Ankle Force Research Articles

Lower limb joint loading during high-impact activities: implication for bone health.

Osteoporosis results in low-trauma fractures affecting millions globally, in particular elderly populations. Despite the inclusion of physical activity in fracture prevention strategies, the optimal bone-strengthening exercises remain uncertain, highlighting the need for a deeper understanding of lower limb joint loading dynamics across various exercise types and levels. This study examines lower limb joint loading during high-impact exercises across different intensities. A total of 40 healthy, active participants were recruited (mean ± SD: age of 40.3 ± 13.1yr; height 1.71 ± 0.08m; and mass 68.44 ± 11.67kg). Motion capture data and ground reaction forces of 6 different exercises: a self-selected level of walking, running, countermovement jump, squat jump, unilateral hopping, and bilateral hopping were collected for each participant. Joint reaction forces were estimated using lower body musculoskeletal models developed in OpenSim. Running and hopping increased joint forces compared to walking, notably at the hip (83% and 21%), knee (134% and 94%), and ankle (94% and 77%), while jump exercises reduced hip and ankle loading compared to walking (36% and 19%). Joint loading varied with exercise type and intensity, with running faster increasing forces on all joints, particularly at the hip. Sprinting increased forces at the hip but lowered knee and ankle forces. Higher jumps intensified forces on all joints, while faster hopping reduced forces. The wide variation of lower limb joint loading observed across the exercises tested in this study underscores the importance of implementing diverse exercise routines to optimize overall bone health and strengthen the musculoskeletal structure. Practitioners must therefore ensure that exercise programs include movements that are specifically suitable for their intended purpose.

Balance Control Deficits are Associated With Diminished Ankle Force Sense, Not Position Sense, in Athletes With Chronic Ankle Instability

ObjectivesTo compare balance control and ankle proprioception between athletes with and without chronic ankle instability (CAI). A further objective was to explore the relationship between balance control performance and ankle proprioception in athletes with CAI. DesignCross-sectional study. SettingsSports Rehabilitation Laboratory. ParticipantsEighty-eight recreational athletes (47 CAI and 41 healthy control) were recruited. InterventionsNo applicable. Main Outcome MeasuresBalance control performance was assessed using the sway velocity of the center of the pressure during the one-leg standing tasks. Ankle proprioception, including joint position sense and force sense, were tested using absolute error (AE) associated with joint position reproduction and force reproduction tasks in 4 directions, that is, plantarflexion, dorsiflexion, inversion, and eversion. ResultsAthletes with CAI performed significantly worse than those without CAI in balance control tasks. In addition, CAI athletes showed significantly worse joint position sense and force sense in all 3 movement directions tested (plantarflexion, inversion, and eversion). Correlation analysis showed that the AE of the plantarflexion force sense was significantly moderately correlated with medial-lateral sway velocity in the one-leg standing with eyes open and closed conditions (r=.372-.403, P=.006-.012), and the AE of inversion force sense was significantly moderately correlated with medial-lateral sway velocity in the one-leg standing with eyes open (r=.345, P=.018) in athletes with CAI, but the joint position sense measures were not (all P>0.05). ConclusionsAthletes with CAI showed significantly impaired balance control performance and diminished ankle proprioception. Deficit in force sense was deemed as a moderate predictor of one-leg standing balance control deficits in athletes with dominant-side injury CAI, whereas ankle position sense may be a small predictor.

Biomechanical variations in patients with flatfoot deformity: Impact of gender, age, and BMI on foot kinetics and kinematics

