Early Swing Phase Research Articles

Differences in gait analysis and clinical outcome after dynamic fixation or screw fixation in acute syndesmosis tear: a prospective randomized pilot study.

Acute syndesmosis tears can be treated by static screw or dynamic fixation. Various studies have compared these techniques regarding postoperative outcome. However, to our knowledge, no study has used 3D-instrumented gait analysis (IGA). We hypothesized that a dynamic fixation would perform non-inferior to screw fixation in terms of biomechanical and clinical outcomes. Patients were prospectively randomized to both groups. All patients received the same follow-up rehabilitation and consultations (6 and 12 weeks; 6 and 12 months) postoperatively. Standardized questionnaires were used to objectify pain and ankle function. At 6 months follow-up, IGA was conducted additionally to objectify the biomechanical outcome. Twenty-five patients in the dynamic fixation (DF) group using TightRope® and twenty-five in the screw fixation group (SF) completed gait analysis. The DF group showed significantly higher mean values for maximum moment in the affected ankle joint (DF: 1.40 ± 0.21 Nm, SF: 1.23 ± 0.30 Nm; p = 0.023) and the unaffected ankle joint (DF: 1.52 ± 0.20 Nm, SF: 1.37 ± 0.27 Nm; p = 0.035). The difference between the affected and unaffected ankle joint was significantly higher in the SF group for active plantarflexion (DF: 1.52 ± 0.20°, SF: 1.37 ± 0.27°; p = 0.035). Both dynamic and screw fixation groups exhibited significantly reduced plantarflexion during the push-off and early swing phase, with moments and powers in the ankle joint also significantly impaired. Our study demonstrated that dynamic fixation has better or similar biomechanical and clinical outcomes compared to screw fixation. Future research should focus on biomechanical differences during gait as well as clinical outcomes in case of earlier weight-bearing after dynamic fixation. DRKS00013562 Date of Registration: 07/12/2017.

Characterizing Muscle Activity in Soccer Players with a History of Hamstring Strain Injuries during Accelerated Sprinting.

This study aimed to characterize muscle activity in male soccer players with a history of hamstring strain injuries (HSI) during accelerated sprinting. Thirteen patients each in the HSI group (history of HSI) and in the healthy group (with no history of HSI) were included. 26 male soccer players of which 13 with and 13 without HSI history were included in this study. Ten muscles were evaluated on electromyography activity during overground sprinting. The testing protocol consisted of a maximal sprint over a distance of 30 meters. One running stride was divided into the early stance phase, late stance phase, early swing phase, mid-swing phase, and late swing phase, and the average muscle activity per phase and the timing of the peak root-mean-square value appearance during each stride were calculated. Statistical analysis was performed using repeated-measures two-way ANOVA (group × phase), and multiple comparison tests were performed using the Bonferroni method when the interaction or main effect was significant. The statistical significance level was set at p < 0.05. Gluteus maximus (Gmax), gluteus medius (Gmed), and external oblique (EO) showed activity differences based on HSI history. Gmax was 30% lower, EO was 20% lower, and Gmed was 40% higher in HSI group. This study suggests that, despite previous findings that HSI is most likely during the late swing phase, the HSI group shows a higher injury risk in the early stance phase. This is due to differences in trunk and gluteal muscle activity between the late swing and early stance phases compared to the healthy group. In summary, HSI group had lower activity in the muscles contributing to trunk instability, especially EO and Gmax, before and after ground impact during accelerated sprinting, compared to Healthy.

How boots affect the kinematics and kinetics of lower limb joints during walking compared to casual footwear

