Influence Of Foot Research Articles

Influence of foot posture focused racing shoes on running motion

Influence of foot posture focused racing shoes on running motion

Bridging the Gap: The Influence of Foot and Ankle Pathomechanics in Total Knee Arthroplasty.

Altered spinopelvic mechanics can have dramatic influences on the success of hip arthroplasty as seen with concomitant hip and spine disease. Interestingly, limited focus has been directed toward a similar codependent relationship between concurrent knee and foot deformities. By bridging this interdisciplinary gap, we attempt to explore the current understanding and clinical implications of concomitant knee and foot pathology while reviewing management options for addressing this unique yet ubiquitous patient population. Multiple authors have demonstrated an inverse relationship between progressive coronal plane deformities concerning the knee and hindfoot. The utility of a conventional mechanical axis during total knee arthroplasty may be limited in the presence of foot deformity where ground reactive forces often markedly deviate with the hindfoot, potentially leading to eccentric knee loading. The use of alternative indices, such as ground mechanical axis deviation, may offer a more reliable metric for achieving an accurate neutral mechanical axis. In addition, although foot deformity and compensation can often improve to a limited degree after total knee arthroplasty, residual deformity may have deleterious effects on the success of the procedure. A comprehensive understanding of the functional relationship between the foot and the knee can allow surgeons to better guide appropriate treatment sequence, often beginning with the more symptomatic deformity. Future research is needed to further elucidate the implications and appropriate management of concomitant knee and foot deformity.

Influence of hexapod robot foot shape on sinking considering multibody dynamics

Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage greatly reduce its walking performance. The influence of foot’s shape is usually ignored or simply studied without considering the multibody dynamics of the robot. This study is focused on the influence of the foot shape on the walking performance of a robot by coupling the sinkage with multibody dynamics. A composite contact model based on the Bekker, spring-damping, and Janosi-Hanamoto models was used to model the interaction of the robot and soft soil. Non-uniform rational B-spline (NURBS) surface and mesh were used to describe the geometries of foot and soft soil, respectively. The influences of three foot shapes on the sinkage and walking stability of the robot were analyzed by comparsion. The improved X-shaped foot reduced the robot’s sinkage and improved its walking stability.

The influence of foot and back massage on blood pressure and sleep quality in females with essential hypertension: a randomized controlled study.

The present study was conducted with the aim of investigating the influence of foot and back massage on blood pressure and sleep quality in females with essential hypertension. Non-pharmacologic methods like massage may be effective for balancing blood pressure and solving sleep problems. This is a randomized controlled study conducted in accordance with CONSORT rules. Females with essential hypertension were applied a total of six sessions of 30 min of foot and back massage twice weekly during 3 weeks. The study included a total of 90 patients of whom 60 were in intervention group (foot massage group, back massage group) and 30 in control group. Data were collected through personal data form (PDF) which included descriptive characteristics, Pittsburgh Sleep Quality Index (PSQI). Six sessions of foot massage and back massage were detected to lead to a reduction in systolic blood pressure (SBP) and diastolic blood pressure (DBP) values and the difference was statistically significant (p < 0.001). A strong statistical difference was found between mean pretest posttest scores of overall and sub-dimensional scores of PSQI in females in intervention group (p < 0.001). Foot and back massage was found to be effective in reducing blood pressure and improving sleep quality.

Influence of foot posture on immediate biomechanical responses during walking to variable-stiffness supported lateral wedge insole designs

BackgroundNovel designs of lateral wedge insoles with arch support can alter walking biomechanics as a conservative treatment option for knee osteoarthritis. However, variations in foot posture may influence individual responses to insole intervention and these effects are not yet known. Research questionHow does foot posture influence biomechanical responses to novel designs of lateral wedge insoles with arch support? MethodsThis exploratory biomechanical investigation categorized forty healthy volunteers (age 23–34) into pronated (n = 16), neutral (n = 15), and supinated (n = 9) foot posture groups based on the Foot Posture Index. Three-dimensional gait analysis was conducted during walking with six orthotic insole conditions: flat control, lateral wedge, uniform-stiffness arch support, variable-stiffness arch support, and lateral wedge + each arch support. Frontal plane knee and ankle/subtalar joint kinetic and kinematic outcomes were compared among insole conditions and foot posture groups using a repeated measures analysis of variance. ResultsThe lateral wedge alone and lateral wedge + variable-stiffness arch support were the only insole conditions effective at reducing the knee adduction moment. However, the lateral wedge + variable-stiffness arch support had a smaller increase in peak ankle/subtalar eversion moment than the lateral wedge alone. Supinated feet had smaller ankle/subtalar eversion excursion and moment impulse than neutral and pronated feet, across all insole conditions. SignificanceSupinated feet have less mobile ankle/subtalar joints than neutral and pronated feet and, as a result, may be less likely to respond to biomechanical intervention from orthotic insoles. Supported lateral wedge insoles incorporating an arch support design that is variable-stiffness may be better than uniform-stiffness since reductions in the knee adduction moment can be achieved while minimizing increases in the ankle/subtalar eversion moment.

