Direct continuous electromyographic control of a powered prosthetic ankle for improved postural control after guided physical training: A case study

Abstract Despite the promise of powered lower limb prostheses, existing controllers do not assist many daily activities that require continuous control of prosthetic joints according to human states and environments. The objective of this case study was to investigate the feasibility of direct, continuous electromyographic (dEMG) control of a powered ankle prosthesis, combined with physical therapist-guided training, for improved standing postural control in an individual with transtibial amputation. Specifically, EMG signals of the residual antagonistic muscles (i.e. lateral gastrocnemius and tibialis anterior) were used to proportionally drive pneumatical artificial muscles to move a prosthetic ankle. Clinical-based activities were used in the training and evaluation protocol of the control paradigm. We quantified the EMG signals in the bilateral shank muscles as well as measures of postural control and stability. Compared to the participant’s daily passive prosthesis, the dEMG-controlled ankle, combined with the training, yielded improved clinical balance scores and reduced compensation from intact joints. Cross-correlation coefficient of bilateral center of pressure excursions, a metric for quantifying standing postural control, increased to .83(±.07) when using dEMG ankle control (passive device: .39(±.29)). We observed synchronized activation of homologous muscles, rapid improvement in performance on the first day of the training for load transfer tasks, and further improvement in performance across training days (p = .006). This case study showed the feasibility of this dEMG control paradigm of a powered prosthetic ankle to assist postural control. This study lays the foundation for future study to extend these results through the inclusion of more participants and activities.

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Direct Continuous EMG control of a Powered Prosthetic Ankle for Improved Postural Control after Guided Physical Training: a Case Study

10.1101/2020.09.11.293373 ◽

2020 ◽

Author(s):

Aaron Fleming ◽

Stephanie Huang ◽

Elizabeth Buxton ◽

Frank Hodges ◽

He (Helen) Huang

Keyword(s):

Postural Control ◽

Load Transfer ◽

Assessment Tool ◽

Control Method ◽

Physical Therapist ◽

Continuous Control ◽

Rapid Improvement ◽

Transtibial Amputation ◽

Prosthetic Joints

AbstractBackgroundDespite the promise of powered lower limb prostheses, the existing control of these modern devices is insufficient to assist many daily activities, such as postural control while lifting weight, that require continuous control of prosthetic joints according to human states and environments. The objective of this case study was to investigate the feasibility and potential of direct, continuous electromyographic (dEMG) control of a powered ankle prosthesis, combined with physical therapist (PT)-guided training, for improved standing postural control in an individual with transtibial amputation.MethodsA powered prosthetic ankle was directly controlled by EMG signals of the residual lateral gastrocnemius and tibialis anterior muscles. The participant with transtibial amputation received 4-week PT-guided training on posture while using the dEMG control of powered ankle. A subset of activities in the mini-BESTest (a clinical balance assessment tool) were used in the training and evaluation protocol. We quantified EMG signals in the bilateral shank muscles, biomechanics that captures postural control and stability, and score for the clinical balance evaluation.ResultsCompared to the participant’s daily passive prosthesis, the dEMG-controlled ankle, combined with the training, yielded improved clinical balance score and reduced compensation from the intact joints. In addition, cross correlation coefficient of bilateral CoP excursions, a metric for quantifying standing postural control, increased to 0.83(±0.07) when using dEMG ankle control, compared with 0.39(±0.29) when using the passive device. Between-limb coordination was also observed as synchronized activation of homologous muscles in the shank. We witnessed rapid improvement in performance on the first day of the training for load transfer tasks, where bilateral CoP synchronization improvement was significantly related to repetition order (R=0.459, p = 0.045). Finally, the participant further improved this performance significantly across training days.ConclusionThis case study showed the feasibility of dEMG control of powered prosthetic ankle by a transtibial amputee after a PT-guided training to assist postural control. This study’s training protocol and dEMG control method that lays the foundation for future study to extend these results through the inclusion of more participants and activities.

