Analysis of electrode locations on limb condition effect for myoelectric pattern recognition.

BACKGROUND: Gesture recognition using surface electromyography (sEMG) has garnered significant attention due to its potential for intuitive and natural control in wearable human-machine interfaces. However, ensuring robustness remains essential and is currently the primary challenge for practical applications. METHODS: This study investigates the impact of limb conditions and analyzes the influence of electrode placement. Both static and dynamic limb conditions were examined using electrodes positioned on the wrist, elbow, and the midpoint between them. Initially, we compared classification performance across various training conditions at these three electrode locations. Subsequently, a feature space analysis was conducted to quantify the effects of limb conditions. Finally, strategies for group training and feature selection were explored to mitigate these effects. RESULTS: The results indicate that with the state-of-the-art method, classification performance at the wrist was comparable to that at the middle position, both of which outperformed the elbow, consistent with the findings from the feature space analysis. In inter-condition classification, training under dynamic limb conditions yielded better results than training under static conditions, especially at the positions covered by dynamic training. Additionally, fast and slow movement speeds produced similar performance outcomes. To mitigate the effects of limb conditions, adding more training conditions reduced classification errors; however, this reduction plateaued after four conditions, resulting in classification errors of 22.72%, 22.65%, and 26.58% for the wrist, middle, and elbow, respectively. Feature selection further improved classification performance, reducing errors to 19.98%, 19.75%, and 27.14% at the respective electrode locations, using three optimal features derived from single-condition training. CONCLUSIONS: The study demonstrated that the impact of limb conditions was mitigated when electrodes were placed near the wrist. Dynamic limb condition training, combined with feature optimization, proved to be an effective strategy for reducing this effect. This work contributes to enhancing the robustness of myoelectric-controlled interfaces, thereby advancing the development of wearable intelligent devices.

Estimation of the muscle force by perineural intramuscular electrical stimulation in healthy volunteers.

The present study aimed to evaluate the elbow flexor force induced by perineural intramuscular stimulation compared with surface electrical stimulation (ES) and maximal voluntary contraction. Thirty nondominant arms of healthy volunteers were evaluated. Isometric elbow flexion force was evaluated using a surface electrode stimulation at the biceps brachii muscle, a perineural intramuscular stimulation around the musculocutaneous nerve, and maximum voluntary contraction. The elbow flexion force was measured at the wrist volar area in a 90° elbow flexion posture, fixed with a rigid elbow orthosis. Pain and discomfort associated with ES were evaluated using a numeric rating scale. The mean maximum elbow flexion force was 16.6 ±â€…4.1 kgf via voluntary contraction. The mean elbow flexion force by ES was 2.9 ±â€…2.0 kgf, stimulation intensity was 24.8 ±â€…5.5 mA, and the numeric rating scale was 5.0 ±â€…2.5 via surface electrode stimulation and 3.1 ±â€…2.0 kgf, 5.0 mA, and 3.8 ±â€…1.9 via perineural stimulation, respectively. ES provides 16% to 18% of the maximal voluntary contraction force in elbow flexion, which corresponds to a fair grade of muscle force. Perineural intramuscular stimulation can generate an equivocal contraction force with less discomfort in elbow flexion than surface electrode stimulation.

Evaluation of the efficacy of low-level laser therapy in the treatment of ulnar neuropathy at the elbow in terms of symptoms and clinical and electrophysiological findings: a randomized, prospective, double-blind clinical trial.

