Association of Head and Neck Anatomic Zones with Microvascular Reconstruction Outcomes.

Head and neck free flap survival relies on adequate tissue perfusion from the external carotid artery (ECA), and vessel length is inversely proportional to blood flow rate. Investigate whether distance from the ECA (as a proxy for pedicle vessel length) predicts flap survival or complications. Retrospective review of free flaps performed at three academic centers from 9/2006 to 8/2021. Flaps were categorized by distance from the ECA: orbit and above (zone 1), maxilla to parotid (zone 2), and mandible and below (zone 3). Secondary analysis assessed flap outcomes stratified by average historical pedicle length. A total of 2,369 flaps were identified in zones 1 ( = 109), 2 ( = 1878), and 3 ( = 382). Rates of flap failure (4.9%) and perioperative complications (36.3%) did not differ by zone or pedicle length. Zone 3 flaps, most commonly located in the larynx and hypopharynx, had significantly higher rates of fistula and infection. Conversely, 30-day readmission rates were significantly lower in patients with zone 2 flaps ( < 0.001). Rates of all other complications did not differ significantly between zones. Proximity to mucosal anatomic sites was a more powerful predictor of free flap viability than pedicle length or ECA proximity.