Cutaneous innervation of the ankle: an anatomical study showing danger zones for ankle surgery.

Three nerves innervate the skin in the foot and ankle region: the saphenous, sural, and superficial peroneal nerves. Because they are close to the medial and lateral malleoli, these nerves are at significant risk during orthopedic interventions. The aims of this study were to investigate the distal courses of the three cutaneous nerves of the ankle and to determine their exact relationships with easily identifiable bony landmarks. Ten freshly frozen and 40 embalmed lower extremities of adults were dissected. The positions of the superficial peroneal, sural, and saphenous nerves were determined using reference lines based on easily palpable osseous landmarks. The frequencies and distributions of all three nerves and their branches were converted into absolute numbers. A danger zone for each nerve was established on the basis of the distribution of crossings between the nerves and the different reference lines. Determination of the exact orientation of the nerves around the ankle should help minimize the nerve injury rate during surgical approaches in this area. Using this easily translatable new grid system, the course and danger zones of each cutaneous nerve around the ankle can be estimated clinically.