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy and presents with symptoms such as pain, paresthesia, and weakness in the elbow. Provocative tests and electrophysiological examinations are helpful in the diagnosis of UNE. Low-level laser therapy is one of the conservative treatments of UNE however, limited results were reported on the effectiveness of low-level laser therapy (LLLT) in the treatment of UNE. In our study, we aimed to the efficacy of LLLT in reducing symptoms and providing clinical and electrophysiological improvement in patients with UNE. This study with a randomized-sham controlled, and double-blind design included 68 patients aged 18-60 years who were diagnosed with UNE. LLLT was applied to the first group, and sham laser was applied to the second group. The VAS pain, paresthesia, and weakness scores, grip strength, and provocative test positivity were evaluated in clinical examination. The QuickDASH questionnaire was administered to assess functional status. Electrophysiologically, motor distal latency (MDL) differences, sensory distal latency (SDL), motor and sensory nerve conduction velocity (NCV) were examined. Evaluations were performed before treatment and on the 15th day and at the third month after treatment. The LLLT group showed improvement in symptoms, clinical findings, motor NCV, and MDL at both post-treatment evaluations and sensory NCV on the post-treatment 15th day (p < 0.05). The comparison of post-treatment changes between the two groups revealed that the LLLT group had greater improvement in VAS day and night pain scores at both post-treatment evaluation times, QuickDASH scores at the third month, and sensory NCV on the 15th day (p < 0.05) compared to the SL group. There were no significant differences between the groups in terms of the post-treatment changes in VAS weakness scores, grip strength and electrophysiological findings (p > 0.05). It was observed that splinting alone was effective in UNE, but the addition of LLLT, one of the conservative treatment methods, enhanced treatment outcomes.

A Comparison of Throwing Arm Kinetics and Ball Velocity in High School Pitchers With Overall Fast and Overall Slow Cumulative Joint and Segment Velocities.

BACKGROUND: Individual maximum joint and segment angular velocities have shown positive associations with throwing arm kinetics and ball velocity in baseball pitchers. PURPOSE: To observe how cumulative maximum joint and segment angular velocities, irrespective of sequence, affect ball velocity and throwing arm kinetics in high school pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: High school (n = 55) pitchers threw 8 to 12 fastball pitches while being evaluated with 3-dimensional motion capture (480 Hz). Maximum joint and segment angular velocities (lead knee extension, pelvis rotation, trunk rotation, shoulder internal rotation, and forearm pronation) were calculated for each pitcher. Pitchers were classified as overall fast, overall slow, or high velocity for each joint or segment velocity subcategory, or as population, with any pitcher eligible to be included in multiple subcategories. Kinematic and kinetic parameters were compared among the various subgroups using t tests with post hoc regressions and multivariable regression models created to predict throwing arm kinetics and ball velocity, respectively. RESULTS: The lead knee extension and pelvis rotation velocity subgroups achieved significantly higher normalized elbow varus torque (P = .016) and elbow flexion torque (P = .018) compared with population, with equivalent ball velocity (P = .118). For every 1-SD increase in maximum pelvis rotation velocity (87 deg/s), the normalized elbow distractive force increased by 4.7% body weight (BW) (B = 0.054; ß = 0.290; P = .013). The overall fast group was older (mean ± standard deviation, 16.9 ± 1.4 vs 15.4 ± 0.9 years; P = .007), had 8.9-mph faster ball velocity (32.7 ± 3.1 vs 28.7 ± 2.3 m/s; P = .002), and had significantly higher shoulder internal rotation torque (63.1 ± 17.4 vs 43.6 ± 12.0 Nm; P = .005), elbow varus torque (61.8 ± 16.4 vs 41.6 ± 11.4 Nm; P = .002), and elbow flexion torque (46.4 ± 12.0 vs 29.5 ± 6.8 Nm; P < .001) compared with the overall slow group. A multiregression model for ball velocity based on maximum joint and segment angular velocities and anthropometrics predicted 53.0% of variance. CONCLUSION: High school pitchers with higher maximum joint and segment velocities, irrespective of sequence, demonstrated older age and faster ball velocity at the cost of increased throwing shoulder and elbow kinetics. CLINICAL RELEVANCE: Pitchers and coaching staff should consider this trade-off between faster ball velocity and increasing throwing arm kinetics, an established risk factor for elbow injury.

The Crossing Motor Ulnar Nerve Branch at Elbow.

