Post-burn microstomia: anatomy and elimination with trapeze-flap plasty.

Perioral contractures after burn (microstomia) is a common consequence of facial burns. A small oral opening creates a problem for oral hygiene, food intake and intubation. Therefore, contracture treatment is beneficial once severe limitation of function is realised. Traditionally, this type of contracture is released and the defect is closed with Y-V or Z-plasty. A commonly used technique consists of scar excision in the zone of the commissural apex down to the mucosal lining; the mobilised mucosal flaps are rotated up and down to cover the defect. Anatomical studies and surgical treatment experience for scar microstomia (345 patients) showed that a microstomia contracture could be described as an 'edge' contracture and is caused by a fold located at the oral angle. The lateral (exterior) sheet of the fold the scar causing the contracture; the medial sheet is the mucosa. The scar-surface deficit exists in the exterior sheet of the fold and the angle zone. Therefore, additional excision of scar deforms the oral angle. The contracture release, with a Y-shaped incision, and wound coverage (scar-surface-deficit compensation) with the single mucosal flap allows complete microstomia release and oral angle restoration. After the incisional contracture release, the wound, as a rule, accepts a trapezoid form. The defect (wound) is closed with a similar-shaped mucosal advancement flap. Good functional and cosmetic results were achieved in all cases. The commissural angle accepted a normal shape; the mucosal flap was invisible when the mouth was closed; the mouth had a normal appearance when the mouth orifice was open. After an adequate correction, no recurrence of contractures took place. Thus, scar dissection and wound coverage with the trapeze-flap plasty becomes a preferred reconstructive technique for microstomia release after burn.