Symmetric Gait Research Articles

Augmenting propulsion demands during split-belt walking increases locomotor adaptation of asymmetric step lengths

BackgroundPromising studies have shown that the gait symmetry of individuals with hemiparesis due to brain lesions, such as stroke, can improve through motor adaptation protocols forcing patients to use their affected limb more. However, little is known about how to facilitate this process. Here we asked if increasing propulsion demands during split-belt walking (i.e., legs moving at different speeds) leads to more motor adaptation and more symmetric gait in survivors of a stroke, as we previously observed in subjects without neurological disorders.MethodsWe investigated the effect of propulsion forces on locomotor adaptation during and after split-belt walking in the asymmetric motor system post-stroke. To test this, 12 subjects in the chronic phase post-stroke experienced a split-belt protocol in a flat and incline session so as to contrast the effects of two different propulsion demands. Step length asymmetry and propulsion forces were used to compare the motor behavior between the two sessions because these are clinically relevant measures that are altered by split-belt walking.ResultsThe incline session resulted in more symmetric step lengths during late split-belt walking and larger after-effects following split-belt walking. In both testing sessions, subjects who have had a stroke adapted to regain speed and slope-specific leg orientations similarly to young, intact adults. Importantly, leg orientations, which were set by kinetic demands, during baseline walking were predictive of those achieved during split-belt walking, which in turn predicted each individual’s post-adaptation behavior. These results are relevant because they provide evidence that survivors of a stroke can generate the leg-specific forces to walk more symmetrically, but also because we provide insight into factors underlying the therapeutic effect of split-belt walking.ConclusionsIndividuals post-stroke at a chronic stage can adapt more during split-belt walking and have greater after-effects when propulsion demands are augmented by inclining the treadmill surface. Our results are promising since they suggest that increasing propulsion demands during paradigms that force patients to use their paretic side more could correct gait asymmetries post-stroke more effectively.

Step length symmetry adaptation to split-belt treadmill walking after acquired non-traumatic transtibial amputation

BackgroundBetween-limb step length asymmetry is common following transtibial amputation (TTA) and contributes to negative health consequences. There are limited evidence-based interventions targeting reduced gait asymmetry for people with TTA. Split-belt treadmill walking with asymmetrical belt speeds has successfully reduced gait asymmetry in other patient populations. However, individuals with non-traumatic TTA have critical health-related impairments that may influence the ability to respond to split-belt treadmill walking. Research QuestionDo people with acquired, non-traumatic TTA adapt and retain a more symmetrical gait pattern in response to split-belt treadmill walking? MethodsStep length asymmetry was measured during split-belt treadmill walking. Eight participants walked under two alternating belt speed conditions: symmetrical (3 sets; Baseline, TIED1, TIED2) and asymmetrical belt speeds (5 sets; SPLIT1–5). One-way repeated-measures ANOVA with post-hoc Tukey’s HSD tests were used to assess adaptation and short-term retention of step length symmetry. Adaptation was assessed as the level of asymmetry during TIED walking following repeated exposure to SPLIT walking. Retention was measured as the change in level of asymmetry during each set of SPLIT walking. ResultsSignificant adaptation to split-belt walking was observed from late Baseline to early TIED1 and early TIED2. Between-limb step length asymmetry decreased from late Baseline (5.3 ± 3.4) to early TIED1 (-9.4 ± 3.6) and this change was sustained between early TIED1 and early TIED2 (-11.2 ± 3.1) (ANOVA F = 73.043, p < .001). Adaptations were retained as step length asymmetry decreased from early SPLIT1 (48.5 ± 5.3) to early SPLIT3 (31.4 ± 3.5) to early SPLIT5 (23.9 ± 5.1) (ANOVA F = 35.284, p < .001). SignificanceIndividuals with non-traumatic TTA are capable of gait adaptation to split-belt walking and short-term retention of adaptations after removal of the asymmetrical belt speeds. Adaptability of step length symmetry is possible without modification to the prosthetic limb. Split-belt walking should be tested as a potential intervention to help people with acquired, non-traumatic TTA increase between-limb step symmetry.