BackgroundFlatfoot is considered by the collapse of the foot arch, altered biomechanics and impacting functional abilities. The biomechanical gait alteration of foot kinematics and kinetics in individuals with flatfoot, based on gender, age and Body mass index (BMI) in each cohort is unclear. This study explores how gender, age, and body mass index (BMI) impact distinct foot biomechanical characteristics, including ankle joint angle (Jc°), Ground force reaction angle (GFR°), Achilles tendon force (T), Ankle joint force (Jc) and vertical ground reaction force (VGRF) during the gait stance phase, in flatfoot versus normal-foot individuals on Indian Population. MethodA foot pressure test and sagittal plane motion analysis were performed on 142 individuals with normal-foot arches and 102 with flatfoot, stratified by gender, age, and BMI. Calculations of the magnitude and direction of forces in ankle joint equilibrants relied on inverse dynamic analysis, vertical ground force reaction and mapping motion data of the gait stance phases. ResultIn the midstance phase, females with high BMI (HBMI) in the middle and older age group (p = 0.029 and p = 0.014), and males with HBMI in the older age group (p = 0.039) demonstrate significantly higher VGRF. Females and males with HBMI in middle and older age groups, along with males with normal BMI in the older age cohort, show positive and negative ranges of GFR°, indicating gait instability. In the push-off phase, females with HBMI in a middle-aged group exhibit significantly lower TandJc (p = 0.023 and p = 0.026) respectively. ConclusionThe biomechanical issues in individuals with flatfoot, while accounting for the influence of gender, age and BMI, are crucial for tailored interventions and precise solutions to biomechanical issues, thereby enhancing foot function and reducing discomfort.

Cerebral hemodynamics underlying ankle force sense modulated by high-definition transcranial direct current stimulation.

This study aimed to investigate the effects of high-definition transcranial direct current stimulation on ankle force sense and underlying cerebral hemodynamics. Sixteen healthy adults (8 males and 8 females) were recruited in the study. Each participant received either real or sham high-definition transcranial direct current stimulation interventions in a randomly assigned order on 2 visits. An isokinetic dynamometer was used to assess the force sense of the dominant ankle; while the functional near-infrared spectroscopy was employed to monitor the hemodynamics of the sensorimotor cortex. Two-way analyses of variance with repeated measures and Pearson correlation analyses were performed. The results showed that the absolute error and root mean square error of ankle force sense dropped more after real stimulation than after sham stimulation (dropped by 23.4% vs. 14.9% for absolute error, and 20.0% vs. 10.2% for root mean square error). The supplementary motor area activation significantly increased after real high-definition transcranial direct current stimulation. The decrease in interhemispheric functional connectivity within the Brodmann's areas 6 was significantly correlated with ankle force sense improvement after real high-definition transcranial direct current stimulation. In conclusion, high-definition transcranial direct current stimulation can be used as a potential intervention for improving ankle force sense. Changes in cerebral hemodynamics could be one of the explanations for the energetic effect of high-definition transcranial direct current stimulation.

Cueing Dancers to "Externally Rotate From the Hips" Improves Potentially Injurious Ankle Joint Angles and Contact Forces During a Demipointe Ballet Position.

Introduction: The demipointe dance position puts the ankle at high risk of overuse injury and posteromedial ankle pain due to increased ankle valgus forces. Previous work has shown that creating lower limb external rotation intrinsic to demipointe with hip external rotation reduces foot pronation that causes ankle valgus stress. Therefore, the purpose of this work was to examine long axis rotation kinematics of the hip, knee, and ankle as well as the ankle joint contact forces in demipointe to better understand the biomechanical impact(s) of the specific cue to increase hip external rotation in this position. Methods: Three-dimensional motion capture and force plate data were collected from 23 contemporary or ballet pre-professional dancers (age: 19.94 ± 1.34 years) who each performed 3 dancer-selected (DS) demipointe positions and 3 demipointes with the cue to "externally rotate from the hips." Results: The cue to increase hip external rotation resulted in significantly increased hip external rotation angle [DS: 37.5; 9.42° (median; interquartile range), Cued: 39.9; 10.8°, P < .0001)] and significantly reduced ankle eversion angle (DS: 8.13; 11.4°, Cued: 7.77; 10.3°, P = .023). However, total turnout angle was also significantly decreased (DS: 75.8; 7.91°, Cued: 75.4; 7.73°, P < .0001), which is undesirable for proper esthetic performance of demipointe. Total ankle joint force remained unchanged, but ankle eversion force was significantly reduced (DS: 15.3; 4.18 %bodyweight (BW), Cued: 14.7; 4.99 %BW, P < .0001) with use of the cue. Discussion/Conclusion: Utilization of a cue to increase hip external rotation was successful in increasing hip contribution to turnout angle and reducing injurious ankle eversion force. Further coaching using this cue may allow dancers to produce these advantageous mechanics while maintaining turnout angle.