BACKGROUND AND OBJECTIVES: Cubital tunnel syndrome is the second most common nerve entrapment, and understanding the anatomy is crucial for the success of the nerve release. During ulnar nerve release for cubital tunnel syndrome, a motor branch is frequently encountered crossing anteriorly over the ulnar nerve from its medial/ulnar side proximally to the lateral/radial side distally. Little has been noted about this crossing branch in the literature. In this anatomic study, we sought to characterize this branch further and discuss its potential significance in cubital tunnel release. METHODS: We performed a cadaveric dissection of 48 elbow specimens as if performing a cubital tunnel release. We assessed for the presence of the crossing motor branch of the ulnar nerve and measured the distance from the medial epicondyle to the branch takeoff and to its target of innervation. RESULTS: Of our 48 specimens, 34 (71%) were noted to have a crossing motor branch at the area of compression by the deep flexor carpi ulnaris muscle fascia (common aponeurosis). On average, the distance from the medial epicondyle to the branch origin from the ulnar nerve was 18.2 mm and to the target muscle innervation was 28.4 mm. CONCLUSION: Identifying this branch is important for performing a cubital tunnel release, and awareness of this anatomy during ulnar nerve decompression procedures may help avoid injury to this motor branch.

The Effects of the StartReact on Reaction Time, Rate of Force Development, and Muscle Activity in Biceps Brachii.

The StartReact test, increasingly popular for assessing cortico-reticular functioning, is a valid method to influence the firing of reticulospinal tract neurons noninvasively. However, there remains limited evidence on how different stimuli employed in the StartReact test impact motor output in humans. The present study tested elbow flexor responses of 33 adults (aged 26-48 years) to visual stimuli only (LED light), audio-visual (80 dB) stimuli, and startle-inducing audio-visual (120 dB) stimuli sitting with the arm supinated in an electromechanical dynamometer. Surface electromyogram (EMG) recorded muscle activity from the right biceps brachii muscle. Participants were presented with 20 stimuli for each of the three conditions in pseudorandom order with interstimulus intervals of ~8 s. Reaction times were calculated from the stimulus trigger to the initial rise in the EMG signal above 7 × SD from baseline. Rate of torque development (RTD) and EMG signals were recorded throughout and analyzed over their initial 50 ms and 100 ms time-windows. Reaction times were reduced from visual (169 ± 23) to audio-visual (140 ± 23) and further reduced to startle-inducing audio-visual stimuli (108 ± 19, p < 0.001). While RTD and EMG were consistently greatest following startle-inducing stimuli (p < 0.001), they were also enhanced following all audio-visual stimuli over 100 ms (p < 0.05). It appears that startle-inducing audio-visual stimuli result in shorter reaction times, increased RTD, and enhanced muscle activity within the initial 50 ms, likely from subcortical upregulation. However, the 100 ms time-window suggests cortical upregulation following all audio-visual stimuli considering the longer transmission times.

Tall and Fall Versus Drop and Drive Strategy in College Baseball Pitchers for Velocity and Elbow Valgus Torque.

BACKGROUND: Depending on anthropometrics and coaching style, pitchers are taught to pitch with a stride strategy that are traditionally classified as "tall and fall" or "drop and drive" for the purpose of maximizing pitch velocity. PURPOSE/HYPOTHESIS: The purpose of this study was to determine the effects of stride strategy (tall and fall vs drop and drive) in college baseball pitching on pitch velocity and elbow valgus torque. It was hypothesized that pitch velocity and elbow valgus torque would increase as pitchers aligned more with the tall and fall technique. STUDY DESIGN: Controlled laboratory study. METHODS: Markerless motion capture data were recorded on 64 collegiate pitchers (height, 1.89 ± 0.06 m; weight, 93.06 ± 9.44 kg) during game play at the host institution during the 2023 season. Peak magnitudes of body center of mass (COM) vertical displacement were determined using a straight-line trajectory between peak knee height and lead foot contact and used as a continuous variable. Pitchers were required to throw ≥4 fastballs during their outing to be included in the analysis. Multilevel modeling was used to determine associations between peak magnitudes of positive and negative vertical displacement of COM on pitch velocity and elbow valgus torque. Every fastball throughout the season with biomechanics data for each pitcher was included in the multilevel model. RESULTS: Fastball velocity was mean ± SD 90.68 ± 2.90 mph (40.54 ± 1.29 m/s). Mean maximal negative vertical COM displacement was -0.91 ± 0.47 inches (-0.023 ± 0.012 m), which occurred 18.1% ± 5.75% of the way between peak knee height and stride foot contact. Mean maximal positive vertical COM displacement was 1.73 ± 1.14 inches (0.044 ± 0.029 m), which occurred 65.7% ± 7.8% of the time from peak knee height to stride foot contact. Positive COM displacement (ß = 0.54; P < .001) and timing of peak positive COM displacement (ß = 1.82; P = .023) reduced interpitcher variance by 9.9% and improved the ability of our model to predict fastball velocity. Negative COM displacement improved the ability of our model to predict ball velocity (ß = -0.45; P = .021). Vertical COM displacement did not influence elbow valgus torque. CONCLUSION: Increasing vertical COM displacement in either the positive or the negative direction resulted in increased fastball velocity but did not result in greater elbow valgus torque. This indicates that the stride method may be used for performance enhancement but is unlikely to influence ulnar collateral ligament injury risk in college baseball pitchers. CLINICAL RELEVANCE: Clinicians should not use stride mechanics as an injury risk indicator or diagnostic factor in injury etiology for college baseball pitchers.

