The Midfoot Joint Complex (Foot Arch) Contributes to the Upper Body Position in Bipedal Walking and Coordinates With the Lower Limb Joints.

This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior-posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints' contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ -.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints' contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints.

New Perspectives on Foot Segment Forces and Joint Kinetics-Integrating Plantar Shear Stresses and Pressures with Multi-segment Foot Modeling.

The role of the many small foot articulations and plantar tissues in gait is not well understood. While kinematic multi-segment foot models have increased our knowledge of foot segmental motions, the integration of kinetics with these models could further advance our understanding of foot mechanics and energetics. However, capturing and effectively utilizing segmental ground reaction forces remains challenging. The purposes of this study were to (1) develop methodology to integrate plantar pressures and shear stresses with a multi-segment foot model, and (2) generate and concisely display key normative data from this combined system. Twenty-six young healthy adults walked barefoot (1.3 m/s) across a pressure/shear sensor with markers matching a published 4-segment foot model. A novel anatomical/geometric template-based masking method was developed that successfully separated regions aligned with model segmentation. Directional shear force plots were created to summarize complex plantar shear distributions, showing opposing shear forces both between and within segments. Segment centers of pressure (CoPs) were shown to be primarily stationary within each segment, suggesting that forward progression in healthy gait arises primarily from redistributing weight across relatively fixed contact points as opposed to CoP movement within a segment. Inverse dynamics-based normative foot joint moments and power were presented in the context of these CoPs to aid in interpretation of tissue stresses. Overall, this work represents a successful integration of motion capture with direct plantar pressure and shear measurements for multi-segment foot kinetics. The presented tools are versatile enough to be used with other models and contexts, while the presented normative database may be useful as a baseline comparison for clinical work in gait energetics and efficiency, balance, and motor control. We hope that this work will aid in the advancement and availability of kinetic MSF modeling, increase our knowledge of foot mechanics, and eventually lead to improved clinical diagnosis, rehabilitation, and treatment.

Young females with hallux valgus show lower foot joint movement stability compared to controls: An investigation of coordination patterns and variability.

BACKGROUND: A kinematic coupling relationship exists between foot joints during gait. In individuals with hallux valgus, forefoot or hallux kinematics may be affected by adjacent or nonadjacent joint motion. Thus, this study aimed to investigate the foot joint coordination pattern and variability during gait in young females with hallux valgus. METHODS: Twenty-five young females with hallux valgus and 25 healthy young females without hallux valgus were enrolled. Reflective markers were attached according to a multisegment foot model. Kinematic data were obtained using a three-dimensional motion analysis system. Joint angles between distal and proximal segments were calculated using analysis software. Foot joint coordination pattern and variability were assessed using a vector-coding technique. FINDINGS: Individuals with hallux valgus had a larger rearfoot relative to shank eversion and forefoot relative to midfoot dorsiflexion during terminal stance and pre-swing compared with those without hallux valgus. There were no significant differences in coordination patterns, but the consistency of coordination between the rearfoot relative to shank motion in the frontal plane and forefoot relative to midfoot motion in the sagittal plane during terminal stance was greater in the hallux valgus group than in the control group. INTERPRETATION: The soft tissue composing the first ray might suffer from more severe stress due to the large motion that occurred with low variability in individuals with hallux valgus. This finding may suggest that the altered kinematics and coordination variability in foot joints are related to hallux valgus biomechanical etiology.

The influence of the windlass mechanism on kinematic and kinetic foot joint coupling.