Mech-Walker:A Novel Single-DOF Linkage Device With Movable Frame for Gait Rehabilitation

In this article, a novel lower extremity gait rehabilitation device with a single actuator is presented. The proposed device, Mech-Walker, utilizes the single-degree of freedom eight-bar Jansen's mechanism. The mechanism is synthesized to generate the ankle trajectory of human gait, relative to the hip, in terms of both position and time. Two mechanisms, one for each leg, are applied reciprocally and are mechanically synchronized to guarantee symmetric gait. A custom designed seat-type weight support system mounted over a commercially available treadmill is also introduced. It not only supports the user and the mechanisms but also links the mechanism's base to the subject's hip. This vertically movable base allows ground contact proprioception for the user which is crucial in gait training. As this is a nonanthropomorphic design interacting with the leg only at hip and ankle via seat and footrest, respectively, it does not need to be aligned with the subject's joints, which facilitates the donning and doffing of the device. Adjustability of mechanism to different users has also been considered to provide an effective training tool. A prototype is manufactured, and pilot study with a healthy subject is conducted. Due to ease of control, cost-effectiveness, and high intrinsic safety, the proposed system potentially offers a novel tool for gait training.

Design of a powered ankle-foot prosthesis with an adjustable stiffness toe joint

ABSTRACTThis paper proposes a powered ankle-foot prosthesis called PANTOE II, which includes an ankle and a segmented foot with a toe joint. The ankle and toe joints are both driven by series elastic actuators, which can reduce the required velocity and energy consumption of the actuators. The mechanical design of the ankle and toe joints makes the prosthesis more compact. In addition, PANTOE II employs a more human-like foot, which includes the heel, the mid foot, and the toe. Both the heel and the toe are made of leaf springs, and the mid foot is used to install the transmission mechanisms. The finite state control strategy is used for controlling the prosthesis. To evaluate the basic performance of PANTOE II, experiments are conducted on a subject with a transtibial amputation. Wearing PANTOE II, the amputee feels more comfortable and presents more symmetrical walking gaits.

Hip resurfacing generates a more physiological gait than total hip replacement: A case-control study

BackgroundRestoration of the constitutional joint anatomy after hip replacement favours physiological peri-articular soft-tissue tension and kinematics, and is likely to be functionally beneficial. Hip resurfacing (HR) and conventional total hip replacement (THR) are two different options for replacing degenerated hips, and are likely to result in different anatomical reconstruction. We initiated this study to investigate the differences in gait performance between these two prosthetic options, and aimed to answer the following questions: (1) does HR result in better restoration of the frontal hip anatomical parameters, (2) and generate a more physiological gait compared to THR? (3) Does the quality of the anatomical restoration after THR influence gait performance? HypothesesOur hypothesis was that a better anatomical restoration using HR versus THR would produce more physiological (symmetric) gait. MethodsWe retrospectively reviewed 52 patients who had unilateral primary osteoarthritis successfully treated by replacement (40 THRs and 12 HRs). Hip anatomical parameters were measured on standing pelvic radiographs on both the prosthetic and the contralateral healthy hips. Patients undertook gait assessment under both normal and stress conditions at a mean follow-up of 14 months (7 to 16 months). Gait performances were compared between HR and THR, and the relationship between gait performances and quality of frontal anatomical restoration (estimated on radiograph) were assessed. ResultsCompared to the native contralateral side, the HR procedure tended to decrease all independent anatomical radiographic parameters with the exception of the vertical centre of rotation offset, whilst the THR procedure tended to increase them; the difference between HR and THR was only statistically significant for femoral offset and global horizontal offset (increased after THR while reduced after HR). Only 50% of THR and 25% of HR procedures closely anatomically (±15%) recreated both global horizontal offset and global vertical offset. Under normal conditions (normal walking speed and flat ramp), the gait was fairly symmetric for both the HR and the THR patients with a symmetry index of 0.62% and 3.14% respectively. At high walking speed (stress conditions), the symmetry index degraded for both groups, but the gait remained more symmetric in the HR group (2.09%), compared to the THR group (5.74%); nevertheless, the difference remained not statistically significant (p=0.159). We were unable to detect any significant relationship between gait performances and radiographically measured hip frontal anatomical parameters. Discussion/conclusionsHR procedure is more consistent than conventional THR in generating a more physiological gait under stress conditions. Radiographic estimation of the quality of the frontal anatomical hip restoration is of poor value to predict gait performances of THR patients. Level of evidenceIII – retrospective case-control study with prospective data collection.

