Reconstructing degenerated nerve defects with a degenerated nerve graft – preliminary results
Philipp Tratnig-Frankl, MD1, Udo Maierhofer, MD2, Martin Schmoll, PhD3, Lisa Jöns, Medical Student4, Homayon Zirak, Medical Student4, Christopher Festin, MD4, Vlad Tereshenko, MD, PhD4, Konstantin Bergmeister, MD, PhD4,5 and Oskar C Aszmann, MD1,2, 1Department of Plastic and Reconstructive Surgery, Medical University of Vienna, General Hospital of Vienna, Vienna, Austria, 2Medical University of Vienna, Vienna, Austria, 3Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 4Clinical Laboratory for Bionic Extremity Reconstruction, Medical University of Vienna, Vienna, Austria, 5Karl Landsteiner University of Health Sciences, St. Pölten, Austria
Introduction
When reconstructing peripheral nerve defects in global plexopathy patients, additionally to the sural nerves, the medial brachial, antebrachial and occasionally also the ulnar nerve can be used, despite the primary lesion involving a lower root rupture or avulsion. The question arises whether a predegenerated nerve can provide sufficient regenerative support as both the conductive matrix and the reactive Schwann cells have undergone significant changes in structure and function that may not be ideal to support regenerating axons. This study thus aims to investigate the potential of degenerated donor nerves in promoting nerve regeneration as compared to standard fresh grafts in the reconstruction of critical nerve defects in an animal model.
Materials
This experimental study involved 35 adult Sprague Dawley rats, which were divided into two groups. The initial surgical procedure created a unilateral two-centimeter defect in the peroneal nerve. In the first group, the sural nerve was left intact, while in the second group, it was cut proximally during the same procedure. After a three-week period, the nerve defect was reconstructed using either a fresh or the predegenerated sural nerve.
Methods
After a six-week follow-up, rats were anesthetized, and bilateral isometric force measurements of the tibialis anterior muscles were performed, including tetanic force during a maximal evoked contraction (MEC) and maximal twitch force. Following the measurements, all animals were euthanized, and histological samples were taken.
Results
A comparative analysis was conducted between experimental groups, expressing the recovery as a ratio between injured and healthy side. In the fresh graft group, the mean MEC was measured at 9.6% ± 6.9%, compared to 7.6% ± 4.4% in the predegenerated graft. The mean maximum twitch force in the first group was 6.0% ± 3.1% compared to 5.6% ± 3.9% in the second group. The mean weight of the tibialis anterior muscle, comparing the injured to the uninjured side was 34% in the first group and 32% in the second group. All measurements showed no statistical inferiority between the groups. The histological analysis demonstrates axonal ingrowth in both the predegenerated and fresh nerve graft.
Conclusions
In regards of muscle strength, recovery and muscle weight, the preliminary results show comparable outcomes for predegenerated and fresh nerve grafts. Overall, these results are promising particularly in the context of critical nerve defects involving multiple nerves, as well as plexus injuries, where the use of a degenerated graft often remains the only additional source of graft material.
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