Transfemoral Amputee Gait Research Articles

Transfemoral Amputee Stumble Detection through Machine-Learning Classification: Initial Exploration with Three Subjects

Transfemoral Amputee Stumble Detection through Machine-Learning Classification: Initial Exploration with Three Subjects

Is there a trade-off between economy and task goal variability in transfemoral amputee gait?

BackgroundEnergy cost minimization has been widely accepted to regulate gait. Optimization principles have been frequently used to explain how individuals adapt their gait pattern. However, there have been rare attempts to account for the role of variability in this optimization process. Motor redundancy can enable individuals to perform tasks reliably while achieving energy optimization. However, we do not know how the non-goal-equivalent and goal-equivalent variability is regulated. In this study, we investigated how unilateral transfemoral amputees regulate step and stride variability based on the task to achieve energy economy.MethodsNine individuals with unilateral transfemoral amputation walked on a treadmill at speeds of 0.6, 0.8, 1.0, 1.2 and 1.4 m/s using their prescribed passive prostheses. We calculated the step-to-step and stride-to-stride variability and applied goal equivalent manifold (GEM) based control to decompose goal-equivalent and non-goal-equivalent manifold. To quantify the energy economy, the energy recovery rate (R) was calculated based on potential energy and kinetic energy. Comparisons were made between GEM variabilities and commonly used standard deviation measurements. A linear regression model was used to investigate the trade-off between R and GEM variabilities.ResultsOur analysis shows greater variability along the goal-equivalent manifold compared to the non-goal-equivalent manifold (p < 0.001). Moreover, our analysis shows lower energy recovery rate for amputee gait compared to nonamputee gait (at least 20% less at faster walking speed). We found a negative relationship between energy recovery rate and non-goal-equivalent variability. Compared to the standard deviation measurements, the variability decomposed using GEM reflected the preferred walking speed and the limitation of the passive prosthetic device.ConclusionIndividuals with amputation cleverly leverage task redundancy, regulating step and stride variability to the GEM. This result suggests that task redundancy enables unilateral amputees to benefit from motor variability in terms of energy economy. The differences observed between prosthetic step and intact step support the development of prosthetic limbs capable of enhancing positive work during the double support phase and of powered prosthesis controllers that allow for variability along the task space while minimizing variability that interferes with the task goal. This study provides a different perspective on amputee gait analysis and challenges the field to think differently about the role of variability.

On the impact of the erroneous identification of inertial sensors' locations on segments and whole-body centers of mass accelerations: a sensitivity study in one transfemoral amputee.

The kinematics of the body center of mass (bCoM) may provide crucial information supporting the rehabilitation process of people with transfemoral amputation. The use of magneto-inertial measurement units (MIMUs) is promising as it may allow in-the-field bCoM motion monitoring. Indeed, bCoM acceleration might be obtained by fusing the estimated accelerations of body segments' centers of mass (sCoM), the formers being computed from the measured accelerations by segment-mounted MIMUs and the known relative position between each pair of MIMU and underlying sCoM. This paper investigates how erroneous identifications of MIMUs positions impact the accuracy of estimated 3D sCoM and bCoM accelerations in transfemoral amputee gait. Using an experimental design approach, 215 simulations of erroneous identifications of MIMUs positions (up to 0.02 m in each direction) were simulated over seven recorded gait cycles of one participant. MIMUs located on the trunk and sound lower limbs were shown to explain up to 77% of the variance in the accuracy of the estimated bCoM acceleration, presumably due to the higher mass and/or angular velocity of these segments during gait of lower-limb amputees. Therefore, a special attention should be paid when identifying the positions of MIMUs located on segments contributing the most to the investigated motion. Sensitivity of the estimated vertical body center of mass acceleration to erroneous identifications of MIMU positions in the anteroposterior (AP), mediolateral (ML), and vertical (V) directions, expressed in percentage of the total variance of the estimation accuracy.