BACKGROUND: Previous research shows kinematic and kinetic coupling between the metatarsophalangeal (MTP) and midtarsal joints during gait. Studying the effects of MTP position as well as foot structure on this coupling may help determine to what extent foot coupling during dynamic and active movement is due to the windlass mechanism. This study's purpose was to investigate the kinematic and kinetic foot coupling during controlled passive, active, and dynamic movements. METHODS: After arch height and flexibility were measured, participants performed four conditions: Seated Passive MTP Extension, Seated Active MTP Extension, Standing Passive MTP Extension, and Standing Active MTP Extension. Next, participants performed three heel raise conditions that manipulated the starting position of the MTP joint: Neutral, Toe Extension, and Toe Flexion. A multisegment foot model was created in Visual 3D and used to calculate ankle, midtarsal, and MTP joint kinematics and kinetics. RESULTS: Kinematic coupling (ratio of midtarsal to MTP angular displacement) was approximately six times greater in Neutral heel raises compared to Seated Passive MTP Extension, suggesting that the windlass only plays a small kinematic role in dynamic tasks. As the starting position of the MTP joint became increasingly extended during heel raises, the amount of negative work at the MTP joint and positive work at the midtarsal joint increased proportionally, while distal-to-hindfoot work remained unchanged. Correlations suggest that there is not a strong relationship between static arch height/flexibility and kinematic foot coupling. CONCLUSIONS: Our results show that there is kinematic and kinetic coupling within the distal foot, but this coupling is attributed only in small measure to the windlass mechanism. Additional sources of coupling include foot muscles and elastic energy storage and return within ligaments and tendons. Furthermore, our results suggest that the plantar aponeurosis does not function as a rigid cable but likely has extensibility that affects the effectiveness of the windlass mechanism. Arch structure did not affect foot coupling, suggesting that static arch height or arch flexibility alone may not be adequate predictors of dynamic foot function.

Effect of Ropivacaine-Loaded Magnetic Nanoparticles on Ankle Nerve Block in Rats.

AIM: Our study is to determine the influence of ropivacaine-loaded magnetic nanoparticles (MNP/Rop) on ankle nerve block in rats. MATERIALS AND METHODS: MNP/Rop was prepared and then injected intravenously into rats to evaluate its anesthetic effect on rat limbs. Mechanical pain thresholds paw withdrawal threshold (PWT) and paw withdrawal thermal latency (PWL) were employed for the assessment of ankle nerve block in rats. RESULTS: PWT increased from T1 to T4 in each group (P < 0.05). The intergroup comparison determined no distinct difference in the PWT value among the three series at T1 (P > 0.05); however, PWT values at T2-T4 were higher in nerve block control group (NBCG) and MNP/Rop group than in blank group (BG), and they remained slightly higher in MNP/Rop group than in NBCG. The intragroup comparison revealed that from T1 to T4, PWL in each group showed a rising trend. The PWL at T1 showed no evident difference among the three series (P > 0.05); however, PWL values at T2-T4 were higher in NBCG and MNP/Rop group than in BG, and they remained slightly higher in MNP/Rop group than in NBCG. In MNP/Rop group, both PWT and PWL increased with the increase of Fe3O4 load in MNP/Rop (P < 0.05), while PWT and PWL remained unchanged when the load was 2.189%; moreover, PWT and PWL elevated as Rop concentration increased in MNP/Rop (P < 0.05), while they kept unaltered under 40 µL 1% Rop. CONCLUSION: Intravenous injection of MNP/Rop into rats and inhalation of MNP into the ankle joint can effectively block ankle nerve conduction in rats.

Biomechanical maturation of foot joints in typically developing boys: Novel insight in mechanics and energetics from a cross-sectional study.

BACKGROUND: A growing body of quantitative evidence has been provided regarding age-related differences in plantar foot loading, multi-segment foot kinematics and muscle activity. Fundamental insight into the joint mechanics and energetics of the maturing foot has yet to be provided. RESEARCH QUESTION/HYPOTHESIS: It was hypothesized that so-called 'biomechancial maturation' joint kinetics would be observed in children underneath the age of eight and that older age-groups would not differ from each other in these parameters. METHODS: Fourty-three typically developing boys were recruited and allocated to three different age groups: 1) an early childhood group, 2) a middle childhood group, and 3) an early and late adolescence group. Multi-segment joint kinematics and kinetics of the Ankle-, Chopart-, Lisfranc- and Hallux joint were collected during barefoot walking. One-way Analysis of Covariance was conducted to examine differences among the outcome measures with group as a fixed factor and walking cadence as covariate. RESULTS: The youngest group differed significantly from the other two age groups with respect to their ankle and chopart joint peak plantarflexion moment (p < 0.05). Ankle and chopart joint peak power generation as well as the lisfranc peak plantarflexion moment was found to be significantly lower in the youngest age group compared to the oldest group (p < 0.05). At the lisfranc joint, the youngest age group demonstrated a significantly higher peak plantarflexion velocity compared to the two older age groups (p < 0.05). SIGNIFICANCE: This study provides novel insight into the biomechanical maturation of the developing foot which may guide clinical interventions in paediatric cohorts.

