Extensor Digitorum Research Articles

Correlation of single-fiber electromyography studies and functional status in patients with amyotrophic lateral sclerosis.

Our aim was to examine the significance of single-fiber electromyography (SFEMG) in patients diagnosed with amyotrophic lateral sclerosis (ALS) and determine the best correlating parameter with SFEMG parameters and clinical scales across different muscles including facial muscles. SFEMG examinations were conducted on the extensor digitorum (ED), frontalis, and orbicularis oculi muscles. Mean jitter, percentage of increased jitter, fiber density (FD), and impulse blocking percentage were compared to reference values and functional scales. Significant differences (p < 0.001) were observed between the patients' SFEMG results and reference values in all muscles. Significant correlations were found between SFEMG parameters and clinical scales, particularly when considering both FD and jitter. A notable value of the ALS Functional Rating Scale Revised (ALSFRS-R) was detected in all muscles: 31 points in the ED muscle, 30 in the orbicularis oculi muscle, and 31 in the frontalis muscle. Below this ALSFRS-R threshold, the percentage of increased jitter was higher, while FD remained relatively low. SFEMG examination emerges as a valuable tool for better understanding ALS and holds potential for assessing prognosis. Combined jitter and FD analysis showed the strongest correlation with clinical scales. In addition to the ED muscle, the orbicularis oculi muscle may be important in the assessment.

Ergonomic evaluation of upper extremities muscle activity pattern during 60-min smartphone texting.

Smartphone usage has increased rapidly in the last decade due to rapid technological advancements. This extensive usage of smartphones led to physiological problems and musculoskeletal disorders (MSD) due to inappropriate postures. Past studies have reported the effects/discomfort of smartphone usage for short periods, ranging from 3-20 min, which does not represent the current era of smartphone dependency (approximately 7-hr/day). This study was performed on fifty-four participants aged 20-28 with 1-hr smartphone texting in a sitting posture. Flexion angles, both sides (dominant and non-dominant) muscle activity (maximum voluntary contraction %) at sternocleidomastoid (SCM), upper-trapezius (TRP), extensor digitorum (EDM) and abductor pollicis brevis (APB) muscles, and subjective discomfort were analyzed. After 1-hr smartphone texting, the muscle activity at eight upper extremities: SCM (24.80%), TRP (29.45%), EDM (14.44%) and APB (19.87%) significantly (p < 0.001) increased by 1.5-1.9 times with 27.4±3.18° and 82.94±7.03° head and lower-arm flexion angles, respectively. The mechanical loads on the cervical spine increased by 4.6 times, and subjective discomfort by 3 times. Maintaining the same posture for a long duration causes postural stress, muscular imbalances, and discomfort, leading to MSD with increased cervical intervertebral disc pressure.

New Insights into Boxer's Knuckle Injury of the Little Finger.

The original description of boxer's knuckle injury of the fifth ray mentions that the injury occurs between the extensor digitorum communis (EDC) and the extensor digiti minimi (EDM). Subsequent reports claim similar findings. Anatomical studies show that the EDC of the fifth ray is absent in most patients, while the EDM is generally composed of two slips. We present a modification of the current description of boxer's knuckle injury of the little finger based on the correlation between advanced preoperative 3D imaging and intraoperative findings. Five patients were investigated preoperatively using high-resolution ultrasound and 3D tendon reconstruction-based MR arthrography. Surgical exploration identified the lesion site relative to the EDM and EDC. All patients had two slips of the EDM and no EDC to the fifth ray. The injury appeared as a longitudinal tear of the EDM between its two slips. The mean gap was 7.8 mm (range 4.5-10 mm) on the pathological side vs. 1.3 mm (range 1-2 mm) on the healthy contralateral side. We believe that previous descriptions of boxer's knuckle of the fifth ray are inaccurate. High-resolution ultrasound and 3D reconstructions based on MR arthrography are reliable diagnostic tools allowing to locate the injury with precision.

Two classes of action-stabilizing synergies reflecting spinal and supraspinal circuitry.