Estimation of 3D Body Center of Mass Acceleration and Instantaneous Velocity from a Wearable Inertial Sensor Network in Transfemoral Amputee Gait: A Case Study.

The analysis of the body center of mass (BCoM) 3D kinematics provides insights on crucial aspects of locomotion, especially in populations with gait impairment such as people with amputation. In this paper, a wearable framework based on the use of different magneto-inertial measurement unit (MIMU) networks is proposed to obtain both BCoM acceleration and velocity. The proposed framework was validated as a proof of concept in one transfemoral amputee against data from force plates (acceleration) and an optoelectronic system (acceleration and velocity). The impact in terms of estimation accuracy when using a sensor network rather than a single MIMU at trunk level was also investigated. The estimated velocity and acceleration reached a strong agreement (ρ > 0.89) and good accuracy compared to reference data (normalized root mean square error (NRMSE) < 13.7%) in the anteroposterior and vertical directions when using three MIMUs on the trunk and both shanks and in all three directions when adding MIMUs on both thighs (ρ > 0.89, NRMSE ≤ 14.0% in the mediolateral direction). Conversely, only the vertical component of the BCoM kinematics was accurately captured when considering a single MIMU. These results suggest that inertial sensor networks may represent a valid alternative to laboratory-based instruments for 3D BCoM kinematics quantification in lower-limb amputees.

Effects of a Powered Knee-Ankle Prosthesis on Amputee Hip Compensations: A Case Series.

Transfemoral amputee gait often exhibits compensations due to the lack of ankle push-off power and control over swing foot position using passive prostheses. Powered prostheses can restore this functionality, but their effects on compensatory behaviors, specifically at the residual hip, are not well understood. This paper investigates residual hip compensations through walking experiments with three transfemoral amputees using a low-impedance powered knee-ankle prosthesis compared to their day-to-day passive prosthesis. The powered prosthesis used impedance control during stance for compliant interaction with the ground, a time-based push-off controller to deliver high torque and power, and phase-based trajectory tracking during swing to provide user control over foot placement. Experiments show that when subjects utilized the powered ankle push-off, less mechanical pull-off power was required from the residual hip to progress the limb forward. Overall positive work at the residual hip was reduced for 2 of 3 subjects, and negative work was reduced for all subjects. Moreover, all subjects displayed increased step length, increased propulsive impulses on the prosthetic side, and improved impulse symmetries. Hip circumduction improved for subjects who had previously exhibited this compensation on their passive prosthesis. These improvements in gait, especially reduced residual hip power and work, have the potential to reduce fatigue and overuse injuries in persons with transfemoral amputation.

Effects on ankle power and sound limb load with an active prosthetic foot

Abstract The performance of conventional prosthetic feet depends on material and construction principles. Certain powered feet can even generate net positive mechanical work in order to provide an active push-off. The aim of this study was to evaluate the influence of ankle power on the gait of transfemoral amputees. For this purpose level walking of six transfemoral amputees was analysed with a basic and an active foot and three different power settings of the latter. The results show clear advantages of the active foot in comparison with a basic foot. However, a strong relation of the sound side knee loading parameters with the varied ankle power outputs of the active foot couldn’t be shown.

