Surgical construction, conditioning and activation of functional muscle grafts

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Patient Motion Using a Computerized Leg Brace in Everyday Locomotion Tasks

Exoskeletal systems are becoming a rehabilitation standard of care for persons with lower limb paralysis. As muscular dysfunctions affect a heterogeneous patient group, each individual develops their own strategy to negotiate everyday locomotion challenges. This paper introduces a microprocessor controlled orthotic system that passively supports people with lower limb paralyses in their everyday locomotion tasks while incorporating the user as the highest control entity. A clinical study with seven patients with a range of leg pareses investigated the functionality and usage of the system while capturing the mechanical stress on the device. Data from the knee joint was recorded in locomotion tasks including level walking, ramp, and stair negotiation. For all patients, the measurements demonstrate that the motion for level walking was close to the motion of healthy individuals. In other tasks, variations between the patients were large with respect to motion kinematics, power, and torque requirements. As the control concept supported individualized motion patterns, patients perceived the system functionality as intuitive. The mechanically most demanding task was stair descent with a peak torque of 1.47 Nm/kg and peak dissipative power up to 2.67 W/kg. Intra-subject variability makes prediction of movements and loads challenging

An Insulated Flexible Sensor for Stable Electromyography Detection : Application to Prosthesis Control

Electromyography (EMG), the measurement of electrical muscle activity, is used in a variety of applications, including myoelectric upper-limb prostheses, which help amputees to regain independence and a higher quality of life. The state-of-the-art sensors in prostheses have a conductive connection to the skin and are therefore sensitive to sweat and require preparation of the skin. They are applied with some pressure to ensure a conductive connection, which may result in pressure marks and can be problematic for patients with circulatory disorders, who constitute a major group of amputees. Due to their insulating layer between skin and sensor area, capacitive sensors are insensitive to the skin condition, they require neither conductive connection to the skin nor electrolytic paste or skin preparation. Here, we describe a highly stable, low-power capacitive EMG measurement set-up that is suitable for real-world application. Various flexible multi-layer sensor set-ups made of copper and insulating foils, flex print and textiles were compared. These flexible sensor set-ups adapt to the anatomy of the human forearm, therefore they provide high wearing comfort and ensure stability against motion artifacts. The influence of the materials used in the sensor set-up on the magnitude of the coupled signal was demonstrated based on both theoretical analysis and measurement.The amplifier circuit was optimized for high signal quality, low power consumption and mobile application. Different shielding and guarding concepts were compared, leading to high SNR.(VLID)344807

Acquisition of muscle activity with a fully implantable multi-channel measurement system

This work presents intramuscular measurements of the electromyogram (EMG) during goal directed arm movements. Thin film electrode arrays were epimysially implanted on the deltoideus of a rhesus macaque and the encapsulation process was monitored by impedance measurements. Increase of impedance plateaued after four weeks indicating a complete incorporation of electrodes. EMG recorded with these electrodes yielded a signal to noise ratio of about 80 dB at 200 Hz. The EMG recorded during goal directed arm movements showed high similarity amongst movements in the same direction while presenting clear differences between different movement directions. A second implantation of the whole measurement system for nine weeks proved good handling and biotolerance. © 2012 IEEE

Reactive Exercises with Interactive Objects: Interim Analysis of a Randomized Trial on Task-Driven NMES Grasp Rehabilitation for Subacute and Early Chronic Stroke Patients

Enriched environments and tools are believed to promote grasp rehabilitation after stroke. We designed S2, an interactive grasp rehabilitation system consisting of smart objects, custom orthoses for selective grasp constraining, and an electrode array system for forearm NMES. Motor improvements and perceived usability of a new enriched upper limb training system for sub-acute stroke patients was assessed in this interim analysis. Inclusion criteria: sub-acute stroke patients with MMSE>20, ipsilesional MI>80%, and contralesional MI<80%. Effects of 30-min therapy supplements, conventional vs. S2 prototype, are compared through a parallel two-arms dose-matched open-label trial, lasting 27 sessions. Clinical centres: Asklepios Neurologische Klinik Falkenstein, Königstein im Taunus, Germany, and Clinica Villa Beretta, Costa Masnaga, Italy. Assessment scales: ARAT, System Usability, and Technology Acceptance. Methodology: 26 participants were block randomized, allocated to the study (control N=12, experimental N=14) and underwent the training protocol. Among them, 11 participants with ARAT score at inclusion below 35, n = 6 in the experimental group, and n = 5 in the control group were analysed. Results: participants in the enriched treatment group displayed a larger improvement in the ARAT scale (+14.9 pts, pval=0.0494). Perceived usability differed between clinics. No adverse effect was observed in relation to the treatments. Trial status: closed. Conclusions: The S2 system, developed according to shared clinical directives, was tested in a clinical proof of concept. Variations of ARAT scores confirm the feasibility of clinical investigation for hand rehabilitation after stroke.EC/H2020/644721/EU/REaching and grasping Training based on Robotic hybrid AssIstance for Neurological patients: End users Real life evaluation/RETRAINE

Broadband Prosthetic Interfaces: Combining Nerve Transfers and Implantable Multichannel EMG Technology to Decode Spinal Motor Neuron Activity

Modern robotic hands/upper limbs may replace multiple degrees of freedom of extremity function. However, their intuitive use requires a high number of control signals, which current man-machine interfaces do not provide. Here, we discuss a broadband control interface that combines targeted muscle reinnervation, implantable multichannel electromyographic sensors, and advanced decoding to address the increasing capabilities of modern robotic limbs. With targeted muscle reinnervation, nerves that have lost their targets due to an amputation are surgically transferred to residual stump muscles to increase the number of intuitive prosthetic control signals. This surgery re-establishes a nerve-muscle connection that is used for sensing nerve activity with myoelectric interfaces. Moreover, the nerve transfer determines neurophysiological effects, such as muscular hyper-reinnervation and cortical reafferentation that can be exploited by the myoelectric interface. Modern implantable multichannel EMG sensors provide signals from which it is possible to disentangle the behavior of single motor neurons. Recent studies have shown that the neural drive to muscles can be decoded from these signals and thereby the user’s intention can be reliably estimated. By combining these concepts in chronic implants and embedded electronics, we believe that it is in principle possible to establish a broadband man-machine interface, with specific applications in prosthesis control. This perspective illustrates this concept, based on combining advanced surgical techniques with recording hardware and processing algorithms. Here we describe the scientific evidence for this concept, current state of investigations, challenges, and alternative approaches to improve current prosthetic interfaces.peerReviewe