We explored force-stabilizing synergies during accurate four-finger constant force production tasks in spaces of finger modes (commands to fingers computed to account for the finger interdependence) and of motor unit (MU) firing frequencies. The main specific hypothesis was that the multifinger synergies would disappear during unintentional force drifts without visual feedback on the force magnitude, whereas MU-based synergies would be robust to such drifts. Healthy participants performed four-finger accurate cyclical force production trials followed by trials of constant force production. Individual MUs were identified in the flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC). Principal component analysis was applied to motor unit frequencies to identify robust MU groups (MU-modes) with parallel scaling of the firing frequencies in FDS, in EDC, and the combined MUs of FDS + EDC. The framework of the uncontrolled manifold hypothesis was used to quantify force-stabilizing synergies when visual feedback on the force magnitude was available and 15 s after turning the visual feedback off. Removing visual feedback led to a force drift toward lower magnitudes, accompanied by the disappearance of multifinger synergies. In contrast, MU-mode synergies were minimally affected by removing visual feedback off and continued to be robust for the FDS and for the EDC, while being absent for the (FDS + EDC) analysis. We interpret the findings within the theory of hierarchical control of action with spatial referent coordinates. The qualitatively different behavior of the multifinger and MU-mode-based synergies likely reflects the difference in the involved neural circuitry, supraspinal for the former and spinal for the latter.NEW & NOTEWORTHY Two types of synergies, in the space of commands to individual fingers and in the space of motor unit groups, show qualitatively different behaviors during accurate multifinger force-production tasks. After removing visual feedback, finger force synergies disappear, whereas motor unit-based synergies persist. These results point at different neural circuitry involved in these two basic classes of synergies: supraspinal for multieffector synergies, and spinal for motor unit-based synergies.

Motor unit activity and synaptic inputs to motoneurons in the caudal part of the injured spinal cord.

Spinal cord injury (SCI) disrupts neuronal function below the lesion epicenter, causing disuse muscle atrophy. We investigated motor unit (MU) activity and synaptic inputs to motoneurons in the caudal region of the injured spinal cord. Participants with C4-C7 cervical injuries were studied. The extensor digitorum communis (EDC) muscle, which is mainly innervated by C8, was assessed for disuse muscle atrophy. Using advanced electromyography and signal-processing techniques, we examined the concurrent activation of a substantial population of MUs during force-tracking tasks. We found that in participants with SCI (n = 9), both MU discharge rates and the amplitudes of MU action potentials were significantly lower than in controls (n = 9). After SCI, MUs were recruited in a limited force range as the strength of muscle contractions increased, implying a disruption in the orderly MU recruitment pattern. Coherence analysis revealed reduced synaptic inputs to motoneurons in the delta band (0.5-5 Hz) for participants with SCI, suggesting diminished common synaptic inputs to the EDC muscle. In addition, participants with SCI exhibited greater muscle force variability. Using principal component analysis on low-frequency MU discharge rates, we found that the first common component (FCC) captured the most discharge variability in participants with SCI. The coefficients of variation (CV) of the FCC correlated with force signal CVs, suggesting force variability mainly results from common synaptic inputs to the EDC muscle after SCI. These results advance our understanding of the neurophysiology of disuse muscle atrophy in human SCI, paving the way for therapeutic interventions to restore muscle function.NEW & NOTEWORTHY This study analyzed motor unit (MU) function below the lesion epicenter in patients with spinal cord injury (SCI). We found reduced MU discharge rates and action potential amplitudes in participants with SCI compared with controls. The strength of common synaptic inputs to motoneurons was reduced in patients with SCI, with increased force variability primarily due to low-frequency oscillations of common inputs. This study enhances understanding of neurophysiological and behavioral changes in disuse muscle atrophy post-SCI.

