Active Ankle Research Articles

Feasibility of Training a Random Forest Model With Incomplete User-Specific Data for Devising a Control Strategy for Active Biomimetic Ankle.

Intelligent control strategies for active biomimetic prostheses could exploit the inter-joint coordination of limbs in human gait in order to mimic the functioning of a biological joint. A machine learning regression model could be employed to learn an input-output relationship between the coordinated limb motion in human gait and predict the motion of a particular limb/joint given the motion of other limbs/joints. Such a model could be potentially used as a controller for an intelligent prosthesis which aims to restore the functioning similar to an intact biological joint. For this, the model needs to be tailored for each user by learning the gait pattern specific to the user. The challenge of training such machine learning regression models in prosthetic control is that, the desired reference output cannot be obtained from an amputee due to the missing limb. In this study, we investigate the feasibility of using two different methods for training a random forest algorithm using incomplete amputee-specific data to predict the ankle kinematics and dynamics from hip, knee, and shank kinematics. First is an inter-subject approach which learns a generalized input-output relationship from a group of able-bodied individuals and then applies this generalized relationship to amputees. Second is a subject-specific approach which maps the amputee's inputs to a desired normative reference output calculated from able-bodied individuals. The subject-specific model outperformed the inter-subject model in predicting the ankle angle and moment in most cases and can be potentially used for devising a control strategy for an intelligent biomimetic ankle.

Effect of Chronic Ankle Sprain on Pain, Range of Motion, Proprioception, and Balance among Athletes.

Background: Ankle sprains are common among physically active individuals, especially among athletes. Majority of those who suffer ankle sprains have residual symptoms including pain, episodes of giving way, compromised proprioception and neuromuscular control, and re-injury leading to chronic ankle instability. The aim of this study was to see the effect of chronic ankle sprain on pain, range of motion, proprioception, and, static and dynamic balance among athletes. Methods: A total of 80 athletes, aged 18 to 25 years, involved in track-and-field sports were invited to participate in this study. They were divided in two groups. Athletes with history of grade 1 or 2 ankle sprain on either side requiring medical care who reported at least three episodes of ankle giving way in past 12 months were included in group A. An equal number of healthy athletes without any history of ankle sprain or injury in the lower limbs in the past one year matched by sex, age, height, weight, and limb dominance, were included in group B (control). Outcome measures: Participant’s pain, range of motion, proprioception and balance (static and dynamic) was measured using visual analog scale, half circle goniometer, degree of foot position sense, single leg stance time and Y-balance test respectively. Results: Although there were no differences in the active ankle joint range of motion (p > 0.05) in comparison to the control group, athletes with chronic ankle sprain reported mild pain and statistically significant (p < 0.05) deficits in foot proprioception, static and dynamic balance. Conclusions: Deficits in foot proprioception, static and dynamic balance even one year after the ankle sprain could be the reason for limitations in the dynamic defense system of the joint that predisposes to recurrent injury and instability. It is essential to understand the normal clinical course and risk factors for athletes who sustain sprain before devising a long term comprehensive rehabilitation program that focuses on mechanical and functional insufficiencies in order to improve their functional performance and prevent the risk of recurrent sprain.

Comparison of Lower Extremity EMG Muscle Testing With Hands-Free Single Crutch vs Standard Axillary Crutches.

Background:In order to maintain nonweightbearing restrictions of the lower extremity, an assistive device must be utilized. Currently most devices require the restricted limb to be held in a static position while the contralateral extremity provides forward propulsion. Atrophy and disuse conditions ensue rapidly, slowing healing and prolonging recovery. A hands-free single crutch (HFSC) utilizes both lower extremities, potentially reducing atrophy. The purpose of this study was to examine the electromyographic (EMG) differences between an HFSC and standard axillary crutches (SAC).Methods:A prospective, crossover study was performed using 21 healthy volunteers from an active duty foot and ankle clinic. Demographic data were obtained and then subjects were fitted with an HFSC and SAC. Wireless surface EMG sensors were applied to the belly of the rectus femoris (RF), vastus lateralis (VL), lateral gastrocnemius (LG), and the gluteus maximus (GM) by a board-certified orthopedic surgeon. Subjects then ambulated at a self-selected velocity for 30 m while 15 seconds of the gait cycle were recorded for each device. Mean muscle activity and the maximum voluntary isometric contraction (MVIC) were recorded.Results:The RF, GM, and LG showed significantly increased levels of muscle activity while using the HFSC compared to SAC (respectively P = .05, P = .03, P = .03). The VL did not show significantly higher muscle activity while using the HFSC (P = .051). The RF, GM, and VL showed statistically significant higher MVIC percentages while using the HFSC compared with SAC (respectively P = .005, P = .005, P = .013). The LG did not show significantly higher MVIC percentage while using the HFSC (P = .076).Conclusion:The HFSC subjects demonstrated increased muscle recruitment and intensity while maintaining cyclic contractions consistent with bipedal gait pattern. SAC demonstrated less recruitment and intensity with an isometric pattern regardless of the phase of gait.Clinical Relevance:Muscle atrophy following lower extremity immobilization.