Abstract 12: Strategies To Optimize Functional Recovery In Distal Nerve Transfers For Common Fibular Nerve Injuries

Purpose: Footdrop secondary to injury of the common fibular nerve has significant implications on patient function and quality of life. Outcomes following distal nerve transfers (DNT) for restoration of common fibular nerve function are unsatisfactory and often unpredictable. A perioperative technique to improve regeneration and reinnervation of end-targets is therefore of significant clinical interest. We investigated the effects of conditioning electrical stimulation (CES) and daily exercise therapy on regeneration and functional recovery in a rodent model of a DNT. Methods: Sprague Dawley rats were equally divided into a) CES, b) training, c) CES + training, and d) DNT. One week prior to DNT, animals randomized to a CES-cohort received one hour of intermittent electrical stimulation. In keeping with current clinical practice, DNT was performed by identifying the branch of the tibial nerve supplying the lateral gastrocnemius muscle, which was transected and coapted to the distal stump of the denervated common fibular nerve. Post-operatively, animals randomized to a training cohort had one-hour of treadmill training daily for 1 month at 10m/min. Length of axonal extension was quantified after two weeks of regeneration, and motor reinnervation was evaluated weekly by gait analysis of kinetic and kinematic outcomes and skilled locomotion testing. Results: Animals treated with CES prior to DNT had significantly greater regeneration and functional recovery. Two weeks postoperative, the length of axon extension in CES-treated nerves was, significantly longer than in non-conditioned control DNTs (p<0.001). By 8 weeks of regeneration, animals treated with CES+training had significantly higher foot placement scores on the horizontal ladder test (4.3 + 0.3) than DNT-controls (2.6 + 0.2, p<0.001)Animals treated with CES+training had the earliest return of dorsiflexion. By 12 weeks of regeneration, animals treated with CES+training (12.6 ± 2.8o) or with CES (11.2 ± 3.5o), had significantly greater recovery of dorsiflexion when compared to those animals trained only (3.9 ± 2.5o, p<0.001) or DNT controls (no dorsiflexion, p<0.001). Restoration to a more symmetrical gait pattern was significantly improved (p<0.001) among CES+training treated animals; with increased weight bearing (vertical peak forces 0.7 ± 0.03) and increased contact time of the affected limb (duty factor= contralateral - ipsilateral contact time; 0.039 ± 0.007) compared to the other groups (p<0.001). By week 12 of regeneration, CES treated animals exhibited a recovery to symmetry with increased vertical peak forces injured limb (0.65 + 0.02) and reduced differences between limb duty factors (0.046 + 0.05) compared to all other cohorts (p<0.05). Conclusion: Preoperative CES with and without exercise enhances functional recovery with improved dorsiflexion and accelerated restoration of normal gait following DNT for reinnervating common fibular nerve targets. As electrical stimulation has already been proven to be safe in a human patient population, and given that DNTs are performed electively and thus preoperative intervention is possible, delivery of CES in the footdrop patient population may significantly improve the efficacy and reliability in patients undergoing a distal nerve transfer.

Wearer-Prosthesis Interaction for Symmetrical Gait: A Study Enabled by Reinforcement Learning Prosthesis Control.

