Search Results (64)

This study investigated the feasibility and biomechanical effects of volitional electromyography (EMG)-based control of a powered transtibial ankle prosthesis. Four male participants completed static and dynamic EMG assessments and gait analysis while using both their prescribed passive prosthesis and an EMG-controlled powered prototype during level walking at self-selected and fast speeds, as well as ramp ascent and descent. Selective activation of residual tibialis anterior and gastrocnemius muscles was quantified using a co-contraction index, and lower-limb kinematics and kinetics were compared between prosthetic conditions. Participants were able to generate task-dependent residual muscle activity, supporting the feasibility of EMG-based volitional control. However, muscle selectivity was reduced during dynamic tasks, with higher co-contraction during gait than during seated static contractions, and substantial inter-subject variability was observed. Compared to the prescribed passive prosthesis, the EMG-controlled prototype generally produced lower prosthetic-side ankle range of motion and ankle power, although ankle moments were sometimes slightly greater. These findings suggest that EMG control is feasible, but that future controller design must remain flexible to individual users’ neuromuscular abilities and dynamic control limitations. The results provide important guidance for the development and testing of more adaptive, personalized, and functionally effective EMG-controlled prosthetic ankle systems. Full article

Background/Objectives: Statistical shape modeling (SSM) is used to describe transtibial residual-limb morphology for prosthetic socket design, simulation, and future structural testing. However, conventional intrinsic metrics such as compactness, generality, and specificity may not directly reflect geometric fidelity to the original shape. This study examined the relationship between geometric fidelity and SSM evaluation and assessed a cross-sectional shape representation framework for transtibial residual limbs. Methods: Residual-limb surfaces were acquired from 62 adults with unilateral transtibial amputation using a structured-light 3D scanner while preserving habitual limb posture. Two surface-based registration methods, non-rigid iterative closest point and Bayesian coherent point drift, were compared with a cross-sectional representation in which proximal and distal regions were sectioned separately and reconstructed by strip triangulation. Geometric fidelity to the original mesh was quantified using average symmetric surface distance (ASSD). SSM performance was evaluated using compactness, generality, and specificity. Results: The optimal cross-sectional configuration was 60 sections × 72 points. The proposed method showed the best geometric fidelity (ASSD, 1.30 ± 0.14 mm), followed by Bayesian coherent point drift (1.33 ± 0.14 mm) and non-rigid iterative closest point (1.48 ± 0.48 mm). Compactness was highest for the proposed method, reaching 95% cumulative variance in four modes, compared with five and seven modes, respectively, for the two surface-based methods. In geometry-space evaluation, the proposed method showed the lowest specificity error, while differences in generality were statistically significant but small in magnitude. Conclusions: Intrinsic SSM metrics alone were insufficient to judge registration quality in transtibial residual-limb modeling. The cross-sectional representation preserved the original surface geometry more faithfully than the evaluated surface-based methods while maintaining competitive SSM performance. Full article

Background and Clinical Significance: Conventional hard sockets are reported to result in skin breakdown for almost half of transtibial prosthesis users. Adjustable sockets have been developed to better accommodate residual limb shape and volume changes. They have demonstrated optimal skin health in prospective adult clinical studies. Case Presentation: We present the case of a 57-year-old male with a transtibial amputation who enrolled in a research study at the University of Pennsylvania. In the year before enrollment, he experienced frequent, near-constant skin breakdown of the distal residual limb at the anterior tibia due to limb volume fluctuations and excessive pressure from a conventional hard socket and was frequently unable to use his socket due to skin breakdown. The subject was fit with an adjustable, immediate fit transtibial prosthesis (iFIT Prosthetics^®). After a two-week home trial, he rated the adjustable prosthesis 62 out of 70 on an adapted Prosthetic Evaluation Questionnaire, compared with a score of 20 for his conventional prosthesis. Due to improved comfort, he discontinued the use of his conventional device. The subject was followed for over one year and wore the adjustable prosthesis exclusively without a recurrence of skin breakdown. Residual limb volume changes commonly lead to poor socket fit and skin irritation in conventionally fabricated hard sockets, often progressing to skin breakdown. In individuals with diabetes, wound healing can be prolonged and functionally limiting. In this case, an adjustable prosthesis successfully eliminated anterior tibial skin breakdown in a subject predisposed to this injury when using conventional hard sockets. Conclusions: Adjustable sockets can prevent skin breakdown in individuals with transtibial limb loss. Full article

