Biomechanics of A-to-T flap design

Objectives/Hypothesis: The objective of this study was to determine the ver tical height, horizontal incision width, and extent of undermining that cor related with the lowest closure tension. Study Design: Prospective, cadaver study. Methods: Forty "A-to-T" naps were made on the torso and lower extre mities of fresh cadavers, Tea naps each were designed at heights of three, four, and five defect radii. Closing tensions were measured for each of the se flaps initially, followed by serial base extensions. Eased on the inform ation from these first naps, 10 additional flaps were made at the optimal h eight and base extensions. These flaps were then serially undermined and te nsion measurements taken. Results: Our results suggest that making the vert ical height of the "A" twice the height of the defect yields a significant decrease in tension of closure when compared with a vertical height one and a half times the defect (P < .01), while increasing the height to two and a half times the defect height provides only a minimal further reduction in closure tension. Extending the base (horizontal) incision one defect diame ter in each direction offers the greatest reduction in closing tension. Und ermining up to three times the diameter of the defect offers progressive im provement in the tension of closure, while further undermining confers litt le additional benefit. Conclusions: Our findings indicate that the ideal A- to-T flap is designed to be twice the height of the original defect, with b ase extensions one defect diameter in each direction, and undermined to thr ee times the diameter of the defect.