Search Results (378)

Upper-limb impairments affect a substantial portion of the global population, often limiting the ability to perform daily activities. Robotic rehabilitation systems offer a promising solution by enabling high-dose, task-oriented therapy with consistent and objective feedback. However, user acceptance and perceived comfort are critical for their successful adoption. This work presents a feasibility, performance, and comfort evaluation of a 2-degree-of-freedom upper-limb rehabilitation exoskeleton capable of performing elbow flexion/extension and forearm pronation/supination. A total of 47 healthy participants were enrolled and tested across three rehabilitation modalities: passive assist, active assist, and active resist. Passive assist enabled full range-of-motion execution, active assist supported movement, and active resist provided variable resistance via a sliding bar (0–100%). Objective performance metrics, including position, current, and temperature, were recorded and analyzed, revealing trajectory-tracking errors during passive assistance of 4.82° ± 0.02° for forearm movement and 1.20° ± 0.04° for elbow movement, with actuator temperatures remaining below their rated limits throughout the study. The active assist mode did not achieve a true assist-as-needed performance, indicating a need for further refinement. Subjective evaluation included the System Usability Scale, yielding a score of 87.1 ± 9.6, indicating excellent usability, and a safety and comfort assessment averaging 4.4 ± 0.4 out of 5. Perceived effort was assessed using the Borg CR-10 scale and generally scaled appropriately across modalities, although some variability suggests the need for further investigation. Qualitative feedback identified areas for improvement, particularly in ergonomics and control behavior. Overall, the results support the feasibility, usability, and safe operation of the proposed exoskeleton and provide insights for future device refinement and evaluation with target user populations. Full article

Background and Objectives: The surgical management of displaced scapular fractures remains controversial, particularly regarding the importance of restoring scapular alignment. This study evaluated radiologic restoration and clinical outcomes following posterior fixation of displaced scapular fractures, with a particular focus on correction of lateral border offset (LBO) and angular deformity. Materials and Methods: This retrospective case series included 20 patients who underwent posterior open reduction and internal fixation for displaced scapular fractures between 2017 and 2024 with a minimum follow-up of 12 months. Surgical indications included lateral border offset (LBO) > 20 mm, angular deformity > 30°, or displaced intra-articular fractures with step-off > 3 mm. Radiologic parameters including LBO, angular deformity, and intra-articular step-off were measured using computed tomography before and after surgery. Clinical outcomes were evaluated using shoulder range of motion (ROM), Disabilities of the Arm, Shoulder and Hand (DASH) score, and modified American Shoulder and Elbow Surgeons (ASES) score. Results: Significant postoperative improvement was observed in all radiologic parameters. Mean LBO improved from 18.9 ± 10.7 mm (range, 0–45.5 mm) to 3.1 ± 7.1 mm (range, 0–29.9 mm), angular deformity improved from 28.7° ± 11.3° (range, 10.2–48.1°) to 0.9° ± 3.9° (range, 0–17.8°), and intra-articular step-off improved from 6.4 ± 2.0 mm (range, 3.7–9.7 mm) to 1.8 ± 0.5 mm (range, 1–2.5 mm). At final follow-up, mean forward flexion was 126° ± 34.4° (range, 10–170°) and external rotation was 62.3° ± 20.8° (range, 0–90°). Mean DASH and modified ASES scores were 27.3 ± 17.3 (range, 8.3–74.2) and 71.6 ± 15.0 (range, 25.8–89), respectively. Glenoid involvement was not associated with inferior clinical outcomes, whereas associated ipsilateral upper extremity injuries tended to be related to poorer functional results. Conclusions: Posterior fixation effectively restored scapular alignment and articular congruity in displaced scapular fractures. Restoration of LBO and correction of angular deformity may represent important surgical objectives for correction of glenoid medialization and restoration of normal scapular alignment. Full article

