Vascular Supply of the Distally Based Superficial Sural Artery Flap: Surgical Safe Zones Based on Component Analysis Using Three-Dimensional Computed Tomographic Angiography

Background: Distal lower limb reconstruction remains challenging for surgeons. Since its description, the distally based superficial sural artery flap (sural flap) has gained popularity for these indications. The authors' aim was to determine which components were necessary to maintain this flap's arterial supply. Methods: Anatomical components were studied on 24 fresh adult cadaver legs and included the following: skin, adipose tissue, lesser saphenous vein, deep fascia, and sural nerve. Thirty-two flaps were harvested and divided into the following combination groups: cutaneous-venoneuroadipofascial (n = 5), venoneuroadipofascial (n = 3), neurofascial (n = 4), cutaneous-adipovenous (n = 2), cutaneous-venoadipofascial (n = 9), venoadipofascial (n = 5), and purely fascial (n = 4). Leg length, location of the sural nerve crossing the deep fascia, and location of peroneal and posterior tibial artery perforators were recorded. Twenty-eight of the combination flaps were injected with barium sulfate. Three-dimensional computed tomographic angiography was used to analyze the vascular territory of each flap. Results: The cutaneous-venoneuroadipofascial and cutaneous-venoadipofascial flaps were perfused 86.5 percent and 80.2 percent, respectively, followed by cutaneous- adipovenous (75.7 percent), venoneuroadipofascial (87.1 percent), and venoadipofascial (74.8 percent) flaps. In contrast, the neurofascial and purely fascial flaps were merely perfused 40.8 percent and 44.1 percent, respectively, using only a perineural vascular network, with minimal fascial contribution. Conclusions: The lesser saphenous vein and the deep adipose tissue are necessary for the arterial supply of the sural flap. The deep fascia serves only as mechanical support. The sural nerve contributes to the vascular network, but its inclusion does not increase the vascular territory. Noninclusion of the sural nerve defines a new pivot point that should be identified before the harvest of the sural flap.