Keystone Island Flap: Effects of Islanding on Vascularity

Based on his clinical observations the “red dot sign” and hyperemic flare, Behan has advocated the superior vascularity of the island flap design for at least 2 decades. The aim of this study was to determine whether (1) surgical islanding of a flap alters the vascularity or blood supply of the flap and (2) these changes in blood supply explain Behan’s clinical observations of “red dot sign” and hyperemic flare. METHODS: Patients undergoing local island fasciocutaneous flaps or anterolateral thigh fasciocutaneous free flaps were recruited for this trial from a single institution over a 10-month period (September 2013 to July 2014). Three adjacent specimens of skin and subcutaneous fat (control, non-island, and island) were harvested from each patient at various stages of their surgery for histological assessment. A pathologist reviewed randomized specimens for microvascular variables, including arteriole wall thickness, arteriole diameter, venule wall thickness, and venule diameter. RESULTS: Thirteen patients (with 14 sets of specimen) were recruited for this study. When compared with the control state, both arteriole diameter and venule diameter in island flaps were significantly increased. CONCLUSIONS: These results validate Behan’s clinical observations of “red dot sign” and hyperemic flare. Further studies are required to directly compare island and non-island flap designs.