Assessment of the Influence of Cell Technologies on Denervation-Reinnervation Processes in Muscles after Gunshot Injury Using Shear Wave Elastography (SWE)

Objective. The purpose of this article is to determine the feasibility of using shear-wave elastography (SWE) in assessing the influence of cell technologies on denervation-reinnevaration processes in the muscles of gunshot injury.&#x0D; Material and Methods. Ultrasound examination and elastography were performed on a GE Healthcare LOGIQ P9 device with a 5-12 MHz multi-frequency probe. 19 injured males aged 35-57 (average age 45.31±0.95 years) with denervation-reinnervation processes in muscles due to gunshot damage were examined. The examination was performed on the affected limb and on the contralateral healthy limb. Statistical processing was performed using Microsoft Excel and StatSoft Inc. STATISTICA.&#x0D; Results: 11 patients with lesions of the radial nerve on the upper limb and 8 people of the peroneal nerve on the lower leg were included in the study. With lesions of the radial nerve, we examined m. extensor digitorum on the forearm. For lesions of the peroneal nerve, m. tibialis anterior of the lower leg was chosen. After the examination, all patients underwent the procedure of injecting BMAC (Bone Marrow Aspirate Concentrate) into the target muscle. Control studies of shear wave elastography were performed again one month after the procedure. The obtained statistical data on the state of muscle stiffness in dynamics allow us to conclude about the reliably positive outcome of the treatment.&#x0D; Conclusions. Ultrasound of muscles with shear wave elastography is a reliable and innovative method of obtaining information about the state of muscle stiffness when assessing the influence of cellular technologies on denervation-reinnervation processes in patients after gunshot injuries.

Wrist Extensor Muscle Fatigue During a Dual Task With Two Muscular and Cognitive Load Levels in Younger and Older Adults.

To examine the effect of concurrent physical and cognitive demands as well as age on indicators of muscle fatigue at the wrist. There are few studies examining risk indicators for musculoskeletal disorders associated with work-related physical and cognitive demands that often occur simultaneously in the workplace. Twenty-four gender-balanced older and 24 gender-balanced younger (mean age 60 and 23years) participants performed four 30min dual tasks. Tasks differed by the muscular load level during force tracking: 5% and 10% of maximum voluntary contraction force (MVC) and concurrent cognitive demands on the working memory: easy and difficult. Muscle fatigue was assessed by MVC decline and changes in surface electromyography (increased root mean square: RMS, decreased median frequency: MF) at the extensor digitorum (ED) and extensor carpi ulnaris (EU). A decline in MVC was found in all participants when tracking was performed at 10% MVC (mean ± SD: 137.9 ± 49.2 - 123.0 ± 45.3N). Irrespective of age, muscular, or cognitive load, RMS increased (ED 12.3 ± 6.5 - 14.1 ± 7.0% MVE, EU 15.4 ± 7.6 - 16.9 ± 8.6% MVE) and MF decreased (ED 85.4 ± 13.6 - 83.2 ± 12.8Hz, EU 107.2 ± 17.1 - 104.3 ± 16.7Hz) in both muscles. However, changes in MF of EU tended to be more pronounced in the older group at higher cognitive and lower muscular load, without reaching statistical significance. Maximum voluntary contraction indicated no interaction between muscle fatigue, cognitive load, or age. However, the tendencies toward altered muscle activity due to an increase in cognitive load and older age suggest muscular adaptations while maintaining tracking performance during the onset of fatigue signs in the sEMG signal. If the tendencies in muscle activity are confirmed by further studies, ergonomic assessments in industrial workplaces should consider cognitive load and age when describing the risk of musculoskeletal disorders.

Electromyography based hand movement classification and feature extraction using machine learning algorithms

The categorization of hand gestures holds significant importance in controlling orthotic and prosthetic devices, enabling human-machine interaction, and facilitating telerehabilitation applications. For many years, methods of motion analysis based on image processing techniques have been employed to detect hand motions. However, recent research has focused on utilizing muscle contraction for detecting hand movements. Specifically, there has been an increase in studies that classify hand movements using surface electromyography (sEMG) data from the muscles of the hand and arm. In our study, we estimated the open (extension of the fingers) and closed (flexion of the fingers) positions of the hand by analyzing EMG data obtained from 4 volunteer participants' Extensor digitorum and Flexor carpi radialis muscles. In order to accurately discriminate EMG signals, various statistical measures such as variance, standard deviation, root mean square, average energy, minimum and maximum features were utilized. The dataset containing these additional features was then subjected to classification algorithms including Support Vector Machines (SVM), K Nearest Neighbour (KNN), Decision Tree (DT), and Gaussian Naive Bayes (GNB) for the purpose of classifying hand positions into open or closed states. Among the tested algorithms, SVM achieved the highest success rate with a maximum accuracy of 73.1%, while KNN yielded the lowest success rate at a minimum accuracy of 55.9%. To further enhance prediction accuracy in future studies, it is suggested that data from a larger set of muscles be collected.