Aquatic Therapy Versus Combined Aquatic and Land-Based Therapy in the Treatment of Chronic Lateral Ankle Sprain

Abstract Purpose. To compare the impact of the combined program containing land-based exercises and hydrotherapy to land-based exercises alone in patients with chronic lateral ankle sprain. Material and Methods. After being illegible for the study, forty patients assigned randomly into two equal groups, (group A) represented the hydrotherapy group; (group B) administered the combined hydrotherapy and land-based program with a frequency of two sessions weekly for one month. Results. Findings revealed that patients in both the hydrotherapy group and the combined group had improved in pain, ankle functional ability, ROM, and satisfaction where there were no significant difference between groups (p > 0.05). Also, there was no significant difference in satisfaction between both groups post-treatment. Conclusion Both the implemented combined water and land exercise, and land based exercise programs could be recommended for rehabilitation to improve the precision of active ankle repositioning of individuals with residual symptoms of chronic ankle instability.

Influence of type 1 diabetes on the postural control of women in the third gestational trimester

BackgroundDiabetes can cause biomechanical alterations that may be responsible for additional changes to those existing in a regular gestational period. The way a maternal body responds when affected by diabetes has not been clearly understood. This study aimed to describe the influence of type 1 diabetes on pregnant women's postural control. MethodsForty pregnant women in their third gestational trimester were allocated in two equal groups - the control group and the type 1 diabetic group. The variables related to postural control and balance were assessed using photogrammetry (head protrusion; cervical lordosis; thoracic kyphosis; lumbar lordosis; pelvic anteversion, knee flexion, tibiotarsal and foot inclination angles were measured), and baropodometry (anteroposterior and mediolateral distance trajectory of the center of pressure, amplitude and average speed of displacement of the center of pressure). FindingsThe results of the type 1 diabetic group showed, in the postural analysis, lower head protrusion and pelvic anteversion angles, while there was higher cervical lordosis, thoracic kyphosis, and lumbar lordosis angles. In the baropodometry, the anteroposterior distance and the amplitude of the center of pressure displacement with eyes open and closed were higher. InterpretationThe findings suggest that type 1 diabetes mellitus in the third trimester of pregnancy is associated with postural changes, a decrease in the active ankle range of motion and increase in the anteroposterior oscillation of the center of pressure, with negative repercussions for postural control.

Functional electrical stimulation of the peroneal nerve improves post-stroke gait speed when combined with physiotherapy. A systematic review and meta-analysis.

Functional electrical stimulation (FES) applied to the paretic peroneal nerve has positive clinical effects on foot drop secondary to stroke. To evaluate the effectiveness of FES applied to the paretic peroneal nerve on gait speed, active ankle dorsiflexion mobility, balance, and functional mobility. Electronic databases were searched for articles published from inception to January 2020. We included randomized controlled trials or crossover trials focused on determining the effects of FES combined or not with other therapies in individuals with foot drop after stroke. Characteristics of studies, participants, comparison groups, interventions, and outcomes were extracted. Statistical heterogeneity was assessed with the I2 statistic. We included 14 studies providing data for 1115 participants. FES did not enhance gait speed as compared with conventional treatments (i.e., supervised/unsupervised exercises and regular activities at home). FES combined with supervised exercises (i.e., physiotherapy) was better than supervised exercises alone for improving gait speed. We found no effect of FES combined with unsupervised exercises and inconclusive effects when FES was combined with regular activities at home. When FES was compared with conventional treatments, it improved ankle dorsiflexion, balance and functional mobility, albeit with high heterogeneity for these last 2 outcomes. This meta-analysis revealed low quality of evidence for positive effects of FES on gait speed when combined with physiotherapy. FES can improve ankle dorsiflexion, balance, and functional mobility. However, considering the low quality of evidence and the high heterogeneity, these results must be interpreted carefully.

