Optimal design of O-to-Z flaps for closure of facial skin defects

Objective: To determine the optimal design of an Oto-Z flap for closure of facial skin defects. Methods: Prospective cadaver study. Multiple 2-cmdiameter circular skin defects were created in fresh cadavers. Three types of O-to-Z flaps were designed, varying the angle of a curved line about concentric radii of the defect: acute, intermediate, or wide angle flap. The tension of closure of each was-measured and compared at different lengths of incision and extents of undermining. Results: The acute angle flap had a significantly lower closing tension at all lengths of incision and extents of undermining than the intermediate and wide angle flaps. Increasing the amount of undermining alone without incising the flap did not significantly decrease the closing tension. Incising the acute angle flap to 4 radii created a nearly tension-free closure. Conclusions: The optimal design for reducing tension of the O-to Z flap is an acute angle flap. The optimal length of incision and undermining necessary to minimize closing tension is discussed.