Effects on prosthetic foot ankle power on transfemoral amputee gait

Prosthetic feet are available in a range of stiffness categories, however, there is limited evidence to guide optimal selection during prosthetic foot prescription. The aim of this study was to determine the effect of commercial prosthetic foot stiffness category on foot-ankle biomechanics, gait symmetry, community ambulation, and relative foot stiffness perception.Participants were fit in randomized order with three consecutive stiffness categories of a commonly-prescribed prosthetic foot. Prosthetic foot roll-over shape and ankle push-off power and work were determined via data collected during walking in a motion analysis laboratory. Step activity was recorded during community use of each foot. Self-reported perception of relative foot stiffness was assessed with an ad hoc survey.Seventeen males with transtibial amputation completed the study. Prosthetic foot roll-over radius increased with increased prosthetic foot stiffness categories (p < 0.001). Both prosthetic ankle push-off peak power and work decreased with increased foot stiffness categories (p = 0.002). There was no association between prosthetic foot stiffness category and step length symmetry or steps per day. When assessed post-accommodation, there was no association between relative foot stiffness perception and the stiffness category across prosthetic foot conditions.Prosthetic foot stiffness category was significantly associated with changes in prosthetic foot-ankle biomechanical variables, however, was not associated with changes in gait symmetry or community ambulation. Relative prosthetic foot stiffness perception after accommodation was generally inconsistent with the order of prosthetic foot stiffness categories.While there were quantifiable differences in prosthetic foot-ankle biomechanics across stiffness categories, no significant differences were detected in gait symmetry or mean daily step count in the community. Furthermore, after community use, participants perceptions of relative stiffness across feet were generally inconsistent with the order of prosthetic foot stiffness categories. These findings raise questions as to whether changes in commercial prosthetic foot stiffness category (within a clinically relevant range) affect subjective and objective measures relevant to successful outcomes from prosthetic foot prescription.

Lower Limb Inter-Joint Coordination of Unilateral Transfemoral Amputees: Implications for Adaptation Control

The gait of transfemoral amputees can be made smoother by adjusting the inter-joint coordination of both lower limbs. In this study, we compared the inter-joint coordination of the amputated and non-amputated limbs of unilateral amputees to able-bodied controls. Eight amputees and eight able-bodied control participants were recruited. Walking speed, stance–swing time ratio, joint angle, joint angular velocity, and inter-joint coordination parameters—including continuous relative phase (CRP) and decomposition index (DI)—of the lower-limb joint pairs in stance and swing phases were investigated. Similarity of the CRP between groups was evaluated using cross-correlation measures and root-mean-square, and the variability of the CRP was examined by deviation phase (DP). There were significant differences between the amputated limbs and controls in CRP of hip–knee and knee–ankle in stance and swing, DP of knee–ankle and hip–ankle in stance, and DI of hip–knee in swing. For the non-amputated limbs, there were significant differences in CRP and DP of knee–ankle, and DI of hip–knee in swing compared to controls. The amputees utilized unique inter-joint coordination patterns for both limbs—particularly the hip joint—to compensate for the support-capability impairment due to limb salvage and ensure foot placement accuracy.

CLINICAL GAIT ANALYSIS OF SUBJECTS WITH TRANS-FEMORAL AMPUTATION USING POLYCENTRIC FOUR-BAR LINKAGE PROSTHETIC KNEE JOINT

Background: Adequate research is not reported so far to underline the influence of commonly used polycentric knee joints on gait performance of subjects with trans-femoral amputation. Objective: The intent of this investigation is to analyze prosthetic gait of unilateral traumatic trans-femoral amputees with polycentric four-bar linkage knee and compare it with normal subjects for evaluating any asymmetry in gait performance. Methods: Objective three-dimensional gait analysis of 15 subjects [mean (age): 36.4 (10.7) years] were performed in gait lab through force plate and optoelectronic devices to measure temporal-spatial parameters, kinematic and kinetic performances. Gait patterns of amputees were compared with those of 15 individuals with normal gait to analyze distinct functionalities of existing polycentric knee. Results: Asymmetry in gait was observed between amputees and normal subjects for all variables concerned ([Formula: see text]). Amputee gait was with significantly lesser velocity, cadence with shorter step and stride length. There was significantly less hip, knee and pelvic motions, however, pelvic obliquity and rotation did not show significant difference from the normal subjects. The vertical component of the ground reaction force differed significantly between prosthetic and intact limb [49.7 (8.5)% and 90.4 (7.4)% body weight] and also from normal subjects [107.5 (2.4)% body weight] during stance ([Formula: see text]). Interpretation and Conclusion: This difference may be attributed to nonproportionate loading of limbs and mechanical adaptations for counteracting deficiencies of prosthetic side. This study will help to explain gait asymmetry in trans-femoral amputees and to identify underlying mechanisms to enhance the quality of the existing design of prosthetic knee through optimizing design parameters and utilizing appropriate materials.