From Simulation to Reality: Predicting Torque With Fatigue Onset via Transfer Learning.

Muscle fatigue impacts upper extremity function but is often overlooked in biomechanical models. The present work leveraged a transfer learning approach to improve torque predictions during fatiguing upper extremity movements. We developed two artificial neural networks to model sustained elbow flexion: one trained solely on recorded data (i.e., direct learning) and one pre-trained on simulated data and fine-tuned on recorded data (i.e., transfer learning). We simulated muscle activations and joint torques using a musculoskeletal model and a muscle fatigue model (n = 1,701 simulations). We also recorded static subject-specific features (e.g., anthropometric measurements) and dynamic muscle activations and torques during sustained elbow flexion in healthy young adults (n = 25 subjects). Using the simulated dataset, we pre-trained a long short-term memory neural network (LSTM) to regress fatiguing elbow flexion torque from muscle activations. We concatenated this pre-trained LSTM with a feedforward architecture, and fine-tuned the model on recorded muscle activations and static features to predict elbow flexion torques. We trained a similar architecture solely on the recorded data and compared each neural network's predictions on 5 leave-out subjects' data. The transfer learning model outperformed the direct learning model, as indicated by a decrease of 24.9% in their root-mean-square-errors (6.22 Nm and 8.28 Nm, respectively). The transfer learning model and direct learning model outperformed analogous musculoskeletal simulations, which consistently underpredicted elbow flexion torque. Our results suggest that transfer learning from simulated to recorded datasets can decrease reliance on assumptions inherent to biomechanical models and yield predictions robust to real-world conditions.

Direct Suturing of Ulnar or Median Nerve Defects in High-Degree Elbow Flexion: An Experimental Cadaver Study.

OBJECTIVE: The aim of this study is to determine the maximum loss of median and ulnar nerve substances that can be treated by direct suture in elbow flexion and to quantify this elbow flexion. The other objective is to determine the participation of the wrist position in this direct suture in elbow flexion. METHODS: We performed an experimental study on 6 ulnar nerve lesions and 6 median nerve lesions. For each defect, a direct tensionless suture was performed with elbow flexion and in three different positions of the wrist (wrist extension, neutral position, and wrist flexion). RESULTS: A 90° elbow flexion allowed direct suturing of defects up to 40 mm in the 3 positions of the wrist. A bowstringing effect (i.e., increase of the perpendicular distance of the nerve from the axis of rotation of the elbow) was noted starting from 25 mm of nerve defect. Wrist extension placed tension on the nerve suture for both nerves. CONCLUSIONS: The results of this first anatomical study clarified the conditions for direct suturing of ulnar and median nerve defects in the flexed elbow position and flexed wrist position. This is an approach to consider for limited nerve defects to the elbow or when allograft harvesting is to be avoided.

Design and Development of a Powered Myoelectric Elbow Orthosis for Neuromuscular Injuries.

