Comparison of Fascicular Turnover Flap and Autograft in a Rat Facial Nerve Model

Background: Fascicular turnover flap (FTF) is a donor-sparing option for segmental facial nerve repair. This study compared autologous nerve grafting with proximally based and distally based FTF in a rat facial nerve model. Methods: Adult male Wistar rats were randomized to autograft, proximal FTF, or distal FTF (n = 8 per group). A single additional animal with an untreated defect served as a qualitative histological reference. The prespecified primary endpoint was whisker motion amplitude at week 8; the secondary endpoints were central section histomorphometry (nerve tissue area, µm²) and variability metrics (IQR, SD, and coefficient of variation) as measures of reproducibility. Non-parametric tests (Kruskal-Wallis; Mann-Whitney U) were used; pairwise functional comparisons were Holm-corrected; and effect sizes were expressed as Cliff's δ. Results: At week 8, the overall functional comparison was significant (Kruskal-Wallis p = 0.047), but no pairwise contrast remained significant after Holm correction. Functional recovery was highest in the autograft group, followed by proximal FTF and distal FTF. Both FTF groups showed lower inter-animal variability than autograft for the week-8 functional endpoint, with the distal FTF showing the lowest dispersion. Central section nerve area comparisons did not reach global significance; effect sizes and descriptive statistics favored autograft, and a single unadjusted pairwise contrast (autograft > proximal FTF) should be interpreted cautiously. Conclusions: Both FTF configurations achieved measurable functional and structural regeneration while avoiding an additional free donor nerve graft. Within an 8-week window, autograft remained the benchmark. Between FTF variants, distal FTF produced more stable functional outcomes, but this did not translate into superior functional recovery. Confirmation in larger, balanced cohorts with longer follow-up and vascular/neural labeling is warranted.