Varus thrust visualized during gait was associated with inverted foot in patients with knee osteoarthritis: An exploratory study

The foot is speculated to play a role in knee joint kinematics. This exploratory cross-sectional study examined the association between static foot posture and the presence of varus thrust visualized during gait in patients with medial knee osteoarthritis (OA). Patients (n = 88 patients and 134 knees; age, 61–91 years; 68.2% female) with Kellgren/Lawrence (K/L) grade ≥1 in the medial compartment were included in this study and underwent gait observation for varus thrust. These patients’ three-dimensional static foot posture while standing was evaluated and their tibiofemoral joint K/L grades and anatomical axis angles were also assessed as covariates. Knees with varus thrust (22 knees, 16.4%) on average had a 4° more inverted calcaneus relative to the floor than those without varus thrust (P < 0.001). A logistic regression analysis showed that an increased calcaneus inversion angle was significantly associated with higher odds of the presence of varus thrust with adjustments for age, sex, body mass index, K/L grade, and anatomical axis angle. The other predictors, such as navicular height, navicular height/foot length, and rearfoot angle relative to the lower leg, were not significantly associated with varus thrust. These results suggest that patients with varus thrust had a different static rearfoot posture as compared with those without varus thrust, a finding that may indicate an important role of static rearfoot posture in the pathogenesis of varus thrust. Furthermore, investigating the potential influence of foot posture on the efficacy of biomechanical interventions, such as lateral wedge insole use, on varus thrust would be of particular interest in the further studies.

Influence of foot posture on the functioning of the windlass mechanism

The absence of a functioning windlass mechanism may delay re-supination of the foot during locomotion and put excess stress on the mid-tarsal joint and soft tissues of the foot. The purpose of this study was to describe the foot posture of individuals that have an impaired or absent windlass mechanism.Forty-seven individuals (34 females and 13 males) with a mean age of 26 years were recruited to participate in this study. The Foot Posture Index was used to visually assess the posture of both feet. In addition, a digital gauge was used to measure dorsal arch height and midfoot width in bilateral resting standing. Dorsal arch height and mid-foot width were also measured in non-weight bearing. Finally, for those individuals without a functioning windlass mechanism, the amount of medial wedging needed to restore its function was measured.Subjects with an “absent” or “impaired” windlass mechanism had a mean Foot Posture Index of +6.8 (sd=2.5) compared to +2.5 (sd=3.1) for those with a functioning windlass mechanism. A series of independent t-tests showed that individuals without a functioning windlass mechanism had a more pronated foot posture, a lower dorsal arch height and a wider mid-foot width compared to those that had a functioning windlass mechanism. Finally, an average medial wedge of 5.1mm (sd=2.1) was able to produce a functioning windlass mechanism in those individuals that previously lacked one.

The influence of foot posture on dorsiflexion range of motion and postural control in those with chronic ankle instability

BackgroundTo investigate the effect of foot posture on postural control and dorsiflexion range of motion in individuals with chronic ankle instability. MethodsThe study employed a cross-sectional, single-blinded design. Twenty-one individuals with self-reported chronic ankle instability (male=5; age=23.76(4.18)years; height=169.27(11.46)cm; weight=73.65(13.37)kg; number of past ankle sprains=4.71(4.10); episode of giving way=17.00(18.20); Cumberland Ankle Instability Score=18.24(4.52); Ankle Instability Index=5.86(1.39)) participated. The foot posture index was used to categorize subjects into pronated (n=8; Foot Posture Index=7.50(0.93)) and neutral (n=13; Foot Posture Index=3.08(1.93)) groups. The dependent variables of dorsiflexion ROM and dynamic and static postural control were collected for both groups at a single session. FindingsThere were no significant differences in dorsiflexion range of motion between groups (p=0.22) or any of the eyes open time-to-boundary variables (p>0.13). The pronated group had significantly less dynamic postural control than the neutral group as assessed by the anterior direction of the Star Excursion Balance Test (p<0.04). However, the pronated group had significantly higher time-to-boundary values than the neutral group for all eyes closed time-to-boundary variables (p≤0.05), which indicates better eyes closed static postural control. InterpretationFoot posture had a significant effect on dynamic postural control and eyes closed static postural control in individuals with chronic ankle instability. These findings suggest that foot posture may influence postural control in those with chronic ankle instability.