With advances in robotic prostheses, rese-archers attempt to improve amputee's gait performance (e.g., gait symmetry) beyond restoring normative knee kinematics/kinetics. Yet, little is known about how the prosthesis mechanics/control influence wearer-prosthesis' gait performance, such as gait symmetry, stability, etc. This study aimed to investigate the influence of robotic transfemoral prosthesis mechanics on human wearers' gait symmetry. The investigation was enabled by our previously designed reinforcement learning (RL) supplementary control, which simultaneously tuned 12 control parameters that determined the prosthesis mechanics throughout a gait cycle. The RL control design facilitated safe explorations of prosthesis mechanics with the human in the loop. Subjects were recruited and walked with a robotic transfemoral prosthesis on a treadmill while the RL controller tuned the control parameters. Stance time symmetry, step length symmetry, and bilateral anteroposterior (AP) impulses were measured. The data analysis showed that changes in robotic knee mechanics led to movement variations in both lower limbs and therefore gait temporal-spatial symmetry measures. Consistent across all the subjects, inter-limb AP impulse measurements explained gait symmetry: the stance time symmetry was significantly correlated with the net inter-limb AP impulse, and the step length symmetry was significantly correlated with braking and propulsive impulse symmetry. The results suggest that it is possible to personalize transfemoral prosthesis control for improved temporal-spatial gait symmetry. However, adjusting prosthesis mechanics alone was insufficient to maximize the gait symmetry. Rather, achieving gait symmetry may require coordination between the wearer's motor control of the intact limb and adaptive control of the prosthetic joints. The results also indicated that the RL-based prosthesis tuning system was a potential tool for studying wearer-prosthesis interactions.

Asymmetrical gait kinematics of free-ranging callitrichine primates in response to changes in substrate diameter and orientation.

Arboreal environments present considerable biomechanical challenges for animals moving and foraging among substrates varying in diameter, orientation and compliance. Most studies of quadrupedal gait kinematics in primates and other arboreal mammals have focused on symmetrical walking gaits and the significance of diagonal sequence gaits. Considerably less research has examined asymmetrical gaits, despite their prevalence in small-bodied arboreal taxa. Here, we examined whether and how free-ranging callitrichine primates adjust asymmetrical gait kinematics to changes in substrate diameter and orientation, as well as how variation in gait kinematics affects substrate displacement. We used high-speed video to film free-ranging Saguinus tripartitus and Cebuella pygmaea inhabiting the Tiputini Biodiversity Station, Ecuador. We found that S. tripartitus used bounding and half-bounding gaits on larger substrates versus gallops and symmetrical gaits on smaller substrates, and also shifted several kinematic parameters consistent with attenuating forces transferred from the animal to the substrate. Similarly, C. pygmaea shifted from high-impact bounding gaits on larger substrates to using more half-bounding gaits on smaller substrates; however, kinematic adjustments to substrate diameter were not as profound as in S. tripartitus Both species adjusted gait kinematics to changes in substrate orientation; however, gait kinematics did not significantly affect empirical measures of substrate displacement in either species. Because of their small body size, claw-like nails and reduced grasping capabilities, callitrichines arguably represent extant biomechanical analogs for an early stage in primate evolution. As such, greater attention should be placed on understanding asymmetrical gait dynamics for insight into hypotheses concerning early primate locomotor evolution. .

Divergent evolution of terrestrial locomotor abilities in extant Crocodylia

Extant Crocodylia are exceptional because they employ almost the full range of quadrupedal footfall patterns (“gaits”) used by mammals; including asymmetrical gaits such as galloping and bounding. Perhaps this capacity evolved in stem Crocodylomorpha, during the Triassic when taxa were smaller, terrestrial, and long-legged. However, confusion about which Crocodylia use asymmetrical gaits and why persists, impeding reconstructions of locomotor evolution. Our experimental gait analysis of locomotor kinematics across 42 individuals from 15 species of Crocodylia obtained 184 data points for a wide velocity range (0.15–4.35 ms−1). Our results suggest either that asymmetrical gaits are ancestral for Crocodylia and lost in the alligator lineage, or that asymmetrical gaits evolved within Crocodylia at the base of the crocodile line. Regardless, we recorded usage of asymmetrical gaits in 7 species of Crocodyloidea (crocodiles); including novel documentation of these behaviours in 5 species (3 critically endangered). Larger Crocodylia use relatively less extreme gait kinematics consistent with steeply decreasing athletic ability with size. We found differences between asymmetrical and symmetrical gaits in Crocodylia: asymmetrical gaits involved greater size-normalized stride frequencies and smaller duty factors (relative ground contact times), consistent with increased mechanical demands. Remarkably, these gaits did not differ in maximal velocities obtained: whether in Alligatoroidea or Crocodyloidea, trotting or bounding achieved similar velocities, revealing that the alligator lineage is capable of hitherto unappreciated extreme locomotor performance despite a lack of asymmetrical gait usage. Hence asymmetrical gaits have benefits other than velocity capacity that explain their prevalence in Crocodyloidea and absence in Alligatoroidea—and their broader evolution.

