Association between microvascular free-flap arterial anastomosis caliber and risk for development of osteoradionecrosis.

Objectives: Osteoradionecrosis (ORN) following radiation therapy (RT) is a serious complication for patients undergoing head and neck cancer treatment. Recent literature has found an association between ipsilateral external carotid artery (ECA) diameter and the development of ORN. This study evaluates microvascular free-flap arterial anastomosis diameter and the development of ORN.

Materials and methods: Sixty-six patients underwent fibular free-flap reconstruction followed by RT between 2012-2019 at the University of Florida. Anastomosis and ECA diameters pre- and post-RT were measured from computed tomography images. Multivariate regression analysis identified significant factors in the development of ORN.

Results: Incidence of ORN was 33.3 % (N = 22/66). Mean post-RT anastomosis diameters were 2.3 and 2.2 for the ORN group and no-ORN group, respectively (p = 0.548). Mean post-RT ipsilateral ECA diameters were 4.7 and 4.2 for the ORN group and no-ORN groups, respectively (p = 0.040). The change in pre-RT versus post-RT ipsilateral ECA diameters was different in patients with RT dose above and below 55 Gy (p = 0.041). Neither post-RT anastomosis (OR = 1.78, 95% CI: 0.43, 8.65, p = 0.434), nor ECA (OR = 1.44, 95% CI: 0.78, 2.83, p = 0.250) diameters were associated with development of ORN while controlling RT dose (OR = 1.15, 95% CI: 1.04, 1.28, p = 0.006), post-operative fistula (OR = 9.11, 95% CI: 1.65, 93.7, p = 0.010), and post-operative infection (OR = 3.48. 95% CI = 1.01, 12.7, p = 0.048), and CCI (OR = 0.61, 95 % CI: 0.36, 0.96, p = 0.031).

Conclusion: A higher degree of narrowing in ipsilateral ECA following RT may be linked to development of ORN. RT doses ≥ 55 Gy were associated with a high risk of ORN.