Optimization of Muscle Selection for Needle Electromyography in Isolated C6 Root Lesion: A Prospective Chart Review Study.

The aim of the study is to evaluate muscles with more prominent needle electromyographic findings to optimize needle electromyography screening of isolated C6 radiculopathy in patients with C6 root lesions. This prospective clinical study was performed on 39 patients with isolated and unilateral cervical radiculopathy selected from all referrals of 1733 patients to the electrodiagnosis unit of the physical medicine and rehabilitation department of a tertiary medical center (from April 2021 to December 2021). The presence of fibrillation potentials, positive sharp waves, and/or neurogenic motor action potentials that occurred in isolation or combination with selected muscles was considered an abnormal finding. Of 1733 referrals, 39 patients (18 males [46.1%] and 21 females [53.8%]), with a mean age of 49.7 ± 9.6 yrs, were found eligible. According to needle electromyography findings, the most involved muscles in C6 root lesion were pronator teres (100%), followed by extensor carpi radialis longus (94.8%), flexor carpi radialis (89.7%), brachioradialis (82%), infraspinatus (82%), supraspinatus (79.4%), deltoid (74.3%), biceps brachii (64.1%), extensor digitorum communis (33.3%), and triceps brachii (15.3%) muscles. The pronator teres is the most involved muscle of patients diagnosed with C6 radiculopathy. It might be considered the key muscle for screening and accurate diagnosis of C6 root involvement.

3D muscle networks based on vibrational mechanomyography

Objective. Muscle network modeling maps synergistic control during complex motor tasks. Intermuscular coherence (IMC) is key to isolate synchronization underlying coupling in such neuromuscular control. Model inputs, however, rely on electromyography, which can limit the depth of muscle and spatial information acquisition across muscle fibers. Approach. We introduce three-dimensional (3D) muscle networks based on vibrational mechanomyography (vMMG) and IMC analysis to evaluate the functional co-modulation of muscles across frequency bands in concert with the longitudinal, lateral, and transverse directions of muscle fibers. vMMG is collected from twenty subjects using a bespoke armband of accelerometers while participants perform four hand gestures. IMC from four superficial muscles (flexor carpi radialis, brachioradialis, extensor digitorum communis, and flexor carpi ulnaris) is decomposed using matrix factorization into three frequency bands. We further evaluate the practical utility of the proposed technique by analyzing the network responses to various sensor-skin contact force levels, studying changes in quality, and discriminative power of vMMG. Main results. Results show distinct topological differences, with coherent coupling as high as 57% between specific muscle pairs, depending on the frequency band, gesture, and direction. No statistical decrease in signal strength was observed with higher contact force. Significance. Results support the usability vMMG as a tool for muscle connectivity analyses and demonstrate the use of IMC as a new feature space for hand gesture classification. Comparison of spectrotemporal and muscle network properties between levels of force support the robustness of vMMG-based network models to variations in tissue compression. We argue 3D models of vMMG-based muscle networks provide a new foundation for studying synergistic muscle activation, particularly in out-of-clinic scenarios where electrical recording is impractical.

Impact of task variation and microbreaks on muscle fatigue at seated and standing postures.