Immediate Effects of High-frequency Diathermy on Muscle Architecture and Flexibility in Subjects With Gastrocnemius Tightness

Background: The gastrocnemius (GCM) is one of the lower extremity muscles that tend to tighten easily. GCM tightness results in limited ankle dorsi-flexion (DF), especially when the knee joint is fully extended. Joint flexibility is determined by the morphological and physiological characteristics of joints, muscles, tendons, and ligaments. Impaired joint flexibility can be attributed to increased susceptibility to muscle injury. High-frequency diathermy is clinically used to reduce pain and muscle tightness and to improve limited range of motion. Objects: This study aimed to investigate the immediate effects of high-frequency therapy in subjects with GCM tightness. Methods: The study was designed as a one-group before–after trial. The subjects included 28 volunteers with GCM tightness (an active ankle DF angle of less than 12°) without any known neurological and musculoskeletal pathologies in the ankle and calf areas. WINBACK Transfer Electrode Capacitive and Resistive Therapy equipment was used to apply high-frequency therapy to the subjects’ GCMs for 10–15 minutes. The pennation angle and the fascicle length of the GCM were measured using ultrasonography. The flexibility of the ankle joint, peak torque to the passive ankle DF (Biodex), and soft tissue stiffness (MyotonPRO) were also measured. Results: The pennation angle was significantly decreased following the treatment; however, no significant difference in the fascicle length was found (p < 0.05). The flexibility was significantly increased and both the passive peak torque to passive ankle DF and the soft tissue stiffness significantly decreased (p < 0.05). Conclusion: High-frequency therapy is immediately effective for improving the muscle’s architectural properties and functional factors in subjects with GCM tightness. Further longitudinal clinical studies are required to investigate the long-term effects of high-frequency therapy on subjects with GCM tightness from various causes.

Bilateral and asymmetrical contributions of passive and active ankle plantar flexors stiffness to spasticity in humans with spinal cord injury.

Spasticity is one of the most common symptoms present in humans with spinal cord injury (SCI); however, its clinical assessment remains underdeveloped. The purpose of the study was to examine the contribution of passive muscle stiffness and active spinal reflex mechanisms to clinical outcomes of spasticity after SCI. It is important that passive and active contributions to increased muscle stiffness are distinguished to make appropriate decisions about antispastic treatments and to monitor its effectiveness. To address this question, we combined biomechanical and electrophysiological assessments of ankle plantarflexor muscles bilaterally in individuals with and without chronic SCI. Spasticity was assessed using the Modified Ashworth Scale (MAS) and a self-reported questionnaire. We performed slow and fast dorsiflexion stretches of the ankle joint to measure passive muscle stiffness and reflex-induced torque using a dynamometer and the soleus H reflex using electrical stimulation over the posterior tibial nerve. All SCI participants reported the presence of spasticity. While 96% of them reported higher spasticity on one side compared with the other, the MAS detected differences across sides in only 25% of the them. Passive muscle stiffness and the reflex-induced torque were larger in SCI compared with controls more on one side compared with the other. The soleus stretch reflex, but not the H reflex, was larger in SCI compared with controls and showed differences across sides, with a larger reflex in the side showing a higher reflex-induced torque. MAS scores were not correlated with biomechanical and electrophysiological outcomes. These findings provide evidence for bilateral and asymmetric contributions of passive and active ankle plantar flexors stiffness to spasticity in humans with chronic SCI and highlight a poor agreement between a self-reported questionnaire and the MAS for detecting asymmetries in spasticity across sides.NEW & NOTEWORTHY Spasticity affects a number of people with spinal cord injury (SCI). Using biomechanical, electrophysiological, and clinical assessments, we found that passive muscle properties and active spinal reflex mechanisms contribute bilaterally and asymmetrically to spasticity in ankle plantarflexor muscles in humans with chronic SCI. A self-reported questionnaire had poor agreement with the Modified Ashworth Scale in detecting asymmetries in spasticity. The nature of these changes might contribute to the poor sensitivity of clinical exams.