Foot joint coupling variability differences between habitual rearfoot and forefoot runners prior to and following an exhaustive run.

As joint coupling variability has been associated with running-related lower extremity injury, the purpose of this study was to identify how variability within the foot may be different between forefoot (FFS) and rearfoot strike (RFS) runners. Identifying typical variability in uninjured runners may contribute to understanding of ideal coordination associated with running foot strike patterns. Fifteen FFS and 15 RFS runners performed a maximal-effort 5 km treadmill run. A 7-segment foot model identified 6 functional articulations (rearfoot, medial and lateral midfoot and forefoot, and 1st metatarsophalangeal) for analysis. Beginning and end of the run motion capture data were analyzed. Vector coding was used to calculate 6 joint couples. Standard deviations of the coupling angles were used to identify variability within subphases of stance (loading, mid-stance, terminal, and pre-swing). Mixed between-within subjects ANOVAs compared differences between the foot strikes, pre and post run. Increased variability was identified within medial foot coupling for FFS and within lateral foot coupling for RFS during loading and mid-stance. The exhaustive run increased variability during mid-stance for both groups. Interpretation. Joint coupling variability profiles for FFS and RFS runners suggest different foot regions have varying coordination needs which should be considered when comparing the strike patterns.

Reliability of measurements assessing the Lisfranc joint using weightbearing computed tomography imaging.

INTRODUCTION: Subtle Lisfranc joint injuries remain challenging to diagnose in clinical practice. Although of questionable accuracy, bilateral weightbearing radiographs are considered the current gold standard to assess these injuries. However, weightbearing computed tomography (WBCT), which provides clearer visualization of bony landmarks, can also be used for evaluation. This study aims to design a protocol that reliably measures the distance between the medial cuneiform (C1) and second metatarsal (M2) to assess the Lisfranc joint using WBCT imaging. METHODS: Two unique methods of measuring the C1-M2 distance were designed that localize the center of the interosseous Lisfranc ligament (ILL, reference point). This reference point was located by (I) measuring a specific distance at the M2 base, or (II) approximating from nearby bony landmarks, on both axial (Ax) and coronal (Cor) WBCT images. Four parameters (I-Ax, I-Cor, II-Ax, and II-Cor) were evaluated for each of 96 specimens. Measurements were recorded by three independent observers and repeated for inter- and intra-observer agreement. RESULTS: In total, 96 patient image series were included and assessed in our study with an average age of 46 (19-66, SD 16.1) and average BMI of 25.8 (17.8-30.5, SD 4.3). I-Ax showed excellent agreement for intra-observer evaluation (R = 0.802) and good agreement for inter-observer evaluation (R = 0.727). I-Cor demonstrated excellent inter- (R = 0.814) and intra-observer (R = 0.840) agreement. Good agreement was found for both II-Ax and II-Cor for both intra- (R = 0.730, R = 0.708) and inter-observer (R = 0.705, R = 0.645) evaluation. CONCLUSION: Measuring the C1-M2 joint space with coronal WBCT imaging through a protocol that localizes the ILL is reproducible, simple, and can potentially be utilized clinically to evaluate the Lisfranc joint.

Validity of Using Automated Two-Dimensional Video Analysis to Measure Continuous Sagittal Plane Running Kinematics.