Human locomotion relies on a proximal–distal organization of joint mechanical work that adapts to task constraints, such as those imposed by inclined walking. In individuals with transtibial amputation, loss of the biological ankle disrupts this organization, leading to proximal alterations and inter-limb asymmetries. Active mechatronic prosthetic feet have been developed within a biomechanical biomimicry framework to restore distal positive mechanical work. This exploratory study quantified the effects of an active mechatronic prosthetic foot on joint mechanical work during inclined walking. Four individuals with transtibial amputation performed instrumented treadmill walking at −3°, 0°, and +3° using their habitual passive foot and a powered foot. Positive and negative mechanical work at the ankle, knee, and hip were computed using inverse dynamics and compared with a normative reference database (n = 20). The powered foot induced modest, task-dependent modifications, mainly at the ankle and knee. In downhill walking, it promoted a more symmetrical redistribution of negative mechanical work, particularly at the knee, suggesting a partial reduction in contralateral overload. In uphill walking, distal assistance increased prosthetic-side positive work, reflecting slope-dependent reallocation rather than normalization. Although a multivariate deviation score indicated reduced deviation under the powered condition, full convergence toward the asymptomatic organization was not achieved. Full article

Background: Lower limb amputation affects physical function, mental health, and body image. Rehabilitation outcomes depend on both psychological adjustment and functional performance, including mobility and prosthesis satisfaction. This study aimed to evaluate psychological adjustment, activity restriction, and prosthesis satisfaction among lower-limb prosthetic users in Jordan using the Arabic TAPES-R. Objective: To assess, using a validated tool, the psychological adjustment, activity restriction, and prosthesis satisfaction of lower-limb prosthetic users in Jordan, aligning with the study title and cross-sectional design. Methods: This cross-sectional study included 74 unilateral lower-limb prosthetic users (66.2% male, mean age 42.4 ± 13.1 years). Sociodemographic and body composition characteristics were recorded. Participants completed the Arabic TAPES-R between September 2024 and April 2025. The TAPES-R measured psychosocial adjustment, activity restriction, and prosthesis satisfaction. Data were analyzed using descriptive statistics, Cronbach’s alpha for internal consistency, independent-samples t-tests, and Pearson correlations (p < 0.05). Results: Participants demonstrated generally positive psychosocial adjustment (Psychosocial Total = 3.08 ± 0.52) and moderate prosthesis satisfaction (Total Satisfaction = 2.23 ± 0.47), with variable activity restriction (8.76 ± 5.61). Internal consistency was strong across TAPES-R subscales (α = 0.816–0.955). Functional Satisfaction was higher in those with transfemoral than transtibial amputation (p = 0.041). Psychosocial adjustment correlated positively with prosthesis satisfaction (r = 0.48, p < 0.001) and negatively with activity restriction (r = −0.52, p < 0.001). Residual limb pain (45.9%) was associated with higher activity restriction (p = 0.022), and phantom limb pain (55.4%) with lower prosthetic satisfaction (p = 0.031). Conclusions: The Arabic TAPES-R effectively identifies psychological adjustment, activity restriction, and prosthesis satisfaction in lower-limb prosthetic users in Jordan. Participants generally reported positive psychosocial adjustment and moderate prosthesis satisfaction, but functional limitations remain, particularly in those with residual or phantom limb pain. These findings support the use of the TAPES-R as a clinical and research screening tool and provide guidance for targeted rehabilitation interventions. Full article