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Recovery Trajectory of Postural Control Impairments Following a Concussion: A Case Study

Journal of Sport Rehabilitation ◽

10.1123/jsr.2018-0440 ◽

2020 ◽

Vol 29 (3) ◽

pp. 346-351

Author(s):

Adam C. King

Keyword(s):

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Recovery Phase ◽

Multiscale Entropy ◽

Single Subject ◽

Healthy Controls ◽

Post Injury ◽

Recovery Trajectory

Context: Altered postural control represents one of the most common motor consequences following a concussion and there is a paucity of data monitoring the recovery trajectory that identifies the persistent changes of postural control. Objective: To determine whether the recovery trajectory of postural control was consistent across different measures of postural stability and whether increased postural challenge (ie, sloped surface) revealed subtle postural impairments. Design: A single-subject case study. Setting: Research laboratory. Patients or Other Participants: One concussed individual with a cohort of healthy controls (n = 10) used for comparison. Main Outcome Measures: Center of pressure variability (linear—SD and nonlinear—multiscale entropy) was used to index postural sway preinjury and at periodic intervals following the concussion. Results: The concussed individuals displayed reduced amounts of sway during the initial recovery phase that failed to returned to preinjury levels but reached the level of healthy controls at 1-month postinjury. The multiscale entropy analysis revealed increased center of pressure irregularity throughout recovery that persisted up to 1-month post injury. Conclusions: The findings identified subtle, persistent postural control impairments revealed through the nonlinear analysis of center of pressure and supports the notion that the consequences of a concussion (ie, impaired postural control) need to be considered beyond the resolution of behavioral symptoms.

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Effect of running exercise with and without the use of equipment Kangoo Jumps, in postural control: a case study.

Manual Therapy Posturology & Rehabilitation Journal ◽

10.17784/mtprehabjournal.2014.12.179 ◽

2014 ◽

Vol 12 ◽

pp. 179 ◽

Cited By ~ 1

Author(s):

Rodrigo Franco De Oliveira ◽

Priscila Daniele De Oliveira ◽

Stheace Kelly Fernandes Szezerbaty ◽

Laís Campos De Oliveira ◽

Juliana Serpeloni De Almeida ◽

...

Keyword(s):

Postural Control ◽

Postural Balance ◽

Postural Stability ◽

Center Of Pressure ◽

Submaximal Exercise ◽

Running Exercise ◽

Before And After ◽

Control Objective ◽

Swing Speed

Introduction: There is increasing interest from the general population, the search for the most suitable and safe exercise programs. Some equipment, such as Kangoo Jumps (KJ), allow performing exercises with less impact on the joints, and probably infer on postural control. Objective: To investigate the effect of exercise submaximal exercise running with and without the use of equipment KJ on postural control variables. Method: Participated in the study with an individual 20 years old, male, equivalent to 86kg body weight. The test was to evaluate the postural balance using a force platform with bipedal before and after conventional and adapted from Cooper (using the KJ) test support. The equilibrium parameters were recorded: (A- COP in cm2) of displacement of the center of pressure; average swing speed of the COP (MVeloc in cm/s) in the anteroposterior planes (A/P) and medial-lateral (M/L). Results: The results showed that after using the equipment KJ, A-COP (-39.70%) MVeloc the A/P (-20.66%) and M/L (-20.48%) were best compared with the race without using KJ test. Conclusion: It is concluded that after running exercise on submaximal exercise with the use of equipment KJ had become favorable outcome for postural balance. One such reason would be because of its system of absorption and dissipation of impact, which allows a better activation of the proprioceptive system through increasing the speed of afferent estimate. The intervention of this study shows that the use of the KJ has significant equipment to maintain postural stability near control values benefits. However, further studies are needed, due to lack of evidence of the parameters of this equipment and the small number in our sample.

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“Going Backward”: Effects of age and fatigue on posterior-directed falls in Parkinson disease

Neurorehabilitation ◽

10.3233/nre-210040 ◽

2021 ◽

pp. 1-9

Author(s):

Evan V. Papa ◽

Rita M. Patterson ◽

Nicoleta Bugnariu

Keyword(s):