Prolonged and sustained work posture among computer users is one of the main factors that contributes to musculoskeletal discomfort. Rest-break interventions such as task variation and microbreaks may help prevent muscle fatigue and work-related musculoskeletal disorder. We aimed to investigate the effects of task variation and microbreaks at seated and standing workstations on forearm muscle activity, namely extensor digitorum communis, extensor carpi ulnaris, flexor digitorum superficialis, and flexor carpi ulnaris; mouse operation force (vertical compression force); mouse operation parameters; and perceived body discomfort during mouse operation. Twelve healthy right-handed young adults were recruited (male: n = 7, 21.6±1.4 years; female: n = 5, 21.4±1.7 years). Participants performed three blocks of computer tasks (computer mouse operation and typing) in both seated and standing postures with each block lasting for 30 min. Surface electromyography (EMG) of the forearm muscles and operation force were monitored during computer mouse operation. Body discomfort rating was recorded at the end of each block. With simulated task variation and microbreaks, work posture and work time showed no significant difference with EMG amplitude and mouse operation force. Task variation and microbreaks could be of benefit to computer users by reducing muscle fatigue during long hours of computer work at both seated and standing workstations.

Total hip arthroplasty following the failure of intertrochanteric nailing: First implant or salvage surgery?

Proximal femur fractures, including both intracapsular (femoral neck fractures) and extracapsular fractures (intertrochanteric femoral fractures, IFFs), affect around 1.5 million people per year worldwide. Mechanical failures of intertrochanteric nailing in IFFs could be managed with revision total hip arthroplasty (THA). To describe the surgical complexity and the procedure-related complication rates in patients with trochanteric nailing failure and treated with THA. Patients referred to our level I trauma center between April 2012 and July 2018 with failed cephalomedullary nailing following trochanteric fractures were retrospectively recruited. All patients underwent a salvage surgical procedure, i.e., cephalomedullary nail removal and conversion to THA. The same surgical and anesthesiology team performed the surgical procedures under spinal anesthesia. All patients underwent clinical and radiographic follow-ups for at least 24 mo. Complications and re-operations were recorded. Seventy-four patients met the inclusion criteria (male: 29; female: 45; mean age: 73.8-years-old; range: 65-89) and were included in the current study. The average operative time was 117 min (76-192 min). The average blood loss was 585 mL (430-1720 mL). Among the 74 patients, 43 (58.1%) required transfusion of three or more blood units. Two patients died within the 4th d after surgery because of pulmonary embolism, and 1 patient died 9 mo after surgery due to ischemic myocardial infarction. The complication rate in the 71 patients who completed the minimum 24-mo follow-up was 22.5%. In 3 cases out of 71 (4.2%) periprosthetic acetabular fracture was observed during the follow-up. One of these periacetabular fractures occurred intraoperatively. An intraoperative periprosthetic femur fracture was observed in 5 patients out of 71 (7.0%). Four of these patients needed a re-operation to fix the fracture with plates and cerclages; in one of these patients, femoral stem revision was also necessary. In 4 patients out of 71 (5.6%), an early THA dislocation was observed, whereas in 1 case (1.4%) a late THA dislocation was observed. Three patients out of 71 (4.2%) developed a periprosthetic joint infection during the study follow-up. The present study demonstrated that salvage options for IFF fixation failure are complex procedures with a relevant intraoperative and postoperative complication rate.

Treatment of symptomatic end-stage osteoarthritis of the ankle with anterolateral approach and an anatomical plate

The aim of this paper is to describe the anterolateral approach using an anatomical plate for ankle arthrodesis and to present the first mid-term results with this technique in ahigh-risk population. The indication for arthrodesis of the ankle joint with this described technique is moderate to severe osteoarthritis of the ankle. In addition to the general contraindications typical of any operation, there is a specific contraindication in cases of active infection of the soft tissues and accompanying osteomyelitis at the ankle. The incision is made along the course of the peroneus tertius muscle. After that, the mobilization of the peroneus superficialis nerve is carried out, followed by the mobilization of the long extensor tendons, especially the extensor digitorum muscle in amedial direction opening the capsule and removal of the residual cartilage on the distal tibia and talus. Subsequently, the subchondral sclerosis is opened, and the implantation of a suitable osteosynthesis material, e.g., an anatomical angle-stable plate, is carried out. Finally, wound closure is performed involving the muscle belly of the extensor digitorum muscle covering the plate. Immobilization of the ankle for 5-7days in adorsal knee-high splint. Retention in awalker after decongestion for another 5weeks. Increased loading can be done after X‑ray/computed tomography (CT) control from the 6thweek. In all, 11patients were observed retrospectively for an average of 14months. There were no complications. The European Foot and Ankle Society (EFAS) score improved significantly from 3.3 to 17.8 points. All patients were subjectively satisfied with the result and would have the operation again.