Monitoring the activities of athletes with lower-limb amputations who use running-specific prostheses is essential for evaluating their training regimes, as well as the effectiveness and mechanical fatigue wear of their prostheses over time. Recent advancements in Inertial Measurement Units (IMUs) and activity detection algorithms offer new opportunities for objective assessment, but their application in Paralympic sports remains unexplored. The aims of this work were to design and implement an innovative protocol and analytical software for short-term and long-term activity detection of athletes with transtibial and transfemoral amputation and then test its validity on a sample of elite Paralympic runners and triathletes. Overall, the ability of the model to detect activities presented an accuracy of 98%, and the error in the stride counting for all activities fell within a 1% margin. Full article

Since elevated temperature and humidity may occur at the prosthetic socket–skin interface, it is essential to collect thermal data from the residual limb, as this information serves as an indicator of adverse effects such as irritation, postural problems, and significant damage to health. These data are obtained non-invasively through the execution of a thermal imaging (TI) procedure. However, the precision and repeatability of a TI procedure rely significantly on its execution technique. This work presents the design and implementation of a mechatronic device that automates a thermal imaging technique. The application of the device is in lower-limb prosthetics evaluation. The proposed system improves data acquisition consistency by reducing execution time and minimizing human error, thereby enhancing the reproducibility and reliability of thermal measurements. The introduced device, Thermal Imaging Booth, proposes an automated solution for TI standardization in clinical and research settings. By minimizing inconsistencies, this system improves the diagnostic potential of thermography, facilitating its adoption in biomedical applications. Full article

Background: This scoping review systematically maps and synthesises contemporary literature on the biomechanics of active below-knee prosthetic devices, focusing on gait kinematics, kinetics, energy expenditure, and muscle activation. It further evaluates design advancements, including powered ankle–foot prostheses and variable impedance systems, that seek to emulate physiological ankle function and enhance mobility outcomes for transtibial amputees. Methods: This review followed the PRISMA-ScR guidelines. A comprehensive literature search was conducted on ScienceDirect, PubMed and IEEE Xplore for studies published between 2013 and 2023. Search terms were structured according to the Population, Intervention, Comparator, and Outcome (PICO) framework. From 971 identified articles, 27 peer-reviewed studies were found to meet the inclusion criteria between January 2013 and December 2023. Data were extracted on biomechanical parameters, prosthetic design characteristics, and participant demographics to identify prevailing trends and research gaps. This scoping review was registered with Research Registry under the following registration number: reviewregistry 2055. Results: The reviewed studies demonstrate that active below-knee prosthetic systems substantially improve gait symmetry and ankle joint range of motion compared with passive devices. However, compensatory trunk and pelvic movements persist, indicating that full restoration of natural gait mechanics remains incomplete. Metabolic efficiency varied considerably across studies, influenced by device design, control strategies, and user adaptation. Notably, the literature exhibits a pronounced gender imbalance, with only 10.7% female participants, and a reliance on controlled laboratory conditions, limiting ecological validity. Conclusions: Active prosthetic technologies represent a significant advancement in lower-limb rehabilitation. Nevertheless, complete biomechanical normalisation has yet to be achieved. Future research should focus on long-term, real-world evaluations using larger, more diverse cohorts and adaptive technologies such as variable impedance actuators and multi-level control systems to reduce asymmetrical loading and optimise gait efficiency. Full article

