilateral brace condition on the unbraced side; in addition, participants also had higher peak extension moments in the unilateral brace condition compared to the bilateral brace condition (p<0.05). On the braced side, participants had lower peak plantarflexion moments at the ankle and lower peak flexion angles at the hip when walking with bilateral SAFOs, compared to walking with unilateral SAFOs (p<0.05). In the second study, we found that peak internal knee and hip abduction moments were 3% and 4% higher, respectively, in the unbraced limb in the unilateral brace condition at 1.25m/s (p≤0.041) compared to the same side in the shod condition. Peak vertical ground reaction force was 3% higher in the unbraced limb in the unilateral brace condition at both speeds (p=0.002). Findings indicate that walking with unilateral ankle foot orthoses presents an increased risk of developing secondary conditions.

Children with cerebral palsy (CP) have a higher than normal O2 uptake (VO2) during walking. While various interventions are used to improve locomotion, little is known about their effect on the metabolic and cardiopulmonary cost of walking. We therefore assessed the effects of one popular intervention, hinged ankle foot orthoses (AFO), on cardiopulmonary and metabolic variables during 2 min of steady state treadmill walking at three speeds: 3 kph, comfortable walking speed (CWS) and fast walking speed (FWS). We also assessed the effect of these braces on comfortable and maximum ground walking speed and on gross motor abilities using the Gross Motor Function Measure. Ten children with spastic diplegic CP (9.01 years ± 2.10) who habitually used hinged AFO participated. Not all children could walk at all speeds on the treadmill however, and some cardiopulmonary and metabolic data on three children were missing due to equipment failure. We performed an ANOVA on data for children who walked at 3 kph and CWS (n=8 for heart rate (HR); n=9 for pulmonary ventilation and metabolic variables) and a t-test on data at FWS (n=9 for HR, n=8 for pulmonary ventilation and metabolic variables). When children wore AFO, absolute VO2 was reduced by 4.6% at 3 kph and by 4.1% at FWS, and absolute VO2 per metre walked by 4.6% and 4.4% at the same speeds, respectively. Adjusting VO2 for body mass, or for resting VO2 or calculating energy expenditure in kJ, revealed the same pattern. Pulmonary ventilation was lower with AFO on by 7.17%, but only at 3 kph. AFO did not affect gross motor abilities. Nor did it affect HR, or the respiratory exchange ratio at any speed, nor any physiologic variable at CWS. We suggest the lower O2 cost may reflect an increase in stability and a corresponding decrease in coactivation of lower limb antagonistic muscles. / Thesis / Master of Science (MSc)

Individuals with various lower-limb neuromuscular and musculoskeletal impairments are often prescribed passive-dynamic ankle-foot orthoses (PD-AFOs) to compensate for impaired ankle muscle weakness. Several studies have demonstrated the beneficial effects of PD-AFOs on pathological gait, but few studies have examined the influence of the AFO stiffness characteristics on gait performance. One challenge to performing such studies is the difficulty of manufacturing custom AFOs with a wide range of controlled stiffness levels. However, selective laser sintering (SLS) is a well-suited additive manufacturing technique for generating subject-specific PD-AFOs of varied stiffness. Therefore, the overall goal of this study was to use SLS manufactured PD-AFOs to identify the relationships between AFO stiffness and gait performance in patients with various lower-limb neuromuscular and musculoskeletal impairments. Six subjects with unilateral impairments were enrolled in this study. For each subject, one subject-specific PD-AFO equivalent to the subject’s clinically prescribed carbon fiber PD-AFO (nominal), one 20% more compliant and one 20% more stiff were manufactured using SLS. Three-dimensional kinematic and kinetic data were collected from each subject while ambulating with each PD-AFO at two different speeds to allow a comprehensive biomechanical analysis to assess the influence of PD-AFO stiffness on gait performance. The results showed that in the compliant AFO condition, the AFO limb vertical ground reaction force (GRF) impulse during loading and the non-AFO limb medial GRF impulse during push-off decreased. In addition, the AFO limb braking GRF impulse during loading and the non-AFO limb braking GRF impulse in early single-limb stance decreased. Furthermore, in the compliant AFO condition, negative knee work during early single-limb stance increased while positive hip work in early swing decreased in the AFO limb. Overall, as AFO stiffness decreased, the AFO limb contributed less to body support and braking. In addition, a decreased medial GRF impulse coupled with an increased vertical GRF impulse during non-AFO single-limb stance suggests that walking stability may be compromised as AFO stiffness decreases. Thus, a tradeoff may exist between preserving stability and increasing net propulsion, which should be considered when assessing the mobility needs of individuals prescribed PD-AFOs as a result of various neuromuscular and musculoskeletal impairments. / text