Effects of extended stance time on a powered knee prosthesis and gait symmetry on the lateral control of balance during walking in individuals with unilateral amputation

BackgroundIndividuals with lower limb amputation commonly exhibit large gait asymmetries that are associated with secondary health issues. It has been shown that they are capable of attaining improved temporal and propulsive symmetry when walking with a powered knee prosthesis and visual feedback, but they perceive this pattern of gait to be more difficult. Rather than improving the efficiency of gait, improved gait symmetry may be increasing individuals’ effort associated with maintaining lateral balance.MethodsIn this study, we used a simple visual feedback paradigm to increase the prosthesis-side stance time of six individuals with unilateral TFA or KD as they walked on a powered knee prosthesis at their self-selected speed. As they walked more symmetrically, we evaluated changes in medial-lateral center-of-mass excursion, lateral margin of stability, stride width, and hip abductor activity.ResultsAs the subjects increased their prosthesis-side stance time, their center-of-mass excursion and hip abductor activity significantly increased, while their lateral margin of stability significantly decreased on the prosthesis-side only. Stride width remained relatively unchanged with testing condition.ConclusionsExtended stance time on a powered knee prosthesis (yielding more symmetric gait) challenged the lateral balance of individuals with lower limb amputation. Lateral stability may be a reason they prefer an asymmetric gait, even with more advanced technology. Hip muscular changes post-amputation may contribute to the decline in stability on the prosthesis side. Interventions and advancements in prosthesis control aimed at improving their control of lateral balance may ameliorate the difficulty in walking with improved gait symmetry.

The gaits of marsupials and the evolution of diagonal-sequence walking in primates.

Documenting the variety of quadrupedal walking gaits in a variety of marsupials (arboreal vs. terrestrial, with and without grasping hind feet), to aid in developing and refining a general theory of gait evolution in primates. Video records of koalas, ringtail possums, tree kangaroos, sugar gliders, squirrel gliders, wombats, numbats, quolls, a thylacine, and an opossum walking on a variety of substrates were made and analyzed to derive duty factors and diagonalities for symmetrical walking gaits. The resulting distributions of data points were compared with published data and theories. Terrestrial marsupials' gaits overwhelmingly plot slightly below the theoretical "horse line" (Cartmill et al., Zoological Journal of the Linnean Society. 2002;136:401-420) typical of terrestrial mammals; arboreal marsupials' gaits overwhelmingly plot more decisively above it. Both distributions are roughly parallel to the horse line, but arboreal animals exhibit increased diagonality, so that their higher-speed walking gaits overlap with those of typical primates on the Hildebrand diagram of diagonality against duty factor. Quadrupeds avoid gaits lying exactly on the (theoretically optimum) horse line, to avoid fore/hind limb interference ("forging"). This can be accomplished by either a slight reduction in diagonality ("downshifting") or a more decisive increase ("upshifting"). Tree-dwellers adopt the second option to eliminate unilateral bipods of support from the gait cycle. The upshifted horse line represents an early phase in the evolution of primate-like diagonal-sequence gaits.

Gait after Birmingham Hip Resurfacing: an age-matched controlled prospective study.