Background/Objective: Postural control differs between individuals with lower limb amputation and the general population. Although previous studies examined the effects of unexpected surface perturbations on postural control in individuals with transtibial amputation (TTA) and individuals with transfemoral amputation (TFA), their impact on lower limb muscle activation remains unclear. This study aimed to assess postural control on a stable surface and to evaluate the effects of unexpected surface perturbations on lower limb muscle activation in unilateral TTAs, TFAs, and in a healthy control group (CG). Methods: The study included 10 TTAs, 9 TFAs, and 10 healthy controls. Postural control was assessed using a force platform, and lower limb muscle activity was recorded with surface electromyography during unexpected surface perturbations. Results: The TFAs showed the highest anteroposterior and lateral postural sway under compliant surface eyes closed and the highest lateral sway under normal surface eyes closed, whereas the CG showed the lowest values (p < 0.05). During forward perturbations, rectus femoris (RF) and tibialis anterior (TA) activations were significantly higher than biceps femoris (BF) and medial head of the gastrocnemius (GM) activations, respectively, across all groups (p < 0.05). During backward perturbations, GM activations exceeded TA activations in all groups, while BF activations were higher than RF only in TTAs (p < 0.05). Significant group effects were found for RF and BF during forward perturbations, and side effects for BF (forward) and RF (backward) activations (p < 0.05). Conclusions: Postural control responses vary with the level of lower limb amputation. TFAs relied more on visual input during quiet standing, whereas TTAs demonstrated greater reliance on thigh muscle activation during surface perturbations. These findings highlight the need to consider amputation level in balance and rehabilitation programs. Full article

Monitoring mobility outcomes in real-world environments can provide a distinct perspective compared to traditional outcome measures obtained in laboratory or clinical settings, which may be limited by environmental factors or behavioral modification. Here, we present an ecologically valid framework for collecting mobility outcomes in everyday life by utilizing prosthesis-mounted wearable sensors. The custom sensor suite, consisting of five inertial measurement units, GPS, and environmental sensors, was worn by 14 individuals with unilateral transtibial amputation for approximately 4 weeks each. Across the monitoring period, 49,577 ± 30,468 (mean ± SD) strides were identified per participant (~10.2 sensor-hours per day). Strides were characterized according to walking bout duration, with most walking observed in relatively short walking bouts (<30 s) at slow walking speeds (~0.5 m/s). Turns were identified and characterized by magnitude, direction, strides, and time taken to complete. The percentage of prosthetic-inside turns was around 50% for less than 90° turns, but higher turn angles showed bias toward prosthetic-outside turns, on average. Most individual participants showed bias toward one direction or the other. Participants also averaged ~28.3 stair-steps per sensor-day. Stair-steps were biased toward upstairs (vs. downstairs) walking and toward step-over-step (vs. step-by-step) strategies. Collectively, these data provide a uniquely detailed evaluation of locomotion behaviors among persons with lower limb loss in everyday living. Future work could utilize the ecological framework described here for establishing functional benchmarks, assisting with device prescription, and otherwise guiding long-term care for optimizing mobility outcomes and quality of life after lower limb loss. Full article

Background/Objectives: The projected rise in limb amputations highlights the need for advancements in prosthetic technology. Current transtibial prosthetic designs primarily focus on sagittal plane kinematics but often neglect both the ankle kinematics and kinetics in the coronal plane, and the metatarsophalangeal joint, which play critical roles in gait stability and efficiency. This study aims to evaluate the combined effects of compliance in the coronal plane and a flexible toe joint on prosthetic gait using non-amputated participants as a model. Methods: We conducted gait trials on ten non-amputated individuals in the presence and absence of compliance in the coronal plane and toe compliance, using a previously developed three-degree-of-freedom (DOF) prosthetic foot with a prosthetic simulator. We recorded and analyzed sagittal and coronal kinematic data, ground reaction forces, and electromyographic signals from muscles involved in the control of gait. Results: The addition of compliance in the coronal plane and toe compliance had significant kinematic and muscular effects. Notably, this compliance combination reduced peak pelvis obliquity by 27%, preserved the swing stance/ratio, and decreased gluteus medius’ activation by 34% on the non-prosthetic side, compared to the laterally rigid version of the prosthesis without toe compliance. Conclusions: The results underscore the importance of integrating compliance in the coronal plane and toe compliance in prosthetic feet designs as they show potential in improving gait metrics related to mediolateral movements and balance, while also decreasing muscle activation. Still, these findings remain to be validated in people with transtibial amputations. Full article