Semi-active control of a swing phase dynamic model of transfemoral prosthetic device based on inverse dynamic model

Improving the gait of transfemoral amputees and making it biomimetic and stable has always been a major effort. A dynamic model of the prosthetic device can predict the kinetic and kinematic performances, when incorporated with a musculoskeletal model. In this regard, a dynamic model of a recent trend of variable damping technology will help a great deal in evaluating the performance of the prosthetic device and also in studying the effect of various parameters on the prostheses. The current paper presents the dynamic model of a single axis two segmental prosthetic knee implemented with a magneto-rheological (MR) damper as a variable damping element. The MR damper is modeled mathematically using Bouc–Wen model with model parameters evaluated by minimizing the error norms for time, displacement and velocity between the experimental and the model-generated results using a genetic algorithm. Two different experimental data sets are used, one for mathematical modeling and other to assess the accuracy of the fit model. A Proportional Derivative plus Controlled Torque controller is employed, and the parameters are tuned to minimize the error between the desired and control input torques. Further, an inverse dynamic model using Bouc–Wen model variables is assumed and validated later. This model predicts the current directly and avoids the necessity of solving any quadratic equation, which is required in the case of inverse models based on modified Bouc–Wen. The dynamic model of the prosthesis is analyzed for the swing phase alone, and the results show that the model traces the desired knee angle and also the shank reaches full knee extension at the end of this phase with terminal velocity small enough to be handled by an extension stop.

A characterisation of established unilateral transfemoral amputee gait using 3D kinematics, kinetics and oxygen consumption measures

BackgroundPersons with unilateral transfemoral (UTF) amputation are known to walk with less efficiency than able-bodied individuals, therefore understanding the gait deviations that drive this inefficiency was considered to be important. Research questionsWhat are the differences in gait outcomes between persons with UTF amputation and able-bodied persons? What is the prevalence of specific gait deviations within this group? MethodsUsing a cross-sectional study design, the level over ground gait of established prosthetics service users with UTF amputation using mechanical knee joints (n=60) were compared with able-bodied persons (n=10). Gait profile score, walking velocity, step length, step length symmetry ratio, step time symmetry ratio, vertical ground reaction force symmetry index, base of support, centre of mass deviation and metabolic energy expenditure were measured. All data were captured during walking on level ground at a self-selected speed. Prevalence of gait deviations for each UTF participant were assessed by inspection, using a predefined list of lower limb kinematic, upper body kinematic, ground reaction force and lower limb kinetic gait deviations. ResultsStatistically significant between-groups differences across all outcome measures were found, with all p-values <0.005, and effect sizes ranging from 'large' to 'huge'. The most prevalent gait deviations included: lack of prosthetic knee flexion in early stance (98%); lack of hip extension on the prosthetic side in late stance (82%): increased trunk side flexion range of motion across the gait cycle (92%); reduced anterior propulsion force on the prosthetic side in late stance (100%) and reduced prosthetic hip adduction moment in early stance (96%). SignificanceThe results of this study indicate that the magnitude of the differences between UTF amputees and able-bodied persons, across a comprehensive range of gait measures, are such that significant research into all aspects of prosthetic rehabilitation to reduce these differences is clearly justified.

Are wearable insoles a validated tool for quantifying transfemoral amputee gait asymmetry?