그라스톤을 이용한 연부조직가동술과 근에너지기법이 발목관절 가동성과 장딴지근 깃각 및 압통에 미치는 영향

This study aimed to identify alterations in the pennation angle of the gastrocnemius, active ankle dorsiflexion range-of-motion and pressure pain threshold in response to passive stretching(PS), instrument assisted soft tissue mobilization (IASTM) using Graston, and muscle energy technique (MET). Twenty-four people with no orthopedic or neurological diseases volunteered to participate in the study. Their both legs were allocated either the PS, IASTM, or MET groups, 16 in each. Outcome measure included the pennation angle of the gastrocnemius, active ankle dorsiflexion range-of-motion and pressure pain threshold. Intervention was a 4 repetitions of 30-sec stretch for the PS group, a 2-min sweeping the soft tissue for the IASTM, and a 8 repetitions of isometric contraction and 7-sec relaxation for the MET group. As a result of this study, pre- and post-treatment changes in the pennation angle and range-of-motion were significantly different for the three groups(p<.01). Pre- and post-treatment changes in the pressure pain threshold were significantly different for the IASTM and MET groups(p<.05). But not different for the PS groups(p>.05). There were found statistically significant differences in the active ankle dorsiflexion ROM between the PS group and the others.(p<.05). This study suggests that IASTM and MET are more recommended than PS to increase the active ankle dorsiflexion ROM effectively.

Active Ankle Point Orthosis Based On Artificial Muscle Fibers

One of the most important forms of human movement is walking. The foot-shank-complex with the associated...

Development of an Improved Rotational Orthosis for Walking With Arm Swing and Active Ankle Control.

Based on interlimb neural coupling, gait robotic systems should produce walking-like movement in both upper and lower limbs for effective walking restoration. Two orthoses were previously designed in our lab to provide passive walking with arm swing. However, an active system for walking with arm swing is desirable to serve as a testbed for investigation of interlimb neural coupling in response to voluntary input. Given the important function of the ankle joint during normal walking, this work aimed to develop an improved rotational orthosis for walking with arm swing, which is called ROWAS II, and especially to develop and evaluate the algorithms for active ankle control. After description of the mechanical structure and control schemes of the overall ROWAS II system, the closed-loop position control and adjustable admittance control algorithms were firstly deduced, then simulated in Matlab/Simulink and finally implemented in the ROWAS II system. Six able-bodied participants were recruited to use the ROWAS II system in passive mode, and then to estimate the active ankle mechanism. It was showed that the closed-loop position control algorithms enabled the ROWAS II system to track the target arm-leg walking movement patterns well in passive mode, with the tracking error of each joint <0.7°. The adjustable admittance control algorithms enabled the participants to voluntarily adjust the ankle movement by exerting various active force. Higher admittance gains enabled the participants to more easily adjust the movement trajectory of the ankle mechanism. The ROWAS II system is technically feasible to produce walking-like movement in the bilateral upper and lower limbs in passive mode, and the ankle mechanism has technical potential to provide various active ankle training during gait rehabilitation. This novel ROWAS II system can serve as a testbed for further investigation of interlimb neural coupling in response to voluntary ankle movement and is technically feasible to provide a new training paradigm of walking with arm swing and active ankle control.

Acute Effects of Tissue Flossing on Ankle Range of Motion and Tensiomyography Parameters.

Recently, a few papers have suggested that tissue flossing (TF) acutely improves range of motion (ROM) and neuromuscular performance. However, the effects of TF on muscle contractile properties are yet to be defined. To investigate the acute effects of TF on ankle ROM and associated muscle gastrocnemius medialis displacement and contraction time assessed with tensiomyography. Crossover design in a single session. University laboratory. Thirty recreationally trained volunteers (age 23.00 [4.51]y). Active ankle plantar flexion and dorsiflexion were performed for the duration of 2 minutes (3 sets, 2-min rest between sets), while a randomly selected ankle was wrapped using TF elastic band (BAND) and the other ankle served as a control condition (CON). Participants performed an active ankle plantar flexion and dorsiflexion ROM test and muscle gastrocnemius medialis tensiomyography displacement and contraction time measurement pre, 5, 15, 30, and 45minutes after the floss band application. There were no statistically significant differences between BAND and CON conditions (active ankle plantar flexion ROM: P = .09; active ankle dorsiflexion ROM: P = .85); however, all ROM measurements were associated with medium or large effect sizes in favor of BAND compared with CON. No significant changes were observed in the tensiomyography parameters. The results of this study suggest that TF applied to the ankle is a valid method to increase ROM and at the same time maintaining muscular stiffness.

