The Multivector Gracilis Free Functional Muscle Flap for Facial Reanimation

Abstract

Importance: A multivector functional muscle flap that closely simulates the biomechanical effects of facial muscle groups is essential for complete smile restoration after facial paralysis.

Objective: To determine the feasibility of a multivector gracilis muscle flap design for reanimation after facial paralysis and to analyze the effect on the smile display zone.

Design, setting, and participants: Prospective analysis of patients who underwent a double paddle multivector gracilis flap for complete facial paralysis between June 2015 and December 2016 was carried out in a tertiary hospital.

Interventions: The gracilis muscle was harvested as a double paddle flap and inserted along 2 vectors for facial reanimation.

Main outcomes and measures: The primary outcome measures were: (1) dental display (the number of maxillary teeth displayed on paralyzed vs normal sides), (2) exposed maxillary gingival scaffold width, (3) interlabial gap at midline and canine, (4) facial asymmetry index (FAI), and (5) dynamic periorbital wrinkling.

Results: There were 10 women and 2 men between ages 20 and 64 years (mean [SD], 46 [15] years). Five flaps were reinnervated with facial and masseteric nerves, 5 with masseteric nerve only, and 2 with crossfacial nerve only. There was functional muscle recovery in all cases. On average there was additional 3.1 maxillary teeth exposed posttreatment when smiling (5.5 vs 8.6; CI, 7.9 to 16.6; P < .001). The mean exposed maxillary gingival scaffold width improved from 31.5 mm to 43.7 mm (95% CI, 1.9 to 4.3; P < .001). There was no significant difference in interlabial exposure at midline (7.1 mm vs 7.7 mm; CI, -1.5 to 2.7; P = .56) but a 56.4% improvement at the level of the canines (3.9 vs 6.1; CI, 0.1 to 4.3; P = .04). The mean FAI when smiling was reduced from 9.1 mm to 4.5 mm (CI, -8.0 to -1.2; P = .01). Dynamic wrinkling of the periorbital area with smiling was noted in 4 patients.

Conclusions and relevance: The gracilis flap can be reliably designed as a functional double paddle muscle flap for a multivector facial reanimation. The multivector gracilis flap design is effective in improving all components of the smile display zone and has the potential for producing periorbital-wrinkling characteristic of a Duchenne smile.

Level of evidence: 4.

Figure 1.. The Anatomy of a Smile

A, A full smile is the result of a multivector (black arrowheads) and multizonal action (blue triangle, square, and circle zones) of the smile muscles. Upper lip and commissure elevation results from muscle action within the square and triangular zones respectively, and periorbital wrinkling in the circular zone. B, The upper and lower lip frames the smile display zone. In this framework are the components of a smile including the gingival scaffold and displayed teeth. C, The smile display zone. D, The paralyzed upper lip drapes over the smile display zone obscuring the gingival scaffold and limiting dental display. Correction of the paralytic labial drape requires a multivector muscle action (blue arrowheads). E, The horizontal and vertical components of the smile display zone can be analyzed by measuring the maximal gingival scaffold width and interlabial gap at the midline and between the canines.

Figure 2.. Design and Insertion of the Multivector Gracilis Flap

A, A right-sided gracilis flap designed for a left-sided paralysis. The tendinous segment (blue arrowheads) was inserted into the orbicular oris and the distal end (black arrowheads) fixated to the periosteum of the malar bone and zygoma. The primary (larger) muscle paddle was harvested from the anterior aspect of the gracilis muscle and the secondary (smaller) paddle from the posterior aspect. Image copyright www.dnaillustrations.com. B, Two divergent muscle vectors simulating the function of the zygomaticus and levator labii muscles. C, Outline of planned muscle insertion. D, Design of 3-paddle multivector gracilis flap. E, The gracilis flap is harvested as a free functional composite flap with 2 isolated muscle paddles connected by a common-source neurovascular pedicle.

Figure 3.. Sample Smile Outcome Following Multivector Double Paddle Gracilis Flap in 2 Patients With Complete Facial Paralysis