Boots are widely used by many people for various purposes, but their impact on gait biomechanics and injury risk is not well understood. This study investigated the effects of boots on walking biomechanics, compared to casual footwear. The lower limb joint kinematics and kinetics of 20 healthy male participants aged 20 to 30 years old were compared during self-paced walking with boots and shoes. The results showed that walking with boots is associated with greater hip extensor (P = 0.009) and ankle dorsiflexor (P < 0.001) moments in early stance, hip power generation (P < 0.001) and knee power absorption (P < 0.001) in early swing phase, hip abductor (P < 0.001) and knee adduction (P < 0.001) moments in the entire stance, net concentric work for the hip joint in sagittal (13.9%, P = 0.001) and frontal (21.7%, P = 0.002) planes. In contrast, the subtalar supinator moment in the entire stance (P < 0.001), ankle angular velocity in late stance (P < 0.001), and net concentric (− 42.7%, P < 0.001) and eccentric (− 44.6%, P = 0.004) works of subtalar joint were significantly lower in the boot condition. The compensatory adjustments in the hip and knee joints may result from ankle restrictions. While boots may aid those with ankle disorders, lower limb loading and the risk of musculoskeletal injuries and osteoarthritis could be increased. This study offers new perspectives on the biomechanical impact of boots on gait, potential prevention and treatment strategies of related injuries, and advancing footwear design.

Unraveling stroke gait deviations with movement analytics, more than meets the eye: a case control study.

This study aimed to identify and quantify the kinematic and kinetic gait deviations in post-stroke hemiplegic patients with matched healthy controls using Statistical Parametric Mapping (SPM). Fifteen chronic stroke patients [4 females, 11 males; age 53.7 (standard deviation 12.2) years; body mass 65.4 (10.4) kg; standing height 168.5 (9.6) cm] and 15 matched healthy controls [4 females, 11 males; age 52.9 (11.7) years; body weight 66.5 (10.7) years; standing height 168.3 (8.8) cm] were recruited. In a 10-m walking task, joint angles, ground reaction forces (GRF), and joint moments were collected, analyzed, and compared using SPM for an entire gait cycle. Generally, when comparing the stroke patients' affected (hemiplegic) and less-affected (contralateral) limbs with the control group, SPM identified significant differences in the late stance phase and early swing phase in the joint angles and moments in bilateral limbs (all p < 0.005). In addition, the vertical and anteroposterior components of GRF were significantly different in various periods of the stance phase (all p < 0.005), while the mediolateral component showed no differences between the two groups. SPM was able to detect abnormal gait patterns in both the affected and less-affected limbs of stroke patients with significant differences when compared with matched controls. The findings draw attention to significant quantifiable gait deviations in the less-affected post-stroke limb with the potential impact to inform gait retraining strategies for clinicians and physiotherapists.

Особливості кутових характеристик техніки прямого удару правою рукою з лівосторонньої стійки у висококваліфікованих спортсменів, які спеціалізуються в рукопашному бою

Topicality. Among the most urgent and fundamental areas of hand-to-hand combat technique research, one can single out kinematic analysis within certain phases, as well as within the framework of a complete exercise. The Research Purpose is to determine of the angular characteristics of the right-hand strike technique from the left-sided stance of highly qualified athletes specializing in hand-to-hand combat. 12 highly qualified athletes took part in the research. The following Research Methods as theoretical analysis, pedagogical and mathematical methods have been used in the study. The Research Results. Since there is no swing phase of straight kick, the preparation phase of kicking immediately precedes the impact action phase. During the preparation phase, athletes slightly bend their left leg, the left knee joint angle decreases by 3,8° (from 123,1° to 119,3°), and in the left hip joint by 4,2° (from 134,4° to 130,2°). Since there is no early swing phase of straight kick, the preparation kick phase immediately precedes the percussive impact phase. During the preparation phase, athletes slightly bend their left leg, the left knee joint angle decreases by 3,8° (from 123,1° to 119,3°), and in the left hip joint angle – by 4,2° (from 134,4° to 130,2°). The right leg remains practically immobile: the right knee joint angle at the beginning of the phase is 137,1°, and at the end of the phase it is 136,5°, that is, it decreases by only 0,6°; the right hip joint angle at the beginning of the phase is 145,9°, and at the end of the phase is 147,8°, increasing by 1,9°. The angular indicators of the upper limbs movements during the preparation phase for the impact have the following changes: the left shoulder joint angle increases by 6° (from 44.6° to 50,6°), the left elbow joint angle decreases by 6° (from 57,3° to 51,3°), the right shoulder joint angle increases by 4,5° (from 30,4° to 34,9°), and in the right elbow joint angle increases by 19,8° (from 51,8° to 71,6°). Findings. The straight right hand kick from the left stance is one of the most widely used and effective kicks in hand-to-hand combat. Also, due this kick, the greatest damage is inflicted on the opponent.