The Effect of Dry Needling on Lower Limb Dysfunction in Poststroke Survivors

Background: Spasticity is one of the main complications in poststroke survivors leading to difficulties in walking and standing resulting in high levels of disability. Objective: The aim of the study was to investigate the effects of deep dry needling on lower limb dysfunction in poststroke spastic patients. Methods: A randomized clinical trial conducted in poststroke survivors who were assigned to one of 2 groups: Deep dry needling (intervention group) and sham dry needling (control group). The primary outcome measures were Modified Modified Ashworth Scale (MMAS) and functional tests (timed up and go test, 10-meter walk test). Secondary outcome measures were active ankle dorsiflexion range of motion (AROM), passive ankle dorsiflexion range of motion (PROM), single leg stance test, and Barthel index. All measurements were assessed at baseline (T0), immediately after the third session 1 week later (T1), and 1 month after the end of the intervention (T2). Results: We recruited 24 patients (71% male; mean age 57 ± 10 years; 26.4 ± 1.8 kg•m−2; time since event: 25.2 ± 12.5 months). There were significant improvements in MMAS, timed up and go test, 10-meter walk test, Barthel scale, and PROM (P < .05) in the intervention group compared to controls across the time-points. There were no significant improvements in AROM assessments (P > .05). Conclusions: Deep dry needling decreases muscle spasticity and improves lower limb function and gait speed in poststroke survivors.

Joint position reproduction and joint position discrimination at the ankle are not related

Purpose: Limited data in current literature can be found on the relation between the two commonly-used active proprioception assessment methods –active joint position reproduction (JPR) and active movement extent discrimination assessment (AMEDA). The current study compared the two active methods, JPR and AMEDA, to investigate their interrelationship over two studies that differed in task difficulty, using active ankle inversion movements made in weight-bearing to maximise ecological validity.Methods: 50 participants volunteered in this research, 20 of whom on a harder protocol and the other 30 on an easier protocol, were tested by both methods, JPR and AMEDA. Proprioceptive acuity was represented by absolute error (AE) and variable error (VE) for JPR and by AE and the area under the curve (AUC) for AMEDA.Results: Proprioceptive acuity scores are found to be significantly correlated within test methods but not between methods for either hard or easy tasks, where JPR AE and VE scores were not correlated with either AMEDA AE or AUC. Further, proprioceptive acuity scores were significantly higher on the easy task when tested with the AMEDA method, but not with JPR method.Conclusion: Scores obtained from the two active movement proprioception tests, movement extent discrimination and joint position reproduction, were not significantly correlated. Taken together with previous findings, these results show that for proprioception, scores from the three classical psychophysical methods for measuring sensitivity (adjustment, limits and constant stimuli) are not correlated with each other. This suggests that each proprioception measurement system assesses a different aspect of proprioception.

Ultrasound Evaluation of the Peroneal Tendons in an Asymptomatic Elite Military Population: A Prospective Cohort Study.

The purpose of this study was to identify the location of the peroneal tendons in relationship to the fibular groove in an asymptomatic population of elite U.S. Military Service members. The peroneal tendons of 41 active duty U.S. Army Rangers were examined. Subjects were placed in a lateral recumbent position with the ankle in a resting neutral position to visualize the tendon in a retromalleolar short-axis view. Maximum active ankle eversion followed by gravity inversion was facilitated while the ultrasound probe was maintained in its original position. Distance from the fibrous lateral ridge of the retromalleolar groove to the anterior aspect of the peroneal brevis was measured in the short axis in neutral, eversion, and inversion. The mean sagittal distance and standard deviation was 0.48±0.9mm. No subjects demonstrated greater than 1mm difference between positions, and no dislocations were identified. Side-to-side difference and dominant vs nondominant differences were not statistically significant. The study demonstrates that the distance between the peroneal brevis and the lateral fibular ridge is consistent throughout extremes of motion. These results further the understanding of peroneal tendon function under dynamic examination. Our findings also establish side-to-side consistency prompting a bilateral examination to help identify abnormal pathology.