The influence of foot and ankle injury patterns and treatment delays on outcomes in a tertiary hospital; a one-year prospective observation

BackgroundAnkle and foot fractures are amongst the most common injuries, and patterns may vary from primary care set up to tertiary hospitals. Severe foot injuries are projected to have significantly worse outcomes and surgical delays are thought to alter prognosis. MethodsAll patients with foot and ankle trauma were prospectively evaluated at a Tertiary trauma centre over one year. The incidence, fracture patterns, risk factors, and outcomes were evaluated, and cases were divided into simple foot injuries (FASS≤3) and severe foot injuries (FASS>3). Injury mechanisms, associated injuries, and delays in treatment were evaluated, and outcomes were analyzed using Visual–Analogue Scale Foot and Ankle (VASFA), Maryland Foot Score (MFS) and Foot and ankle disability index (FADI). Results294 Foot and Ankle injuries (51 females, 243 males) were encountered in 2919 trauma cases (incidence of 10%). 80 patients (27.2%) had simple foot injuries and 214 (72.8%) had severe foot injuries. 29 patients (9.9%) were below 18years; most (65.3%) patients were between 18 and 45 years age. Road traffic accident was most commonest mode of injury, with ankle fractures (30.6%) the most common. Metatarsal fractures (27.9%) and calcaneal fractures (21.4%) were 2nd and 3rd most common injuries in the foot. Surgical delay averaged 1 day in both severe and simple injuries. Injury led to 32 (10.9%) below knee amputations. Outcome evaluation in 127 (91 severe, 36 simple injuries) patients showed mean Maryland foot score of 89.30 in simple injury group and 84.87 in severe injury group. Mean VASFA score was 82.87 (simple) and 81.87 in severe injury, and mean FADI score was 93.13 (simple) and 91.05 (severe injury). More detailed analysis revealed that more good scores (64.4%) were documented in severe injuries group, and more excellent scores (52.8%) in simple injuries group. ConclusionFoot injuries constitute 10% of all orthopaedic trauma at tertiary hospitals; Majority of them are severe foot injuries, with 68.7% being open injuries. Surgical delay was similar in simple and severe foot and ankle injuries. Outcomes of severe injuries were similar to simple foot and ankle injuries, reflecting on the quality of care that could be administered to them when they present to tertiary hospitals.

Foot and ankle impairments affect balance and mobility in stroke (FAiMiS): the views and experiences of people with stroke

Purpose: To explore the nature and impact of foot and ankle impairments on mobility and balance in community-dwelling, chronic stroke survivors. Methods: A qualitative research design using face to face semi-structured, audio recorded interviews. Thirteen community-dwelling stroke survivors, all of whom had self-reported foot and ankle impairments, were interviewed (female n = 6, mean age = 67 years, SD = 12 years, mean time since stroke = 4 years, SD = 6 years, right stroke n = 7, left stroke n = 6). A framework analysis approach was used to analyse and interpret transcribed interviews. Results: Three themes emerged: (1) Impact. The influence of foot and ankle impairments on mobility and balance. (2) Standing out. How participants felt they “stood out” because of their impairments and wanted to be normal. (3) Help. The specific help and advice participants received in managing their problems. Conclusions: Foot and ankle impairments such as pain, altered somatosensory input and weakness significantly contribute to problems with community ambulation, balance and fear of falling in people with chronic stroke. Specific foot and ankle impairments may also negatively contribute to perceptions of physical appearance and self-esteem. Therapeutic management approaches within clinical practice appear to focus mostly on the gross performance of the lower limb with little emphasis on the specific assessment or treatment of the foot or ankle.Implications for RehabilitationFoot pain, sensory impairments and muscle weakness in the foot and ankle can impact on community ambulation, balance and fear of falling following stroke.Foot and ankle function post-stroke should be routinely assessed and monitored.Clinicians should be aware of the potentially distressing negative perceptions associated with altered gait patterns, footwear and orthotic use.