Amputee gait is known to be asymmetrical, especially during loading of the lower limb. Monitoring asymmetry could be useful in quantifying patient performance during rehabilitation. Wearable insoles can provide normal ground reaction force asymmetry in real-life conditions. To characterize the validity of Loadsol® insoles versus force plates in quantifying normal ground reaction force and gait asymmetry. To determine the influence walking speed has on loading asymmetry in transfemoral amputees. This is a prospective study. Six transfemoral amputees, wearing Loadsol® insoles, walked at three self-selected speeds on force plates. Validity was assessed by comparing normal ground reaction force data from the insoles and force plates. The Absolute Symmetry Index was used to calculate gait loading asymmetry at each speed. Normalized root mean square errors for the normal ground reaction forces were 6.6% (standard deviation = 2.3%) and 8.9% (standard deviation = 3.8%); correlation coefficients were 0.91 and 0.95 for the prosthetic and intact limb, respectively. The mean error for Absolute Symmetry Index parameters ranged from -2.67% to 4.35%. Loading asymmetry increased with walking speed. This study quantified the validity of Loadsol® insoles in assessing loading asymmetry during gait in transfemoral amputees. The calibration protocol could be improved to better integrate it into a clinical setting. However, our results support the relevance of using such insoles during the clinical follow-up of transfemoral amputees. This is the first study to validate Loadsol® insoles versus force plates and report on loading asymmetry during gait at three different speeds in transfemoral amputees. Loadsol® insoles, which provide visual and audio feedback, are clinically easy to use and could have beneficial application in the amputee's rehabilitation and follow-up.

Development of a Mechanistic Hypothesis Linking Compensatory Biomechanics and Stepping Asymmetry during Gait of Transfemoral Amputees.

Objective Gait asymmetry is a common adaptation observed in lower-extremity amputees, but the underlying mechanisms that explain this gait behavior remain unclear for amputees that use above-knee prostheses. Our objective was to develop a working hypothesis to explain chronic stepping asymmetry in otherwise healthy amputees that use above-knee prostheses. Methods Two amputees (both through-knee; one with microprocessor knee, one with hydraulic knee) and fourteen control subjects participated. 3D kinematics and kinetics were acquired at normal, fast, and slow walking speeds. Data were analyzed for the push-off and collision limbs during a double support phase. We examined gait parameters to identify the stepping asymmetry then examined the external work rate (centre of mass) and internal (joint) power profiles to formulate a working hypothesis to mechanistically explain the observed stepping asymmetry. Results Stepping asymmetry at all three gait speeds in amputees was characterized by increased stance phase duration of the intact limb versus relatively normal stance phase duration for the prosthesis limb. The prosthesis limb contributed very little to positive and negative work during the double support phase of gait. To compensate, the intact leg at heel strike first provided aid to the deficient prosthetic ankle/foot during its push-off by doing positive work with the intact knee, which caused a delayed stance phase pattern. The resulting delay in toe-off of the intact limb then facilitated the energy transfer from the more robust intact push-off limb to the weaker colliding prosthesis side. This strategy was observed for both amputees. Conclusions There is a sound scientific rationale for a mechanistic hypothesis that stepping asymmetry in amputee participants is a result of a motor adaptation that is both facilitating the lower-leg trajectory enforced by the prosthesis while compensating for the lack of work done by the prosthesis, the cost of which is increased energy expenditure of the intact knee and both hips.

Research of the training methods and structure design of intelligent knee prosthesis based on physiological gait

The performance of intelligent prosthetic knee has an important effect on the realization of physiological gait of transfemoral amputees. A new type of single axis hydraulic damping knee prosthesis was designed based on the analysis of physiological gait. The training methods of the stance and swing phase were proposed. Knee prosthesis test was done through simulation and measurement device. The control target of peak flexion angle during swing of knee prosthesis is chosen to be 60-70°. When the damper valve closure was 0%, maximum swing-phase knee flexion angle of knee prosthesis were (86±2)°, (91±3)° and (97±3)° with the speed of 0.8 m/s, 1.2 m/s and 1.8 m/s, respectively. Once the valve closure was changed, maximum swing-phase knee flexion angle with different speeds could be adjusted between 60° and 70° and the required valve closure percentage were separately 25%, 40% and 70%. The damping adjustment law of intelligent knee prosthesis to achieve physiological gait was revealed.

Gait differences between K3 and K4 persons with transfemoral amputation across level and non-level walking conditions.

