Analysis of the lengthening effect of the muscle repair in functional cleft lip repair.

In 14 patients undergoing functional cleft lip repair, changes in the lengths of the key lip segments were measured preoperatively, after the muscle layer was repaired, and after the skin was repaired using pieces of wire bent to follow the curves of the lip in three dimensions. The cleft side of the lip was shorter than the normal side in the vertical and horizontal dimensions. Freeing the muscle from its dermal insertions, splitting it, and advancing it into the medial side of the cleft lengthened the cleft side of the lip vertically and horizontally. The Z-plasty skin repair further lengthened the cleft side of the lip in the vertical dimension. The lengthening effect of the muscle repair appears to be the result of the loose skin redraping over the dissected muscle and further explains elimination of the orbicularis bulge and superior scar formation in the functional cleft lip repair.