scholarly journals Neuromusculoskeletal simulation reveals abnormal rectus femoris-gluteus medius reflex coupling in post-stroke gait

2018 ◽  
Author(s):  
Tunc Akbas ◽  
Richard R. Neptune ◽  
James Sulzer
Keyword(s):  
Knee Flexion ◽  
Latency Period ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Coordination Pattern ◽  
Healthy Controls ◽  
Post Stroke ◽  
Reflex Latency ◽  
Stiff Knee ◽  
Muscle Activations

ABSTRACTPost-stroke gait is often accompanied by muscle impairments that result in adaptations such as hip circumduction to compensate for lack of knee flexion. Our previous work robotically enhanced knee flexion in individuals post-stroke with Stiff-Knee Gait (SKG), however, this resulted in greater circumduction, suggesting the existence of abnormal coordination in SKG. The purpose of this work is to investigate two possible mechanisms of the abnormal coordination: 1) an involuntary coupling between stretched quadriceps and abductors, and 2) a coupling between volitionally activated knee flexors and abductors. We used previously collected kinematic, kinetic and EMG measures from nine participants with chronic stroke and five healthy controls during walking with and without the applied knee flexion torque perturbations in the pre-swing phase of gait in the neuromusculoskeletal simulation. The measured muscle activity was supplemented by simulated muscle activations to estimate the muscle states of the quadriceps, hamstrings and hip abductors. We used linear mixed models to investigate two hypotheses: H1) association between quadriceps and abductor activation during an involuntary period (reflex latency) following the perturbation and H2) association between hamstrings and abductor activation after the perturbation was removed. We observed significantly higher rectus femoris (RF) activation in stroke participants compared to healthy controls within the reflex latency period following the perturbation based on both measured (H1, p < 0.001) and simulated (H1, p = 0.022) activity. Simulated RF and gluteus medius (GMed) activations were correlated only in those with SKG, which was significantly higher compared to healthy controls (H1, p = 0.030). There was no evidence of voluntary synergistic coupling between any combination of hamstrings and hip abductors (H2, p > 0.05) when the perturbation was removed. The RF-GMed coupling suggests an underlying abnormal reflex coordination pattern in post-stroke SKG. These results challenge earlier assumptions that hip circumduction in stroke is simply a kinematic adaptation due to reduced toe clearance. Instead, abnormal coordination may underlie circumduction, illustrating the deleterious role of abnormal coordination in post-stroke gait.

scholarly journals Rectus femoris hyperreflexia predicts knee flexion angle in Stiff-Knee gait after stroke

2019 ◽  
Author(s):  
Tunc Akbas ◽  
Kyoungsoon Kim ◽  
Kathleen Doyle ◽  
Kathleen Manella ◽  
Robert Lee ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Rectus Femoris ◽  
H Reflex ◽  
Flexion Angle ◽  
Reflex Modulation ◽  
Knee Flexion Angle ◽  
Healthy Individuals ◽  
Reflex Amplitude ◽  
Post Stroke ◽  
Stiff Knee

AbstractStiff-knee gait (SKG) after stroke is often accompanied by decreased knee flexion angle during the swing phase. The decreased knee flexion has been hypothesized to originate from excessive quadriceps activation. However, it is unclear whether this activation is due to poor timing or hyperreflexia, both common post-stroke impairments. The goal of this study was to investigate the relation between quadriceps hyperreflexia in post-stroke SKG with knee flexion angle during walking. The rectus femoris (RF) H-reflex was recorded in eleven participants with post-stroke SKG and ten healthy controls during standing and walking during toe-off. In order to separate the effects of poorly timed quadriceps muscle activation from hyperreflexia, healthy individuals voluntarily increased quadriceps activity using RF electromyographic (EMG) biofeedback during standing and pre-swing upon H-reflex stimulation. We observed a negative correlation (R = −0.92, p=0.001) between knee flexion angle and RF H-reflexes in post-stroke SKG. In contrast, H-reflex amplitude in healthy individuals in presence (R = 0.47, p = 0.23) or absence (R = −0.17, p = 0.46) of increased RF activity had no correlation with knee flexion angle. The RF H-reflex amplitude differed between standing and walking in healthy individuals, including when RF activity was increased voluntarily (d = 2.86, p = 0.007), but was not observed post-stroke (d =0.73, p = 0.296). Thus, RF reflex modulation is impaired in post-stroke SKG. Further, RF hyperreflexia, as opposed to overactivity, may play a role in knee flexion kinematics in post-stroke SKG. Interventions targeting self-regulated quadriceps hyperreflexia may be effective in promoting better neural control of the knee joint and thus better quality of walking post-stroke.

