Search Results (269)

This study introduces a machine-learning-based approach for identifying “pain signatures” using electromyography data from volunteers undergoing acute pain. Leveraging the XGBoost algorithm, our method analyzes electromyography features (variance, mean absolute deviation, integral, peak, and entropy) to classify muscle contractions as painful or non-painful. Fifteen participants performed controlled elbow flexion tasks under three conditions: during painful and painless conditions. The results revealed that electromyographic peak and integral activity were key predictors of pain states, with the model achieving 73% sensitivity in distinguishing painful from painless conditions. Interestingly, placebo-induced responses with less intense pain exhibited muscular adaptations similar to, but less extensive than, those observed under actual pain. These findings underscore the potential of machine learning to enhance pain assessment by providing a non-verbal, objective method for analyzing neuromuscular adaptations, paving the way for personalized pain management and more accurate monitoring of musculoskeletal health. Full article

Voluntary movement arises from a sequence of neural processes that involve planning, preparation, and execution within distributed cortical networks. The readiness potential, a slow negative brain signal preceding self-initiated actions, represents a sensitive indicator of motor preparation. However, it remains unclear how this signal reflects concurrent variations in mechanical and temporal demands. In this study, twenty-eight healthy participants performed self-paced elbow flexions under nine combinations of mechanical load and movement duration while brain electrical activity, muscle activity, and movement kinematics were simultaneously recorded. Linear mixed-effects analyses revealed that the amplitude of the readiness potential increased progressively with greater mechanical load, indicating that cortical readiness scales with the intensity of preparatory effort. In contrast, longer movement durations produced smaller amplitudes, suggesting that extended temporal windows reduce the efficiency of preparatory synchronization. No significant interaction between load and duration was observed, supporting the idea of partially independent neural mechanisms for effort and timing. These findings identify the readiness potential as a neural marker integrating the energetic and temporal dimensions of voluntary movement and provide a basis for understanding how cortical readiness dynamically optimizes human motor performance. Full article

Markerless human pose estimation is increasingly used for kinematic assessment, but evidence of its applicability to upper limb movements across different ranges of motion (ROM) remains limited. This study examined the accuracy and reliability of a markerless pose estimation system for shoulder, elbow and wrist flexion–extension analysis under full and partial ROM tasks. Ten healthy participants performed standardized movements which were synchronously recorded, with an optoelectronic motion capture system used as a reference. Joint angles were compared using RMSE, percentage RMSE (%RMSE), accuracy (Acc), intraclass correlation coefficients (ICC), and Pearson correlation of ROM values. The markerless system reproduced the temporal morphology of the movement with high coherence, showing ICC values above 0.91 for the elbow and 0.94 for the shoulder in full ROM trials. Wrist tracking presented the lowest RMSE values and low inter-subject variability. The main critical aspect was a systematic underestimation of maximum flexion, especially at the shoulder, indicating a magnitude bias likely influenced by occlusion and joint geometry rather than by temporal fluctuations. Despite this limitation, the system adapted consistently to different ROM amplitudes, maintaining proportional variations in joint excursion across tasks. Overall, the findings outline the conditions in which markerless pose estimation provides reliable upper limb kinematics and where methodological improvements are still required, particularly in movements involving extreme flexion and occlusion. Full article

Background/Objectives: Non-traumatic (degenerative) rotator cuff tendinopathy with partial supraspinatus tear (NT-RCTT) is a common source of shoulder pain and disability. Comparative evidence between radial extracorporeal shock wave therapy (rESWT) and multimodal physical therapy modalities (PTMs) remains scarce. Methods: In this single-center randomized controlled trial, 60 adults with MRI-confirmed NT-RCTT were assigned (1:1) to rESWT (one session weekly for six weeks; 2000 impulses per session, 2 bar air pressure, positive energy flux density 0.08 mJ/mm²; 8 impulses per second) or a multimodal PTM program (interferential current, shortwave diathermy and magnetothermal therapy; five sessions weekly for six weeks). All participants performed standardized home exercises. The primary outcome was the American Shoulder and Elbow Surgeons (ASES) total score; secondary outcomes included pain (visual analog scale, VAS), satisfaction, range of motion (ROM), supraspinatus tendon (ST) thickness and acromiohumeral distance (AHD). Assessments were conducted at baseline, and at week 6 (W6) and week 12 (W12) post-baseline. Results: Both interventions significantly improved all outcomes, but rESWT produced greater and faster effects. Mean ASES total scores increased by 31 ± 5 points with rESWT versus 26 ± 6 with PTMs (p < 0.05). VAS pain decreased from 5.2 ± 0.7 to 1.0 ± 0.7 with rESWT and from 5.2 ± 0.8 to 1.7 ± 0.8 with PTMs (p < 0.01). rESWT achieved higher satisfaction and larger gains in abduction, flexion and external rotation. Ultrasound showed reduced ST thickness and increased AHD after rESWT but not after PTMs. No serious adverse events occurred. Conclusions: rESWT yielded superior pain relief, functional recovery and tendon remodeling compared with a multimodal PTM program, with markedly lower treatment time and excellent tolerability. Full article

