THE “SAFE ZONE” IN PERCUTANEOUS CALCANEAL PIN PLACEMENT: AN ANATOMIC CADAVERIC STUDY

Abstract

Pin placement into the medial calcaneus places a number of structures at risk of damage. Research evidence suggests that the greatest risk of posterior pin placement is to the medial calcaneal branch of the tibial nerve. By using palpable anatomical landmarks, we attempted to redefine the safe zone taking into account possible variations. The medial heel region of twenty-four cadavers was dissected to find the major structures at risk. The inferior tip of the medial malleolus (point A), insertion point of tendo calcaneus (point B), navicular tuberosity (point C) and the medial process of the calcaneal tuberosity (point D) were all selected as anatomic landmarks from which to measure the identified structures using digital electronic calipers. The commonest variation in origins of medial calcaneal nerves was found to be one arising before the bifurcation of the tibial nerve along with one arising from the medial plantar nerve (10/24). The safest zone for percutaneous pin placement has been calculated as beyond two-thirds of the distances AB, CD, AD and CB. More posterior pin placement reduces the risk of damage to the medial calcaneal nerve and its branches, although the risk remains and blunt dissection before pin placement is recommended.