Opportunities and challenges of supervised machine learning for the classification of motor evoked potentials according to muscles

BackgroundEven for an experienced neurophysiologist, it is challenging to look at a single graph of an unlabeled motor evoked potential (MEP) and identify the corresponding muscle. We demonstrate that supervised machine learning (ML) can successfully perform this task.MethodsIntraoperative MEP data from supratentorial surgery on 36 patients was included for the classification task with 4 muscles: Extensor digitorum (EXT), abductor pollicis brevis (APB), tibialis anterior (TA) and abductor hallucis (AH). Three different supervised ML classifiers (random forest (RF), k-nearest neighbors (kNN) and logistic regression (LogReg)) were trained and tested on either raw or compressed data. Patient data was classified considering either all 4 muscles simultaneously, 2 muscles within the same extremity (EXT versus APB), or 2 muscles from different extremities (EXT versus TA).ResultsIn all cases, RF classifiers performed best and kNN second best. The highest performances were achieved on raw data (4 muscles 83%, EXT versus APB 89%, EXT versus TA 97% accuracy).ConclusionsStandard ML methods show surprisingly high performance on a classification task with intraoperative MEP signals. This study illustrates the power and challenges of standard ML algorithms when handling intraoperative signals and may lead to intraoperative safety improvements.

The effects of auditory cues and weighted pens on handwriting in individuals with Parkinson’s disease

BackgroundMicrographia, or small handwriting, is a common symptom of Parkinson’s disease (PD). Weighted pens have previously been recommended to improve handwriting, but there is limited research supporting their effectiveness. Additionally, previous research has demonstrated that music as an auditory cue can reduce variability in fine motor movements, but its effect on handwriting in people with PD remains unknown. PurposeThis study explored potential handwriting interventions for people with PD by evaluating the effectiveness of weighted pens and auditory cues on handwriting. Study DesignThis was a pilot cohort study. MethodsEight older adults with PD used a standard pen and a weighted pen to write continuous cursive “l”s on 1.5-cm-lined paper for a total of 10 seconds while listening to auditory cues in 4 conditions: control (silence), metronome, activating music, and relaxing music. Kinematic data were measured with sensors attached to the tip of each pen, and muscle activity was measured with electromyography sensors adhered to the extensor digitorum communis and first dorsal interosseous. ResultsWhen writing with the standard pen, peak-to-peak time was reduced in the metronome (control = 0.807 ± 0.121 seconds, metronome = 0.701 ± 0.100 seconds, p = 0.024) and activating (control = 0.807 ± 0.121 seconds, activating = 0.691 ± 0.113 seconds, p = 0.009) conditions compared to the control condition. Furthermore, the weighted pen increased the variability of distance between letter peaks (standard = 0.187 ± 0.010, weighted = 0.482 ± 0.065, p = 0.033) and the variability of time needed to complete each letter (standard = 0.176 ± 0.010, weighted = 0.187 ± 0.016, p = 0.042) compared to the standard pen. Finally, area under the curve of the extensor digitorum communis was reduced in the metronome (metronome = 66.03 ± 25.74 mV, control = 88.98 ± 30.40 mV, p = 0.034) and activating music (activating = 66.49 ± 26.02 mV, control = 88.98 ± 30.40 mV, p = 0.012) conditions compared to control when writing with the standard pen. ConclusionsThese results suggest that weighted pens may not improve handwriting in novice users, but auditory cues appear beneficial. This can inform future directions in the research and clinical application of handwriting interventions for persons with PD.

