Topographic anatomy of the neurovascular bundle at the tarsal tunnel and its applied significance

Abstract

BACKGROUND: There are different surgical procedures and treatment modalities dealing with medial ankle region such as placement of percutaneous pins in the calcaneus, decompression in tarsal tunnel syndrome, and nerve block. This requires detailed anatomical knowledge about the neurovascular bundle to avoid iatrogenic injury. AIM OF THE WORK: To study the topography of nerves and vessels at the tarsal tunnel in relation to surface anatomical landmarks. MATERIALS AND METHODS: The medial calcaneal region of 20 lower limbs of formalin preserved specimens was dissected. The neurovascular structures were identified within a quadrangle named ABCD, formed by four palpable bony landmarks, respectively: inferior tip of medial malleolus, posterior superior tip of calcaneal tuberosity, posteroinferior aspect of medial calcaneus, and tuberosity of navicular bone. A regression analysis was done to correlate the lengths of the four imaginary lines connecting the four bony landmarks with the location of the neurovascular structures. RESULTS: The posterior tibial artery was located medial to the tibial nerve in 50% of cases. The bifurcation of the artery was found to be proximal to that of the nerve in only one case. The number of the medial calcaneal nerves (MCNs) varied from 1 to 3 branches; the most common was one branch (50%). In two cases, there was high origin of the MCN at a distance of 15.4 and 23.5 cm proximal to the ankle region. CONCLUSION: The location of the neurovascular bundle at the tarsal tunnel could be predicted by measuring the distances between the anatomical bony landmarks.