Experimental analysis of the adjunctive Z-plasty in the closure of fusiform defects.

Facial defects too large for primary closure can sometimes be repaired with the addition of a unilateral or bilateral adjunctive Z-plasty. In this study, the mechanics of the adjunctive Z-plasty are examined experimentally. In vivo experiments using piglets show that closure tension is decreased 30% by each Z-plasty. The true lengthening of the Z when transposed is 80% of that theoretically predicted. The deformation caused by fusiform excision and closure with and without undermining and with one or two Z-plasties is evaluated. In general, the Z-plasty exchanges deformation perpendicular to the long axis of excision for deformation parallel to that axis. A clinical case using the adjunctive Z-plasty for the repair of a large chin defect is reported.