Validation of a Simple Device for the Evaluation of Ankle Plantar- and Dorsi-Flexor Forces Consistent with Standard Clinical Evaluations

Measuring the forces produced at the ankle joint is critical to diagnose musculoskeletal pathologies. In standard clinical practice, ankle force is often assessed through manual joint manipulation and visual observation. This study introduces a simple apparatus, the Ankle Force Transducer (AFT), based on a uniaxial load cell capable of measuring ankle forces in conditions consistent with clinical evaluations. The AFT can be placed at the extremity of any examination couch to measure ankle forces in plantarflexion and dorsiflexion. The repeatability of the AFT was assessed in 30 healthy subjects across three sessions and in two knee postures. One patient with foot-drop condition was evaluated using the same apparatus. The intra-session coefficient of variation for plantarflexion and dorsiflexion forces was around 5% and 8%, respectively. The dominant leg exhibited greater forces than the non-dominant one, and the fully extended knee resulted in significantly larger forces with respect to the flexed knee (p &lt; 0.001). The foot-drop patient showed a 90% reduction in dorsiflexion force in the affected limb. The AFT appears to be a user-friendly tool used to measure ankle forces, which has the potential to provide more repeatable and objective measurements of ankle forces with respect to operator-dependent evaluations.

Statistical Shape Modeling Enables Identification of Subtalar Contact Stress Differences Following Tibiotalar Arthrodesis and Total Ankle Replacement

Category: Hindfoot; Ankle Arthritis Introduction/Purpose: Clinical studies have shown 32% of patients with a TAR progress to subtalar OA within 5 years, whereas 78% of patients with a tibiotalar arthrodesis presented with subtalar OA by 7.5 years. Higher rates of subtalar OA after arthrodesis may be explained by a transfer of ankle forces and stress through the adjacent subtalar joint while TAR may mitigate these changes. The objective of this study was to compare subtalar joint contact stresses between patients treated with tibiotalar arthrodesis and total ankle replacement (TAR) during an overground walking activity using correspondence particles to enable regional analysis. Methods: With IRB approval, ten individuals with unilateral tibiotalar arthrodesis and six individuals with unilateral TAR were imaged with biplane fluoroscopy during overground walking. Discrete element analysis (DEA) was performed to estimate subtalar joint contact stress using the tracked bone models. Cartilage was modeled using linear-elastic material properties (E=12 MPa, v=0.42) and uniformly extruded compressible surfaces from rigid subchondral bone (0.98 mm talar side, 0.75 mm calcaneal side1). A calcaneal statistical shape model (SSM) was created and resulting correspondence particles served as registered locations for comparison of cumulative stress across three phases of normalized stance (loading-response 0-24%, mid 25-54%, and terminal 55- 87%). Two-sample t-tests or Wilcoxon rank-sum tests were used to evaluate differences (p &lt; 0.05) in cumulative contact stresses at each correspondence particle within the 3 phases based upon Shapiro-Wilk findings of normality. Results: There were significant differences in contact stress exposure across all three phases of gait. Differences were identified along the superior-medial aspect of the posterior facet and within the anterior facet (Figure 1). Higher cumulative stresses were observed along the border of the posterior facet and in the medial facet. This model is limited by a lack of validation, uniform cartilage thickness assumptions applied across groups, and that DEA only estimates contact stress without consideration of shear. Conclusion: This study was the first to localize regional differences in subtalar joint stress for patients having undergone TAR and tibiotalar arthrodesis. Interestingly, TAR patients experienced higher stress in this study compared to those with arthrodeses. These ostensibly counterintuitive findings of higher TAR stress may relate to the pre-existence of subtalar OA which is a common indication of TAR versus fusion.