scholarly journals Muscle Contributions to Pre-Swing Biomechanical Tasks Influence Swing Leg Mechanics in Individuals Post-Stroke during Walking

2021 ◽  
Author(s):  
Lydia G. Brough ◽  
Steven A. Kautz ◽  
Richard Neptune
Keyword(s):  
Knee Flexion ◽  
Rectus Femoris ◽  
Compensatory Mechanisms ◽  
Dynamic Simulations ◽  
Post Stroke ◽  
Rehabilitation Outcomes ◽  
Stroke Population ◽  
Musculoskeletal Models ◽  
Peak Knee ◽  
Stiff Knee

Abstract Background Successful walking requires the execution of the pre-swing biomechanical tasks of body propulsion and leg swing initiation, which are often impaired post-stroke. While excess rectus femoris activity during swing is often associated with low knee flexion, previous work has suggested that deficits in propulsion and leg swing initiation may also contribute. The purpose of this study was to determine underlying causes of propulsion, leg swing initiation and knee flexion deficits in pre-swing and their link to stiff knee gait in stroke survivors. Methods Musculoskeletal models and forward dynamic simulations were developed for individuals post-stroke (n=15) and neurotypical participants (n=5). Linear regressions were used to evaluate the relationships between peak knee flexion, braking and propulsion symmetry, and individual muscle contributions to braking, propulsion, knee flexion in pre-swing, and leg swing initiation. Results 27% of individuals post-stroke had higher plantarflexor contributions to propulsion and 47% had higher vasti contributions to braking on their paretic leg relative to their nonparetic leg. Higher gastrocnemius contributions to propulsion were correlated to paretic propulsion symmetry (p=0.005) while soleus contributions were not. Higher vasti contributions to braking in pre-swing predicted lower knee flexion (p=0.022). The rectus femoris and iliopsoas did not directly contribute to lower knee flexion acceleration in pre-swing compared to contributions from the vasti. However, for some individuals with low knee flexion, during pre-swing the rectus femoris absorbed more power and the iliopsoas contributed less power to the paretic leg. Total muscle-tendon work done on the paretic leg in pre-swing was not correlated to knee flexion during swing. Conclusions These results emphasize the multiple causes of propulsion asymmetry in individuals post-stroke, including low plantarflexor contributions to propulsion, increased vasti contributions to braking and reliance on compensatory mechanisms. The results also show that the rectus femoris is not a major contributor to knee flexion in pre-swing, but absorbs more power from the paretic leg in pre-swing in some individuals with stiff knee gait. These results further highlight the heterogeneity of the post-stroke population and the need to identify individual causes of propulsion and knee flexion deficits to improve rehabilitation outcomes.

Effectiveness of botulinum toxin in rectus femoris in patients post-stroke with stiff-knee gait

2013 ◽  
Vol 37 ◽  
pp. S1-S2
Author(s):  
M. Bacchini ◽  
C. Rovacchi ◽  
F. Chiampo ◽  
M. Rossi
Keyword(s):  
Botulinum Toxin ◽  
Rectus Femoris ◽  
Post Stroke ◽  
Stiff Knee

scholarly journals Can non-disabled adults reproduce the stiff-knee gait of individuals with stroke?

