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Reverse Looping for Nerve Repair: An Experimental Study on Retrograde Axonal Regeneration
Leonardo D Lanzarin1, Pedro A H Amaral2, André L Espindola Junior2
1From the Department of Orthopedics and Traumatology, Governador Celso Ramos Hospital.
Background:
Peripheral nerve injuries with segmental loss present significant reconstructive challenges. Autologous nerve grafting, the standard technique, requires 2 coaptation sites, increasing the risk of axonal misdirection and hindering functional recovery. Emerging evidence suggests that retrograde axonal regeneration is possible. Based on this potential, the authors evaluated reverse nerve looping, a technique in which the distal median nerve is pivoted proximally and coapted to the proximal stump using a single suture. The authors compared this approach with conventional nerve graft repair.
Methods:
Fifty-four female Wistar rats underwent 15-mm median and ulnar nerve excision in the arm, followed by reconstruction of the median nerve defect. In the nerve graft group ( n = 22), an autologous nerve graft was interposed, requiring 2 coaptations. In the reverse nerve loop group ( n = 22), the distal median nerve was pivoted and coapted to the proximal stump, creating a single coaptation site. In addition, 10 rats (sham group) underwent nerve dissection without transection. Functional recovery was assessed with grasp strength testing (20 and 30 weeks), electrophysiology, muscle weight analysis, and immunohistochemistry.
Results:
At 30 weeks, grasp strength recovery reached 61% in the nerve graft group and 66% in the reverse nerve loop group ( P > 0.05). Electrophysiology and muscle weight analysis showed similar recovery between groups. Histologic analysis confirmed comparable axonal regeneration.
Conclusions:
Reverse nerve looping provided functional and histologic outcomes comparable to autologous nerve grafting, while reducing coaptation sites. This technique may offer an alternative for selected cases of peripheral nerve reconstruction.
Clinical Relevance Statement:
Given the limited functional outcomes of nerve grafting in proximal injuries, reverse nerve looping may offer a reconstructive alternative in selected cases. This study supports further exploration of retrograde regeneration in clinical nerve repair.
