A comparison of one- versus two-stage surgery in an experimental model of functional muscle transfer with interposed nerve grafting

Abstract

Functional muscle transfer (FMT) combined with cross-facial nerve grafting (CFNG) is the gold standard treatment of chronic unilateral facial palsy, performed by most surgeons over two operative stages to minimise FMT denervation atrophy. Proponents of one-stage surgery cite shorter total recovery time, fewer operative procedures and a possible beneficial neurotrophic effect of muscle attachment. This study aimed to compare one- and two-stage surgery in terms of neural and muscle reinnervation and FMT force production. Forty New Zealand white rabbits underwent one- or two-stage rectus femoris FMT and interposed nerve grafting under different reinnervation conditions. For two-stage surgery, nerve grafting was followed by FMT after three months and by final experiments after a further six months, whereas one-stage groups experienced nerve grafting and FMT together and final experiments after nine months. Outcomes compared were nerve graft and rectus nerve morphometry, FMT reinnervation measured using PGP 9.5, and FMT force production. Statistical analysis was performed by means of the independent samples t-test or the Mann-Whitney Rank Sum test using Statistics Package for the Social Sciences version 11.0.4 for Mac OS X. Nerve graft reinnervation was similar for respective one- and two-stage surgery groups or favoured one-stage surgery. There was no significant difference between respective groups in terms of rectus nerve morphometry, muscle reinnervation, or absolute, weight-adjusted or weight- and control-adjusted tetanic force production. One-stage surgery offers potential advantages including a reduction in the number of surgical procedures, a shorter total recovery time and beneficial economic and healthcare delivery implications. This data supports previous clinical and experimental studies and questions the basis for performing facial reanimation by FMT combined with CFNG over two separate operative stages.