Characteristics of muscle synergy extracted using an autoencoder in patients with stroke during the curved walking in comparison with healthy controls

Background and objectiveThis study investigated the spatial and temporal features of muscle synergy during two types of curved walking (CW), according to whether the analyzed legs were located on the outside (OCW) or inside (ICW) on the basis of the curve direction during CW, in patients with stroke. MethodsThirteen patients with stroke and seven age-matched healthy controls participated in this study. Using the autoencoder technique, four muscle synergies were extracted from eight muscles of the paretic legs in patients with stroke and the dominant legs in healthy controls. Walking speed, variance accounted for (VAF) of the four synergies, and each synergy with the same number were compared. Pearson’s correlation and activation peak timing calculation were used to identify spatial and temporal features, respectively. ResultsRegarding walking speed in patients with stroke, ICW was significantly faster than OCW (P = 0.027). Regarding spatial features, muscle weighting values of patients with stroke in synergy 3 that were mainly involved in the early swing phase had the lowest similarity [r = 0.30] during OCW, and synergy 4 that was mainly involved in the late swing phase had the lowest similarity [r = 0.39] during ICW compared to the healthy group. Meanwhile, in terms of temporal features, activation peak timings of patients with stroke in synergy 1, which was mainly involved in the early stance phase, and synergy 2, which was mainly involved in the mid-late stance phase, were significantly delayed during OCW (P < .001, P = 0.003), while peak timings of synergy 1 and synergy 3 were delayed during ICW (P = .004, P = .002). SignificanceBased on distinctive features of spatial synergy during the swing phase of CW and temporal synergy during the swing-stance transition phase of CW in patients with stroke in gait rehabilitation, specific approaches need to be considered depending on the curve direction and each gait phase.

Walking in high-heel shoes induces redistribution of joint power and work

ABSTRACT Walking in high-heel shoes (HHS) decreases the push-off power and little research has examined the specific muscle groups that compensate for it. The purpose was to examine the effects of walking in HHS compared to barefoot on lower extremity net joint work and power. Fourteen young women walked in HHS and barefoot at a fixed speed of 1.3 m·s−1. Marker position and ground reaction force data were synchronously measured at 100 and 1000 Hz, respectively. Peak power and joint work variables were computed over the power phases of the gait cycle using an inverse dynamic approach. When walking in HHS was compared to barefoot, participants exerted a diminished push-off characterized by lesser peak power and lesser work by the ankle plantar flexors in late stance (A2 phase; p < 0.001). To compensate for the reduced ankle plantar flexor power, greater peak power was generated and work was performed in early stance by hip extensors (H1 phase; p ≤ 0.001), in mid-stance by knee extensors (K2 phase; p < 0.001) and in late stance and early swing phase by hip flexor muscles (H3 phase; p ≤ 0.001). Walking in HHS induces biomechanical plasticity and causes distal-to-proximal redistribution of net joint power and work during walking.

Reaction moments matter when designing lower-extremity robots for tripping recovery.

Balance recovery after tripping often requires an active adaptation of foot placement. Thus far, few attempts have been made to actively assist forward foot placement for balance recovery employing wearable devices. This study aims to explore the possibilities of active forward foot placement through two paradigms of actuation: assistive moments exerted with the reaction moments either internal or external to the human body, namely 'joint' moments and 'free' moments, respectively. Both paradigms can be applied to manipulate the motion of segments of the body (e.g., the shank or thigh), but joint actuators also exert opposing reaction moments on neighbouring body segments, altering posture and potentially inhibiting tripping recovery. We therefore hypothesised that a free moment paradigm is more effective in assisting balance recovery following tripping. The simulation software SCONE was used to simulate gait and tripping over various ground-fixed obstacles during the early swing phase. To aid forward foot placement, joint moments and free moments were applied either on the thigh to augment hip flexion or on the shank to augment knee extension. Two realizations of joint moments on the hip were simulated, with the reaction moment applied to either the pelvis or the contralateral thigh. The simulation results show that assisting hip flexion with either actuation paradigm on the thigh can result in full recovery of gait with a margin of stability and leg kinematics closely matching the unperturbed case. However, when assisting knee extension with moments on the shank, free moment effectively assist balance but joint moments with the reaction moment on the thigh do not. For joint moments assisting hip flexion, placement of the reaction moment on the contralateral thigh was more effective in achieving the desired limb dynamics than placing the reaction on the pelvis. Poor choice of placement of reaction moments may therefore have detrimental consequences for balance recovery, and removing them entirely (i.e., free moment) could be a more effective and reliable alternative. These results challenge conventional assumptions and may inform the design and development of a new generation of minimalistic wearable devices to promote balance during gait.