Two-dimensional video analysis is commonly used to assess kinematics when three-dimensional motion capture is unavailable. However, videos are often assessed using manual digitization, which limits the ability to extract outcomes that require continuous data. Here, we introduced a method to collect continuous kinematic data in 2D using an inexpensive camera and an open-source automated marker tracking program. We tested the validity of this method by comparing 2D video analysis to 3D motion capture for measuring sagittal-plane running kinematics. Twenty uninjured participants ran on a treadmill for 1-min while lower extremity kinematics were collected simultaneously in 3D using a motion capture system and in 2D using a single digital camera, both at 120 Hz. Knee, ankle, and foot angle at contact, peak knee flexion, knee flexion excursion, and knee-ankle flexion vector coding variability were computed using both the 3D and 2D kinematic data, and were compared using intraclass correlation coefficients and Bland-Altman plots. The agreement between collection methods was excellent for foot angle at contact and knee flexion excursion, good for ankle and knee angle at contact and knee-ankle vector coding variability, and moderate for peak knee flexion. However, Bland-Altman plots revealed significant differences between the 2D and 3D collection methods, which varied across study participants. These low-cost methods could be useful for collecting continuous sagittal plane running kinematics in non-laboratory settings.

Readiness for Dancing En Pointe.

Advancing to pointe requires sufficient maturity, strength, and flexibility and adequate ballet training to develop the skills which usually occurs between the ages 11 and 13. Health practitioners can provide studios with an objective assessment to determine if a young dancer is ready to transition to en pointe. The evaluator should be proficient in ballet, because the evaluation largely is dance based and includes a history and physical examination as well as a comprehensive assessment. The plan includes health improvement tips and summarizes technique flaws as well as exercises to improve these and other deficits. The goal is to transition dancers safely to pointe.

Comparing preference of ankle-foot stiffness in below-knee amputees and prosthetists.

When fitting prosthetic feet, prosthetists fuse information from their visual assessment of patient gait with the patient's communicated perceptions and preferences. In this study, we sought to simultaneously and independently assess patient and prosthetist preference for prosthetic foot stiffness using a custom variable-stiffness prosthesis. In the first part of the experiment, seven subjects with below-knee amputation walked on the variable-stiffness prosthetic foot set to a randomized stiffness, while several prosthetist subjects simultaneously observed their gait. After each trial, the amputee subjects and prosthetist subjects indicated the change to stiffness that they would prefer (increase or decrease). This paradigm allowed us to simultaneously measure amputee subject and prosthetist subject preferences, and provided a reliability index indicating the consistency of their preferences. In the second part of the experiment, amputee subjects were instructed to communicate verbally with one prosthetist subject to arrive at a mutually preferred stiffness. On average, prosthetist subjects preferred a 26% higher stiffness than amputee subjects (p < 0.001), though this depended on the amputee subject (p < 0.001). Prosthetist subjects were also considerably less consistent than amputee subjects in their preferences (CV of 5.6% for amputee subjects, CV of 23% for prosthetist subjects; p = 0.014). Mutual preference seemed to be dictated by the specific patient-prosthetist dynamic, and no clear trends emerged.

Paediatric patients with blood-induced ankle joint arthritis demonstrate physiological foot joint mechanics and energetics during walking.

AIM: To compare foot joint kinetics and energetics in male paediatric boys with and without blood-induced ankle joint destruction to these of matched control groups. METHODS: A cross-sectional study was conducted in which 3D gait analysis data were collected from thirty-five male children (6-21 years) with severe or moderate haemophilia and twenty-six typically developing boys. Structural integrity of the tarsal foot joints of all haemophilic patients was assessed using the IPSG-MRI scale. All participants walked barefoot while adopting a physiological gait pattern. Three subgroups were created based on the IPSG-MRI scores: a group with no joint involvement (HealthyHaemo), with uni- or bilaterally involvement (PathoHaemo) and with only unilaterally involvement (Haemo_Unilateral_Patho). RESULTS: The PathoHaemo group presented a significant lower Lisfranc peak dorsiflexion angular velocity (34.7°/s vs 71.4°/s, P = .000, Cohen d = 1.31) and a significantly higher Lisfranc peak plantarflexion angular velocity (-130.5°/s vs -51.8°/s, P = .000, Cohen d = 0.98) compared to the control group. The Haemo_Unilateral_Patho side had a significant higher Chopart peak dorsiflexion angular velocity compared to the Haemo_Unilateral_Healthy side (41.7°/s vs 31.9°/s, P = .002, Cohen d = 1.16). CONCLUSION: No evidence for mild and severe gait deviations could be demonstrated. Internal moments, used as a surrogate measure of joint loading, quantified by the multi-segment foot model were found to be similar within the three subanalyses. We suggest that the ongoing musculoskeletal development in children compensates for structural damage to the ankle joint.