Postural Control ◽

Parkinson Disease ◽

Repeated Measures ◽

Center Of Pressure ◽

Angular Displacement ◽

Reaction Times ◽

Older Individuals ◽

Peak Knee ◽

Significant Difference ◽

Fatiguing Exercise

BACKGROUND: Nearly half of persons with Parkinson disease (PD) report fatigue as a factor in their fall history. However, it is unknown whether these self-reported falls are caused by a sensation of fatigue or performance fatigue. OBJECTIVE: We sought to investigate the influences of performance fatigue and age on postural control in persons with PD. METHODS: Individuals with PD (n = 14) underwent postural control assessments before (T0) and immediately after (T1) fatiguing exercise. Biomechanical data were gathered on participants completing a treadmill-induced, posterior-directed fall. Performance fatigue was produced using lower extremity resistance exercise on an isokinetic ergometer. Repeated measures ANCOVAs were used with age as a covariate to determine the effects of performance fatigue on biomechanical variables. RESULTS: After adjustment for age, there was a statistically significant difference in peak center of pressure (COP) latency during the support phase of recovery. Pairwise comparisons demonstrated a decrease in peak ankle displacement from T0 to T1. Age was also found to be significantly related to reaction time and peak knee displacement while participants were fatigued. CONCLUSIONS: The decreased peak COP latency, along with decreased ankle angular displacement, suggest that persons with PD adopt a stiffening strategy in response to backward directed falls. Postural stiffening is not uncommon in persons with PD and could be a risk factor for falls. Older individuals with PD demonstrate slower mobility scores and decreased reaction times in the setting of fatigue, suggesting a combined effect of the aging and fatigue processes.

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Postural Control Disturbances Induced by Virtual Reality in Stroke Patients

Applied Sciences ◽

10.3390/app11041510 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1510

Author(s):

Charles Morizio ◽

Maxime Billot ◽

Jean-Christophe Daviet ◽

Stéphane Baudry ◽

Christophe Barbanchon ◽

...

Keyword(s):

Virtual Reality ◽

Postural Control ◽

Virtual Environments ◽

Center Of Pressure ◽

Dynamic Condition ◽

Static Condition ◽

Stroke Patients ◽

Post Stroke ◽

Subacute Stroke

People who survive a stroke are often left with long-term neurologic deficits that induce, among other impairments, balance disorders. While virtual reality (VR) is growing in popularity for postural control rehabilitation in post-stroke patients, studies on the effect of challenging virtual environments, simulating common daily situations on postural control in post-stroke patients, are scarce. This study is a first step to document the postural response of stroke patients to different challenging virtual environments. Five subacute stroke patients and fifteen age-matched healthy adults were included. All participants underwent posturographic tests in control conditions (open and closed eyes) and virtual environment without (one static condition) and with avatars (four dynamic conditions) using a head-mounted device for VR. In dynamic environments, we modulated the density of the virtual crowd (dense and light crowd) and the avoidance space with the avatars (near or far). Center of pressure velocity was collected by trial throughout randomized 30-s periods. Results showed that more challenging conditions (dynamic condition) induced greater postural disturbances in stroke patients than in healthy counterparts. Our study suggests that virtual reality environments should be adjusted in light of obtaining more or less challenging conditions.

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Plantar load transfer in children: a descriptive study with two pathological case studies

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04364-9 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Alexis Brierty ◽

Christopher P. Carty ◽

Claudia Giacomozzi ◽

Teresa Phillips ◽

Henry P. J. Walsh ◽

...

Keyword(s):

Case Studies ◽

Load Transfer ◽

Descriptive Study ◽

Transfer Phase ◽

Gait Symmetry ◽

Plantar Pressures ◽

Gait Asymmetry ◽

Mean Pressure ◽

Pathological Case

Abstract Background Typical gait is often considered to be highly symmetrical, with gait asymmetries typically associated with pathological gait. Whilst gait symmetry is often expressed in symmetry ratios, measures of symmetry do not provide insight into how these asymmetries affect gait variables. To fully understand changes caused by gait asymmetry, we must first develop a normative database for comparison. Therefore, the aim of this study was to describe normative reference values of regional plantar load and present comparisons with two pathological case studies. Methods A descriptive study of the load transfer of plantar pressures in typically developed children was conducted to develop a baseline for comparison of the effects of gait asymmetry in paediatric clinical populations. Plantar load and 3D kinematic data was collected for 17 typically developed participants with a mean age of 9.4 ± 4.0 years. Two case studies were also included; a 10-year-old male with clubfoot and an 8-year-old female with a flatfoot deformity. Data was analysed using a kinematics-pressure integration technique for anatomical masking into 5 regions of interest; medial and lateral forefoot, midfoot, and medial and lateral hindfoot. Results Clear differences between the two case studies and the typical dataset were seen for the load transfer phase of gait. For case study one, lateral bias was seen in the forefoot of the trailing foot across all variables, as well as increases in contact area, force and mean pressure in the lateral hindfoot of the leading foot. For case study two, the forefoot of the trailing foot produced results very similar to the typical dataset across all variables. In the hindfoot of the leading foot, medial bias presents most notably in the force and mean pressure graphs. Conclusions This study highlights the clinical significance of the load transfer phase of gait, providing meaningful information for intervention planning.