Factors leading to falls in transfemoral prosthesis users: a case series of sound-side stumble recovery responses

BackgroundTransfemoral prosthesis users’ high fall rate is related to increased injury risk, medical costs, and fear of falling. Better understanding how stumble conditions (e.g., participant age, prosthesis type, side tripped, and swing phase of perturbation) affect transfemoral prosthesis users could provide insight into response deficiencies and inform fall prevention interventions.MethodsSix unilateral transfemoral prosthesis users experienced obstacle perturbations to their sound limb in early, mid, and late swing phase. Fall outcome, recovery strategy, and kinematics of each response were recorded to characterize (1) recoveries versus falls for transfemoral prosthesis users and (2) prosthesis user recoveries versus healthy adult recoveries.ResultsOut of 26 stumbles, 15 resulted in falls with five of six transfemoral prosthesis users falling at least once. By contrast, in a previously published study of seven healthy adults comprising 214 stumbles using the same experimental apparatus, no participants fell. The two oldest prosthesis users fell after every stumble, stumbles in mid swing resulted in the most falls, and prosthesis type was not related to strategy/fall outcomes. Prosthesis users who recovered used the elevating strategy in early swing, lowering strategy in late swing, and elevating or lowering/delayed lowering with hopping in mid swing, but exhibited increased contralateral (prosthetic-side) thigh abduction and trunk flexion relative to healthy controls. Falls occurred if the tripped (sound) limb did not reach ample thigh/knee flexion to sufficiently clear the obstacle in the elevating step, or if the prosthetic limb did not facilitate a successful step response after the initial sound-side elevating or lowering step. Such responses generally led to smaller step lengths, less anterior foot positioning, and more forward trunk flexion/flexion velocity in the resulting foot-strikes.ConclusionsIntroducing training (e.g., muscle strength or task-specific motor skill) and/or modifying assistive devices (e.g., lower-limb prostheses or exoskeletons) may improve responses for transfemoral prosthesis users. Specifically, training or exoskeleton assistance could help facilitate sufficient thigh/knee flexion for elevating; training or prosthesis assistance could provide support-limb counteracting torques to aid in elevating; and training or prosthesis assistance could help initiate and safely complete prosthetic swing.

Differences in causes of stiff knee gait in knee extensor activity or ankle kinematics: A cross-sectional study

BackgroundStiff knee gait (SKG), a common occurrence after the onset of stroke, is caused by hyperactivity of the rectus femoris during the swing phase. Another cause of SKG is the weakness of push-off in hemiparetic gait. Prior research did not consider the effect of the magnitude of knee extensors in their subjects. Research questionDoes the cause of SKG differ between patients with high and low knee extensor activities during the swing phase? MethodsWe examined 38 patients with chronic stroke hemiplegia who presented with SKG. After placing an inertia sensor and an electromyogram, patients walked 10 m at a comfortable speed. All patients were categorized per the sign of the principal component 2 (PC2) as a component with large factor loadings of knee extensors attained from the electromyographic amplitude during the early swing phase of the paretic limb. Then, the kinematic parameters of knee flexion and other gait parameters in each group were compared, and a correlation analysis was performed. ResultsIn the high PC2 group, the timing of peak knee flexion during the swing phase was early, and vastus lateralis activity during the preswing phase negatively correlated with the knee-flexion angle during the swing phase. In the low PC2 group, the angular velocity of ankle plantar flexion at the toe-off was slow, which positively correlated with the knee-flexion angle during the swing phase. SignificanceThe cause of SKG could be an inappropriate activity of the vastus lateralis rather than the rectus femoris in patients with high knee extensor activity and slow plantar-flexion velocity at toe-off in patients with low knee extensor activity. Not all causes of SKG in patients with hemiplegia are common, and different treatment strategies are needed per the individuality of spastic knee extensor activity.