Age-Related Changes in Plantar Sensation and Ankle Proprioception in Adolescents to Older Adults.

Plantar sensation and ankle proprioception occur in a stage-like variance across the life span. However, changes in adolescents, young adults, middle-aged adults, and older adults remain unclear. The aim of this study was to investigate the differences of plantar sensation and ankle proprioception in adolescents to older adults. A total of 212 participants were recruited in the study and were divided into four groups, including adolescents (n = 46), young adults (n = 55), middle-aged adults (n = 47), and older adults (n = 54). Plantar tactile sensitivity/tactile acuity/vibration threshold and ankle movement threshold/joint position sense/force sense were assessed in all groups. The Kruskal-Wallis H test was used to analyze the differences in Semmes-Weinstein monofilaments between different age groups in different plantar positions. One-way analysis of variance was used to determine differences in foot vibration threshold, two-point discrimination, and ankle proprioception between different age groups. Significant differences were found in the Semmes-Weinstein monofilament test (p < .001), the two-point discrimination test (p < .05), and the vibration threshold test (p < .05) in the six tested plantar positions among adolescents, young adults, middle-aged adults, and older adults. For ankle proprioception, significant differences were found in movement thresholds in ankle plantar flexion (p = .01), ankle dorsiflexion (p < .001), ankle inversion (p < .001), and ankle eversion (p < .001), as well as relative absolute errors in the ankle force senses of ankle plantar flexion (p = .02) and ankle dorsiflexion (p = .02) across the four age groups. Plantar sensation and ankle proprioception were sensitive in adolescents and young adults than in middle-aged adults and older adults.

A forefoot strike pattern during 18° uphill walking leads to greater ankle joint and plantar flexor loading

BackgroundThe ankle joint is one of the most involved joints in uphill walking. Furthermore, it is well known that toe walking increases the external dorsiflexion moment in the first half of stance during level walking. However, the effects of different foot-strike patterns on plantar flexor muscle forces, ankle joint forces, and other lower limb joint and muscle forces are unknown. Research questionDo foot-strike patterns during 18° uphill walking affect lower limb sagittal joint angles and moments, as well as joint contact and muscle forces? MethodsThis study was based on a data subset from previous publications, analysing uphill walking on an 18° ramp at a preset speed of 1.1 m/s in 18 male participants (34 limbs analyzed, 27 ± 5 years). Participants were divided into two groups based on their foot-strike pattern at initial contact: heel (HC) and forefoot (FC). Lower limb sagittal joint angles and moments as well as joint contact and muscle forces were assessed. Differences between the groups were assessed using two-sample t-tests. ResultsFC showed increased soleus and gastrocnemius muscle forces as well as ankle joint forces during loading response and mid stance compared to HC. The soleus muscle force impulse was 51.1% higher in the FC group than in the HC group (p < 0.001). On the other hand, FC had a lower absolute centre of mass vertical displacement and reduced knee and hip joint, as well as iliopsoas and hamstring muscle force impulses. SignificanceIn terms of plantar flexor and ankle joint loading, it is advantageous to exhibit a heel strike pattern. The current results can be used to recommend foot-strike patterns for uphill walking, particularly in the presence or prevention of musculoskeletal issues.

Anodal transcranial direct current stimulation enhances ankle force control and modulates the beta-band activity of the sensorimotor cortex.

This study aimed to investigate the cortical responses to the ankle force control and the mechanism underlying changes in ankle force control task induced by transcranial direct current stimulation (tDCS). Sixteen young adults were recruited, and they completed the electroencephalogram (EEG) assessment and high-definition tDCS (HD-tDCS) sessions. Root mean square (RMS) error was used to evaluate ankle force control task performance. Spectral power analysis was conducted to extract the average power spectral density (PSD) in the alpha (8-13Hz) and beta (13-30Hz) bands for resting state and tasking (i.e. task-PSD). The ankle force control task induced significant decreases in alpha and beta PSDs in the central, left, and right primary sensorimotor cortex (SM1) and beta PSD in the central frontal as compared with the resting state. HD-tDCS significantly decreased the RMS and beta task-PSD in the central frontal and SM1. A significant association between the percent change of RMS and the percent change of beta task-PSD in the central SM1 after HD-tDCS was observed. In conclusion, ankle force control task activated a distributed cortical network mainly including the SM1. HD-tDCS applied over SM1 could enhance ankle force control and modulate the beta-band activity of the sensorimotor cortex.