Control of elbow exoskeletons using muscular signals, although promising for the rehabilitation of millions of patients, has not yet been widely commercialized due to challenges in real-time intention estimation and management of dynamic uncertainties. From a practical perspective, millions of patients with stroke, spinal cord injury, or neuromuscular disorders annually require active rehabilitation, and elbow exoskeletons with precise and safe motion intention tracking capabilities can restore functional independence, reduce muscle atrophy, and lower treatment costs. In this research, an intelligent control framework was developed for an elbow joint exoskeleton, designed with the aim of precise and safe real-time tracking of the user’s motion intention. The proposed framework consists of two main stages: (a) real-time estimation of desired joint angle (as a proxy for movement intention) from High-Density Surface Electromyography (HD-sEMG) signals using an LSTM network and (b) implementation and comparison of three PID, impedance, and sliding mode controllers. A public EMG dataset including signals from 12 healthy individuals in four isometric tasks (flexion, extension, pronation, supination) and three effort levels (10, 30, 50 percent MVC) is utilized. After comprehensive preprocessing (Butterworth filter, 50 Hz notch, removal of faulty channels) and extraction of 13 time-domain features with 99 percent overlapping windows, the LSTM network with optimal architecture (128 units, Dropout, batch normalization) is trained. The model attained an RMSE of 0.630 Nm, R² of 0.965, and a Pearson correlation of 0.985 for the full dataset, indicating a 47% improvement in R² relative to traditional statistical approaches, where EMG is converted to desired angle via joint stiffness. An assessment of 12 motion–effort combinations reveals that the sliding mode controller consistently surpassed the alternatives, achieving the minimal tracking errors (average RMSE = 0.21 Nm, R² ≈ 0.96) and showing superior resilience across all tasks and effort levels. The impedance controller demonstrates superior performance in flexion/extension (average RMSE ≈ 0.22 Nm, R² > 0.94) but experiences moderate deterioration in pronation/supination under increased loads, while the classical PID controller shows significant errors (RMSE reaching 17.24 Nm, negative R² in multiple scenarios) and so it is inappropriate for direct myoelectric control. The proposed LSTM–sliding mode hybrid architecture shows exceptional accuracy, robustness, and transparency in real-time intention monitoring, demonstrating promising performance in offline simulation, with potential for real-time clinical applications pending hardware validation for advanced upper-limb exoskeletons in neurorehabilitation and assistive applications. Full article

Background: Immersive virtual reality (VR) has emerged as a promising tool to enhance neuroplasticity, motivation, and engagement during post-stroke motor rehabilitation. However, evidence on its feasibility and data-driven integration into clinical practice remains limited. Objective: This pilot study aimed to evaluate the feasibility, usability, and short-term motor outcomes of an immersive VR-assisted rehabilitation program using the Travee-VR system. Methods: Fourteen adults with post-stroke upper-limb paresis completed a 10-day hybrid rehabilitation program combining conventional therapy with immersive VR sessions. Feasibility and tolerability were assessed through adherence, adverse events, the System Usability Scale (SUS), and the Simulator Sickness Questionnaire (SSQ). Motor outcomes included active and passive range of motion (AROM, PROM) and a derived GAP index (PROM–AROM). Correlations between clinical changes and in-game performance metrics were explored to identify potential digital performance metrics of recovery. Results: All participants completed the program without adverse events. Usability was rated as high (mean SUS = 79 ± 11.3), and cybersickness remained mild (SSQ < 40). Significant improvements were observed in shoulder abduction (+7.3°, p < 0.01) and elbow flexion (+5.8°, p < 0.05), with moderate-to-large effect sizes. Performance gains in the Fire and Fruits games correlated with clinical improvement in shoulder AROM (ρ = 0.45, p = 0.041). Cluster analysis identified distinct responder profiles, reflecting individual variability in neuroplastic adaptation. Conclusions: The Travee-VR system proved feasible, well tolerated, and associated with measurable short-term improvements in upper-limb function. By linking clinical outcomes with real-time kinematic data, this study supports the role of immersive, feedback-driven VR as a catalyst for data-informed neuroplastic recovery. These results lay the groundwork for adaptive, clinic-to-home rehabilitation models integrating clinical and exploratory digital performance metrics. Full article