AimsThe aim of this study was to assess the functional gain achieved following hip resurfacing arthroplasty (HRA).Patients and MethodsA total of 28 patients (23 male, five female; mean age, 56 years (25 to 73)) awaiting Birmingham HRA volunteered for this prospective gait study, with an age-matched control group of 26 healthy adults (16 male, ten female; mean age, 56 years (33 to 84)). The Oxford Hip Score (OHS) and gait analysis using an instrumented treadmill were used preoperatively and more than two years postoperatively to measure the functional change attributable to the intervention.ResultsThe mean OHS improved significantly from 27 to 46 points (p < 0.001) at a mean of 29 months (12 to 60) after HRA. The mean metal ion levels at a mean 32 months (13 to 60) postoperatively were 1.71 (0.77 to 4.83) µg/l (ppb) and 1.77 (0.68 to 4.16) µg/l (ppb) for cobalt and chromium, respectively. When compared with healthy controls, preoperative patients overloaded the contralateral good hip, limping significantly. After HRA, patients walked at high speeds, with symmetrical gait, statistically indistinguishable from healthy controls over almost all characteristics. The control group could only be distinguished by an increased push-off force at higher speeds, which may reflect the operative approach.ConclusionPatients undergoing HRA improved their preoperative gait pattern of a significant limp to a symmetrical gait at high speeds and on inclines, almost indistinguishable from normal controls. HRA with an approved device offers substantial functional gains, almost indistinguishable from healthy controls.Cite this article: Bone Joint J 2019;101-B:1423–1430.

Cognitive profile of patients with manganese-methcathinone encephalopathy

Manganese-methcathinone encephalopathy (MME) is a rare parkinsonian syndrome described in drug addicts who have self-injected a home-made mixture containing methcathinone and manganese. We assessed 14 patients with MME and compared their results with 14 matched control subjects. The patients had a parkinsonian syndrome with symmetrical bradykinesia, dystonias, and postural, gait and speech impairment, with moderate restrictions in activities of daily living. Their cognitive status was assessed with the Russian version of the Wechsler Adult Intelligence Scale (WAIS) and with tests of attention (Trail Making Test, Bourdon-Wiersma Dot Cancellation Test), memory (Auditory Verbal Learning Test, Rey-Osterrieth Complex Figure), motor skills (Grooved Pegboard), visuospatial skills (Money Road Map Test, Benton Judgment of Line Orientation), and executive abilities (Verbal Fluency, 5-Point Test, Wisconsin Card Sorting Test). Only a few significant differences emerged. After controlling for multiple comparisons, the results in the WAIS Object Assembly subtest, the Grooved Pegboard test (dominant and nondominant hand) and the Verbal Fluency test remained significant.

Effect of ankle-foot orthosis on level walking in healthy subjects.

An ankle-foot orthosis is often prescribed in the rehabilitation of patients with neurological motor disorders such as hemiparesis. However, walking with a unilateral ankle-foot orthosis may not be effectively achieved just by trying to reproduce normal intact walking with a symmetrical gait pattern. Understanding skills to facilitate walking gait with a unilateral ankle-foot orthosis has implications for better rehabilitative interventions to help restore walking ability in patients with stroke. We, therefore, analyzed the kinematics and ground reaction forces of walking with and without an ankle-foot orthosis in healthy subjects to infer the possible skills to facilitate walking gait with a unilateral ankle-foot orthosis. Adult male participants were asked to walk with and without an ankle-foot orthosis across two force platforms set in a wooden walkway, and body kinematics and ground reaction force profiles in the sagittal plane were simultaneously recorded. We found that the forward tilting angle of the trunk at the time of toe-off of the leg with the ankle-foot orthosis was significantly larger than that of the leg without the ankle-foot orthosis, to adaptively compensate for the loss of ankle joint mobility due to the unilateral ankle-foot orthosis. Furthermore, the peak vertical ground reaction force at heel-contact was significantly larger in the leg without the ankle-foot orthosis than in the leg with the ankle-foot orthosis owing to the fact that the stance phase duration of the leg with the ankle-foot orthosis was relatively shorter. Such information may potentially be applied to facilitate walking training in stroke patients wearing a unilateral ankle-foot orthosis.