Independently ambulatory children with spina bifida experience near-typical knee and ankle joint moments and forces during walking

BackgroundSpina bifida, a neurological defect, can result in lower-limb muscle weakness. Altered ambulation and reduced musculoskeletal loading can yield decreased bone strength in individuals with spina bifida, yet individuals who remain ambulatory can exhibit normal bone outcomes. Research questionDuring walking, how do lower-limb joint kinematics and moments and tibial forces in independently ambulatory children with spina bifida differ from those of children with typical development? MethodsWe retrospectively analyzed data from 16 independently ambulatory children with spina bifida and 16 children with typical development and confirmed that tibial bone strength was similar between the two groups. Plantar flexor muscle strength was measured by manual muscle testing, and 14 of the children with spina bifida wore activity monitors for an average of 5 days. We estimated tibial forces at the knee and ankle using motion capture data and musculoskeletal simulations. We used Statistical Parametric Mapping t-tests to compare lower-limb joint kinematic and kinetic waveforms between the groups with spina bifida and typical development. Within the group with spina bifida, we examined relationships between plantar flexor muscle strength and peak tibial forces by calculating Spearman correlations. ResultsActivity monitors from the children with spina bifida reported typical daily steps (9656 [SD 3095]). Despite slower walking speeds (p = 0.004) and altered lower-body kinematics (p < 0.001), children with spina bifida had knee and ankle joint moments and forces similar to those of children with typical development, with no detectable differences during stance. Plantar flexor muscle weakness was associated with increased compressive knee force (p = 0.002) and shear ankle force (p = 0.009). SignificanceHigh-functioning, independently ambulatory children with spina bifida exhibited near-typical tibial bone strength and near-typical step counts and tibial load magnitudes. Our results suggest that the tibial forces in this group are of sufficient magnitudes to support the development of normal tibial bone strength.

Aberrant movement-related somatosensory cortical activity mediates the extent of the mobility impairments in persons with cerebral palsy.

There are numerous clinical reports showing that persons with cerebral palsy (CP) have proprioceptive, stereognosis, and tactile discrimination deficits. The current consensus is that these altered perceptions are attributable to aberrant somatosensory cortical activity. It has been inferred from these data that persons with CP do not adequately process ongoing sensory feedback during motor actions, which accentuates the extent of their mobility impairments. However, this hypothesis has yet to be directly tested. We used magnetoencephalographic brain imaging to address this knowledge gap by quantifying the somatosensory dynamics evoked by applying electrical stimulation to the tibial nerve in 22 persons with CP and 25 neurotypical controls at rest and during an ankle plantarflexion isometric force motor task. We also quantified the spatiotemporal gait biomechanics of participants outside the scanner. Consistent with the literature, our results confirmed that the strength of somatosensory cortical activity was weaker in the persons with CP compared to the neurotypical controls. Our results also showed that the strength of the somatosensory cortical responses were significantly weaker during the isometric ankle force task than at rest. Most importantly, our results showed that the strength of somatosensory cortical activity during the ankle plantarflexion force production task mediated the relationship between somatosensory cortical activity at rest and both walking velocity and step length. These results suggest that youth with CP have aberrant somatosensory cortical activity during isometric force generation, which ultimately contributes to the extent of mobility impairments seen in this patient population. KEY POINTS: Persons with cerebral palsy have reduced somatosensory cortical responses at rest and during movement. The somatosensory cortical responses during movement mediate the relationship between the somatosensory cortical responses at rest and mobility. Persons with cerebral palsy may have altered sensorimotor feedback that ultimately contributes to impaired mobility.