INTRODUCTION: Recovering from neuromuscular injuries or conditions can be a challenging journey that involves complex surgeries and extensive physical rehabilitation. During this process, individuals often rely on orthotic devices to support and enable movement of the affected limb. However, users have criticized current commercially available powered orthotic devices for their bulky and heavy design. To address these limitations, we developed a novel powered myoelectric elbow orthosis. MATERIALS AND METHODS: The orthosis incorporates 3 mechanisms: a solenoid brake, a Bowden cable-powered constant torque elbow mechanism, and an extension limiter. The device controller and battery are in a backpack to reduce the weight on the affected arm. We performed extensive calculations and testing to ensure that the orthosis could withstand at least 15 Nm of elbow torque. We developed a custom software effectively control the orthosis, enhancing its usability and functionality. A certified orthotist fitted a subject who had undergone a gracilis free functioning muscle transfer surgery with the device. We studied the subject under Mayo clinic IRB no. 20-006849 and obtained objective measurements to assess the orthosis's impact on upper extremity functionality during daily activities. RESULTS: The results are promising since the orthosis significantly improved elbow flexion range of motion by 40° and reduced compensatory movements at the shoulder (humerothoracic joint) by 50°. Additionally, the subject was able to perform tasks which were not possible before, such as carrying a basket with weights, highlighting the enhanced functionality provided by the orthosis. CONCLUSION: In brief, by addressing the limitations of existing devices, this novel powered myoelectric elbow orthosis offers individuals with neuromuscular injuries/conditions improved quality of life. Further research will expand the patient population and control mechanisms.

Acute Dosing Strategy with Vistula Tart Cherries for Recovery of Strenuous Exercise-A Feasibility Study.

Tart cherry (TC) consumption has become a popular nutritional strategy for recovery, particularly for the attenuation of markers associated with muscle damage. However, there are relatively few studies that have examined an acute dosing strategy. The aim of this pilot study was to explore the feasibility of using powdered Vistula TC for recovery following a bout of muscle-damaging exercise. Twenty-two recreationally active participants (mean ± SD age, stature, and mass were 23 ± 3 years old, 173 ± 10 cm, and 74 ± 17 kg, respectively) performed 40 (5 sets of 8 repetitions) maximal lengthening contractions of the elbow flexors. The participants were randomised to receive either a spray-dried TC extract or a calorie-matched placebo (12 TC, 10 placebo) for 4 days in total, starting on the day of exercise. Dependent measures of maximal voluntary contraction (MVC), muscle soreness (assessed via visual analogue scales; VAS), pain pressure threshold (PPT), range of motion (ROM), and upper arm limb girth were taken at baseline (pre), 24, 48, and 72 h post damaging exercise. There were significant changes over time among all the variables (MVC, VAS, PPT, ROM, and girth, p ≤ 0.014). There were no significant differences between the conditions for any of the variables (MVC, VAS, PPT, ROM, and girth, p > 0.3). The TC group did not recover at an accelerated rate compared to the placebo. This study provides initial insights into the use of powdered Vistula TC and its effect following strenuous (damaging) exercise bouts. Vistula TC did not improve recovery when taken acutely following a bout of damaging exercise to the elbow flexors.

The functional and clinical outcomes of primary and metastatic malignancies of the elbow.

OBJECTIVES: This study aims to investigate the etiological distribution of primary and metastatic malignancies around the elbow and the effect of surgical and adjuvant treatments on clinical outcome. PATIENTS AND METHODS: Between January 2006 and December 2020, medical records of a total of 33 patients with elbow neoplasm (15 males, 18 females; median age: 55 years; range, 39 to 71 years) who underwent surgical treatment and with or without clinical treatment were retrospectively analyzed. The outcomes and frequencies of the elbow metastatic and primary malignancies were evaluated. Data were collected from patients' medical and radiological documents, and a dedicated archive was created for this study. RESULTS: Most tumors occurred on the right side and were intra-articular or distal to the humerus. A total of 75.8% (25/33) of the patients had tumors of any diameter ≥5 cm. Most patients were treated with extensive resection. A total of 81.8% (27/33) of the patients had wide resected tumor margins, and 18.2% (6/33) had intralesional tumor margins. The median follow-up was 42 (range, 1 to 83) months. Synovial sarcoma and malignant peripheral nerve sheath tumors were the most common soft tissue sarcomas, and pulmonary adenoma and multiple myeloma were found in metastatic lesions. CONCLUSION: Elbow surgery is particularly challenging due to the interrelationship of major neurovascular structures. Synovial sarcoma and malignant peripheral nerve sheath tumors are the most common soft tissue sarcomas, and pulmonary adenoma and multiple myeloma are found in metastatic lesions. Limb-sparing surgery is the gold-standard method recently.