Upper-limb rehabilitation and elderly exercise programs require lightweight, reliable, and physiotherapy-oriented assistive technologies capable of supporting controlled joint motion while enabling objective performance assessment. This paper presents experimental validation of ASSIST-FEEv3, a cable-driven elbow assisting device that is designed for flexion–extension exercises with emphasis on usability, portability, and physiotherapy integration. The device employs a dual-cable antagonistic mechanism that is actuated by servomotors housed in a compact module, allowing guided motion in the arm sagittal plane with minimal wearable load mass. A testing campaign was conducted with 25 healthy volunteers under the supervision of physiotherapy experts following a properly designed protocol for three sessions of ten repetitions each. Joint kinematics was acquired through integrated sensing, and performance metrics including maximum flexion, maximum extension, and range of motion (ROM) were analyzed to assess repeatability, motion smoothness, and user-specific variability. The results demonstrate consistent motion assistance across repeated cycles, variability between sessions, and comparable ROM distributions between sexes. Observed deviations were considered due to individual temporary conditions rather than device-related limitations. The device operated with low energy consumption as required in home-based applications. Test findings validate both the mechanical reliability and the physiotherapy-oriented operational framework of the ASSIST-FEEv3 device. Full article

Inspired by the energy-efficient resonance strategy of the human elbow joint during periodic arm swing, this paper investigates the energy-saving motion and performance of a robotic variable stiffness joint. A modular stiffness adjustment mechanism with continuously adjustable stiffness based on Archimedean spiral grooves is proposed. A co-simulation model using MATLAB (R2022b)/ADAMS (2020) is established, and dynamic equations are derived to reveal the correlation between resonance/anti-resonance frequencies and joint rotational stiffness. Mimicking the biological principle of stiffness-frequency matching, an energy-saving controller leveraging the resonance effect is designed, which includes a motor energy consumption model to quantify losses and an optimization strategy to match the joint rotational stiffness with the load anti-resonance frequency. Simulation results demonstrate that in variable stiffness mode, aligning the system anti-resonance frequency with the task trajectory frequency significantly reduces joint energy consumption, validating the bioinspired approach. In contrast, the high-stiffness (rigid) mode leads to a surge in system energy consumption. Full article

Objective: Volleyball athletes require well-developed balance control during spiking, blocking, rapid movement, and landing. Joint range of motion (ROM) may also influence limb extension, support adjustment, and center-of-mass control. Previous studies have usually examined balance ability and joint ROM as separate factors related to volleyball performance. However, the associations between dynamic balance, static balance, and multi-joint ROM in the upper and lower limbs remain insufficiently understood. This study therefore aimed to examine the relationship between balance performance and upper- and lower-limb joint ROM in female college volleyball athletes. Methods: Thirty-five female college volleyball athletes were included. Dynamic balance of the upper and lower limbs was assessed using the Y-Balance Test, and static balance was evaluated under eyes-open and eyes-closed conditions using a static balance platform. Upper- and lower-limb ROM was measured using an electronic goniometer and the knee-to-wall test. Paired-sample t-tests were used to compare bilateral differences and differences between visual conditions. Pearson correlation analysis was performed to examine associations between joint ROM and balance performance, and false discovery rate (FDR) correction was applied to account for multiple comparisons. Results: (1) No significant bilateral difference was observed in upper-limb YBT-UQ performance (p > 0.05); for lower-limb YBT-LQ performance, a significant difference was found only in the anterior direction, with the right side showing higher values than the left side (p < 0.01). (2) Static balance parameters under the eyes-closed condition were significantly poorer than those under the eyes-open condition (p < 0.01); under the same visual condition, only the total sway path length of the right foot was significantly shorter than that of the left foot (p < 0.05). (3) The ranges of motion of right shoulder flexion, shoulder horizontal adduction, shoulder external rotation, elbow flexion, and knee-to-wall distance were significantly greater than that of the left side (all p < 0.05), and right hip internal rotation ROM was also significantly greater than that of the left side (p < 0.01). (4) Dynamic balance was correlated with selected joint ROM measures. Specifically, the anterior reach direction of the right YBT-LQ was positively correlated with hip flexion ROM (r = 0.593, p < 0.01) and knee-to-wall distance (r = 0.653, p < 0.01), and these correlations remained statistically significant after FDR correction. (5) Static balance parameters were correlated with selected lower-limb joint ROM measures in the original correlation analysis; however, these correlations did not remain significant after FDR correction. Conclusions: Female college volleyball athletes demonstrated a certain degree of bilateral asymmetry in dynamic balance and a pronounced dependence on visual input during static balance tasks. After FDR correction, the associations between the anterior reach direction of the right YBT-LQ and both hip flexion ROM and knee-to-wall distance remained stable, suggesting that these ROM measures may be related to anterior dynamic balance performance. These findings may provide a reference for postural control assessment and the development of sport-specific training programs for female volleyball athletes. Full article