A transfemoral amputee's functional level can be classified from K-level 0 (lowest) to K-level 4 (highest). Knowledge of the biomechanical differences between K3 and K4 transfemoral amputation could help inform clinical professionals and researchers in amputee care and gait assessment. Explore gait differences between K3- and K4-level transfemoral amputation across different surface conditions. Cross-sectional study. Four K3 and six K4 transfemoral amputation and 10 matched able-bodied individuals walked in a virtual environment with simulated level and non-level surfaces on a self-paced treadmill. Stability measures included medial-lateral margin of stability, step parameters, and gait variability (standard deviations for speed, temporal-spatial parameters, root-mean-square of medial-lateral trunk acceleration). K3 walked slower than K4 with wider steps, greater root-mean-square of medial-lateral trunk acceleration, and greater medial-lateral margin of stability standard deviations, indicating their stability was further challenged. K3 participants had greater asymmetry in double support time and trunk acceleration root-mean-square in the medial-lateral direction, but similar asymmetry overall. K3 participants had larger differences from AB and in more parameters than K4, although K4 differed from AB in trunk acceleration root-mean-square in the medial-lateral direction, walking speed, and double support time standard deviations. The findings improve our understanding of K3 and K4 transfemoral amputation gait on slopes and simulated uneven surfaces. High performing and community ambulatory transfemoral amputees cannot match the ambulatory abilities of ablebodied individuals. Understanding gait differences between these groups under conditions that challenge balance is required to develop rehabilitation protocols and prosthetic componentry targeted at improving transfemoral amputee gait and overall mobility in their chosen environment.

Maintaining stable transfemoral amputee gait on level, sloped and simulated uneven conditions in a virtual environment

Purpose: Describe and quantify how people with transfemoral amputations (TFA) maintain stable gait over a variety of surfaces; including, downhill and uphill, top and bottom-cross-slopes, medial-lateral translations, rolling hills and simulated rocky surfaces.Methods: Ten TFA and ten matched people without amputations (NA) walked in a virtual environment with level, sloped and simulated uneven surfaces on a self-paced treadmill. Stability was quantified using medial-lateral margin of stability (ML-MoS), step parameters, and gait variability (standard deviations for speed, temporal-spatial parameters, foot clearance and root-mean-square of medial-lateral trunk acceleration).Results and conclusions: TFA and NA adapted to non-level conditions by changing their walking speed, step width, and foot clearance. Variability for most parameters increased across conditions, compared to level. TFA walked slower than NA with shorter, wider and longer duration steps (most differences related to speed). ML-MoS did not change compared to level; however, ML-MoS was greater on the prosthetic side than both intact side and NA limbs. Foot clearance and root-mean-square of medial-lateral trunk acceleration were greater on the prosthetic side than the intact side and NA limbs. This research provides a comprehensive analysis of the different adaptations made by people without amputations compared to people with transfemoral amputations over non-level conditions and establishes significant differences between slopes and simulated uneven surfaces for TFA.Implications for RehabilitationTransfemoral amputation and no amputation groups adapted walking biomechanics when traversing non-level surfaces.Greatest temporal-spatial gait adaptations were walking speed, step width and foot clearance.Gait parameter variability typically increased from the level condition in both groups.Transfemoral amputation group walked slower than no amputation group with shorter, wider steps and longer duration steps. This was related to speed.Transfemoral amputation group had more trunk motion variability on the prosthetic side than no amputation group; could be related to prosthetic fit.