Subchondral pressures and perfusion during weight bearing.

BACKGROUND: Joints withstand huge forces, but little is known about subchondral pressures and perfusion during loading. We developed an in vitro calf foot model to explore intraosseous pressure (IOP) and subchondral perfusion during weight bearing. METHODS: Freshly culled calf forefeet were perfused with serum. IOP was measured at three sites in the foot using intraosseous needles, pressure transducers, and digital recorders. IOP was measured during perfusion, with and without a tourniquet and with differing weights, including static loading and dynamic loading to resemble walking. RESULTS: IOP varied with perfusion pressure. Static loading increased subchondral IOP whether the bone was non-perfused, perfused, or perfused with a proximal venous tourniquet (p < 0.0001). Under all perfusion states, IOP was proportional to the load (R2 = 0.984). Subchondral IOP often exceeded perfusion pressure. On removal of a load, IOP fell to below the pre-load value. Repetitive loading led to a falling IOP whether the foot was perfused or not. CONCLUSION: Superimposed on a variable background IOP, increased perfusion and physiological loading caused a significant increase in subchondral IOP. Force was thereby transmitted through subchondral bone partly by hydraulic pressure. A falling IOP with repeat loading suggests that there is an intraosseous one-way valve. This offers a new understanding of subchondral perfusion physiology.

Contribution of foot joints in the energetics of human running.

The foot seems to demonstrate considerable power absorption and generation characteristics during running. These have been mainly accounted to the mechanics of the ankle joint, however, evidence suggests that joint kinetics have been overestimated by single-segment foot models. The scope of the present study was to estimate the energetics of the ankle-, chopart-, lisfranc- and hallux joint during heel-strike running. Power absorption and generation occuring at different segments of the foot of seven asymptomatic adults was modelled using a four-segment kinetic foot model. Participants ran barefoot with an average running speed 3.5 m/s along a 10 meter walkway. The peak power generation of the ankle, chopart, lisfranc, and hallux joint reached respectively an average of 13.9, 4.12, 1.08 and 0.32 Watt/kg. The Lisfranc joint showed poor power absorption compared to the other three joints. It was further demonstrated that the Ankle and Chopart joints seem to have both receptive and propulsive characteristics. The behavior of the Lisfranc joint complied almost exclusively with propulsive characteristics. Finally, it can be concluded that the midfoot accounts for approximately 25% of the total power absorption occuring at the foot joints and not 50% as initially hypothesized.

Intrinsic foot joints adapt a stabilized-resistive configuration during the stance phase.