Comparison of joint load, motions and contact stress and bone‐implant interface micromotion of three implant designs for total ankle arthroplasty

Background and ObjectiveLoosening and wear are still the main problems for the failure of total ankle arthroplasty, which are closely related to the micromotion at the bone-implant interface and the contact stress and joint motions at the articular surfaces. Implant design is a key factor to influence the ankle force, motions, contact stress, and bone-implant interface micromotion. The purpose of this study is to evaluate the differences in these parameters of INBONE II, INFINITY, and a new anatomic ankle implant under the physiological walking gait of three patients. MethodsThis was achieved by using an in-silico simulation framework combining patient-specific musculoskeletal multibody dynamics and finite element analysis. Each implant was implanted into the musculoskeletal multibody dynamics model, respectively, which was driven by the gait data to calculate ankle forces and motions. These were then used as the boundary conditions for the finite element model, and the contact stress and the bone-implant interface micromotions were calculated. ResultsThe total ankle contact forces were not significantly affected by articular surface geometries of ankle implants. The range of motion of the ankle joint implanted with INFINITY was a little larger than that with INBONE II. The anatomic ankle implant design produced a greater range of motion than INBONE II, especially the internal-external rotation. The fixation design of INFINITY achieved lower bone-implant interface micromotion compared with INBONE II. The anatomic ankle implant design produced smaller contact stress with no evident edge contact and a smaller tibia-implant interface micromotion. In addition, significant differences in the magnitudes and tendencies of total ankle contact forces and motions among different patients were found. ConclusionsThe articular surface geometry of ankle implants not only affected the ankle motions and contact stress distribution but also affected the bone-implant interface micromotions. The anatomic ankle implant had good performance in recovering ankle joint motion, equalizing contact stress, and reducing bone-implant interface micromotion. INFINITY's fixation design could achieve smaller bone-implant interface micromotion than INBONE II.

Force sense deficits in chronic ankle instability: A systematic review and meta-analysis.

Patients with chronic ankle instability (CAI) may experience ankle force sense deficits due to mechanoreceptor injury and proprioceptive deafferentation in the affected ankles. This study aimed to systematically review the literature and investigate (1) whether patients with CAI have impaired force sense when compared with uninjured contralateral sides or healthy controls, and (2) which characteristics of CAI (e.g., any measurement of CAI symptoms, clinical questionnaires, or functional tests on the injured ankles) are correlated with force sense deficits. TYPE: Systematic review and meta-analysis. PubMed, Embase, Web of Science, Cochrane Library, Scopus, CINAHL, and SPORTDiscus were searched for ankle-related, injury-related, and force sense-related terms from inception to February 2, 2022. The following information was extracted from included articles: demographic data, sample size, selection criteria, methodology, force reproduction test outcomes, and correlations between force sense and other characteristics of CAI. Meta-analyses were conducted for the force sense outcomes, and a narrative review was undertaken for the correlation between force sense deficits and other characteristics of CAI. Eight studies were included. The meta-analyses revealed eversion force sense deficits of the injured ankles in absolute error (magnitude of force reproduction error) at 20% maximal voluntary isometric contractions (MVIC) (standardized mean difference [SMD]=0.67, 95% confidence interval [CI] 0.23-1.11) and variable error (consistency of force reproduction) at 30% MVIC (SMD=0.46, 95% CI 0.07-0.85), as compared with healthy controls. None of the included studies reported a significant correlation between these two deficits and other characteristics of CAI. Patients with CAI have eversion force sense deficits in the magnitude of force reproduction error at 20% MVIC and the consistency of force reproduction at 30% MVIC.

Contributions of individual muscle forces to hip, knee, and ankle contact forces during the stance phase of running: a model-based study.