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Objective: Patients with rheumatoid arthritis (RA) have an increased risk of falls. Foot pain/ deformities affect the majority of patients with RA. The objective of this study was to determine the influence of foot pain/deformities on risk of fall in patients with RA. Methods: This study comprised 89 patients (75 females, 14 males) with RA. Patients were queried about pain in the hip, knee and foot. The diagnoses of foot deformities were based on clinical and radiographic evaluation. Patients’ risk of fall was assessed using the Tinetti Performance Oriented Mobility Assessment . Results: Mean age and disease duration of the patients were 46.84 ± 13.20 and 7.82 ± 7.01 years, respectively. Twelve (13%) patients had risk of fall. The patients with risk of fall had a higher numeric rating scale (NRS) for foot pain (4.08 ± 1.44 vs 2.62 ± 2.51; p = 0.012) and number of foot deformities (1.41 ± 1.67 vs 0.55 ± 1.11; p = 0.009) than those without risk of fall. There were correlations between the TPOMA scores and NRS for foot pain (r = -0.264; p = 0.013) and number of foot deformities (r = -0.374; p = 0.001). Conclusion: The results of this study demonstrate that RA patients with foot pain/deformities have higher risk of fall . We suggest that early diagnosis and better control of disease activity will prevent foot pain/deformities in order to reduce the risk and the burden of falls.

Functional impairments characterizing mild, moderate, and severe hallux valgus.

Hallux valgus (HV) has been linked to functional disability and increased risk of falls, but mechanisms underpinning functional disability are unclear. This study investigated functional performance, muscle strength, and plantar pressures in adults with mild, moderate, and severe HV compared to controls, while considering the influence of foot pain. Sixty adults with HV (classified as mild, moderate, and severe on dorsalplantar radiographs) and 30 controls participated. Measures included hallux plantar flexion and abduction strength, walking performance, postural sway, and forefoot plantar pressures. Multivariate analysis of covariance and pairwise comparisons (P < 0.05 after Bonferroni adjustment) were used to investigate differences between groups, adjusting for age, sex, body mass index, and foot pain. Hallux plantar flexion and abduction strength were significantly reduced in those with moderate (mean differences: plantar flexion -45.8 N, abduction -12.3 N; P < 0.001) and severe HV (plantar flexion -50.1 N; P < 0.001, abduction -11.2 N; P = 0.01) compared to controls. A significant reduction in hallux peak pressure and pressure-time integral was evident in moderate (peak pressure -90.8 kPa; P < 0.001) and severe HV (peak pressure -106.2 kPa; P < 0.001) compared to controls. Those with severe HV also demonstrated increased mediolateral postural sway in single leg stance compared to controls (3.5 cm; P = 0.01). Moderate to severe HV is associated with reduced hallux plantar pressures and strength measures, while relatively normal function compared to controls was found in those with mild deformity. Greater understanding of specific functional deficits associated with different stages of HV will help inform clinical management and future research.

Foot and Ankle Kinematics in Rheumatoid Arthritis: Influence of Foot and Ankle Joint and Leg Tendon Pathologies

From early onset of the disease, patients with rheumatoid arthritis (RA) experience walking impairments. Pathologic effects of RA on foot and ankle structures have been studied clinically, but little is known as to how they relate to kinematic changes during gait. The aim of this study was to explore the relationship between clinically observed pathologies of foot and ankle joints and leg tendons and the corresponding gait kinematics. The gait of 25 subjects with varying stages of RA was recorded and foot and ankle kinematics were assessed. Magnetic resonance imaging was performed for each subject: first metatarsophalangeal (MTP) joint, midfoot, and hindfoot synovitis, erosion scores, and leg tendon involvement were determined. The joint alignment and motion score represented daily clinical assessment. The 95% confidence intervals of the Spearman's correlation coefficient tests were used to explore the relationships between the clinical and kinematic parameters. Maximum first MTP joint dorsiflexion at preswing was related to reduced first MTP joint passive motion, first MTP joint synovitis and erosion, midfoot synovitis and erosion, and hindfoot erosion. Midfoot pronation range of motion during single stance was related to subtalar alignment and Achilles tendon involvement. Hindfoot eversion range of motion during single stance was related to subtalar alignment and peroneus longus tendon involvement. Involvement of the tibialis posterior tendon could not be identified as an independent factor influencing foot or ankle kinematics. Our findings suggest moderate to strong relationships between foot and ankle gait kinematics and structural pathologies.