A single-center retrospective comparison of muscle versus cutaneous free flaps for posterior elbow defect reconstruction.

INTRODUCTION: Comparative data on free flap outcomes for elbow defect reconstruction are still lacking. This study aimed to compare complication rates of free muscle flaps (MFs) versus cutaneous flaps (CFs) for posterior elbow reconstruction. METHODS: In a single-center retrospective analysis, patients who underwent posterior elbow reconstruction with free MFs and CFs from 2000 to 2021 were analyzed. Retrospective chart review included patient demographics, operative details, and post-operative complications. Outcomes of interest that were compared included microvascular complications, partial or total flap necroses, wound dehiscence, hematoma or flap infection, and donor-site complications. RESULTS: Sixty-six free flaps (CFs: n = 42; MFs: n = 24) were included, with a trend over time toward using CFs (64%). MFs were used for larger defects (CF: 175 ± 82 vs. MF: 212 ± 146 cm2; p = 0.13). Outcome analysis revealed an equal distribution of microvascular complications (10% vs. 13%; p = 0.7), partial flap necrosis (7% vs. 8%; p > 0.9), wound dehiscence (7% vs. 4%; p > 0.9), evacuation of hematoma (10% vs. 4%; p = 0.7), and infection (0% vs. 4%; p = 0.4). Total flap necrosis requiring additional flap surgery was necessary in one CF (2%) and in no MF (0%) (p > 0.9). CONCLUSION: Surgical outcomes, flap necrosis rates, and microsurgical complications did not differ between CFs and MFs. Both flap types are safe and effective options. The free anterolateral thigh and latissimus dorsi flaps represent indispensable workhorses for the reconstruction of extensive elbow defects.

Describing the Flick Movement Kinematic Biomechanically and Investigating the Effect of Thrower's Ten Exercises in Underwater Hockey Players.

CONTEXT: Analyzing flick movement kinematics biomechanically is important to prevent sport-related injuries in underwater hockey players since the aquatic-based flick movement is completely different from land-based flick movements. The study aimed to describe the flick movement kinematic biomechanically in underwater hockey players. Moreover, this study further aimed to investigate the effect of the Thrower's Ten exercises on flick movement kinematics in underwater hockey players. DESIGN: Descriptive laboratory study. METHODS: Seventeen underwater hockey players (age: 26.2 [4.3] y; sports age: 6.2 [4.5] y) were included. First, 2 underwater cameras using motion capture video analysis MATLAB were used to biomechanically analyze the angular changes on the shoulder, elbow, wrist, and body while players were performing the flick movements. Players were then recruited to the Thrower's Ten exercise program for 6 weeks. Flick movement kinematics and flick-throwing distance were recorded at baseline and 6 weeks. RESULTS: The flick movement kinematic patterns demonstrated increased shoulder flexion (from 102.5° to 144.9°), wrist extension (from 9.5° to 10.8°), and upper-extremity rotation (from 5.7° to 56.8°) while decreased elbow extension (from 107.7° to 159.2°) from the stick met the puck until the competition of the movement. The Thrower's Ten exercises improved the elbow extension (P = .04), wrist extension (P = .01), body rotation (P < .001), and flick-throwing distance (P < .001) from baseline to 6 weeks. CONCLUSION: This study describes the underwater flick kinematic technique biomechanically and interprets preliminary findings for the first time. Thus, 6 weeks of Thrower's Ten exercise program provides more body muscle movements than the smaller ones during the flick movements and higher flick-throwing distance in underwater hockey players.

Sex-related differences in corticospinal excitability outcome measures of the biceps brachii during a submaximal elbow flexor contraction.

