Surgical nerve transfers are used to efficiently treat peripheral nerve injuries, neuromas, phantom limb pain or improve bionic prosthetic control. Commonly, one donor nerve is transferred to one target muscle. However, the transfer of multiple nerves onto a single target muscle may increase the number of muscle signals for myoelectric prosthetic control and facilitate the treatment of multiple neuromas. Currently, no experimental models are available for multiple nerve transfers to a common target muscle in the upper extremity. This study describes a novel experimental model to investigate the neurophysiological effects of peripheral double nerve transfers. For this purpose, we developed a forelimb model to enable tension-free transfer of one or two donor nerves in the upper extremity. Anatomic dissections were performed to design the double nerve transfer model (n=8). In 62 male Sprague-Dawley rats the ulnar nerve of the antebrachium alone (n=30) or together with the anterior interosseus nerve (n=32) was transferred to reinnervate the long head of the biceps brachii. Before neurotization, the motor branch to the biceps’ long head was transected at the motor entry point and resected up to its original branch to prevent auto-reinnervation. In all animals, coaptation of both nerves to the motor entry point could be performed tension-free. Mean duration of the procedure was 49 ± 13 min for the single nerve transfer and 78 ± 20 min for the double nerve transfer. Twelve weeks after surgery, muscle response to neurotomy, behavioral testing, retrograde labeling and structural analyses were performed to assess reinnervation. These analyses indicated that all nerves successfully reinnervated the target muscle. No aberrant reinnervation was observed by the originally innervating nerve. Our observations suggest a minimal burden for the animal with no signs of functional deficit in daily activities or auto-mutilation in both procedures. Furthermore, standard neurophysiological analyses for nerve and muscle regeneration were applicable. This newly developed nerve transfer model allows for the reliable and standardized investigation of neural and functional changes following the transfer of multiple donor nerves to one target muscle.
Muscle mass data have been deposited in Dryad under the DOI: https://doi.org/10.5061/dryad.3j9kd51jb.Retrograde labeling data has been deposited in Dryad under the DOI: https://doi.org/10.5061/dryad.6q573n60c.
Muscle mass of the long head of the biceps following single and double nerve transferDryad Digital Repository, doi:10.5061/dryad.3j9kd51jb.
Labeled motor neurons following single and double nerve reinnervation of the long head of the bicepsDryad Digital Repository, doi:10.5061/dryad.6q573n60c.
- Matthias Luft
- Vlad Tereshenko
- Christopher Festin
- Gregor Laengle
- Olga Politikou
- Udo Maierhofer
- Dario Farina
- Oskar C Aszmann
- Konstantin Davide Bergmeister
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: The protocols for the experiments were approved by the ethics committee of the Medical University of Vienna and the Austrian Ministry for Research and Science (reference number BMBWF- 66.009/0413-V/3b/2019) and strictly followed the principles of laboratory animal care as recommended by the Federation of European Laboratory Animal Science Associations (FELASA).
- Samantha R Santacruz, The University of Texas at Austin, United States
- Received: June 16, 2021
- Accepted: September 30, 2021
- Accepted Manuscript published: October 1, 2021 (version 1)
© 2021, Luft et al.
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