Knowledge of muscle forces' contributions to the joint contact forces can assist in the evaluation of muscle function, joint injury prevention, treatment of gait disorders, and arthroplasty planning. This study's objective was to evaluate the contributions of human lower limb muscles to the hip, knee, and ankle joint contact forces during the stance phase of running. A total of 25 muscles (or groups) were investigated based on the OpenSim framework along the anterior-posterior, superoinferior, and mediolateral components of each joint coordinate system. It was revealed that, during the running stance phase, the gluteus medius, gluteus maximus, and iliopsoas mainly contributed to the hip contact force. The soleus, vastus group, and rectus femoris primarily contributed to the knee contact force, while the peroneus, soleus, gluteus medius, and gastrocnemius mainly contributed to the ankle joint force; some muscles simultaneously offloaded the joints during the stance phase. The distributivepattern of the individual muscle functions contributing to the joint load may substantially differ during the running and walking stance phases. This study's findings may further provide suggestive information for the design of lower limb joint prosthesis, the study of the biomechanics of pathologic walking and running, and the progression of joint osteoarthritis.

Articular geometry can affect joint kinematics, contact mechanics, and implant-bone micromotion in total ankle arthroplasty.

Implant loosening and bearing surface wear remain the most common failure problems of total ankle arthroplasty (TAA). One of the main factors leading to these problems is the nonphysiologic design of articular surfaces. The goals of this study were to reveal the effects of the anatomical medial-lateral borders height differences, coronal and sagittal radii on the joint kinematics, contact mechanics, and implant-bone micromotion in TAA. A previously developed and validated musculoskeletal (MSK) multibody dynamics (MBD) modeling method of TAA based on AnyBody generic MSK MBD model (five simulations for each implant) was used by combining with a finite element analysis. Five ankle implant models with different articular surface morphologies were created according to the anatomic characteristics of Chinese measurement data, marked as Implant A to E. The total ankle forces and motions during walking simulation were predicted by MSK MBD models and the contact mechanics of the bearing surface and the micromotion of the implant-bone interface of TAA were predicted by FE models. Compared with Implant A, the internal-external rotation in Implant E increased by 12.14%, the maximum of anterior-posterior translation in Implant E increased by 5.62%, the maximum reduction of tibial micromotion in Implant E was 59.98%, and for talar, micromotion was 15.36%. The ankle implant with similar anatomic articular surface has the potential to allow patients to recover better motions and reduce the risk of early loosening. This study would provide design guidance for the development of new ankle implants and further advance the development of TAA. Clinical Significance: This study promoted the improvement of ankle implant design and made contributions to improve the service life of ankle implant and patient satisfaction.

Motor Training After Stroke: A Novel Approach for Driving Rehabilitation.

BackgroundA key component of safe driving is a well-timed braking performance. Stroke-related decline in motor and cognitive processes slows braking response and puts individuals with stroke at a higher risk for car crashes. Although the impact of cognitive training on driving has been extensively investigated, the influence of motor interventions and their effectiveness in enhancing specific driving-related skills after stroke remains less understood. We compare the effectiveness of two motor interventions (force-control vs. strength training) to facilitate braking, an essential skill for safe driving.MethodsTwenty-two stroke survivors were randomized to force-control training or strength training. Before and after training, participants performed a braking task during car-following in a driving simulator. We quantified the cognitive and motor components of the braking task with cognitive processing time and movement execution time.ResultsThe cognitive processing time did not change for either training group. In contrast, the movement execution became significantly faster (14%) following force-control training but not strength training. In addition, task-specific effects of training were found in each group. The force-control group showed improved accuracy and steadiness of ankle movements, whereas the strength training group showed increased dorsiflexion strength following training.ConclusionMotor intervention that trains ankle force control in stroke survivors improves the speed of movement execution during braking. Driving rehabilitation after stroke might benefit from incorporating force-control training to enhance the movement speed for a well-timed braking response.

Comparison of ankle force, mobility, flexibility, and plantar pressure values in athletes according to foot posture index.