The purpose of this study was to investigate the effects of sex, muscle thickness, and subcutaneous fat thickness (SFT) on corticospinal excitability outcome measures of the biceps brachii. Eighteen participants (10 males and 8 females) completed this study. Ultrasound was used to assess biceps brachii muscle thickness and the overlying SFT. Transcranial magnetic stimulation (TMS) was used to determine corticospinal excitability by inducing motor-evoked potentials (MEPs) at eight different TMS intensities from 90% to 160% of active motor threshold (AMT) from the biceps brachii during an isometric contraction of the elbow flexors at 10% of maximum voluntary contraction (MVC). Biceps brachii maximal compound muscle action potential (Mmax) was also recorded prior to and after TMS. Males had higher (p < 0.001) biceps brachii muscle thickness and lower SFT, produced higher levels of MVC force and had, on average, higher (p < 0.001) MEP amplitudes at lower (p < 0.05) percentages of maximal stimulator output than females during the 10% elbow flexion MVC. Multiple linear regression modeling revealed that sex was not associated with any of the neurophysiological parameters examined, while SFT showed a positive association with the stimulation intensity required at AMT (p = 0.035) and a negative association with biceps brachii pre-stimulus electromyography (EMG) activity (p = 0.021). Additionally, there was a small positive association between muscle thickness and biceps brachii pre-stimulus EMG activity (p = 0.049). Overall, this study suggests that some measures of corticospinal excitability may be different between the sexes and influenced by SFT and muscle thickness.

[Anatomical cartography of the radial nerve at the elbow level for intraradial nerve transfers for finger extension reconstruction in spastic upper limb - A cadaveric study]. / Cartographie anatomique du nerf radial dans la région du coude pour son application aux transferts nerveux intraradiaux dans la chirurgie de la spasticité.

INTRODUCTION: Upper limb spasticity is a surgical challenge, both in diminishing agonists spasticity and reconstructing antagonist function. Brachioradialis (BR) is often involved in elbow flexors spasticity. Finger extension is often impaired in spastic patients. This study aims to demonstrate the feasibility of BR motor branch to posterior interosseous nerve (PIN) during BR selective neurectomies, and to describe fascicles topography inside the radial nerve to facilitate PIN dissection. MATERIAL AND METHOD: Ten upper limbs from 10 fresh frozen anatomical specimens were dissected. Motor branches to the BR, wrist extensors, supinator, PIN and radial sensory branch were identified. BR to PIN transfer was realized and its feasibility was studies (donor length, tensionless suture). RESULTS: BR to PIN transfer was achievable in 9 out of 10 cases. The position of the sensory branch of the radial nerve was inferior or medial in all cases. The position of the PIN was lateral in 90% of the cases. CONCLUSION: BR to PIN nerve transfer is achievable in most cases (90%). The lateral topography of the PIN and the inferomedial topography of the sensory branch in most cases allows for an easier intraoperative finding of the PIN when stimulation is not possible. LEVEL: IV, feasibility study.

Elbow Gesture Recognition with an Array of Inductive Sensors and Machine Learning.

This work presents a novel approach for elbow gesture recognition using an array of inductive sensors and a machine learning algorithm (MLA). This paper describes the design of the inductive sensor array integrated into a flexible and wearable sleeve. The sensor array consists of coils sewn onto the sleeve, which form an LC tank circuit along with the externally connected inductors and capacitors. Changes in the elbow position modulate the inductance of these coils, allowing the sensor array to capture a range of elbow movements. The signal processing and random forest MLA to recognize 10 different elbow gestures are described. Rigorous evaluation on 8 subjects and data augmentation, which leveraged the dataset to 1270 trials per gesture, enabled the system to achieve remarkable accuracy of 98.3% and 98.5% using 5-fold cross-validation and leave-one-subject-out cross-validation, respectively. The test performance was then assessed using data collected from five new subjects. The high classification accuracy of 94% demonstrates the generalizability of the designed system. The proposed solution addresses the limitations of existing elbow gesture recognition designs and offers a practical and effective approach for intuitive human-machine interaction.

MEFFNet: Forecasting Myoelectric Indices of Muscle Fatigue in Healthy and Post-Stroke During Voluntary and FES-Induced Dynamic Contractions.