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The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18052741 ◽

2021 ◽

Vol 18 (5) ◽

pp. 2741

Author(s):

María del Mar Moreno-Muñoz ◽

Fidel Hita-Contreras ◽

María Dolores Estudillo-Martínez ◽

Agustín Aibar-Almazán ◽

Yolanda Castellote-Caballero ◽

...

Keyword(s):

Postural Control ◽

Muscle Activation ◽

Center Of Pressure ◽

Controlled Trial ◽

Trunk Muscle ◽

Posture Control ◽

Trunk Muscles ◽

Control Group ◽

Female Population ◽

Imaging Results

Background: Abdominal Hypopressive Training (AHT) provides postural improvement, and enhances deep trunk muscle activation. However, until recently, there was a lack of scientific literature supporting these statements. The major purpose of this study was to investigate the effect of AHT on posture control and deep trunk muscle function. Methods: 125 female participants aged 18–60 were randomly allocated to the Experimental Group (EG), consisting of two sessions of 30 min per week for 8 weeks of AHT, or the Control Group (CG), who did not receive any treatment. Postural control was measured with a stabilometric platform to assess the static balance and the activation of deep trunk muscles (specifically the Transverse Abdominal muscle (TrA)), which was measured by real-time ultrasound imaging. Results: The groups were homogeneous at baseline. Statistical differences were identified between both groups after intervention in the Surface of the Center of Pressure (CoP) Open-Eyes (S-OE) (p = 0.001, Cohen’s d = 0.60) and the Velocity of CoP under both conditions; Open-Eyes (V-OE) (p = 0.001, Cohen´s d = 0.63) and Close-Eyes (V-CE) (p = 0.016, Cohen´s d = 0.016), with the EG achieving substantial improvements. Likewise, there were statistically significant differences between measurements over time for the EG on S-OE (p < 0.001, Cohen´s d = 0.99); V-OE (p = 0.038, Cohen´s d = 0.27); V-CE (p = 0.006, Cohen´s d = 0.39), anteroposterior movements of CoP with Open-Eyes (RMSY-OE) (p = 0.038, Cohen´s d = 0.60) and activity of TrA under contraction conditions (p < 0.001, Cohen´s d = 0.53). Conclusions: The application of eight weeks of AHT leads to positive outcomes in posture control, as well as an improvement in the deep trunk muscle contraction in the female population.

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Habitual Physical Activity as a Determinant of the Effect of Moderate Physical Exercise on Postural Control in Older Men

American Journal of Men s Health ◽

10.1177/1557988312460268 ◽

2012 ◽

Vol 7 (1) ◽

pp. 58-65 ◽

Cited By ~ 3

Author(s):

Rafał Stemplewski ◽

Janusz Maciaszek ◽

Maciej Tomczak ◽

Robert Szeklicki ◽

Dorota Sadowska ◽

...

Keyword(s):

Physical Activity ◽

Postural Control ◽

Sagittal Plane ◽

Center Of Pressure ◽

Force Plate ◽

Frontal Plane ◽

Habitual Physical Activity ◽

Similar Reaction ◽

Mean Velocity ◽

Ergometer Exercise

The aim of the study was to compare the effect of exercise on postural control (PC) among the elderly with lower or higher level of habitual physical activity (HPA). The study involved 17 elderly men (mean age 72.9 ± 4.79 years). Mean velocity of the center of pressure (COP) displacements was measured using a force plate both before and after cycle ergometer exercise. A significantly higher increase in mean velocity of COP displacements and its component in the sagittal plane were observed in the group with lower level of HPA in comparison with the group with higher HPA level. Simultaneously, a relatively similar reaction to the exercise in the frontal plane was observed in both groups, possibly connected to the specific type of used exercise, which mainly activated the sagittal muscles.

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