The Effects of Short-Term Wearing of Customized 3D Printed Single-Sided Lateral Wedge Insoles on Lower Limbs in Healthy Males: A Randomized Controlled Trial.

BackgroundUnbalanced standing and gait asymmetry are common in individuals with musculoskeletal disorders. Achieving symmetrical posture and gait is an important goal of rehabilitation. This study investigated the biomechanical differences in the lower extremities observed immediately after an insole was used and without the use of different one-sided insoles.Material/MethodsThirty young, healthy adult males received 3 different insole interventions: experimental group A had a customized 3-dimensional (3D)-printed single-sided lateral wedge insole (CLWI) inserted on the left side, and experimental group B had on the left side, a traditional single insert. The control had unilateral flat insoles; no insole inserted into the socks. Motion mechanics and gait parameters were collected at the 2-time points, after insertion of the insole and after 20 minutes of walking with the insole.ResultsAsymmetric posture and gait appeared immediately after using the 2 insoles (lower joint moment, P<0.05). Compared with the control group, the abnormal posture and gait of experimental group B after wearing the traditional insole for 20 minutes were not obvious (P>0.05). However, the asymmetrical posture and gait remained in experimental group A after wearing the CLWI for 20 minutes (P<0.05). The center of pressure (COP) trajectory of the left foot of experimental group A was significantly higher than that of experimental group B and the control group at the 2-time points (P<0.05).ConclusionsThe asymmetry of posture and gait can be observed in a short time using a customized 3D-printed single-sided lateral wedge insole. This experiment provides guidance for the application of customized 3D-printed single-sided lateral wedge insoles for gait rehabilitation.

The effects of natural substrate discontinuities on the quadrupedal gait kinematics of free‐ranging Saimiri sciureus

Wild primates encounter complex matrices of substrates that differ in size, orientation, height, and compliance, and often move on multiple, discontinuous substrates within a single bout of locomotion. Our current understanding of primate gait is limited by artificial laboratory settings in which primate quadrupedal gait has primarily been studied. This study analyzes wild Saimiri sciureus (common squirrel monkey) gait on discontinuous substrates to capture the realistic effects of the complex arboreal habitat on walking kinematics. We collected high-speed video footage at Tiputini Biodiversity Station, Ecuador between August and October 2017. Overall, the squirrel monkeys used more asymmetrical walking gaits than symmetrical gaits, and specifically asymmetrical lateral sequence walking gaits when moving across discontinuous substrates. When individuals used symmetrical gaits, they used diagonal sequence gaits more than lateral sequence gaits. In addition, individuals were more likely to change their footfall sequence during strides on discontinuous substrates. Squirrel monkeys increased the time lag between touchdowns both of ipsilaterally paired limbs (pair lag) and of the paired forelimbs (forelimb lag) when walking across discontinuous substrates compared to continuous substrates. Results indicate that gait flexibility and the ability to alter footfall patterns during quadrupedal walking may be critical for primates to safely move in their complex arboreal habitats. Notably, wild squirrel monkey quadrupedalism is diverse and flexible with high proportions of asymmetrical walking. Studying kinematics in the wild is critical for understanding the complexity of primate quadrupedalism.

Bilateral temporal control determines mediolateral margins of stability in symmetric and asymmetric human walking

Human bipedal gait requires active control of mediolateral dynamic balance to stay upright. The margin of stability is considered a measure of dynamic balance, and larger margins are by many authors assumed to reflect better balance control. The inverted pendulum model of gait indicates that changes in the mediolateral margin of stability are related to changes in bilateral single support times. We propose updated equations for the mediolateral margin of stability in temporally symmetric and asymmetric gait, which now include the single support times of both legs. Based on these equations, we study the relation between bilateral single support times and the mediolateral margin of stability in symmetric, asymmetric, and adaptive human gait. In all conditions, the mediolateral margin of stability during walking followed predictably from bilateral single support times, whereas foot placement co-varied less with the mediolateral margin of stability. Overall, these results demonstrate that the bilateral temporal regulation of gait profoundly affects the mediolateral margin of stability. By exploiting the passive dynamics of bipedal gait, bilateral temporal control may be an efficient mechanism to safeguard dynamic stability during walking, and keep an inherently unstable moving human body upright.