2020 ◽  
Author(s):  
Odair Bacca ◽  
Melissa Celestino ◽  
José Barela ◽  
Anna Lima ◽  
Ana Barela
Keyword(s):  
Lower Limb ◽  
Knee Flexion ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Gait Pattern ◽  
Activation Level ◽  
Stiff Knee ◽  
Mechanical Constraint ◽  
Disabled Adults

AbstractThis study investigated whether a mechanical constraint of knee flexion in non-disabled individuals could help with reproducing the gait pattern of individuals with stroke. Eleven non-disabled adults (26.6±6.5 years old) and 12 individuals with stroke (52.0±12.8 years old) walked at a self-selected comfortable speed as kinematic and electromyographic data were acquired. Non-disabled adults also walked with an orthosis that limited to 45 degrees of knee flexion. The hip, knee, and ankle joint angles and the muscle activation of the rectus femoris, vastus medialis and lateralis, tibialis anterior, semitendinosus, biceps femoris, and gastrocnemius medialis and lateralis were analyzed. The results demonstrated that non-disabled adults presented similar lower limb excursion to individuals with stroke that affects most joints, although, they displayed a different muscle activation level for most muscles. These results suggest that a mechanical constraint of knee flexion leads to temporal and joint excursion alterations in the lower limb of non-disabled individuals, thereby enabling the reproduction of a gait pattern similar to individuals with stroke. It is also observed that these individuals use different strategies to control muscle activation, which might be related to the lack of control in coordinating muscle activation during gait that is present in individuals with stroke.

scholarly journals Hip circumduction is not a compensation for reduced knee flexion angle during gait

2019 ◽  
Author(s):  
Tunc Akbas ◽  
Sunil Prajapati ◽  
David Ziemnicki ◽  
Poornima Tamma ◽  
Sarah Gross ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Frontal Plane ◽  
Pelvic Obliquity ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
Compensatory Mechanisms ◽  
Ankle Foot Orthosis ◽  
Post Stroke ◽  
Hip Abduction ◽  
Stiff Knee

AbstractIt has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction significantly increased pelvic obliquity (2.79°, p<0.01) compared to unrestricted walking (1.5°, p<0.01), but similar to post-stroke SKG (3.4°). However, those with post-stroke SKG had significantly greater hip abduction (8.2°) compared to unimpaired individuals with restricted knee flexion (4.2°, p<0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.

scholarly journals Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

2021 ◽  
Vol 2 ◽  
Author(s):  
Rand Hidayah ◽  
Dongbao Sui ◽  
Kennedi A. Wade ◽  
Biing-Chwen Chang ◽  
Sunil Agrawal
Keyword(s):  
Outcome Measures ◽  
Muscle Activation ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Lower Limbs ◽  
Flexion Angle ◽  
Coil Spring ◽  
Foot Pressure ◽  
Low Profile ◽  
Muscle Activations

Abstract Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

scholarly journals Healthy subjects with lax knees use less knee flexion rather than muscle control to limit anterior tibia translation during landing

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Michèle N. J. Keizer ◽  
Juha M. Hijmans ◽  
Alli Gokeler ◽  
Anne Benjaminse ◽  
Egbert Otten
Keyword(s):  
Knee Flexion ◽  
Muscle Activation ◽  
Reaction Force ◽  
Rectus Femoris ◽  
Knee Laxity ◽  
Biceps Femoris ◽  
Level Of Evidence ◽  
Jump Landing ◽  
Muscle Activation Patterns ◽  
Healthy Participants

Abstract Purpose It has been reported that there is no correlation between anterior tibia translation (ATT) in passive and dynamic situations. Passive ATT (ATTp) may be different to dynamic ATT (ATTd) due to muscle activation patterns. This study aimed to investigate whether muscle activation during jumping can control ATT in healthy participants. Methods ATTp of twenty-one healthy participants was measured using a KT-1000 arthrometer. All participants performed single leg hops for distance during which ATTd, knee flexion angles and knee flexion moments were measured using a 3D motion capture system. During both tests, sEMG signals were recorded. Results A negative correlation was found between ATTp and the maximal ATTd (r = − 0.47, p = 0.028). An N-Way ANOVA showed that larger semitendinosus activity was seen when ATTd was larger, while less biceps femoris activity and rectus femoris activity were seen. Moreover, larger knee extension moment, knee flexion angle and ground reaction force in the anterior-posterior direction were seen when ATTd was larger. Conclusion Participants with more ATTp showed smaller ATTd during jump landing. Muscle activation did not contribute to reduce ATTd during impact of a jump-landing at the observed knee angles. However, subjects with large ATTp landed with less knee flexion and consequently showed less ATTd. The results of this study give information on how healthy people control knee laxity during jump-landing. Level of evidence III

