Modeling and Evaluation of a Novel Hybrid-Driven Compliant Hand Exoskeleton Based on Human-Machine Coupling Model

This paper presents the modeling design method for a novel hybrid-driven compliant hand exoskeleton based on the human-machine coupling model for the patients who have requirements on training and assisting. Firstly, the human-machine coupling model is established based on the kinematics characteristics of human fingers and the Bernoulli beam formula. On this basis, the variable stiffness flexible hinge (VSFH) is used to drive the finger extension and the cable-driven mechanism is used to implement the movement of the finger flexion. Here, a hand orthosis is designed in the proposed hand exoskeleton to act as the base and maintain the function position of the hand for patients with hand dysfunction. Then, a final design prototype is fabricated to evaluate the proposed modeling method. In the end, a series of experiments based on the prototype is proceeded to evaluate its capabilities on stretching force for extension, bio-imitability, finger flexion capability, and fingertip force. The results show that the prototype has a significant improvement in all aspects of the ability mentioned above, and has good bionics. The proposed design method can be utilized to implement the rapid design of the hybrid-driven compliant hand exoskeleton with the changed requirements. The novel modeling method can be easily applied in personalized design in rehabilitation engineering.

Tools for Assessing the Function of the Upper Extremity in Patients with Stroke: the Prognostic Role of Finger Extension

The purpose of the study was to determine the prognostic role of finger extension and to assess the function of the upper extremity in patients with stroke. Materials and methods. The study was performed on the basis of the Medical Center "Expert Health" and clinical units of Petro Mohyla Black Sea National University, Mykolaiv, Ukraine during 2020-2021. 89 patients who underwent acute cerebrovascular accident by ischemic type with paresis of the upper extremity were examined. All patients were examined in accordance with current clinical protocols in 3 and 6 months after undergoing stroke. Additionally, patients underwent a standard hand function test – Action Research Arm Test, as well as an extended test – Action Research Arm Test +in its own modification (IsoTren LTD). Statistical processing was performed by methods of analysis of variance and correlation using Statisica 13.0 software (TIBCO, USA). Results and discussion. When assessing the functional status of patients, the average values of Barthel Index were 65.4±1.4 points, which corresponded to 2.7±0.3 points by modified Rankin Scale. The main difficulties were observed in such skills as writing (d170), use of means of communication (landline and mobile phone, computer, gadgets – d360), fine motor movements (d440), cooking (d630), eating (d550), washing (d510), personal hygiene (d520) and toilet use (d530), etc. When evaluated according to the standard Action Research Arm Test 3 months after the stroke, the average score was 39.9±1.5, according to the subtest of the Extensors’ Function Assessment Test – 8.3±0.4 points, which corresponds to the overall score for Action Research Arm Test +of 48.1±1.4 points. After 6 months, the score of the Action Research Arm Test 3 months after the stroke, the average score was 43.4±1.2 points ( = +8.8%), according to the subtest of the Extensors’ Function Assessment Test – 9.9±0.4 points ( = +19.3%), which corresponds to the overall score on Action Research Arm Test +of 53.2±1.3 points ( = +10.6%). Correlation analysis showed that the results of the subtest of the Extensors’ Function Assessment Test and Action Research Arm Test significantly correlate with each other (r = 0.72 p <0.01). The developed original test to assess the function of extensors has a specificity of 95.6% with a sensitivity of 98.5% (J = 0.95). This estimate corresponds to LR += 24.75, which allows us to assess the prognostic value of finger extension as very high. When assessing the internal consistency of the standard test Action Research Arm Test and Action Research Arm Test +, it was found that Cronbach = 0.87, which indicates a high degree of consistency of the tests. Conclusion. It is advisable to use the extensor function assessment test together with the standard Action Research Arm Test (modified Action Research Arm Test +)

Supinator to Posterior Interosseous Nerve Transfer for Restoration of Finger Extension

BACKGROUND Cervical spinal cord injuries result in a severe loss of function and independence. The primary goal for these patients is the restoration of hand function. Nerve transfers have recently become a powerful intervention to restore the ability to grasp and release objects. The supinator muscle, although a suboptimal tendon transfer donor, serves as an ideal distal nerve donor for reconstructive strategies of the hand. This transfer is also applicable to lower brachial plexus injuries. OBJECTIVE To describe the supinator to posterior interosseous nerve transfer with the goal of restoring finger extension following spinal cord or lower brachial plexus injury. METHODS Nerve branches to the supinator muscle are transferred to the posterior interosseous nerve supplying the finger extensor muscles in the forearm. RESULTS The supinator to posterior interosseous nerve transfer is effective in restoring finger extension following spinal cord or lower brachial plexus injury. CONCLUSION This procedure represents an optimal nerve transfer as the donor nerve is adjacent to the target nerve and its associated muscles. The supinator muscle is innervated by the C5-6 nerve roots and is often available in cases of cervical SCI and injuries of the lower brachial plexus. Additionally, supination function is retained by supination action of the biceps muscle.