The influence of foot posture, support stiffness, heel pad loading and tissue mechanical properties on biomechanical factors associated with a risk of heel ulceration

Heel ulcers (HU) are the second most common type of pressure ulcers. In this work, we developed the first anatomically-realistic three-dimensional finite element model of the posterior heel for studying the risk for HU in bedridden patients. We specifically simulated a heel that is resting on supports with different stiffnesses at upright and inclined foot postures. Our objective was to examine the effects of foot posture and stiffness of the support on strains and stresses within the fat pad of the resting heel. We found that strains and stresses in the fat pad of the heel are considerably reduced when the foot is positioned so that its lateral aspect is at 90° with respect to the horizon compared to an abducted (60°) foot posture. The study therefore indicates that theoretically, an inclined foot posture puts a bedridden patient at a higher risk for HU with respect to an upright foot posture, which may be explained by the anatomy of the heel that faces a lower curvature and better cushioned region against the support when the foot is upright.

The influence of foot posture on the cost of transport in humans

Although humans appear to be specialized for endurance running, the plantigrade posture of our feet, in which the heel contacts the substrate at the beginning of a step, seems incompatible with economical running. In this study, we tested the hypothesis that plantigrade foot posture reduces the energetic cost of transport (COT) during walking in humans. When human subjects walked with their heels slightly elevated in a 'low-digitigrade' posture, COT increased by 53% above that of normal plantigrade walking. By contrast, there was no difference in COT when subjects ran with digitigrade versus plantigrade foot posture. Stride frequency increased and stride length decreased when subjects switched to digitigrade walking; however, this change did not influence the COT. Additionally, we found that possible reductions in postural stability appear not to have caused the elevated cost of digitigrade walking. Digitigrade walking, however, did (1) increase the external mechanical work performed by the limbs; (2) reduce the pendular exchange of kinetic and potential energy of the center of mass; (3) increase the average ground reaction force moment at the ankle joint; and (4) increase the recruitment of major extensor muscles of the ankle, knee, hip and back. These observations suggest that plantigrade foot posture improves the economy of walking. Relative to other mammals, humans are economical walkers, but not economical runners. Given the great distances hunter-gatherers travel, it is not surprising that humans retained a foot posture, inherited from our more arboreal great ape ancestors, that facilitates economical walking.

The Influence of Foot Position on Stretching of the Plantar Fascia

A recent study found nonweightbearing stretching exercises specific to the plantar fascia to be superior to the standard program of weightbearing Achilles tendon-stretching exercises in patients with chronic plantar fasciitis. The present study used a cadaver model to demonstrate the influence of foot and ankle position on stretching of the plantar fascia. Twelve fresh-frozen lower-leg specimens were tested in 15 different configurations representing various combinations of ankle and metatarsophalangeal (MTP) joint dorsiflexion, midtarsal transverse plane abduction and adduction, and forefoot varus and valgus. Measurements were recorded by a differential variable reluctance transducer (DVRT) implanted into the medial band of the plantar fascia, and primary measurement was a percent deformation of the plantar fascia (stretch) with respect to a reference position (90 degrees ankle dorsiflexion, 0 degrees midtarsal and forefoot orientation, and 0 degrees MTP dorsiflexion). Ankle and MTP joint dorsiflexion produced a significant increase (14.91%) in stretch compared to the position of either ankle dorsiflexion alone (9.31% increase, p < 0.001) or MTP dorsiflexion alone (7.33% increase, p < 0.01). There was no significant increase in stretch with positions of abduction or varus (2.49%, p = 0.27 and 0.55%, p = 0.79). This study provides a mechanical explanation for enhanced outcomes in recent clinical trials using plantar fascia tissue-specific stretching exercises and lends support to the use of ankle and MTP joint dorsiflexion when employing stretching protocols for nonoperative treatment in patients with chronic proximal plantar fasciitis.