Kinematics of gait using bionic and hydraulic knee joints in transfemoral amputees

Background: The development of new technologies has led to further improvements in prosthetic knee joints. Objective: The aim of this study was to compare angle parameters in knee and hip joints during the gait of transfemoral amputees and to determine the effect of the type of knee joint used on their symmetry. The study also compared pelvic movements in transfemoral amputees using different types of knee joints. Method: Eleven patients (5 female, 6 male, mean age 39.2 ± 10.1 years, height 171.8 ± 9.5 cm, mass 71.5 ± 11.0 kg) with a transfemoral amputation (5 used bionic knee, 6 used hydraulic knee) participated in this study. The control group consisted of 10 individuals with no locomotion-related problems (2 female, 8 male). Results: Movement was more symmetrical in the hip joint for all monitored parameters in patients with bionic knee joints. Flexion at heel contact and maximum flexion in the swing phase in the knee joint were more symmetrical in the group with hydraulic knee joints; for all other parameters the group with bionic knee joints achieved better symmetry. The kinematics of pelvic movement in the patients using hydraulic knee joints differed from the control group in all monitored parameters. The greatest difference with excellent effect size (ES = 7.96) was found in pelvic tilt. Pelvic tilt was higher when using hydraulic knee joints. Conclusion: In comparison with the mechanically passive knee joint, gait with the bionic knee joint evinced gait symmetry.

Mechanical work performed by individual limbs of transfemoral amputees during step-to-step transitions: Effect of walking velocity

The greater metabolic demand during the gait of people with a transfemoral amputation limits their autonomy and walking velocity. Major modifications of the kinematic and kinetic patterns of transfemoral amputee gait quantified using gait analysis may explain their greater energy cost. Donelan et al. proposed a method called the individual limb method to explore the relationships between the gait biomechanics and metabolic cost. In the present study, we applied this method to quantify mechanical work performed by the affected and intact limbs of transfemoral amputees. We compared a cohort of six active unilateral transfemoral amputees to a control group of six asymptomatic subjects. Compared to the control group, we found that there was significantly less mechanical work produced by the affected leg and significantly more work performed by the unaffected leg during the step-to-step transition. We also found that this mechanical work increased with walking velocity; the increase was less pronounced for the affected leg and substantial for the unaffected leg. Finally, we observed that the lesser work produced by the affected leg was linked to the increase in the hip flexion moment during the late stance phase, which is necessary for initiating knee flexion in the affected leg. It is possible to quantify the mechanical work performed during gait by people with a transfemoral amputation, using the individual limb method and conventional gait laboratory equipment. The method provides information that is useful for prosthetic fitting and rehabilitation.

Força de Reação do Solo e atividade eletromiográfica da marcha de amputados transfemorais: uma série de casos

Ground reaction forces (GRF) and electromyographic activity form a part of the descriptive data that characterise the biomechanics of gait. The research of these parameters is important in establishing gait training and understanding the impact of amputation and prosthetic components on movement during the act of walking. Therefore, this case series describes the GRF and electromyographic activity in the gait of transfemoral amputees. A force plate was used to measure GRF, and an electromyographic system monitored the vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius lateralis muscles of the non-amputated leg. The average vertical and anteroposterior GRF time-curves, average electromyographic activity, and descriptor variables were then analysed. We observed decreases in vertical and anteroposterior GRF magnitudes as well as in anteroposterior GRF descriptor variables during the propulsive phase in the amputated leg. There were increases in phasic muscle activity and co-activation in the non-amputated leg. We concluded that, during walking, the unilateral transfemoral amputees (who were analysed in this case series) developed lower GRF in the amputated limb and a longer period of electromyographic activity in the non-amputated limb.

A preliminary investigation of powered prostheses for improved walking biomechanics in bilateral transfemoral amputees.

The authors conducted a preliminary investigation of the extent to which a pair of powered prostheses can provide improved gait biomechanics in bilateral transfemoral amputee walking. Specifically, a finite state-based impedance controller for level ground walking was implemented in a pair of powered knee and ankle prostheses. The efficacy of the powered prostheses and impedance-based controllers was tested on a healthy subject using able-body adapters. Motion capture data was collected while the subject performed treadmill walking with the powered prostheses. This kinematic data is compared to that of healthy subjects, and also to previously published data for bilateral transfemoral amputee gait with passive prostheses. The comparison indicates that the powered prostheses are able to provide a walking gait that is considerably more representative of healthy biomechanical gait relative to passive prostheses.