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This study investigates an electromyogram (EMG)-based neural interface toward hand rehabilitation for patients with cerebral palsy (CP). Forty-eight channels of surface EMG signals were recorded from the forearm of eight adult subjects with CP, while they tried to perform six different hand grasp patterns. A series of myoelectric pattern recognition analyses were performed to identify the movement intention of each subject with different EMG feature sets and classifiers. Our results indicate that across all subjects high accuracies (average overall classification accuracy > 98%) can be achieved in classification of six different hand movements, suggesting that there is substantial motor control information contained in paretic muscles of the CP subjects. Furthermore, with a feature selection analysis, it was found that a small number of ranked EMG features can maintain high classification accuracies comparable to those obtained using all the EMG features (average overall classification accuracy > 96% with 16 selected EMG features). The findings of the study suggest that myoelectric pattern recognition may be a useful control strategy for promoting hand rehabilitation in CP patients.

A reliable neural-machine interface is essential for humans to intuitively interact with advanced robotic hands in an unconstrained environment. Existing neural decoding approaches utilize either discrete hand gesture-based pattern recognition or continuous force decoding with one finger at a time. We developed a neural decoding technique that allowed continuous and concurrent prediction of forces of different fingers based on spinal motoneuron firing information. High-density skin-surface electromyogram (HD-EMG) signals of finger extensor muscle were recorded, while human participants produced isometric flexion forces in a dexterous manner (i.e. produced varying forces using either a single finger or multiple fingers concurrently). Motoneuron firing information was extracted from the EMG signals using a blind source separation technique, and each identified neuron was further classified to be associated with a given finger. The forces of individual fingers were then predicted concurrently by utilizing the corresponding motoneuron pool firing frequency of individual fingers. Compared with conventional approaches, our technique led to better prediction performances, i.e. a higher correlation ($0.71\pm 0.11$ versus $0.61\pm 0.09$), a lower prediction error ($5.88\pm 1.34$% MVC versus $7.56\pm 1.60$% MVC), and a higher accuracy in finger state (rest/active) prediction ($88.10\pm 4.65$% versus $80.21\pm 4.32$%). Our decoding method demonstrated the possibility of classifying motoneurons for different fingers, which significantly alleviated the cross-talk issue of EMG recordings from neighboring hand muscles, and allowed the decoding of finger forces individually and concurrently. The outcomes offered a robust neural-machine interface that could allow users to intuitively control robotic hands in a dexterous manner.

Background: Various techniques of opponensplasty have been developed with the aim of restoring the thumb function. The modified Camitz opponensplasty is a simple technique done together with an open carpal tunnel release. It restores thumb palmar abduction soon after the procedure, during such time that the abductor pollicis brevis (APB) is still recovering. The aim of this study was to assess the recovery and level of activity of the abductor pollicis brevis and palmaris longus (PL) muscles during thumb opposition and abduction after performing the modified Camitz opponensplasty.

Methods: The records of 21 patients who underwent modified Camitz opponensplasty for severe carpal tunnel syndrome were reviewed. Thumb function was evaluated using the Van Wetter Apogee test, Kapandji index, tripod pinch strength, and power grip. Electromyography was utilized to evaluate APB recovery; ultrasonography was employed to evaluate PL activity.

Results: Twenty patients reached 80% of the abduction height of the contralateral hand; the Kapandji index was good in thirteen. Palmaris longus activity was evaluated together with the APB muscle recovery. There was significant improvement in the average grip strength and average tripod pinch strength. However, this did not correlate with the degree of neurologic and muscular recovery of the APB. We surmise that the palmaris longus augmented the abductor pollicis brevis muscle even in those with full muscle recovery.

Conclusions: The modified Camitz opponensplasty is a practical option for patients suffering from severe carpal tunnel syndrome with diminished thumb function.

Surgical reconstruction can restore length and function, but cannot adequately resolve the problem of disfigurement. Prosthetic fitting can play a complementary role in enhancing the aesthetic outcomes post reconstruction. However, complex reconstruction involving flaps coupled with the surgical imperative for limb length preservation can lead to outcomes where the reconstructed stumps are challenging to fit with prosthesis. This article describes how prosthetic fitting was tackled in a case of a triple-digit amputation after reconstruction that presented with finger stumps that were bulky, long and stiff in extension contracture, compounded by the presence of substantive scar tissues. We discuss major prosthesis modifications that were unconventional but necessary to enable fitting, the techniques involved, as well as the aesthetic and functional considerations behind the modifications. The results showed that enhanced aesthetic appearance, together with a marginal improvement in hand function, was achieved post-prosthetically, meeting the patient’s and the clinical team’s fitting objective.

Level of Evidence: Level V (Therapeutic)

Background: With ageing of the population, there is an increasing likelihood that elderly people will seek employment, with a resultant increase in the incidence of hand injuries, including digital amputations. However, the surgical indication for replantation of an amputated digit in elderly patients is controversial. The purpose of this study was to compare functional outcomes after single-digit replantation of the thumb to long finger in older (≥65 years old) and younger (<65 years old) patients to assess the feasibility of digit replantation in the elderly population.

Methods: A retrospective cohort study was performed in 25 patients (12 elderly and 13 younger) with successful replantation of the thumb, index or long finger at our hospital. All patients were followed up for more than 1 year. Key pinch strength, Semmes–Weinstein (S–W) test, % total active motion (TAM), Purdue Pegboard Test score (hand dexterity) and Disabilities of the Arm, Shoulder and Hand (DASH) score were investigated.

Results: Elderly patients showed significantly worse results for the S–W test and Purdue Pegboard Test score. The % TAM, key-pinch strength and DASH scores were similar in the two groups.

Conclusions: Replantation surgery in elderly patients results in similar postoperative hand function (finger mobility and pinch strength) and activities of daily living to those in younger patients.

Level of Evidence: Level III (Therapeutic)