Myoelectric indices forecasting is important for muscle fatigue monitoring in wearable technologies, adaptive control of assistive devices like exoskeletons and prostheses, functional electrical stimulation (FES)-based Neuroprostheses, and more. Non-stationary temporal development of these indices in dynamic contractions makes forecasting difficult. This study aims at incorporating transfer learning into a deep learning model, Myoelectric Fatigue Forecasting Network (MEFFNet), to forecast myoelectric indices of fatigue (both time and frequency domain) obtained during voluntary and FES-induced dynamic contractions in healthy and post-stroke subjects respectively. Different state-of-the-art deep learning models along with the novel MEFFNet architecture were tested on myoelectric indices of fatigue obtained during [Formula: see text] voluntary elbow flexion and extension with four different weights (1 kg, 2 kg, 3 kg, and 4 kg) in sixteen healthy subjects, and [Formula: see text] FES-induced elbow flexion in sixteen healthy and seventeen post-stroke subjects under three different stimulation patterns (customized rectangular, trapezoidal, and muscle synergy-based). A version of MEFFNet, named as pretrained MEFFNet, was trained on a dataset of sixty thousand synthetic time series to transfer its learning on real time series of myoelectric indices of fatigue. The pretrained MEFFNet could forecast up to 22.62 seconds, 60 timesteps, in future with a mean absolute percentage error of 15.99 ± 6.48% in voluntary and 11.93 ± 4.77% in FES-induced contractions, outperforming the MEFFNet and other models under consideration. The results suggest combining the proposed model with wearable technology, prosthetics, robotics, stimulation devices, etc. to improve performance. Transfer learning in time series forecasting has potential to improve wearable sensor predictions.

Risk and related factors of elbow musculoskeletal diseases: a nationwide cross-sectional survey in China.

OBJECTIVES: Although studies have shown that work-related musculoskeletal disorders (WMSDs) are common and continue to be a major source of disability and work time loss, there are few reports about elbow WMSDs. The aim of this study was to explore the prevalence and associated factors of elbow WMSDs. METHODS: The valid questionnaires of 57501 workers from 15 different industries nationwide were collected and the c2 test and logistic regression analysis were applied to reveal the prevalence and risk factors of elbow WMSDs. RESULTS: The findings indicated that the overall prevalence of elbow WMSDs among workers was 7.3%. However, the prevalence of elbow WMSDs in toy manufacturing was 21.3%, which was significantly higher than that in other industries (P < .05). Logistic regression analysis showed that age 40 and above, married, very poor health, left-handedness, lifting weights (more than 20 kg each time), work requiring upper limb or hand force, work in an uncomfortable position, repetitive operations within 1 minute, using vibrating tools, work involving cold, cool draughts, or temperature changes, work being completed in the same workshop, work being done outdoors, frequent dealings with customers, 2 shifts, often working overtime, staff shortage, and often working for colleagues were risk factors for elbow WMSDs. A higer education level, monthly income, and enough rest time were protective factors for elbow WMSDs. CONCLUSIONS: Toy manufacturing is a high-risk industry for elbow WMSDs. Promotion of education about ergonomics should be strengthened, and workers' ergonomics awareness should be improved to reduce the impact of WMSDs.

Assessment of the ulnar nerve stiffness during valgus stress of the elbow using shear wave elastography: an observational cross-sectional study.

BACKGROUND: Identification of the relationship between valgus stress in the medial elbow and ulnar nerve strain during maximum external rotation of the shoulder is pivotal for the prevention and management of ulnar neuropathies. In this observational cross-sectional study, we aimed to determine the changes in ulnar nerve stiffness under valgus stress at different nerve entrapment sites. METHODS: Twenty healthy baseball players participated in the study. The stiffness of the ulnar nerve on the throwing side was assessed at two sites, the arcade of Struthers and the Osborne's ligament, at 0°, 60°, and 90° flexion by shear wave elastography using a 10-MHz linear transducer. The arcade of Struthers was defined as the proximal site and the Osborne's ligament as the distal site. Valgus stress was applied to the medial elbow at 0, 30, 50, and 70 N using a Telos stress device, and the stiffness caused by valgus stress was measured. RESULTS: At all elbow flexion angles, the stiffness of the ulnar nerve under 70 N valgus stress was higher than that under 30 N stress. The stiffness of the ulnar nerve at the proximal site was significantly higher than that at the distal site. CONCLUSION: Valgus stress increases ulnar nerve stiffness. In addition, the stiffness of the proximal site increases.