The increasing aging population and the rise in sports injuries have led to greater demand for elbow function rehabilitation and daily assistance. To address the limitations of traditional rigid rehabilitation aids and existing flexible assistive systems, this paper designs a wearable elbow-assist robot that arranges pneumatic muscles based on the distribution of human elbow muscles. By integrating bionic design, experimental research, and mathematical modeling, the proposed approach determines the optimal scheme through comparative experiments on material structures and provides supporting data, while the mathematical model describes the force characteristics of the pneumatic muscles. Final experiments verify that the system can effectively assist elbow movement and significantly enhance flexion torque. Full article

This paper presents the design, prototype, and experimental evaluation of the AlmatyExoElbow, a lightweight cable-driven robotic exoskeleton that is intended to support elbow joint rehabilitation. The device provides two active degrees of freedom for flexion/extension and pronation/supination. It also incorporates a sensor-based control system for accurate motion tracking. The mechanical structure is fabricated using 3D-printed PLA plastic, resulting in a compact, modular, and comfortable design suitable for prolonged use. The control architecture is based on an Arduino Nano microcontroller integrated with IMU sensors, enabling the real-time monitoring of elbow motion and the precise reproduction of physiologically relevant movement patterns. The results of experimental testing demonstrate smooth and stable operation, confirming reliable torque transmission through antagonistic cable mechanisms. Overall, the proposed design achieves a balanced combination of functionality, portability, and user comfort, highlighting its potential for upper-limb rehabilitation applications in both clinical and home-based settings. Full article

Background/Objectives: Periprosthetic humeral fractures (PF) after reverse total shoulder arthroplasty (RSA) are expected to increase. This study investigated PF after RSA with short stems and reported outcomes. Methods: A total of 165 patients underwent short-stem RSAs between 2014 and 2023. Among them, patients who developed postoperative PFs were identified and classified by fracture location and stem loosening. Operative data, complications, and bone union time were analyzed. Clinical outcomes before injury and at final follow-up were evaluated. Results: PF occurred in 5/165 patients (3.0%). Based on our classification, four had type B1 fractures and one had a type B3 fracture. All underwent revision RSA (Re-RSA) with conversion to long-stem implants. Bone union was achieved in four patients, while one patient experienced infection without union. Among the four patients without complications, mean shoulder flexion declined from 138° pre-injury to 103°, abduction from 118° to 95°, external rotation from 37° to 31°, the American Shoulder and Elbow Surgeons (ASES) score from 82.0 to 68.7, Constant Score from 67 to 43, while the Visual Analog Scale (VAS) pain score increased from 1.7 to 2.6. Conclusions: All five cases of PF following short-stem RSA were stem-level (type B) fractures. All patients underwent Re-RSA using long-stem conversion. Four patients had bone union. Clinical outcomes at one year postoperatively had deteriorated mildly compared to pre-fracture. However, this change was not statistically significant. One patient had a postoperative infection, and bone union was not observed. This study indicates the need for caution regarding postoperative infections after RSA. Full article

Background/Objectives: Speech and motor control share overlapping neural mechanisms, yet their quantitative relationships in Parkinson’s disease (PD) remain underexplored. This study investigated bidirectional associations between acoustic voice features and objective motor metrics to better understand how vocal and motor systems relate in PD. Methods: Cross-sectional baseline data from participants in a randomized neuromodulation trial were analyzed (n = 13). Motor performance was captured using an Integrated Motion Analysis Suite (IMAS), which enabled quantitative, objective characterization of motor performance during balance, gait, and upper- and lower-limb tasks. Acoustic analyses included harmonic-to-noise ratio (HNR), smoothed cepstral peak prominence (CPPS), jitter, shimmer, median fundamental frequency (F0), F0 standard deviation (SD F0), and voice intensity. Univariate linear regressions were conducted in both directions (voice ↔ motor), as well as partial correlations controlling for PD motor symptom severity. Results: When modeling voice outcomes, faster motor performance and shorter movement durations were associated with acoustically clearer voice features (e.g., higher elbow flexion-extension peak speed with higher voice HNR, β = 8.5, R² = 0.56, p = 0.01). Similarly, when modeling motor outcomes, clearer voice measures were linked with faster movement speed and shorter movement durations (e.g., higher voice HNR with higher peak movement speed in elbow flexion/extension, β = 0.07, R² = 0.56, p = 0.01). Conclusions: Voice and motor measures in PD showed significant bidirectional associations, suggesting shared sensorimotor control. These exploratory findings, while limited by sample size, support the feasibility of integrated multimodal assessment for future longitudinal studies. Full article