Thigh and Shank, Kinetic and Potential Energies during Gait Swing Phase in Healthy Adults and Stroke Survivors.

Background/Problem. Given the treatment-resistant gait deficits after stroke and known elevated energy cost of gait after stroke, it is important to study the patterns of mechanical energies of the lower limb segments. There is a dearth of information regarding mechanical energies specifically for the thigh and shank across the gait cycle. Therefore, the purpose of the current work was to characterize the following: (1) relative patterns of oscillation kinetic energy (KE) and potential energy (PE) within lower limb segments and across lower limb segments in healthy adults during the swing phase at chosen and slow gait speeds; (2) KE and PE swing phase patterns and values for stroke survivors versus healthy adults walking at slow speed; and (3) KE and PE patterns during the swing phase for two different compensatory gait strategies after stroke,. Methods. This was a gait characterization study, a two-group, parallel-cohort study of fourteen stroke survivors with gait deficits, walking at <0.4 m/s and eight adults with no gait deficits. For testing, the eight healthy adults walked at their chosen speed, and then at the imposed slow speed of <0.04 m/s. We used a standard motion capture system and calculation methods to acquire, calculate, and characterize oscillation patterns of KE and PE of the limb segments (thigh and shank) across the gait cycle. Results. In healthy adults, we identified key energy conservation mechanisms inherent in the interactions of KE and PE, both within the thigh and shank segments and across those limb segments, partially explaining the low cost of energy of the normal adult chosen speed gait pattern, and the underlying mechanism affording the known minimal set of activated muscles during walking, especially during the early swing phase. In contrast, KE was effectively absent for both healthy adults at imposed slow walking speed and stroke survivors at their very slow chosen speed, eliminating the normal conservation of energy between KE and PE within the thigh and across the thigh and shank. Moreover, and in comparison to healthy adult slow speed, stroke survivors exhibited greater abnormalities in mechanical energies patterns, reflected in either a compensatory stepping strategy (over-flexing the hip) or circumducting strategy (stiff-legged gait, with knee extended throughout the swing phase). Conclusions and contribution to the field. Taken together, these findings support targeted training to restore normal balance control and normal activation and de-activation coordination of hip, knee, and ankle muscles, respectively (agonist/antagonist at each joint), so as to eliminate the known post-stroke abnormal co-contractions; this motor training is critical in order to release the limb to swing normally in response to mechanical energies and afford the use of conservation of KE and PE energies within the thigh and across thigh and shank.

The Biomechanics Effect of Hamstring Flexibility on the Risk of Osgood-Schlatter Disease.

Background The relationship between hamstring flexibility and the risk of OSD continues to be a debate, and whether hamstring stretching exercises should be considered as one of the conservative treatments of OSD is still unclear. Objectives To investigate the relationship between hamstring flexibility and the risk of OSD by assessing the changes of loading on the tibial tuberosity caused by the changes of hamstring optimal lengths. Methods Experimental data of a young adult running at 4 m/s were used, which were collected by an eight-camera motion capture system together with an instrumented treadmill. Muscle forces were estimated in OpenSim when hamstring optimal lengths changed in the range of 70–130% of the control case in 5% increments. The force and accumulated force of quadriceps muscle were calculated to evaluate the impact of hamstring optimal lengths on the loading on tibial tuberosity. The changes in muscle forces throughout the gait cycle were compared by using statistical parametric mapping (SPM). The average peak force and accumulated force of five gait cycles were compared. Results Although the maximum force of the quadriceps muscle was slightly affected by changes in hamstring optimal lengths, the accumulated force of quadriceps muscle increased by 21.97% with hamstring optimal lengths decreased by 30% of the control case. The increase of the muscle force mainly occurred in the early stance phase and terminal swing phase (P < 0.05). However, when hamstring optimal lengths were longer than the control, it had a little effect on accumulated force of quadriceps muscle. Conclusions The results of this study indicate that a shorter hamstring optimal length, which means lack of flexibility, can cause a high accumulated force on tibial tuberosity, thus increasing the risk of OSD. Hamstring stretching exercise is only effective for people with lack of hamstring flexibility.