Center of Pressure Trajectory and Spatiotemporal Gait Parameters When Walking with Limited Knee Flexion

2021 ◽  
Vol 65 (1) ◽  
pp. 1490-1493
Author(s):  
Seobin Choi ◽  
Jieon Lee ◽  
Gwanseob Shin
Keyword(s):  
Knee Flexion ◽  
Stance Phase ◽  
Center Of Pressure ◽  
Dynamic Balance ◽  
Left Knee ◽  
Step Width ◽  
Normal Walking ◽  
Gait Stability ◽  
Gait Parameters ◽  
Stiff Knee

Stiff-knee, which indicates reduced range of knee flexion, may decrease gait stability. Although it is closely related to an increase in fall risk, the effect of limited knee flexion on the balance capacity during walking has not been well studied. This study aimed at examining how walking with limited knee flexion would influence the center of pressure (COP) trajectory and spatiotemporal gait parameters. Sixteen healthy young participants conducted four different walking conditions: normal walking and walking with limited knee flexion of their left knee up to 40 and 20 degrees, respectively. Results show that the participants walked significantly (p<0.05) slower with shorter stride length, wider step width, less cadence, and decreased stance phase when walking with limited knee flexion, compared to normal walking. The increase in the asymmetry and variability of the COP was also observed. It indicates that limited knee flexion during walking might affect the dynamic balance.

Abstract W P140: Post-stroke Oculomotor Abnormalities evident during Objective Eye Tracking but Not under Clinical Assessment

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
John-Ross Rizzo ◽  
Todd Hudson ◽  
Briana Kowal ◽  
Michal Wiseman ◽  
Preeti Raghavan
Keyword(s):  
Motor Control ◽  
Eye Movements ◽  
Eye Movement ◽  
Oculomotor Control ◽  
Healthy Controls ◽  
Visually Guided ◽  
Stroke Patients ◽  
Movement Execution ◽  
Post Stroke ◽  
Control Post

Introduction: Visual abnormalities and manual motor control have been studied extensively after stroke, but an understanding of oculomotor control post-stroke has not. Recent studies have revealed that in visually guided reaches arm movements are planned during eye movement execution, which may contribute to increased task complexity. In fact, in healthy controls during visually guided reaches, the onset of eye movement is delayed, its velocity reduced, and endpoint errors are larger relative to isolated eye movements. Our objective in this experiment was to examine the temporal properties of eye movement execution for stroke patients with no diagnosed visual impairment. The goal is to improve understanding of oculomotor control in stroke relative to normal function, and ultimately further understand its coordination with manual motor control during joint eye and hand movements. We hypothesized that stroke patients would show abnormal initiation or onset latency for saccades made in an eye movement task, as compared to healthy controls. Methods: We measured the kinematics of eye movements during point-to-point saccades; there was an initial static, fixation point and the stimulus was a flashed target on a computer monitor. We used a video-based eye tracker for objective recording of the eye at a sampling frequency of 2000 Hz (SR Research, Eyelink). 10 stroke subjects, over 4 months from injury and with no diagnosed visual impairment, and 10 healthy controls completed 432 saccades in a serial fashion. Results: Stroke patients had significantly faster onset latencies as compared to healthy controls during saccades (99.5ms vs. 245.2ms, p=0.00058). Conclusion: A better understanding of the variations in oculomotor control post-stroke, which may go unnoticed during clinical assessment, may improve understanding of how eye control synchronizes with arm or manual motor control. This knowledge could assist in tailoring rehabilitative strategies to amplify motor recovery. For next steps, we will perform objective eye and hand recordings during visually guided reaches post-stroke to better understand the harmonization or lack thereof after neurologic insult.

Sign in / Sign up

Export Citation Format

Share Document