The “safe zone” in medial percutaneous calcaneal pin placement

Abstract

Percutaneous pin insertion into the medial calcaneus places a number of structures at risk. Evidence suggests that the greatest risk is to the medial calcaneal nerve (MCN). The medial calcaneal region of 24 cadavers was dissected to determine the major structures at risk. By using four palpable anatomical landmarks, the inferior tip of the medial malleolus (point A), the posterior superior portion of the calcaneal tuberosity (point B), the navicular tuberosity (point C), and the medial process of the calcaneal tuberosity (point D), we attempted to define the safe zone taking into account all possible variables in our dissections including ankle position, side, gender, and possible anatomical variations of the MCN. The commonest arrangement of the MCN was two MCNs that arose independently, one arising before the bifurcation of the tibial nerve and the other arising from the medial plantar nerve. A zone could be defined posterior to 75% of the distance along the lines AB, CD, AD, and CB which would avoid most structures. The posterior branches of the MCN, however, would still be at risk and placing the pin too far posteriorly risks an avulsion fracture. This is the first study to employ four palpable anatomical landmarks to identify a zone to minimize damage to neurovascular structures. It may not be possible, however, to avoid injury of the MCN and consequent sensory loss to the sole of the foot.

Postoperative complications after closed calcaneus fracture treated by open reduction and internal fixation: A review

“…8 In calcaneal surgery, the most common injury appears to be sensory nerve damage. 26 Neurovascular injury is an iatrogenic injury that is rarely seen postoperatively, and a definite incidence rate has not been reported. In the 21 papers included here, we calculated the incidence rate to be 2.8%.…”

Circular frame fixation for calcaneal fractures risks injury to the medial neurovascular structures: A cadaveric description

“…Slight plantar flexion was noted in the cadaveric feet due to fixation methods but it has been shown that there is only a weak correlation between the degree of flexion and difference in measurement distances 17 . Our specimens had no trauma to the calcaneus and thereby exhibited normal calcaneal anatomy without fracture.…”

“…Some studies have attempted to divide the surfaces of the calcaneus into zones according to increasing risk of injury to neurovascular and tendinous structures [16][17][18][19][20] but have yet to come to a clear agreement. It has been suggested by Labronici et al that vascular structures found superficially to the anteromedial surface of the calcaneus are at high risk of damage during wire fixation performed via the lateral aspect of the hindfoot 20 .…”

Localização segura na colocação dos pinos percutâneos no calcâneo

“…Several authors have attempted to define an anatomical safety zone for placing external fixators and traction pins in the medial region of the calcaneus (7)(8)(9)(10) . The distances of placement sites from tendons and neurovascular structures in various anatomical regions have been used as a method for describing the safety zone in a small number of cadaveric studies (7,8,10,11) .…”

“…The distances of placement sites from tendons and neurovascular structures in various anatomical regions have been used as a method for describing the safety zone in a small number of cadaveric studies (7,8,10,11) . However, these studies present limitations through ignoring variations in the tibial nerve, with its medial, lateral and calcaneal branches, because of the absence of research in the areas at risk or through creation of complex methods that become difficult to use in clinical practice (7,8,11) .…”