Background/Objective: Changes in limb volume affect prosthetic socket fit and limb health, which in turn affects the comfort, stability, and usability of a prosthesis. The objective of this research was to identify and evaluate residual limb fluid volume metrics that could be used to identify the need for a prosthetic socket modification or replacement. Methods: A prospective observational study was conducted with transtibial prosthesis users undergoing socket modification or replacement. Participants performed a morning and afternoon 20 min structured activity protocol and self-reported their average socket comfort and other health outcomes before and after their socket was modified or replaced. Limb fluid volume changes across the protocol were recorded using bioimpedance analysis. Results: Anterior region residual limb fluid volume loss was low when the socket comfort score was high. Participants with ESCS_ave increases of ≥2 points pre- to post-modification experienced less limb fluid volume loss post-modification minus pre-modification (mean +0.6%) compared to participants with ESCS_ave increases of <2 points (mean −0.9%) (p = 0.0002). Conclusions: The percentage of fluid volume in the anterior limb may be a useful quantitative metric to explore for the application of bioimpedance monitoring in clinical care, helping to identify when sufficient change has occurred such that a new socket is warranted. Full article

Standardizing socket design and maintaining a default socket alignment in transtibial prostheses are innovations that aim to simplify fitting procedures and reduce prosthetic service costs, particularly in low-income countries. Objectives: This study evaluated the Mercer Universal Prosthesis (MUP) with a standardized “neutral alignment” against custom-made conventional prostheses (CVPs). Methods: Twenty transtibial amputees (n = 20) completed gait assessments using their CVP and immediately after fitting with an MUP. Temporal–spatial and sagittal plane kinematics (hip, knee, and ankle angles) were analyzed, along with a gait symmetry index. Results: the MUP group reported a significant difference between the prosthetic and the intact limb for both hip and knee kinematics (p < 0.05), but there was no change in the CVP group. When compared with the sound limb in the MUP group, post hoc analysis showed that both hip flexion and the hip range of motion (ROM) in the MUP limb significantly increased by 5.7° and 7.3° (p = 0.002 and p < 0.001, respectively). Spatial and temporal gait parameters were comparable between the MUP and CVP groups, and gait symmetry showed no significant differences. The CVP showed greater symmetry in terms of hip (19%, p = 0.012) and knee flexion (8%, p = 0.026) compared to the MUP, while the MUP had higher plantarflexion symmetry (24.4%, p = 0.013). Conclusions: Immediately post fitting, MUP improved joint mobility in the prosthetic limb, potentially enhancing kinematics. While short-term benefits are evident, further research is needed to assess long-term gait adaptation and quality of life impacts. Full article

Background: Despite the development of manual and passive mechanisms for adjusting prosthesis length, their efficiency remains limited, and users continue to face challenges related to leg length discrepancy (LLD). This dysfunction is an unresolved issue in prosthetics, and the lack of a prosthesis capable of automatically correcting LLD highlights a critical gap in the field. Methods: This study introduces a transtibial self-adaptive prosthesis capable of autonomously compensating for LLD. The prosthesis’s performance was evaluated using the ARAMIS 3D Digital Image Correlation (DIC) system, which monitored the displacement of markers strategically placed on a test mannequin in a strategic manner. Simulated LLDs were generated by inserting standardized plates beneath the mannequin’s intact limb. Results: The proposed prosthesis demonstrated efficient compensation of simulated LLD, with a mean relative error of 8.8% for a 1 mm simulation and 7.2% for a 10 mm simulation. The DIC system highlighted the rapidity and precision of the prosthesis mechanism in adjusting its length to eliminate LLD. Conclusions: The proposed transtibial self-adaptive prosthesis represents a significant advancement in the automatic correction of LLD, enhancing gait symmetry and user stability. The results suggest substantial potential for clinical applications, with promising implications for users of unilateral prostheses. Full article