Plan a gently curved skin incision that is longer on the plantar surface than on the dorsal surface of the foot. The skin of the plantar surface is stronger and can be pulled up to form a good flap over the tips of the metatarsals. Make the skin incision at about the level of the metatarsal heads (Fig. 127.1A). Divide the soft tissues down to the level of the bone. Secure the digital arteries with suture ligatures (Fig. 127.1B).

Division of the skin and superficial fascia of the dorsum of the foot will expose the superficial veins and nerves that occupy the plane between superficial and deep fasciae. The anatomy of the superficial venous network varies; however, recall that the great and lesser (small) saphenous veins begin as continuations of the medial and lateral ends of the dorsal venous arch, respectively. The dorsal venous arch is located roughly over the middle of the second through the fifth metatarsals. The great saphenous vein begins over the proximal end of the first metatarsal, and the lesser saphenous vein begins over the cuboid. The branches of two sensory nerves—the superficial peroneal and sural nerves—lie relatively superficial and may be encountered. The superficial peroneal nerve supplies most of the skin of the dorsum of the foot and toes, except for the first interdigital space and apposing sides of digits 1 and 2 (supplied by a branch of the deep peroneal nerve). The sural nerve provides cutaneous innervation to the lateral side of the foot. The nerves are crossed superficially by the superficial veins.

When the deep fascia of the dorsum of the foot is divided, the dorsalis pedis artery, a continuation of the anterior tibial artery, should be identified and ligated (if necessary) before its division. This artery, accompanied by the deep peroneal nerve, lies lateral to the extensor hallucis longus tendon, passes deep to the inferior extensor retinaculum, and is crossed by the extensor hallucis brevis (Fig. 127.1C). At the proximal end of the first intermetatarsal space, it turns plantarward, between the interosseous muscles of this space, to anastomose with the deep branch of the lateral plantar artery, forming the plantar arterial arch. Branches of the dorsalis pedis artery that must be considered in amputations include the first dorsal metatarsal artery. This artery bifurcates, in the cleft between the first two digits at the level of the metatarsophalangeal joint, into two dorsal digital arteries, which supply the contiguous sides of these two digits. The arcuate artery, a lateral branch of the dorsalis pedis artery that lies deep to the intrinsic extensor musculature and that gives rise to the remaining three dorsal metatarsal arteries, crosses the bases of all metatarsals except the first.