Gait Adaptation Is Different between the Affected and Unaffected Legs in Children with Spastic Hemiplegic Cerebral Palsy While Walking on a Changing Slope

Walking on sloped surfaces requires additional effort; how individuals with spastic hemiplegic cerebral palsy (CP) manage their gait on slopes remains unknown. Herein, we analyzed the difference in gait adaptation between the affected and unaffected legs according to changes in the incline by measuring spatiotemporal and kinematic data in children with spastic hemiplegic CP. Seventeen children underwent instrumented three-dimensional gait analysis on a dynamic pitch treadmill at an incline of +10° to −10° (intervals of 5°). While the step length of the affected legs increased during uphill gait and decreased during downhill gait, the unaffected legs showed no significance. During uphill gait, the hip, knee, and ankle joints of the affected and unaffected legs showed increased flexion, while the unaffected leg showed increased knee flexion throughout most of the stance phase compared with the affected leg. During downhill gait, hip and knee flexion increased in the affected leg, and knee flexion increased in the unaffected leg during the early swing phase. However, the ankle plantar flexion increased during the stance phase only in the unaffected leg. Although alterations in temporospatial variables and joint kinematics occurred in both legs as the slope angle changed, they showed different adaptation mechanisms.

Can We Modify Maximal Speed Running Posture? Implications for Performance and Hamstring Injury Management.

Sprint kinematics have been linked to hamstring injury and performance. This study aimed to examine if a specific 6-week multimodal intervention, combining lumbopelvic control and unning technique exercises, induced changes in pelvis and lower-limb kinematics at maximal speed and improved sprint performance. Healthy amateur athletes were assigned to a control or intervention group (IG). A sprint test with 3-dimensional kinematic measurements was performed before (PRE) and after (POST) 6 weeks of training. The IG program included 3 weekly sessions integrating coaching, strength and conditioning, and physical therapy approaches (eg,manual therapy, mobility, lumbopelvic control, strength and sprint "front-side mechanics"-oriented drills). Analyses of variance showed no between-group differences at PRE. At POST, intragroup analyses showed PRE-POST differences for the pelvic (sagittal and frontal planes) and thigh kinematics and improved sprint performance (split times) for the IG only. Specifically, IG showed (1)a lower anterior pelvic tilt during the late swing phase, (2)greater pelvic obliquity on the free-leg side during the early swing phase, (3)higher vertical position of the front-leg knee, (4)an increase in thigh angular velocity and thigh retraction velocity, (5)lower between-knees distance at initial contact, and (6)a shorter ground contact duration. The intergroup analysis revealed disparate effects (possibly to very likely) in the most relevant variables investigated. The 6-week multimodal training program induced clear pelvic and lower-limb kinematic changes during maximal speed sprinting. These alterations may collectively be associated with reduced risk of muscle strain and were concomitant with significant sprint performance improvement.

Effect of concurrent strength and endurance training on run performance and biomechanics: A randomized controlled trial.

This parallel-group randomized controlled trial investigated the effect of concurrent strength and endurance (CSE) training on running performance, biomechanics, and muscle activity during overground running. Thirty moderately trained distance runners were randomly assigned to 10-week CSE training (n=15; 33.1±7.5years) or a control group (n=15; 34.2±8.2years). Participants ran ≥30km per week and had no experience with strength training. The primary outcome measure was 2-km run time. Secondary outcome measures included lower limb sagittal plane biomechanics and muscle activity during running (3.89ms-1 and maximal sprinting); maximal aerobic capacity (V̇O2 max); running economy; and body composition. CSE training improved 2-km run time (mean difference (MD): -11.3s [95% CI -3.7, -19.0]; p=0.006) and time to exhaustion during the V̇O2 max running test (MD 59.1s [95% CI 8.58, 109.62]; p=0.024). The CSE training group also reduced total body fat (MD: -1.05kg [95% CI -0.21, -1.88]; p=0.016) while total body mass and lean body mass were unchanged. Hip joint angular velocity during the early swing phase of running at 3.89ms-1 was the only biomechanical or muscle activity variable that significantly changed following CSE training. CSE training is beneficial for running performance, but changes in running biomechanics and muscle activity may not be contributing factors to the performance improvement. Future research should consider other possible mechanisms and the effect of CSE training on biomechanics and muscle activity during prolonged running under fatigued conditions.