Thesis (MScPhysio)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: SYSTEMATIC REVIEW ABSTRACT - BACKGROUND: Ankle Foot Orthoses (AFOs) are considered as the most suitable lower limb orthosis to correct gait deficits related to ankle instability. AFOs are recommended to minimize gait deviations and to correct drop foot or equinus foot in hemiplegic patients. OBJECTIVES - To identify the effectiveness of different ankle orthoses and/or supports on the temporal, spatial, kinetic and kinematic gait parameters. To critically appraise the methodological quality of the included studies and to provide a description of the studies with a view to identify opportunities to improve future research quality. METHODS - Search strategy A comprehensive search was conducted between March and October 2010, and updated in August 2011. Thirteen computerized bibliographic databases were individually searched, namely PubMed Central, Cohrane Library, CINAHL, OT Seeker, SPORTDiscus, PsyARTICLE, PEDro, Proquest, Biomed Central, Science Direct, Clinicaltrials.gov, Web of Science, and Ingenta Connect. All databases were searched since their inception. The following key terms were used: stroke, hemipleg*, assistive device*, ankle foot orthos*, AFO, (splint*), taping, and strapping. A secondary search (pearling) was conducted by screening the reference lists of all eligible full text studies. The authors of the unpublished studies were conducted to minimize publication bias. Selection criteria The following selection criteria applied: all relevant randomized and non-randomized controlled trails published in English; participants were post-stroke patients older than eighteen years; interventions included any type of ankle foot orthosis (AFO), ankle taping or strapping and ankle foot splint without any additional intervention and the comparison/control groups were limited to walking without support, either barefoot or walking with shoes only. Studies were excluded when the outcome measures did not focus on at least one of the following: temporal spatial gait parameters, kinetic gait parameters or kinematic gait parameters. Data collection and analysis Two reviewers independently selected trials for inclusion and assessed methodological quality. The data was extracted by the primary reviewer and validated by a second reviewer. In event of disagreement, a third reviewer was asked to re-evaluate until consensus could be reached. Homogenous data were statistically summarized in sub-group meta-analysis using Revman© Review Manager Software. The results of heterogeneous data were summarized in a narrative form. MAIN RESULTS - The search yielded 11134 initial hits. Sixteen studies met the inclusion/exclusion criteria. The studies investigated the immediate effect of various types of AFOs on a broad range of temporal spatial gait parameters mainly gait speed, cadence, stride and step length. Only two studies reported on the kinetic and six on various kinematic gait parameters. The meta-analysis yielded significant improvement in gait speed (0.06 m/s; 95% CI 0.04, 0.08. p < 00001), walking cadence (5.41; 95% CI 3.79, 7.03. p < 00001), stride length (6.67; 95% CI 3.29, 10.06. p < 00001) and step length (2.66; 95% CI 1.59, 3.72. p < 0.00001). CONCLUSION - AFOs are effective to improve mobility, gait speed, cadence, stride and step length for post-stroke patients and may have a positive impact on the daily function of post-stroke patients. . The long term benefit or adverse effects of AFOs are still inconclusive. The effectiveness of AFOs on the kinetic and the frontal- or transverse- plane joint kinematics is largely unresolved. There is insufficient evidence to either support or refute the effectiveness of taping/strapping and splinting of the ankle on hemiplegic gait. EXPERIMENTAL STUDY ABSTRACT - BACKGROUND: Temporal, spatial and affected ankle kinematic gait parameters of adults with hemiplegia are significantly different from the normal able-bodied population. Enabling hemiplegic patients to walk is a major goal of rehabilitation programs. Taping of the plegic ankle could be utilized by therapists as external support of the ankle to improve foot position and placement during gait rehabilitation. OBJECTIVE - The purpose of the study was to describe the immediate effect of neutral ankle taping on temporal spatial gait parameters and ankle joint kinematics of the affected ankle in ambulant adult hemiplegic patients. METHODS - A clinical trial using a crossover randomized testing order was conducted on a convenient sample of ten ambulant hemiplegic patients at the Physiotherapy and Motion Analysis Clinic, Faculty of Health Sciences, Stellenbosch University, Tygerberg, Cape Town, South Africa. The affected ankle joint was taped in a neutral talocrural dorsiflexion/ plantarflexion and neutral hindfoot inversion/ eversion position using rigid adhesive tape (5 cm). The gait parameters were analysed according to the Plug-In Gait Model using a motion analysis system (Vicon Nexus 1.1.7; Vicon Motion System Limited, Oxford, UK). The analyses were repeated six times for each testing condition and the average values were used for further analysis. The data were analyzed using Least Square Means tests and post hoc Fisher (Least Significant Difference) LSD multiple comparison tests to determine the significant differences at 95% confidence level. RESULTS - The main results of the study indicate that taping of the affected ankle joint in a neutral position does not significantly improve (p>0.5) temporal spatial gait parameters and ankle joint kinematics in ambulant adult hemiplegic patients. The following positive trends were however found and need to be further explored in larger homogeneous study samples: ankle taping of ambulant adult hemiplegic patients has limited benefits on selected temporal parameters as ankle taping could potentially improve cadence. Ankle taping could decrease plantarflexion of the plegic leg at initial contact. CONCLUSIONS - A systematic review revealed no conclusive evidence either to support or refute the beneficial effects of ankle taping on gait parameters of ambulant adult hemiplegic patients. Ankle taping of ambulant adult hemiplegic patients has potential clinical benefits on temporal, spatial and affected ankle kinematics, gait cadence and affected leg swing and stance duration.

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.