Background and Objectives: Brachial plexus birth injury (BPBI) is a peripheral nerve injury occurring during birth that may result in upper-extremity weakness and functional impairment. This systematic review aimed to evaluate the effects of neuromuscular electrical stimulation (NMES) on motor function, muscle strength, range of motion, and upper-extremity function in children with BPBI. Materials and Methods: This systematic review was conducted according to PRISMA guidelines and registered in PROSPERO. PubMed, CINAHL, Scopus, Web of Science, PEDro, and the Cochrane Library were searched from inception to 5 May 2026. Only randomized controlled trials were included. Methodological quality was assessed using the PEDro scale, and risk of bias was evaluated using the RoB 2 tool. Results: Seven randomized controlled trials involving 197 participants were included. Several studies reported improvements in shoulder abduction, elbow flexion, wrist extension, muscle strength, and motor function following NMES compared with conventional therapy. The combination of NMES and constraint-induced movement therapy demonstrated favorable outcomes in functional performance. However, substantial heterogeneity was observed across studies regarding participant characteristics, NMES parameters, treatment duration, and outcome measures. The certainty of evidence ranged from low to very low. Conclusions: Current evidence suggests that NMES may serve as a potential adjunct to conventional rehabilitation in children with BPBI. However, given the low to very low certainty of the evidence, high risk of bias, and substantial clinical and methodological heterogeneity among the included studies, definitive clinical recommendations cannot currently be made. Future well-designed randomized controlled trials using standardized protocols, consistent outcome measures, and longer follow-up periods are warranted. Full article

This exploratory study compares the Froude efficiency (η_F), intra-cyclic speed fluctuation (ICSF) and other performance determinants between two freestyle swimming techniques: double-arm backstroke and front crawl, and then demonstrates how Para swimmers with hypertonia differ from non-disabled swimmers when performing double-arm backstroke. Three-dimensional motion analysis was undertaken on three Para swimmers with hypertonia (sport classes 3–4) and eight non-disabled swimmers performing a simulated double-arm backstroke with lower limbs immobile. The non-disabled group also completed front crawl trials. Swimming speed, stroke frequency, stroke length and η_F were significantly greater, and ICSF significantly lower, during front crawl than during double-arm backstroke in non-disabled swimmers. Para swimmers’ double-arm backstroke speed was 45–52% that of the non-disabled group; their stroke length was 58–69% shorter and stroke frequency 26–53% higher. Non-disabled swimmers demonstrated higher peak elbow extension velocity during the push phase than Para swimmers (6.36 ± 1.26 rad∙s⁻¹ vs. 1.50–1.81 rad∙s⁻¹) and their η_F was approximately double the Para swimmers’ (0.33 ± 0.02 vs. 0.14–0.18). Para swimmers displayed poorer body alignment than the non-disabled group; ICSF did not differ between groups. Double-arm backstroke is slower and less efficient than front crawl. Hypertonia may reduce the efficiency of double-arm backstroke by diminishing propulsive movements and worsening body orientation. Full article