Objectives This study aims to compare ankle force, mobility, flexibility, and plantar pressure distribution of athletes according to foot posture index (FPI). Patients and methods Between September 2016 and May 2018, a total of 70 volunteer male athletes (mean age: 21.1±2.3 years; range, 18 to 25 years) were included. The athletes were divided into three groups according to their FPI as follows: having supinated feet (Group 1, n=16), neutral/normal feet (Group 2, n=36), or pronated feet (Group 3, n=18). Ankle range of motion (ROM), muscle flexibility, ankle joint strength, and plantar pressure distribution were measured. Results There were significant differences among the three groups in both right and left ankle dorsiflexion ROM (p=0.009 and p=0.003, respectively). Group 1 had significantly smaller dorsiflexion ROM than the other groups. Group 1 also showed significantly less flexibility in the gastrocnemius and soleus muscles than the other foot posture groups. Groups 2 and 3 exhibited significant differences in the maximum torque (p=0.018), maximum work (p=0.008), and total work (p=0.008) of the right plantar flexor muscles at 60°/sec angular velocity. Peak pressure measurements of the right foot were higher in Group 1, compared to Groups 2 and 3 (p<0.001). Conclusion The results of this study may help to enhance athletic performance by providing a guide for designing training programs appropriate for athletes with different foot types to address their specific muscle flexibility and strength deficiencies.

Efficacy evaluation and systematic review of supramalleolar osteotomy for treatment of varus-type ankle arthritis.

The current surgical treatment plan for medium-term varus-type ankle arthritis is primarily supramalleolar osteotomy (SMOT), but the reliability of this procedure still lacks high-quality evidence-based medical studies, such as randomized controlled clinical trials and meta-analyses of comparative studies. The current study explored whether significant differences were present in the clinical effect, reoperation rate, complications, and failure rate of this type of surgery. Two researchers searched the relevant literature in seven databases, including PubMed, Cochrane Library, EMBASE, the China Biomedical Literature Database, the China Academic Journals Full-text Database, the Wanfang database, and the Weipu Chinese Science and Technology Journal Database. The retrieval time spanned the establishment of the specific database up to September 2020, and the literature was screened to determine their final inclusion in the study. A total of 20 studies were included, including one Chinese and 19 English language studies. The primary indicators included a definitive effect of SMOT on the treatment of medium-term varus-type ankle arthritis. Concerning secondary indicators, although the surgery effect was satisfactory, some patients may require follow-up surgery, which may be unsuccessful with complications. The study results showed that, based on existing literature reports, the effect of SMOT for varus-type ankle arthritis was a satisfactory surgical method with some clinical value for correcting the ankle force line and relieving or even reversing ankle arthritis. However, its risk of complications and failure rate were comparatively high and, accordingly, requires good preoperative planning and close communication with patients. Due to the limited sample size of this study, more data and longer follow-up times involving this type of surgery should be reviewed to confirm this conclusion.

Force-Control vs. Strength Training: The Effect on Gait Variability in Stroke Survivors.

Purpose: Increased gait variability in stroke survivors indicates poor dynamic balance and poses a heightened risk of falling. Two primary motor impairments linked with impaired gait are declines in movement precision and strength. The purpose of the study is to determine whether force-control training or strength training is more effective in reducing gait variability in chronic stroke survivors.Methods: Twenty-two chronic stroke survivors were randomized to force-control training or strength training. Participants completed four training sessions over 2 weeks with increasing intensity. The force-control group practiced increasing and decreasing ankle forces while tracking a sinusoid. The strength group practiced fast ankle motor contractions at a percentage of their maximal force. Both forms of training involved unilateral, isometric contraction of the paretic, and non-paretic ankles in plantarflexion and dorsiflexion. Before and after the training, we assessed gait variability as stride length and stride time variability, and gait speed. To determine the task-specific effects of training, we measured strength, accuracy, and steadiness of ankle movements.Results: Stride length variability and stride time variability reduced significantly after force-control training, but not after strength training. Both groups showed modest improvements in gait speed. We found task-specific effects with strength training improving plantarflexion and dorsiflexion strength and force control training improving motor accuracy and steadiness.Conclusion: Force-control training is superior to strength training in reducing gait variability in chronic stroke survivors. Improving ankle force control may be a promising approach to rehabilitate gait variability and improve safe mobility post-stroke.