Stroke is a leading cause of disability, often resulting in motor, cognitive, and language deficits, with significant impact on upper-limb function. Robotic therapy (RT) has emerged as an effective strategy, providing intensive, repetitive, and adaptable practice to optimize functional recovery. This pilot study aimed to describe and evaluate the effects of robotic rehabilitation as a complement to conventional therapy, using a biomimetic activities-of-daily-living (ADL)-based protocol, on upper-limb function in post-stroke patients. Three participants (aged 30–80 years) undergoing occupational and/or physiotherapy received individualized robotic training with a lightweight cable-driven upper-limb exoskeleton, m-FLEX™, twice a week for ten weeks (30 min per session). Movements were designed to mimic natural upper-limb actions, including elbow flexion-extension, forearm pronation-supination, tripod pinch, and functional tasks such as grasping a cup. Assessments included the Fugl-Meyer (FM) scale, the Functional Independence Measure (FIM), and device satisfaction, performed at baseline, mid-intervention, and post-intervention. Descriptive analysis of the tabulated data revealed improvements in range of motion and functional outcomes. These findings suggest that biomimetic protocol of robotic rehabilitation, when combined with conventional therapy, can enhance motor and functional recovery in post-stroke patients. Full article

Manual wheelchair propulsion is a frequent activity among people with spinal cord injury (SCI) and is linked to upper limb loading and shoulder pain. We compared propulsion strategies at cadences of 30 and 50 bpm. Kinematics and surface electromyography (EMG) were recorded across the propulsion cycle, push/recovery phases, and events. Ranges of motion for shoulder flexion/extension, adduction/abduction, and elbow flexion/extension did not differ significantly, although ROM tended to be smaller at 50 bpm; push angle was larger at 50 bpm but not significant. Propulsion cycle duration was shorter at 50 bpm (p < 0.001). Push duration was similar, but its proportion of the cycle increased at 50 bpm (p < 0.001). Recovery duration was shorter at 50 bpm (p < 0.001), yet its cycle proportion increased (p < 0.01). EMG showed cadence-specific redistribution: higher activity at 50 bpm at preparation (anterior deltoid, pectoralis major, biceps brachii, upper trapezius; p < 0.01) and at contact (posterior deltoid; p < 0.05); higher biceps brachii at release and higher anterior deltoid at end-range extension at 30 bpm (both p < 0.05). Cadence manipulation reorganized timing and muscle demands without large ROM changes, supporting rhythm-based training and propulsion design to mitigate shoulder loading. Full article

Background/Objectives: This study investigated biomechanical differences between right-handed (RHPs) and left-handed (LHPs) youth baseball players by analyzing shoulder and elbow range of motion (ROM), muscle strength, and humeral torsion. Side-to-side asymmetries were also examined to identify potential handedness-related adaptations. Methods: This cross-sectional study included 2008 youth baseball players (1829 RHPs and 179 LHPs) aged 9–13 years; female players were excluded because of their small number, and only male participants were analyzed. Shoulder and elbow ROM, muscle strength, and humeral torsion were evaluated, with humeral torsion data collected from 1024 measurements (946 RHPs, 78 LHPs). Group differences were analyzed using the Mann–Whitney U and Wilcoxon Signed-Rank tests. Logistic regression analysis identified independent factors associated with being an LHP, while Pearson correlation analyses explored the relationships between humeral torsion and external/internal rotation. Results: LHPs exhibited significantly larger nondominant shoulder external rotation (p < 0.001), dominant internal rotation (p = 0.003), dominant shoulder horizontal adduction (p = 0.007), dominant elbow flexion (p = 0.006), and side-to-side prone internal rotation strength ratio (p < 0.001). LHPs also showed smaller dominant shoulder external rotation (p = 0.012), nondominant shoulder internal rotation (p = 0.001), nondominant horizontal adduction (p = 0.037), dominant prone external rotation strength (p = 0.002), and humeral torsion (p = 0.031). Humeral torsion differences correlated with external rotation in LHPs (r = 0.236) and internal rotation in RHPs (r = −0.153). Predictors of left-handedness included lower dominant shoulder external rotation (OR = 0.937) and higher dominant elbow flexion (OR = 1.410). Conclusions: This study provides novel insights into the normal functional characteristics of LHPs, an area that has been relatively underexplored. These findings serve as a basis for future studies on risk assessment, injury prevention, and performance optimization in youth baseball players. Full article