BACKGROUND: This study evaluated the 3D angle between the joint moment and the joint angular velocity vectors at the intrinsic foot joints, and investigated if these joints are predominantly driven or stabilized during gait. METHODS: The participants were 20 asymptomatic subjects. A four-segment kinetic foot model was used to calculate and estimate intrinsic foot joint moments, powers and angular velocities during gait. 3D angles between the joint moment and the joint angular velocity vectors were calculated for the intrinsic foot joints defined as follows: ankle joint motion described between the foot and the shank for the one-segment foot model (hereafter referred as Ankle), and between the calcaneus and the shank for the multi-segment foot model (hereafter referred as Shank-Calcaneus); joint motion described between calcaneus and midfoot segments (hereafter referred as Chopart joint); joint motion described between midfoot and metatarsus segments (hereafter referred as Lisfranc joint); joint motion described between first phalanx and first metatarsal (hereafter referred as First Metatarso-Phalangeal joint). When the vectors were approximately aligned, the moment was considered to result in propulsion (3D angle <60o) or resistance (3D angle >120o) at the joint. When the vectors are approximately orthogonal (3D angle close to 90°), the moment was considered to stabilize the joint. RESULTS: The results showed that the four intrinsic joints of the foot are never fully propelling, resisting or being stabilized, but are instead subject to a combination of stabilization with propulsion or resistance during the majority of the stance phase of gait. However, the results also show that during pre-swing all four the joints are subject to moments that result purely in propulsion. At heel off, the propulsive configuration appears for the Lisfranc joint first at terminal stance, then for the other foot joints at pre-swing in the following order: Ankle, Chopart joint and First Metatarso-Phalangeal joint. CONCLUSIONS: Intrinsic foot joints adopt a stabilized-resistive configuration during the majority of the stance phase, with the exception of pre-swing during which all joints were found to adopt a propulsive configuration. The notion of stabilization, resistance and propulsion should be further investigated in subjects with foot and ankle disorders.

Regular changes in foot strike pattern during prolonged downhill running do not influence neuromuscular, energetics, or biomechanical parameters.

Research has suggested that a high variability in foot strike pattern during downhill running is associated with lower neuromuscular fatigue of the plantar flexors (PF). Given the popularity of trail running, we designed an intervention study to investigate whether a strategy with regular changes in foot strike pattern during downhill running could reduce the extent of fatigue on neuromuscular, energetics and biomechanical parameters as well as increase an uphill time-to-exhaustion trial (TTE) performance. Fourteen experienced trail runners completed two interventional conditions (separated by 15 days) in a pseudo-randomised and counter-balanced order that consisted of 2.5-h of treadmill graded running with (switch condition) or without (control condition) a change between fore- and rear-foot strike pattern every 30 s during the downhill sections. Pre and Post, neuromuscular tests were performed to assess PF central and peripheral fatigue. Energy cost of running was assessed using an indirect calorimetry system and biomechanical gait parameters were acquired with an instrumented treadmill. TTE was performed after both the graded running conditions. There were not significant condition × time interactions (p ≥ .085) for any of the variables considered, and TTE was not different between the two conditions (p = .755). A deliberate strategy to alternate between foot strike patterns did not reduce the extent of fatigue during prolonged graded running. We suggest that it is not the ability to switch between foot strike patterns that minimises fatigue; rather the ability to adapt foot strike pattern to the terrain and therefore a better running technique.

Anteroposterior Translational Malalignment of Ankle Arthrodesis Alters Foot Biomechanics in Cadaveric Gait Simulation.

Tibiotalar arthrodesis is a common surgical treatment for end-stage ankle arthritis. Proper ankle alignment is important as malalignment can lead to complications that may require revision surgery. This study aimed to determine how anteroposterior (AP) translational malalignment of ankle arthrodesis affects distal foot joint kinematics and plantar pressure. Ankle arthrodesis was performed on 10 cadaveric foot specimens using a custom fixture that could fuse the ankle neutrally and induce discrete malalignments (3, 6, and 9 mm) anteriorly and posteriorly. Gait was simulated under each alignment with a robotic gait simulator, and foot bone motion and plantar pressure were quantified. AP translational malalignment did not substantially affect plantar pressure or joint range of motion, but there were several significant differences in joint position throughout stance phase. Differences were seen in five joints (talocalcaneal, talonavicular, calcaneocuboid, fifth tarsometatarsal, and first metatarsophalangeal) and in the position of the first metatarsal relative to the talus. The most extreme effects occurred when the talus was displaced 6 mm or more posteriorly. In vivo, this may lead to aberrant joint loading, which could negatively impact patient outcomes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:450-458, 2020.

The Impact of a Foot-Toe Orthosis on Dynamic Balance: An Exploratory Randomized Control Trial.