Background/Objectives: Accurate and accessible assessment of upper-limb motion is essential for rehabilitation research, ergonomic evaluation, human–machine interaction, and limb exercise. This work presents a comparative evaluation of upper-limb joint angle estimation obtained from wearable inertial measurement units (IMUs) using a Kinect-based practical benchmark during synchronized data acquisition. Methods: The main variables analyzed were shoulder and elbow joint angles, together with IMU-derived acceleration and surface electromyography (sEMG) signals acquired as complementary physiological information during task execution. Ten healthy adult participants performed predefined upper-limb movements while data from both sensing modalities were recorded simultaneously. Joint angles were estimated independently from IMU and Kinect measurements and compared using Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Two One-Sided Tests (TOST) equivalence analysis. Results: For upper- limb motion, IMU-derived estimates showed practical equivalence within the predefined ±10° acceptance margin with small MAE and RMSE values and significant TOST equivalence results (p < 0.001), supporting reliable proximal joint tracking under controlled conditions. Tested elbow motion exhibited large estimation error and large variability, and although the TOST analysis was significant, the equivalence interval slightly exceeded the predefined acceptance bound, indicating comparatively weak agreement between sensing modalities. The presented results should be interpreted as proof-of-concept evidence derived from a comparative benchmark rather than as definitive validation for unrestricted or clinical implementation. The synchronized acceleration and sEMG signals provided complementary temporal information regarding movement execution but were not treated as primary comparative outputs. Conclusions: These findings support the feasibility of wearable IMU-based upper-limb joint angle estimation as a proof-of-concept comparative framework rather than definitive clinical validation. The presented findings support the feasibility of the proposed IMU-based sensing approach for upper-limb joint angle estimation, particularly at the shoulder level, while also highlighting the greater complexity of elbow-related measurements. Further investigation in larger samples, more functionally diverse tasks, and broader populations is required to extend the applicability of the proposed approach. Full article

Resolving the kinematic redundancy of 7-DoF humanoid arms to generate natural, human-like motions remains a fundamental challenge in biomimetic robotics. This paper presents a hybrid inverse kinematics (IK) framework that learns a pose-dependent redundancy parameter and integrates it into a differential IK solver. Specifically, we employ the stereographic Shoulder–Elbow–Wrist (SEW) angle as a well-conditioned geometric parameterization. This formulation transforms the algorithmic singularity into a unidirectional half-line, which can be oriented outside the typical reachable workspace. To specify the optimal configuration within the self-motion manifold, a motion dataset was collected by teleoperating a humanoid arm via an anthropomorphic wearable exoskeleton. This approach translates operator-specific postural preferences into the robot’s joint space. A lightweight neural network was then trained to learn the mapping from end-effector poses to these operator-specific SEW angles. By incorporating the predicted SEW angle as a dynamic secondary objective in the null space of the primary tracking task, the proposed framework enables natural redundancy resolution while preserving end-effector tracking accuracy. Both simulations and real-robot experiments were conducted to validate the approach. Results show that, compared to the average performance of static fixed-parameter strategies, the proposed method improves the Joint Configuration Quality Index (CQI) by 22.5% and reduces energy costs by 11.3%. Moreover, the sub-millisecond inference latency (0.44 ms) facilitates seamless integration into real-time control pipelines. Full article

Accurate and unobtrusive measurement of upper-limb kinematics is critical for advancing wearable sensing technologies used in industrial ergonomics, human–machine interaction, and real-time biomechanics monitoring. This study evaluates the performance of two soft, flexible wearable sensors—BendLabs biaxial angular displacement sensors and StretchSense capacitive stretch sensors—for quantifying wrist and elbow motions during simulated dynamic industrial tasks. Wrist flexion–extension and radial–ulnar deviation were measured using BendLabs sensors mounted on the dorsal hand, while elbow flexion–extension was captured using StretchSense sensors positioned along the elbow joint. A multi-camera optical motion capture system served as the reference standard. Sensor data were preprocessed using baseline correction, smoothing, denoising, and normalized cross-correlation techniques to support temporal alignment with motion-capture recordings. Across all activities, the BendLabs sensors demonstrated moderate agreement with motion capture for wrist kinematics, with generally better performance for radial–ulnar deviation than for flexion–extension. StretchSense sensors demonstrated stronger agreement with motion capture for elbow flexion–extension, with performance that was generally consistent across task types. These findings support the feasibility of soft wearable sensors for capturing upper-limb kinematics during simulated occupational tasks and highlight their potential for integration into ergonomic assessment, occupational monitoring systems, and future industrial wearable platforms. Full article