Altered Modulation of Locomotor Cutaneous Reflexes in Ambulatory Individuals With Chronic Spinal Cord Injury

<h3>Research Objectives</h3> The purpose of this study was to examine lower limb cutaneous (CUT) reflexes during walking in people with chronic incomplete spinal cord injury (SCI). In neurologically intact individuals, CUT reflexes to non-noxious stimulus are phase-dependently modulated during walking with nerve specificity, so as to avoid stumbling and falling [1]. Currently, CUT reflexes in ambulatory individuals with SCI are not well understood. <h3>Design</h3> CUT reflexes were elicited by stimulating the sural (SR), superficial peroneal (SP), or tibial nerve (TN) near the ankle of the clinically more spastic leg. For each nerve stimulation, a 5 × 1-ms pulse train (200 Hz) at ≈1.7 x radiating threshold was delivered pseudo-randomly across the entire step cycle while the participant walked on a treadmill at his/her comfortable speed. Electromyography (EMG) was recorded from the soleus and tibialis anterior (TA) bilaterally, and medial and lateral gastrocnemius, vastus lateralis, and biceps femoris in the stimulated leg. <h3>Setting</h3> University. <h3>Participants</h3> Eight individuals with chronic incomplete SCI volunteered to participate in this study. <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Medium (80-120 ms post-stimulus) latency CUT reflexes were quantified in 8 equal bins of the step cycle. <h3>Results</h3> CUT reflexes are phase-dependently modulated in ambulatory individuals with SCI, with less nerve specificity than that in people without injuries [2]. Nerve specificity was clear for the ipsilateral TA, which showed strong excitation in the early swing phase following TN (56% max non-stimulated EMG) but suppression following SR (-4%) and SP (-13%). Contralateral TA was suppressed during late swing uniformly following TN (-15%), SR (-14%), and SP (-18%). <h3>Conclusions</h3> The presence and patterns of CUT reflex modulation could be useful measures of neuroplasticity in people with SCI. <h3>Author(s) Disclosures</h3> No conflicts.

The effect of asymmetrical gait induced by unilateral knee brace on the knee flexor and extensor muscles.

Asymmetrical stiff knee gait is a mechanical pathology that can disrupt lower extremity muscle coordination. A better understanding ofthis condition can help identify potential complications. This study proposes the use ofdynamic musculoskeletal modelling simulation to investigate theeffect of induced mechanical perturbation onthe kneeand to examine the musclebehaviour without invasive technique. Thirty-eighthealthy participants were recruited. Asymmetrical gait was simulated using knee brace. Knee joint angle, jointmoment and knee flexor and extensor muscle forces were computed using OpenSim. Differences inmuscle force between normal and abnormal conditions were investigated using ANOVA and Tukey-Kramer multiple comparison test.The results revealed that braced knee experienced limited range of motion withsmallerflexion momentoccuring atlate swing phase. Significant differences were found in all flexormuscle forces and in several extensor muscle forces (p<0.05). Normal knee produced larger flexormuscle force than braced knee. Braced knee generated the largest extensormuscle force at early swing phase. In summary, musculoskeletalmodelling simulation can be a computational tool to map and detect thedifferences between normal and asymmetrical gaits.

A Probability Distribution Model-Based Approach for Foot Placement Prediction in the Early Swing Phase With a Wearable IMU Sensor.

