The Fibular Artery Communicating Branch and Fibular Artery Dominance: An Anatomical Hazard for Posterior Approaches to the Ankle

ABSTRACT Open reduction of posterior malleolar fractures (PMFs) increasingly employs direct posterior approaches. The posterolateral and posteromedial approaches both develop the deep posterior compartment in the plane between the fibular and posterior tibial arteries, placing the fibular artery communicating branch (FACB) within the operative field; inadvertent injury to this branch has been associated with limb‐threatening ischemia. This study quantified the prevalence of the FACB and of fibular artery dominance (FAD), a configuration in which the fibular artery provides the principal distal supply because the posterior tibial artery is atretic or absent, and considered the implications for surgical approach selection. In a single‐center cross‐sectional study, 916 consecutive lower‐limb computed tomography angiograms performed over 1 year were screened; 726 met the inclusion criteria and were assessed by trained reviewers for the FACB, FAD, laterality and clinical indication. An FACB was identified in 280 patients (38.6%, 95% CI 35.1–42.2). Its prevalence varied with clinical indication (χ 2 = 33.67, p < 0.001), being highest in peripheral vascular disease (45.1%) and lowest in other vascular referrals (16.4%). FAD occurred exclusively in FACB‐positive limbs, in 28 patients (10.0% of FACB‐positive limbs; 3.9% of the whole cohort, 95% CI 2.7–5.5), and its distribution did not differ by indication (Freeman–Halton exact p = 0.81). Because the FACB lies within the field of the posterolateral and posteromedial approaches but posterior and lateral to the medial‐posteromedial (MPM) approach, the MPM approach avoids the at‐risk plane. These findings support anatomically informed approach selection and caution when a posterolateral or posteromedial approach is planned, particularly in patients with peripheral vascular disease.