Research on human motion representation commonly investigates portable, wearable, and ergonomic sensing systems. Cameras, infrared sensors, and inertial measurement units (IMUs) are widely used to reproduce and validate human movement. Known limitations persist, including increased error during slow movements, the gimbal lock effect in Euler space, and the requirement for one sensor per joint. The objective of this work is twofold: first, to characterize the measurement accuracy of a commercial IMU sensor (BWT901BLE) under controlled conditions using a fixed-arm pendulum model that replicates the single-degree-of-freedom planar kinematics of elbow flexion–extension, comparing angular position, angular velocity, and angular acceleration outputs against a video-based reference system; and second, to describe and publish a complete data processing pipeline—from raw sensor readings to real-time biomechanical motion visualization within OpenSim—demonstrated through upper limb motion recordings from 6 participants, whose data were used to generate motion files and estimate muscle fiber lengths and activation patterns within OpenSim. Regarding sensor characterization, experiments compared sensor data against the video-based reference. The inter-sensor angular position mean error was 0.765° (100 Hz) and 0.445° (200 Hz); angular velocity mean error was 0.124°/s (100 Hz) and 0.277°/s (200 Hz). Direct Euler angle measurements outperformed quaternion-to-Euler conversion (mean RMSE 5.69° vs. 53.1° at 100 Hz; 5.08° vs. 41.8° at 200 Hz). Angular velocity showed the highest agreement with the video-based reference (mean RMSE 0.60 rad/s at 100 Hz and 0.43 rad/s at 200 Hz; mean R = 0.982 and 0.991). Raw accelerometer output showed negligible correlation with the video-based angular acceleration reference (mean R ≈ 0.00–0.05); however, acceleration derived from angular velocity differentiation achieved high accuracy (mean RMSE 4.43 rad/s² at 100 Hz and 3.06 rad/s² at 200 Hz; mean R = 0.976 and 0.989). Regarding the OpenSim integration, the real-time visualization pipeline achieved an effective frame rate of 40–50 fps with an estimated end-to-end latency of 35–50 ms, and the recorded motion data were used to estimate muscle fiber lengths and activation patterns through OpenSim’s analysis tools. These findings confirm that angular velocity is the most reliable output of this sensor class. Full article

Upper-limb exoskeletons require precise geometric alignment between the device’s mechanical axes and the user’s anatomical joints to preserve physiological mobility and prevent functional constraints; however, many occupational exoskeleton designs oversimplify scapulothoracic mobility, potentially reducing the functional workspace and leading to kinematic misalignment during arm elevation tasks. In this context, the present study addresses this limitation by developing the design, kinematic modeling, and experimental validation of a 7-DoF passive upper-limb exoskeleton organized into dorsal, shoulder, and elbow modules, where the proposed architecture explicitly incorporates 3-DoFs in the dorsal region to accommodate scapular motion within a unified serial kinematic chain. From a modeling standpoint, the kinematic formulation is established using the Denavit–Hartenberg convention, enabling the analysis of the workspace, the properties of the Jacobian matrix, and the identification of potential singular configurations; simulation results demonstrate a continuous workspace within the evaluated functional range, with no singularities detected in the region of interest. Regarding experimental validation, two complementary approaches are implemented: a 2D video-based analysis using Kinovea compares joint trajectories with and without the exoskeleton, revealing strong kinematic agreement ($RMSE⩽$ 6.11 mm, $R^2\ge$ 0.8746), while a 3D motion-capture validation using the Qualisys system evaluates the kinematic coupling between the human arm and the exoskeleton during assisted movement, yielding high correspondence between both trajectories ($R^2$ = 0.975). Overall, the results confirm the geometric consistency of the proposed architecture and provide a solid methodological foundation for the future development of passive or hybrid upper-limb exoskeletons with integrated dorsal mobility. Full article

Over the past decade, serious games and virtual reality have gained increasing relevance in upper-limb rehabilitation, yet desktop virtual reality solutions often suffer from reduced spatial correspondence and limited sensory feedback. This work presents the design and preliminary evaluation of a desktop virtual reality-based serious game that combines Leap Motion Controller hand tracking with a custom wireless vibrotactile wearable device to support upper-limb rehabilitation training. Three training scenarios were implemented to target pronation/supination, pinch grip, ulnar/radial deviation, and wrist, elbow, and finger flexion/extension. Usability (System Usability Scale, SUS), user experience (short AttrakDiff), and perceived workload (Raw NASA-TLX), together with functionality and perception questionnaires, were collected from healthy participants randomly assigned to two groups (Group 1: $n=13$, LMC only; Group 2: $n=9$, LMC plus wearable). Across all instruments, the configuration including the wearable device tended to obtain higher usability ratings, more desirable pragmatic and hedonic quality scores, and lower overall workload means than the LMC-only configuration, with moderate effect sizes but limited statistical power due to the small samples. Participants in the wearable condition also reported clearer feedback, a perceived improvement in movement precision, and a stronger perceived alignment between real and virtual actions. These findings suggest that the proposed system may serve as a promising user-centered prototype for desktop VR-based upper-limb rehabilitation and provide preliminary design evidence to support future clinical and kinematic validation studies with larger cohorts. Full article