Background: Marker-based motion capture systems are commonly used for three-dimensional movement analysis in sports. Novel, markerless motion capture systems enable the collection of comparable data under more time-efficient conditions with higher flexibility and fewer restrictions for the athletes during movement execution. Studies show comparable results between markerless and marker-based systems for kinematics of the lower extremities, especially for walking gait. For more complex movements, such as throwing, limited data on the agreement of markerless and marker-based systems is available. The aim of this study is to compare the outcome of a video-based markerless motion capture system with a marker-based approach during an artificial basketball-throwing task. Methods: Thirteen subjects performed five simulated basketball throws under laboratory conditions, and were recorded simultaneously with the marker-based measurement system, as well as two versions of a markerless measurement system (differing in their release date). Knee, hip, shoulder, elbow and wrist joint angles were acquired and root mean square distance (RMSD) was calculated for all subjects, parameters and attempts. Results: The RMSD of all joint angles of the marker-based and markerless systems ranged from 7.17° ± 3.88° to 26.66° ± 14.77° depended on the joint. The newest version of the markerless system showed lower RMSD values compared to the older version, with an RMSD of 16.68 ± 5.03° for elbow flexion, capturing 93.84% of the data’s RMSD of 22.22 ± 5.52, accounting for 87.69% of the data. While both versions showed similar results for right knee flexion, lower differences were observed in the new version for right hip flexion, with an RMSD of 8.17 ± 3.75 compared to the older version’s 13.24 ± 5.78. Additionally, the new version demonstrated lower RMSD values for right hand flexion. Conclusions: Overall, the new version of the markerless system showed lower RMSD values across various joint angles during throwing movement analysis compared to the older version. However, the differences between markerless and marker-based systems are especially large for the upper extremities. In conclusion, it is not clearly explainable if the detected inter-system differences are due to inaccuracies of one system or the other, or a combination of both, as both methodologies possess special limitations (soft tissue vibration or joint center position accuracy). Further investigations are needed to clarify the accordance between markerless and marker-based motion capture systems during complex movements. Full article

Background/Objectives: Distal biceps tendon rupture is a disabling injury that compromises elbow flexion and forearm supination strength, particularly in high-performance athletes. Although several fixation techniques have been proposed, no single method has proven optimal in combining mechanical stability, anatomical restoration, and early functional recovery. This study aimed to evaluate the efficacy, safety, and reproducibility of a hybrid dual-fixation technique combining a Tightrope^® cortical button (Arthrex, Naples, FL, USA) with a PEEK interference screw for anatomic reinsertion of the distal biceps tendon in athletic individuals. Methods: A prospective observational study was conducted on 13 high-performance athletes who underwent distal biceps tendon repair using the hybrid Tightrope–PEEK construct between March 2024 and September 2025. Functional recovery, muscle strength, esthetic contour, and patient satisfaction were evaluated using the Visual Analog Scale (VAS), Mayo Elbow Performance Score (MEPS), Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH), and a 5-point Likert scale over a 12-month follow-up. Descriptive statistical analysis was performed using IBM SPSS Statistics, version 29.0. Results: All patients achieved secure fixation with no intraoperative or postoperative complications, loss of reduction, or hardware failure. Early controlled mobilization began within the first postoperative week. At 6 months, flexion and supination strength were fully restored, and at 12 months, all patients achieved full range of motion and optimal functional scores (mean MEPS 100; QuickDASH 0). No “Popeye” deformities or contour irregularities were observed, and mean patient satisfaction was 5/5. Conclusions: The hybrid Tightrope–PEEK dual-fixation technique provides excellent mechanical stability, allowing early mobilization and rapid functional recovery with minimal complications. Its reproducibility and cosmetic advantages suggest that it represents a safe and effective option for distal biceps tendon reinsertion in high-demand athletes. Full article