CONTEXT: The influence of custom and over-the-counter foot orthoses on dynamic balance has been investigated in the past. However, there has not been an exploration of the use of a foot-toe orthosis for improving balance. The ability of clinicians to influence balance could have important implications for injury prevention and rehabilitation. OBJECTIVE: To determine the impact of a foot-toe orthosis on dynamic balance in healthy, young adults. DESIGN: Randomized control trial. SETTING: Athletic training laboratory. PARTICIPANTS: In total, 64 healthy, recreationally active participants aged 18-29 years were randomly allocated to one of the following groups: the foot-toe orthosis and laboratory-issued shoe group, the laboratory-issued shoe only (SO) group, or the control group. INTERVENTIONS: Subjects in the intervention group wore the foot-toe orthosis and laboratory-issued shoe with activities of daily living for 4 weeks. Subjects in the SO intervention group wore the laboratory-issued shoe with activities of daily living for 4 weeks. Participants in the control group did not receive any intervention. MAIN OUTCOME MEASURES: The instrumented version of the Star Excursion Balance Test, known as the Lower Quarter Y-Balance Test, was used to quantify the dynamic balance at baseline and follow-up. Reaches were normalized for leg length. RESULTS: There were statistically significant differences in postintervention scores on the Lower Quarter Y-Balance Test for both the dominant (P = .03, effect size = 0.84; 95% confidence interval, 0.25 to 1.43) and nondominant (P = .002, effect size = 0.74; 95% confidence interval, 0.15 to 1.32) legs when comparing dynamic balance scores of the foot-toe orthosis and laboratory-issued shoe group with the SO and control groups. No significant differences were observed when comparing dynamic balance between the SO and control groups. CONCLUSIONS: A 4-week intervention with a foot-toe orthosis and laboratory-issued shoe resulted in improved dynamic balance in a healthy young adult population. These findings suggest a novel intervention for increasing balance.

Oxford foot model kinematics in landings: A comparison between professional dancers and non-dancers.

OBJECTIVES: Dancers frequently perform jump-landing activities, with the foot-ankle complex playing an essential role to attenuate the landing forces. However, scarce research has been conducted in professional dancers multi-segmented foot in landings. The aim of this study was to compare the multi-segmented foot kinematics between professional dancers and non-dancers, during forward and lateral single-leg jump-landings. DESIGN: Descriptive group comparison. METHODS: Marker trajectories and synchronized ground reaction forces of 15 professional dancers and 15 non-dancers were collected using motion capture and a force plate, during multidirectional single-leg jump-landings. Sagittal and frontal hindfoot-tibia, forefoot-hindfoot, and hallux-forefoot kinematics of the multi-segmented foot model were computed at initial contact, peak vertical ground reaction force and peak knee flexion. Repeated measures ANOVAs were conducted (p < 0.05). RESULTS: Professional dancers landed with higher hindfoot-tibia and forefoot-hindfoot plantarflexion angles at initial contact (p < 0.001), and hindfoot-tibia dorsiflexion angles at peak vertical ground reaction force and peak knee flexion (p < 0.001) than non-dancers. Also, dancers exhibited higher sagittal hindfoot-tibia and forefoot-hindfoot excursions than non-dancers (p < 0.001). No statistically significant differences were found in the frontal plane. CONCLUSIONS: The multi-segmented foot allows a comprehensive kinematic analysis of the different foot joints. In jump-landings, professional dancers higher hindfoot-tibia, and forefoot-hindfoot plantarflexion at initial contact, compared to non-dancers, contributed to a subsequent higher foot joints excursion. This pattern is commonly linked to a better shock absorption mechanism in landings.