Magic angle effect in MR imaging of ankle tendons: influence of foot positioning on prevalence and site in asymptomatic subjects and cadaveric tendons

The influence of foot positioning on prevalence of the magic angle effect (MAE) in ankle tendons was investigated. In 30 asymptomatic volunteers and five cadaveric feet, MR imaging of the ankle was performed in the supine (neutral position of the foot) and prone (plantar-flexed foot) position. MAE was considered if increased T1-weighted signal at a certain site was seen in one position only. Histological correlation was obtained at 25 sites of the cadaveric posterior tibialis tendons (PTT). MAE occurred in 6/30 vs 1/30 (supine vs prone) anterior tibialis tendons (ATT), 30/30 vs 0/30 extensor hallucis longus and 27/30 vs 0/30 extensor digitorum longus tendons, 29/30 vs 0/30 PTTs, 30/30 vs 0/30 flexor digitorum and flexor hallucis longus tendons, 30/30 vs 1/30 peroneus brevis and 23/30 vs 1/30 peroneus longus tendons. At 12/25 cadaveric PTT sites where MAE was exclusively responsible for the increased signal, histology revealed normal tissue (11/12) or minimal degeneration (1/12). In conclusion, the supine body position with neutral position of the foot, a high prevalence (77-100%) of MAE in ankle tendons except for the ATT (20%) is seen. MAE is almost absent in the prone body position with plantar flexion of the foot.

Influence of foot, leg and shoe characteristics on subjective comfort.

The purpose of this study was to determine the relationships between foot and leg characteristics, shoe characteristics, and the short-term subjective comfort of three different pairs of athletic shoes. Static measurements of foot dimension and leg angles were taken from eighteen subjects. Subjects rated the comfort of three different athletic shoes for standing, walking and running. The shoes were quantified by internal dimensions, hardness, flexibility and torsional stiffness. Average comfort ratings decreased from standing to walking to running. One shoe seemed suited for only a small group of subjects. In contrast, another shoe was generally comfortable for a large group. Skeletal alignment, specifically eversion angle, was related to comfort for one shoe. Therefore, fit of the shoe is not sufficient for comfort. Skeletal alignment, shoe torsional stiffness and cushioning seem to be mechanical variables which may be important for comfort.

Evolution of passerine incubation behavior: influence of food, temperature, and nest predation.

Incubation behavior is one component of reproductive effort and thus influences the evolution of life-history strategies. We examined the relative importance of body mass, frequency of mate feeding, food, nest predation, and ambient temperature to explain interspecific variation in incubation behavior (nest attentiveness, on- and off-bout durations, and nest trips per hour) using comparative analyses for North American passerines in which only females incubate. Body mass and frequency of mate feeding explained little variation in incubation behavior. We were also unable to detect any influence of foot; diet and foraging strategy explained little interspecific variation in incubation behavior. However, the typical temperature encountered during reproduction explained significant variation in incubation behavior: Species breeding in colder environments take shorter bouts off the nest, which prevents eggs from cooling to temperatures below the physiological zero temperature. These species must compensate for shorter off-bouts by taking more of them (thus shorter on-bouts) to obtain needed energy for incubation. Nest predation also explains significant variation in incubation behavior among passerines: Species that endure high nest predation have evolved an incubation strategy (long on- and off-bouts) that minimizes activity that could attract predators. Nest substrate explained additional variation in incubation behavior (cavity-nesting birds have shorter on-bouts and make more frequent nest trips), presumably because nest predation and/or temperature varies among nest substrates. Thus, nest predation can influence reproductive effort in a way previously not demonstrated--by placing a constraint on parental activity at the nest. Incubating birds face an ecological cost associated with reproductive effort (predation of entire brood) that should be considered in future attempts to explain avian life-history evolution.

The influence of foot positioning on ankle sprains

The goal of this study was to examine the influence of changes in foot positioning at touch-down on ankle sprain occurrence. Muscle model driven computer simulations of 10 subjects performing the landing phase of a side-shuffle movement were performed. The relative subtalar joint and talocural joint angles at touchdown were varied, and each subject-specific simulation was exposed to a set of perturbed floor conditions. The touchdown subtalar joint angle was not found to have a considerable influence on sprain occurrence, while increased touchdown plantar flexion caused increased ankle sprain occurrences. Increased touchdown plantar flexion may be the mechanism which causes ankles with a history of ankle sprains to have an increased susceptibility to subsequent sprains. This finding may also reveal a mechanism by which taping of a sprained ankle or the application of an ankle brace leads to decreased ankle sprain susceptibility.