The extensor tendons

The extensor tendon system of the hand includes the forearm-based extrinsic extensors that power wrist and finger extension as well as the hand-based intrinsic extensors that stabilize the digits in extension. The anatomy and interaction of these tendons are described with reference to the topographic classification system of Verdan’s zones. The injuries of the extensors can be either closed or open and the treatment is injury and site specific. The approaches to the individual injuries and treatment are described.

Influence of Visual Stimulation-Induced Passive Reproduction of Motor Images in the Brain on Motor Paralysis After Stroke

Finger flexor spasticity, which is commonly observed among patients with stroke, disrupts finger extension movement, consequently influencing not only upper limb function in daily life but also the outcomes of upper limb therapeutic exercise. Kinesthetic illusion induced by visual stimulation (KINVIS) has been proposed as a potential treatment for spasticity in patients with stroke. However, it remains unclear whether KINVIS intervention alone could improve finger flexor spasticity and finger extension movements without other intervention modalities. Therefore, the current study investigated the effects of a single KINVIS session on finger flexor spasticity, including its underlying neurophysiological mechanisms, and finger extension movements. To this end, 14 patients who experienced their first episode of stroke participated in this study. A computer screen placed over the patient’s forearm displayed a pre-recorded mirror image video of the patient’s non-paretic hand performing flexion–extension movements during KINVIS. The position and size of the artificial hand were adjusted appropriately to create a perception that the artificial hand was the patient’s own. Before and after the 20-min intervention, Modified Ashworth Scale (MAS) scores and active range of finger extension movements of the paretic hand were determined. Accordingly, MAS scores and active metacarpophalangeal joint extension range of motion improved significantly after the intervention. Moreover, additional experimentation was performed using F-waves on eight patients whose spasticity was reduced by KINVIS to determine whether the same intervention also decreased spinal excitability. Our results showed no change in F-wave amplitude and persistence after the intervention. These results demonstrate the potential clinical significance of KINVIS as a novel intervention for improving finger flexor spasticity and extension movements, one of the most significant impairments among patients with stroke. The decrease in finger flexor spasticity following KINVIS may be attributed to neurophysiological changes not detectable by the F-wave, such as changes in presynaptic inhibition of Ia afferents. Further studies are certainly needed to determine the long-term effects of KINVIS on finger spasticity, as well as the neurophysiological mechanisms explaining the reduction in spasticity.

Design and Analysis of a Dynamic Splint Based on Pulley Rotation for Post-Stroke Finger Extension Rehabilitation Device

The presence of rehabilitation tools is essential to more rapidly cure hand muscle disorders of people affected by stroke. One of the tools is a dynamic splint that is fit-sized, lightweight, comfortable to wear, and easy to operate. The paper proposes the design and analysis of new dynamic splints based on pulley rotation as a rehabilitation device for finger extension after stroke. This device consists of the main splint, the pulley, the locker, the finger handles, the ball bearing, and the fishing line. To lock and stop pulley turning, the locking system is designed to complement it which is also the most important mechanical segment. The shear stress of the pulley was 0.026 N/mm2. The deformation, stress, and strain energy of the locking system section were analyzed by the finite element method. The results showed that the deformation distribution around the locker section was at 0.1-0.15 mm intervals. The maximum stress 25.0786 MPa, which is still inferior to the yield strength of ABS Material (28.5 MPa). The safety factor of the structure is about n = 1.14. The largest strain energy was 0.2856 mJ at the same place as with the maximum stress which was close to the conical end of the locker. The correlation between stress-strain energy and moment was linear as well. In future work, a prototype will be fabricated using 3D printers, and it will be applied to the stroke patient. In addition, the therapies will be involved to assess the improvement of the finger extension of stroke patients.

Clinical features and genotypes of Laing distal myopathy in a group of Chinese patients, with in-frame deletions of MYH7 as common mutations

Background Laing distal myopathy is a rare autosomal dominant inherited distal myopathy caused by mutations of the MYH7 gene affecting mainly the rod region. We described the clinical features, muscle MRI and pathological changes as well as genetic mutations in a group of Chinese patients with Laing distal myopathy. Results Six patients with the confirmed diagnoses of Laing distal myopathy were recruited. Ankle dorsiflexion and finger extension weakness, as well as neck flexion weakness were common in our patients. Myopathic as well as neurogenic lesions were suggested by electromyography in different patients. Respiratory abnormality of sleep apnea was detected in two of our patients stressing the necessity of close respiratory monitoring in this disease. Muscle MRIs showed similar features of concentric fatty infiltration of anterior thigh muscles together with early involvement of tibialis anterior and extensor hallucis longus. However, muscle pathological presentations were varied depending on the biopsied muscles and the severity of the disease. In-frame deletions of the MYH7 gene made up 3/4 of mutations in our patients, suggesting that these are common mutations of Laing distal myopathy. Conclusions Our study further expanded the phenotypes and genotypes of Laing distal myopathy. In-frame deletions of the MYH7 gene are common causes of Laing distal myopathy.