Control of a Transtibial Prosthesis with Monoarticular and Biarticular Actuators

Common active ankle joint prostheses comprise monoarticular actuators mimicking the function of the human soleus and tibialis anterior muscles, but lack the function of the biarticular human gastrocnemius muscle. Although these devices can mimic human ankle biomechanics in the sagittal plane, persons with transtibial amputation still show compensatory movements and asymmetric gait patterns. The goal of our research is to investigate the benefits of a biarticular transtibial prosthesis comprising mono- and biarticular actuators. This contribution presents the hardware configuration, control design and bypass testing of a biarticular prosthesis prototype with two actuators. A control structure consisting of a model-based feedforward control and a feedback controller to control the actuator torque is introduced. Modeling of the actuators and identification of all relevant system parameters is demonstrated. A reference trajectory based on healthy human ankle biomechanics and a control allocation are introduced. The system’s capability to track desired torques is demonstrated in a walking experiment. It is able to generate human ankle torques and ankle angles with a variable distribution of torque between the mono- and biarticular actuator. Based on these results, further investigations on the torque allocation to improve the gait patterns of persons with transtibial amputation can be conducted.

Development of active ankle foot orthotic device

A powered ankle foot orthotic (AFO) device has been designed not only for patients having foot drop problem but also improve the movement of ankle joint for patients with lower limb disabilities. Different materials like poly lactic acid (PLA), polypropylene and ABS are been used to be designed and analyzed with computer aided design (CAD) and Finite Element Analysis software and which help to select the best material for fabrication purpose. This research article presents an externally powered portable ankle foot orthosis fitted with microcontroller, stepper motor to provide dorsiflexion and plantar flexion assistance during patients walking suffering from foot drop. At first the 3D model has been analyzed which designed in CAD module with selected material using analysis software and then mechanical structured AFO has been developed on the basis of GAIT parameters accordingly the AFO is assembled. The aim of this paper is to design, manufacture and delivering customized AFO that is patient specific.

Possible predictive formulas for quantitative and time-based estimation of muscle strength during motion.

[Purpose] To examine the validity of the predictive formulas based on the angle information of the segment center of mass and moments of inertia, and to propose a joint moment estimation method. [Participants and Methods] Twenty nine young healthy adults were divided into two groups: the Creation group (20 adults) was needed to create the prediction formulas, and the Verification group (9 adults) was needed to verify the formulas. By monitoring the Creation group, the angular information from inertial motion sensors and moments of inertia of each limb were used to estimate actual ankle joint moment and knee joint moment. Thereafter, the actual joint moments was derived from the Verification group and compared to the predicted values via Pearson correlations. [Results] Good to excellent correlations were obtained between the actual joint moments of the two groups for most of the motions. [Conclusion] It is suggested that the predictive formulas created from the angle information of the segment center of mass and moments of inertia can be used for an approximate estimation of the lower limb joint moments in the sagittal plane and more clinically useful tools need to be considered in the future.

Effects of talus stabilization taping versus ankle kinesio taping in patients with chronic stroke: a randomized controlled trial

Talus stabilization taping (TST) can be utilized to stabilize posteriorly glide of the talus and allows active ankle dorsiflexion movement during walking. The purpose of this study was to compare the effects of ankle kinesio taping with those of TST on ankle dorsiflexion passive range of motion, static balance, the Timed Up and Go test, and the fall risk in patients with chronic stroke and limited ankle dorsiflexion. Participants were randomized into the kinesio taping (n=11) and TST groups (n=11). Both groups were applied the appropriate taping and were asked to walk on the treadmill for 10 min. The ankle dorsiflexion passive range of motion, static balance ability, Timed Up and Go test, and fall risk were assessed in all participants before and after the intervention. The TST group showed greater improvement than the ankle kinesio taping group in all outcomes measured (P<0.05). Furthermore, both groups had significantly decreased in the Timed Up and Go results (P<0.05). This study shows that TST improves functional ability of the ankles of patients with chronic stroke in comparison to the kinesio taping method.

Modelling and reference tracking of the robotic above-knee prosthetic leg with actuated knee and ankle joints during stair climbing

The locomotion of people with amputation is slower, less stable and requires more metabolic energy than the locomotion of physically fit individuals. Individuals with amputation of the lower extremities fall more often than able individuals and often have difficulty moving on uneven terrain and stairs. These challenges can mostly be attributed to the use of passive mechanical prosthetic legs that do not react actively to perturbations. Latest submitted solutions for active prosthetic devices of the lower extremities can significantly improve mobility and quality of life for millions of people with lower limb amputation, but challenges in control mechanisms of such devices are currently limiting their clinical viability. In this paper we present a prototype of an above-knee prosthetic leg with active knee and ankle joints while using the proposed robust control law.