Background: Complex elbow soft-tissue defects often combine exposed critical structures, unstable scars, and high mechanical stress, making durable coverage and early mobilization challenging. Among regional options, the reverse lateral arm flap provides thin fasciocutaneous tissue based on a reliable collateral circulation and preserves major forearm vessels. The aim of this study was to report our single-center experience with the pedicled reverse lateral arm flap for elbow soft-tissue reconstruction, focusing on stable coverage, donor-site morbidity, and functional recovery. Methods: A retrospective single-center case series was conducted at the Division of Plastic Surgery, University Hospital of Padua, Italy. All consecutive patients treated between 2013 and 2023 with a pedicled reverse lateral arm flap for elbow soft-tissue defects were included. Recorded variables included defect etiology, donor-site management, complications, range of motion, and follow-up. Elbow flexion–extension was recorded clinically preoperatively and at last follow-up. Minimum follow-up was 12 months in all patients. Results: Seven patients underwent reconstruction. Defect etiology was burn-related in four cases, shotgun trauma in one, crush injury in one, and melanoma resection in one. All defects were covered with a pedicled reverse lateral arm flap. All flaps survived completely without partial necrosis or flap-related reoperation. Donor-site closure was primary in four patients and required split-thickness skin grafting in three. One patient developed donor-site keloid, and one had donor-site skin-graft partial loss with delayed healing. Elbow flexion–extension improved in all seven cases, with a median gain in arc of motion of 25° (range 15–41°). Conclusions: In this series, the reverse lateral arm flap provided complete coverage of selected elbow defects with preserved motion and limited donor-site morbidity at a minimum follow-up of 12 months. Our findings suggest that it may represent a useful regional option in selected posterior and lateral elbow defects, particularly in post-burn and traumatic settings where thin vascularized tissue is needed, and free-flap reconstruction may be avoidable. Full article

Background/Objectives: Gartland Type III supracondylar humerus fractures (SCHFs) represent the most surgically challenging pediatric elbow injuries, yet controversy persists regarding whether the timing of surgery, specifically after-hours versus working-hours operations, influences clinical and radiological outcomes. This study aimed to compare the functional, cosmetic, and radiological outcomes of Gartland Type III SCHFs managed during working hours versus after hours, with a secondary analysis incorporating the surgical approach (open vs. closed reduction). Methods: A retrospective cohort study was conducted, including 91 pediatric patients who underwent surgical treatment for Gartland Type III SCHFs between January 2020 and June 2025. Patients were stratified into working-hours (n = 48) and after-hours (n = 43) groups. Outcomes were assessed using Flynn’s criteria, radiological parameters, range-of-motion measurements, and complication rates. A secondary subgroup analysis was performed across four groups formed by combining surgical timing and approach. Results: The mean patient age was 70.36 ± 32.97 months with a mean follow-up of 28.07 ± 14.66 months. The time to surgery was significantly shorter in the working-hours group (median 16.0 h; IQR 13.5–20.0) compared with the after-hours group (median 20.0 h; IQR 17.0–27.0) (p = 0.009). No significant differences were observed between the two groups with respect to functional outcomes, cosmetic outcomes, radiological parameters, or overall complication rates (all p > 0.05). However, four-group subgroup analysis revealed a significant difference in Flynn’s functional outcomes (p = 0.019), with the after-hours open reduction subgroup demonstrating a lower rate of excellent results (76.92%) compared with the remaining subgroups (96.88–100%). Conclusions: Working-hours versus after-hours surgical timing alone does not significantly alter clinical or radiological outcomes in Gartland Type III SCHFs. However, the combination of after-hours surgery with open reduction appears to be associated with inferior functional outcomes and a trend toward higher complication rates, suggesting that open reduction for complex fractures should preferably be performed during working hours when optimal theatre conditions and experienced senior surgical teams are readily available. Full article