| 1. |
- Bergmeister, Konstantin D., et al.
(författare)
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Broadband prosthetic interfaces: Combining nerve transfers and implantable multichannel EMG technology to decode spinal motor neuron activity
- 2017
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 11, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Bergmeister, Konstantin Davide, et al.
(författare)
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Motor unit characteristics after selective nerve transfers
- 2021
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Ingår i: Bionic Limb Reconstruction. - Cham : Springer International Publishing. ; , s. 83-91
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Selective nerve transfers are used in biological and bionic extremity reconstruction to restore and improve extremity function. Here, peripheral nerves are rerouted to various target muscles, and thereby the structural composition of motor units is surgically altered. Previous studies have shown a high success rate of successful reinnervation of above 90% after these nerve transfers. In targeted muscle reinnervation, nerve transfers are applied to reroute amputated nerves to more proximal muscles in the stump and thereby increase the number of prosthetic control signals. Because donor nerves physiologically supply multiple muscles but are transferred to a single target muscle, the innervation ratio between donor and recipient is substantially altered. This changes the characteristics of the motor unit of the target muscles that we extensively investigated in a novel nerve transfer animal model. In this chapter, we illustrate this model, the effect of nerve transfers on motor unit physiology, as well as the implications on improving the interface between man and machine in prosthetic extremity reconstruction. In addition, first results on the effect of targeted muscle reinnervation on human motor unit physiology are described.
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| 3. |
- Bergmeister, Konstantin D, et al.
(författare)
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Peripheral nerve transfers change target muscle structure and function
- 2019
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Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Selective nerve transfers surgically rewire motor neurons and are used in extremity reconstruction to restore muscle function or to facilitate intuitive prosthetic control. We investigated the neurophysiological effects of rewiring motor axons originating from spinal motor neuron pools into target muscles with lower innervation ratio in a rat model. Following reinnervation, the target muscle's force regenerated almost completely, with the motor unit population increasing to 116% in functional and 172% in histological assessments with subsequently smaller muscle units. Muscle fiber type populations transformed into the donor nerve's original muscles. We thus demonstrate that axons of alternative spinal origin can hyper-reinnervate target muscles without loss of muscle force regeneration, but with a donor-specific shift in muscle fiber type. These results explain the excellent clinical outcomes following nerve transfers in neuromuscular reconstruction. They indicate that reinnervated muscles can provide an accurate bioscreen to display neural information of lost body parts for high-fidelity prosthetic control.
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| 4. |
- Vujaklija, Ivan, et al.
(författare)
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Biomechanical Analysis of Body Movements of Myoelectric Prosthesis Users During Standardized Clinical Tests
- 2023
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 70:3, s. 789-799
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective clinical evaluation of user's capabilities to handle their prosthesis is done using various tests which primarily focus on the task completion speed and do not explicitly account for the potential presence of compensatory motions. Given that the excessive body compensation is a common indicator of inadequate prosthesis control, tests which include subjective observations on the quality of performed motions have been introduced. However, these metrics are then influenced by the examiner's opinions, skills, and training making them harder to standardize across patient pools and compare across different prosthetic technologies. Here we aim to objectively quantify the severity of body compensations present in myoelectric prosthetic hand users and evaluate the extent to which traditional objective clinical scores are still able to capture them. Methods: We have instructed 9 below-elbow prosthesis users and 9 able-bodied participants to complete three established objective clinical tests: Box-and-Blocks-Test, Clothespin-Relocation-Test, and Southampton-Hand-Assessment-Procedure. During all tests, upper-body kinematics has been recorded. Results: While the analysis showed that there are some correlations between the achieved clinical scores and the individual body segment travel distances and average speeds, there were only weak correlations between the clinical scores and the observed ranges of motion. At the same time, the compensations were observed in all prosthesis users and, for the most part, they were substantial across the tests. Conclusion: The sole reliance on the currently available objective clinical assessment methods seems inadequate as the compensatory movements are prominent in prosthesis users and yet not sufficiently accounted for.
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| 5. |
- Vujaklija, Ivan, et al.
(författare)
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Prospects of neurorehabilitation technologies based on robust decoding of the neural drive to muscles following targeted muscle reinnervation
- 2017
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Ingår i: Biosystems & Biorobotics. - Cham : Springer International Publishing. ; , s. 1359-1363
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Latest advances in neurorehabilitation technologies provide users with reliable mechatronic devices. Nonetheless, the control capabilities of these systems are limited to techniques that rely on indirect measures of neural information using EMG signals. We foresee that the combination of targeted muscle reinnervation (TMR) and high-density EMG electrodes supported by advanced blind source separation techniques (BSS) can substantially enhance current neurorehabilitation solutions. TMR provides access to the nerve activity by connecting nerves to muscles, used as biological amplifiers. Control would benefit from richer information content directly related to spinal motor neuron activity. The motor neuron firing statistics is obtained by applying advanced decomposition algorithms on the multi-channel EMGs from the targeted reinnervated muscles. It is expected that the control of these systems will be more dexterous and precise.
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