A complete knowledge of the topographic anatomy of the foot is requisite to facilitate the exposure of these vessels. The posterior tibial artery bifurcates a short distance inferior to the medial malleolus into two major branches: The lateral and medial plantar arteries (Fig. 27.1). Exposure of the medial or lateral plantar arteries is facilitated by initially dissecting the retromalleolar posterior tibial artery lying deep to the lacinate ligament (flexor retinaculum) (Fig. 27.2). Extension of the incision into the sole of the foot will eventually expose the two main branches of the posterior tibial artery (Fig. 27.3). Although anatomic variation is not rare, the lateral plantar artery most often forms the main plantar arch and is larger than its medial counterpart. The smaller medial plantar artery supplies via small collateral vessels, the intrinsic muscles of the first, second, and third toes (Fig. 27.1). If the lateral plantar branch is occluded, then the medial plantar artery may enlarge and supply the arch via collaterals.

A direct approach to these vessels for several reasons is not suggested. Firstly, due to the thick nature of the skin on the sole of the foot, it is not easily retractable and satisfactory exposure is difficult unless the incision exactly follows the course of the vessel. Secondly, the small diameter of these vessels, coupled with their relatively deep location within the foot, makes their localization difficult when approached directly. Finally, because the lateral plantar artery is usually larger and inferiorly located when the foot is externally rotated, its exposure and isolation is facilitated by observing the branch point from the posterior tibial artery. As soon as either of the vessels is identified and isolated, further exposure can be accomplished by incising the lacinate ligament along with transection of the abductor hallucis muscle. More distal exposure can be obtained by division of the medial border of the plantar aponeurosis and the flexor digitorum brevis muscle.