Retrograde peripheral nerve regeneration from sensory to motor pathways in rats: a new experimental concept in nerve repair

ABSTRACT Background The polarity of nerve grafts does not interfere with axon growth. Our goal was to investigate whether axons can regenerate in a retrograde fashion within sensory pathways and then extend into motor pathways, leading to muscle reinnervation. Methods Fifty-four rats were randomized into four groups. In Group 1, the ulnar nerve was connected end-to-end to the superficial radial nerve after neurectomy of the radial nerve in the axilla. In Group 2, the ulnar nerve was connected end-to-end to the radial nerve distal to the humerus; the radial nerve then was divided in the axilla. In Group 3, the radial nerve was divided in the axilla, but no nerve reconstruction was performed. In Group 4, the radial nerve was crushed in the axilla. Over 6 months, we behaviorally assessed the recovery of toe spread in the right operated-upon forepaw by lifting the rat by its tail and lowering it onto a flat surface. Six months after surgery, rats underwent reoperation, nerve transfers were tested electrophysiologically, and the posterior interosseous nerve (PIN) was removed for histological evaluation. Results Rats in the crush group recovered toe spread between 5 and 8 days after surgery. Rats with nerve transfers demonstrated electrophysiological and histological findings of nerve regeneration but no behavioral recovery. Conclusions Ulnar nerve axons regrew into the superficial radial nerve and then into the PIN to reinnervate the extensor digitorum communis. We were unable to demonstrate behavioral recovery because rats cannot readapt to cross-nerve transfer.

Retrospective Evaluation of Patients with Traumatic Hand Injuries

Objective: This study aimed to retrospectively examine the demographic, etiologic, and clinical characteristics of patients with traumatic hand-wrist injuries and to profile patients with the goal of contributing to preventive measures and protective programs. Methods: The records of 225 patients who came to the Hand Rehabilitation Unit of our clinic with a traumatic hand injury in the last 5 years were reviewed retrospectively. Many parameters were recorded, including demographic characteristics such as age, sex, and occupation, as well as information about the injured hand, dominant hand, type of injury, injured tendon and zone, number of affected fingers, and associated structures. Results: The study included 225 patients. Tendon injuries occurred most frequently in the 3rd decade. Of the injuries, 31.1% were caused by occupational accidents and 55.1% occurred in the dominant hand. Of the tendon injuries, 64% were flexor tendon injuries and 32.4% were extensor tendon injuries. Extensor Digitorum Communis (EDC)-3 tendons were involved in 11.6% of extensor tendon injuries, and Flexor Digitorum Superficialis (FDS)-4/Flexor Digitorum Profundus (FDP)-5 tendons were involved in 18.2% of flexor tendon injuries. In nerve injuries, median and ulnar nerves were equally affected (14.2%). Conclusion: Tendon injuries primarily affect young male workers, resulting in significant disability and an inability to work. Epidemiologic data can expand our knowledge about injury patterns. Occupational training and the prevention of occupational accidents can help patients improve their functional capacity and minimize their economic burden.

Variations in the extensor indicis proprius muscle in the Burmese population: implications for hand reconstructive surgery

BackgroundThe use of extensor indicis proprius (EIP) muscle tendon for tendon grafting and transplantation in the management of hand injuries is common. Anatomical variations of the EIP tendons have been reported with variable prevalence and presentation in different populations worldwide. Knowledge of possible variation patterns is crucial in reconstructive surgery. The current study aims to describe the prevalence of anatomical variations of the EIP in the Burmese population. MethodsA total of 50 cadavers (39 males, and 11 females) were dissected. Both upper limbs of each cadaver were observed. The presence of the EIP, the number of tendons, the origin and insertion of the muscle and its relation with the extensor digitorum communis (EDC) were recorded and variations reported. ResultsOf the 100 limbs studied in the 50 cadavers, only 1/100 limb was reported to have an absent EIP muscle and tendon. Of the remaining 99/100 limbs examined, one of them consists of a double tendon, that is, EIP and extensor indicis et medii communis (EIMC) were inserted separately onto the index finger and middle finger respectively on the dorsum of the left hand. Further to this, there is one case in which an extra muscle belly was observed in the EIP tendon, this muscle is commonly known as the extensor digitorum brevis manus muscle. All the EIP variations were observed in the male cadavers only. ConclusionOf the 50 cadavers studied, 3/100 limbs exhibited EIP variations in the current studied population. Population-specific studies on these variations may aid in a better understanding of the different anatomical patterns of the muscles in the dorsum of the hand. This may lead to improved diagnosis and surgical management of injuries to the dorsum of the hand and for the use of the EIP tendon in surgical grafts and transplantations.