Modificación del índice de postura del pie en pies neutros y pronados bajo efecto de fatiga / Modification of the foot posture index in neutral and pronged feet under the effect of fatigue / Mudança do índice de postura do pé em pés neutros e pronados sob efeito de fadiga

OBJETIVO: Se pretende analizar la modificación de la postura de los pies al ser sometidos a una situación estresante para la musculatura del miembro inferior, y valorar la capacidad de recuperación de esos pies tras un período de descanso. MÉTODO: Se determinó el Índice de Postura del Pie (FPI-6) en 63 sujetos adultos sanos y fueron sometidos a una prueba de "saltos continuos con contramovimiento de 30 segundos de duración". Después, se valora el FPI-6 de cada sujeto, así como tras 15 minutos de descanso. RESULTADOS: Hubo cambios estadísticamente significativos en la postura del pie en ambos grupos al relacionar las tres situaciones experimentales (antes e inmediatamente después de la prueba y tras descanso). Dichos cambios presentan una magnitud del efecto fuerte entre los momentos basales y post, y entre post y descanso; mientras que es débil entre los momentos basales y descanso. Tras la prueba, existe un aumento del valor del FPI-6 respecto a la situación inicial. Tras el descanso los cambios observados fueron significativos en relación a los obtenidos tras la prueba con disminución del valor del FPI-6, aunque no volvieron a los valores iniciales previos a la prueba. CONCLUSIONES: La fatiga producida por la prueba de saltos continuos con contramovimiento de 30 segundos afecta a los valores del FPI, produciendo un aumento de los mismos, pero no es suficiente para modificar la clasificación de la postura del pie en los grupos de pies neutros y pronados estudiados. El tiempo de descanso propuesto no fue suficiente para volver a la situación inicial

OBJECTIVE: To analyse the modification of the Foot Posture Index a stressful situation for the musculature of the lower limb and to value the capacity of recuperation after a period of rest. METHOD: The Foot Posture Index was determined (FPI-6) in 63 healthy adult subjects and they were tested with "continuous counter-movement jumps (CMJ) conducted for 30 seconds". Each subject's FPI-6 was then valued, and again after 15 minutes rest. RESULTS: There were statistically significant changes in the foot posture in both groups when relating the three experimental situations (before and immediately after the test and after the rest). These changes present a strong effect between the basal and post moments, and between the post and rest moments. After the test, there is an increase of the FPI-6 value with respect to the initial situation. After the rest, the changes observed were significant in relation to those obtained after the test with a decrease of the FPI-6 values, although they did not return to the initial values prior to the test. CONCLUSIONS: The fatigue produced by the continuous counter-movement jumps (CMJ) conducted for 30 seconds affects the FPI values, increasing them, but this is not sufficient to modify the foot posture classification in the groups of neutral and pronated feet studied. The time of rest proposed was not enough to return to the initial situation

OBJETIVO: Pretende-se analisar a modificação da postura dos pés ao serem submetidos a uma situação estressante para a musculatura de membros inferiores e avaliar a capacidade de recuperação destes pés após um período de repouso. MÉTODO: Foi determinado o índice de postura do pé (FPI-6) em 63 sujeitos adultos saudáveis que foram submetidos a um teste de "saltos contínuos com contra movimento (CMJ) de 30 segundos de duração". Posteriormente, foi avaliado o FPI-6 de cada sujeito, assim como pós 15 minutos de repouso. RESULTADOS: Houveram mudanças estatisticamente significativas na postura dos pés em ambos os grupos ao relacionar as três situações experimentais (antes, imediatamente após o protocolo de teste e após o repouso). Essas mudanças apresentaram uma magnitude de efeitos forte entre o momento basal e momento pós e entre o pós e o repouso; enquanto que a magnitude foi fraca entre o momento basal e o repouso. Depois do teste houve um aumento do valor de FPI-6 em comparação com a situação inicial. Depois do repouso as mudanças observadas foram significativas em relação àquelas obtidas após o teste com uma redução no valor de FPI-6, embora não tenham retornado aos valores obtidos antes do teste. CONCLUSÃO: A fadiga produzida pelo teste de saltos contínuos com contra movimento (CMJ) de 30 segundos de duração afeta os valores de FPI, resultando em aumento dos mesmos, porém não foi suficiente para modificar a classificação da postura dos pés nos grupos de pés neutros e pronados avaliados. O tempo de descanso proposto não foi suficiente para voltar aos níveis basais