Extensive Primary Thinning of the Free Functional Gracilis Flap is Safe and Does Not Compromise Functional Outcomes in Dynamic Smile Reconstruction

Abstract

Background

Facial reanimation surgery using a free functional gracilis muscle transfer is the standard of care in long-standing facial paralysis. Surgical revision rates are high, with most directed toward flap debulking and improving contour. During the index surgery, the muscle can be thinned extensively to potentially avoid revisions, but there is concern for injuring the neurovascular pedicle or weakening contractility. The authors hypothesize that primary flap thinning is safe without compromising smile contractility.

Methods

Patients undergoing dynamic smile reconstruction with free functional gracilis muscle transfer were retrospectively reviewed over an 8-year period. Functional morphometric outcomes were evaluated with the Emotrics facial expression recognition software. Time to innervation, secondary procedures, and complications were also recorded.

Results

In total, 34 facial reanimation procedures met the inclusion criteria. The average muscle flap weight after primary thinning was 17.0 ± 9.3 g (range 5–46 g). Smile excursion improved by 7.7 ± 5.5 mm in the unilateral and 5.7 ± 3.4 mm in the bilateral paralysis groups, with significant improvement from preoperative commissure (p = 0.001) and smile angle (p = 0.003) measurements. One patient required a secondary debulking procedure. Secondary outcomes of improved reinnervation time and smile excursion weakly trended with decreased gracilis weight but did not achieve statistical significance. Complications included one flap loss, one donor site hematoma, one facial abscess, and one facial hematoma.

Conclusion

Flap thinning at the time of primary free functional gracilis transfer did not result in increased complications or compromise its ability to produce symmetric smiles of adequate excursion. Compared to published cohorts, this technique may reduce the need for secondary revisions.

Keywords

facial reanimation - smile reconstruction - free functional muscle transfer

Authors' Contributions

D.C.: Manuscript and data preparation, data collection and analysis.

A.Y.H.: Data preparation, data collection and analysis.

G.K.: Data collection and analysis, and manuscript review.

K.T.: Manuscript preparation and review.

G.B.S.: Statistical analyses and manuscript review.

A.K.S-W.: Study conceptualization and coordination, surgeries, data analysis, manuscript review.

Publication History

Received: 12 November 2024

Accepted: 12 May 2025

Article published online:
16 June 2025

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