Posterolateral Rotatory Instability Develops Following the Modified Kocher Approach and Does Not Resolve Following Interval Repair.

The modified Kocher and extensor digitorum communis (EDC)-splitting intervals are commonly utilized to approach the lateral elbow. Iatrogenic injury to the lateral ulnar collateral ligament may result in posterolateral rotatory instability (PLRI). in the present cadaveric study, we (1) evaluated lateral elbow stability following the use of these approaches and (2) assessed the accuracy of static lateral elbow radiographs as a diagnostic tool for PLRI. Ten matched-pair cadaveric upper-extremity specimens (n = 20) were randomly assigned to Kocher or EDC-splitting approaches. Specimens underwent evaluation pre-dissection, post-dissection, and following repair of the surgical interval. Clinical evaluation of lateral elbow stability was performed with the lateral pivot-shift maneuver. Radiographic radiocapitellar displacement was evaluated with the fully extended hanging arm test and on lateral elbow 30° flexion radiographs. Paired Wilcoxon signed-rank tests with Bonferroni correction were utilized to compare groups. All Kocher group specimens (10 of 10) developed PLRI on the pivot-shift maneuver following dissection. No EDC-splitting group specimens (0 of 10) developed instability with pivot-shift testing. The fully extended hanging arm test showed no difference in radiocapitellar displacement between groups (p > 0.008). Lateral elbow 30° flexion radiographs in the Kocher group showed an increased radiocapitellar displacement difference (mean, 8.46 mm) following dissection compared with the pre-dissection baseline (p < 0.008). Following repair of the Kocher interval, the radiocapitellar displacement (mean, 6.43 mm) remained greater than pre-dissection (mean, 2.26 mm; p < 0.008). In the EDC-splitting group, no differences were detected in radiocapitellar displacement on lateral elbow radiographs with either the fully extended hanging arm or lateral elbow 30° flexion positions. The Kocher approach produced PLRI that did not return to baseline conditions following repair of the surgical interval. The EDC-splitting approach did not cause elbow instability clinically or radiographically. The hanging arm test was not reliable for the detection of PLRI. The Kocher interval for lateral elbow exposure results in iatrogenic PLRI that is not detectable on the hanging arm test and that does not return to baseline stability following repair of the surgical interval.

Cross-user gesture recognition from sEMG signals using an optimal transport assisted student-teacher framework

The cross-user gesture recognition is a puzzle in the myoelectric control system, owing to great variability in muscle activities across different users. To address this problem, a novel optimal transport (OT) assisted student-teacher (ST) framework (termed OT-ST) was proposed in this paper to facilitate transfer across user domains in an unsupervised domain adaptation (UDA) manner. In this framework, the initial parameters of the ST models were trained with the labeled data from users in the source domain. In the model transfer stage for a new user in the target domain, the teacher model was utilized to generate pseudo labels for unlabeled testing samples, providing guidance to the adaptation of the student model. The OT algorithm was employed to optimize the pseudo labels generated from the teacher model, avoiding the model bias and further improving the effect of domain adaptation. The performance of the proposed OT-ST framework was evaluated via experiments of classifying seven hand gestures using high-density surface electromyogram (HD-sEMG) recordings from extensor digitorum muscles of eight intact-limbed subjects. The OT-ST framework yielded a high accuracy of 96.50 ± 2.88% for new users, and outperformed other common machine learning and UDA methods significantly (p < 0.01), demonstrating its effectiveness. The OT-ST framework does not require special repetitive training or any labeled data for calibration. In addition, it can incrementally learn from new testing samples and improve the recognition ability. This study provides a promising method for developing user-generic myoelectric pattern recognition, with wide applications in human-computer interaction, consumer electronics and prosthesis control.