Predicting the next foot placement of humans during walking can help improve compliant interactions between humans and walking aid robots. Previous studies have focused on foot placement estimation with wearable inertial sensors after heel-strike, but few have predicted foot placements in advance during the early swing phase. In this study, a Bayesian inference-based foot placement prediction approach was proposed. Possible foot placements were modeled as a probability distribution grid map. With selected foot motion feature events detected sequentially in the early swing phase, the foot placement probability map could be updated iteratively using the feature models we built. The weighted center of the probability distribution was regarded as the predicted foot placement. Prediction errors were evaluated with collected walking data sets. When testing with the data from inertial measurement units, the prediction errors were (5.46 cm ± 10.89 cm, -0.83 cm ± 10.56 cm) for cross-velocity walking data and (-4.99 cm ± 12.31 cm, -11.27 cm ± 7.74 cm) for cross-subject-cross-velocity walking data. The results were comparable to previous works yet the prediction could be made earlier. For the subject who walked with more stable gaits, the prediction error can be further decreased. The proposed foot placement prediction approach can be utilized to help walking aid robots adjust their pose before each heel-strike event during walking, which will make human-robot interactions more compliant. This study is also expected to inspire additional probabilistic gait analysis works.

Coordination of lower limbs in patients with knee osteoarthritis during walking

BackgroundThe movement coordination in patients with knee osteoarthritis may be impaired and the identification of the deficits in lower limb inter-segmental coordination is crucial to understand the effect of knee osteoarthritis on knee function. Research questionThis study utilizes continuous relative phase to investigate the pattern and variability of lower limb inter-segmental coordination in patients with knee osteoarthritis and in healthy subjects during walking, and to evaluate inter-segmental coordination alterations in patients. MethodsGait was measured by a three-dimensional motion capture system for 44 patients with late-stage knee osteoarthritis and 22 healthy subjects. Segmental kinematic parameters, continuous relative phase and its variability were calculated. Independent samples t-tests were used to detect differences between patients and healthy subjects. ResultsThigh-shank continuous relative phase of patients is significantly decreased by 16.04° and 16.18° during late stance and swing phase as compared with healthy subjects (P < 0.05). Shank-foot continuous relative phase of patients is significantly decreased by 6.89° during early stance and significantly increased by 5.49° and 6.39° during late stance and swing phase (P < 0.05). Patients also exhibit increased variability of thigh-shank continuous relative phase during late stance and swing phase by 1.90° and 1.65° respectively, and increased variability of shank-foot continuous relative phase during early stance and swing phase by 0.83° and 0.88° respectively as compared to healthy subjects (P < 0.05). SignificancePatients with knee osteoarthritis exhibit altered coordination patterns and increased coordination variability of thigh-shank and shank-foot. Knee dysfunction results in altered lower limbs coordination and unstable motor control during walking. Investigation of inter-segmental coordination could therefore provide insights into changes in neuromuscular control of gait in patients with knee osteoarthritis.

Effects Of Foot Rotation On Knee Joint Reaction Forces During Running

PURPOSE: The purpose of this study was to examine the effects of internal and external foot rotation on knee joint reaction forces during running. METHODS: Motion capture and force data were recorded on nineteen healthy adult runners (22.3±4.0 years, 67.99±10.27 kg, and 1.77±0.10 m) running at 3.5 m/s with normal and maximal comfortable external (EXT) and internal (INT) foot rotation. Musculoskeletal simulations were performed using the Rajagopal 2015 model and OpenSim (SimTK). All data were low pass filtered at 10 Hz and normalized to a full stride (stance: 0-36% & swing: 37-100% stride). Models were scaled to each subject’s anthropometric parameters. Inverse dynamics were derived by combining inverse kinematics and force data. Muscle excitations were derived using Static Optimization, including muscle physiology parameters. Joint Reaction Forces were obtained by combining inverse kinematics, force data, and muscle excitations. Within-subjects ANOVAs via Statistical Parametric Mapping were used to determine differences in resultant knee joint reaction force waveforms. RESULTS: The EXT condition decreased early stance (0-2% stride) and late swing (92-100% stride) phase forces, but increased forces during early swing (44-46%) phase compared to normal. The INT condition reduced forces during very late swing phase (92-94% stride). The EXT reduced forces during early stance (0-1% stride) and late swing (97-100% stride) compared to INT. CONCLUSIONS: Despite the known success of altered foot rotation on reducing external knee abduction moments during walking and running, knee forces were only reduced during low-loading portions of running strides. Thus, it appears altered foot rotations does not improve knee loading during running.