Search algorithm for optimal damping parameters of transfemoral prosthetic limb

• A mathematical model to bring symmetry in knee joints angle trajectories. • A comparison between grid search and optimization is reported. • Damping adjustment of microprocessor based prosthetic knee joint with minimum effort. • An automated and time-efficient method for adjusting damper's parameter. In this paper, we developed a mathematical model to find the parameters of prosthetic damper which will provide a similar trajectory for the prosthetic knee joint. Two popular searching methods namely grid searching and optimization are used to determine the damper's parameters. The proposed model is validated with a simulation process using the data of the able-body individuals. We utilized the ground reaction force of sound limb to determine the values of the damper parameters of a prosthetic knee joint for maximum symmetry. Symmetry between knee moments was also improved in the stance period with optimized parameters. Finally, optimization-based searching was observed to be more computationally efficient than the grid-based searching method. The present study will provide a virtual solution to set the prosthetic dampers parameters based on user needs. In the future, the present method can be used for adjusting damping of microprocessor prosthetic knee joint for symmetrical gait pattern.

Dual Mode Gait Sonification for Rehabilitation After Unilateral Hip Arthroplasty

The pattern of gait after hip arthroplasty strongly affects regeneration and quality of life. Acoustic feedback could be a supportive method for patients to improve their walking ability and to regain a symmetric and steady gait. In this study, a new gait sonification method with two different modes—real-time feedback (RTF) and instructive model sequences (IMS)—is presented. The impact of the method on gait symmetry and steadiness of 20 hip arthroplasty patients was investigated. Patients were either assigned to a sonification group (SG) (n = 10) or a control group (CG) (n = 10). All of them performed 10 gait training sessions (TS) lasting 20 min, in which kinematic data were measured using an inertial sensor system. Results demonstrate converging step lengths of the affected and unaffected leg over time in SG compared with a nearly parallel development of both legs in CG. Within the SG, a higher variability of stride length and stride time was found during the RTF training mode in comparison to the IMS mode. Therefore, the presented dual mode method provides the potential to support gait rehabilitation as well as home-based gait training of orthopedic patients with various restrictions.

Place and Possibilities of the Robotic System Lokomat in the Rehabilitation of Patients After Ischemic Stroke

Ischemic stroke is still a very common disease with quite serious consequences. Modern medicine considers in this regard its main task in the curation of such patients, the maximum possible restoration of the functions of the affected brain and the volume of its control over the body. Due to the rapid development of medicine associated with the emergence of innovative technologies in the field of rehabilitation, hardware methods of rehabilitation today have gone far ahead and have in their arsenal a lot of high-tech tools. For this purpose, a search is being made for means of increasing the activity of brain cells located in the affected area. Of particular importance in this regard are the methods of rehabilitation in the early recovery period after ischemic stroke using robotic methods of mechanotherapy, one of which is the use of the Lokomat system. Among them, a prominent place is occupied by the walking training system - Lokomat, consisting of robotic orthoses and a body support device, which are combined with a treadmill. Information about the successful use of Lokomat during the rehabilitation of patients with movement disorders is still scattered, and this required their generalization and understanding. The main advantage of this system is the ability to effectively control and ensure high intensity, repeatability (reproducibility) and purposefulness of the trained movements. The convincing advantages of automated training on the Lokomat system compared to traditional rehabilitation in terms of various clinical indicators in patients with post-stroke hemiparesis have been identified. It was shown that in patients trained on the Lokomat system, a single support on the paretic leg intensified, which contributed to a more symmetrical gait. This system is more than other devices and technologies designed for learning to walk, in line with the modern approach to the restoration of impaired motor functions. The inclusion of training sessions on the Lokomat robotic system in the comprehensive treatment of patients with post-stroke hemiparesis leads to a marked improvement in movement skills. This is associated with a pronounced restructuring against the background of its use of the motor stereotype of walking, which makes it possible to increase the effectiveness of recreational activities in post-stroke patients.