Anatomical Structures at Risk After Medial Column Nailing

Medial column nails have been introduced into Charcot's neuroarthropathy reconstruction as superconstruct fixation with high fatigue strength and pullout resistance. Similar to intramedullary nailing throughout other long-bone fixation, injury to neurovascular and musculotendinous structures secondary to percutaneous interlocking screw fixation may exist. We sought to identify structures at risk for injury during the interlocking of a medial column nail.

Medial column nails were inserted into ten cadaveric limbs. The proximal (talar), middle (first metatarsal), and distal (first metatarsal) locations for the interlocking screws were drilled, and a 0.062 Kirschner wire was inserted into respective drillholes to simulate interlocking screws. After dissection, the distances of each Kirschner wire to nearby anatomical structures were measured. Levels of risk were assigned to each soft-tissue structure based on distance to each Kirschner wire: high (0-3.5 mm), intermediate (3.6-7.0 mm), and low (>7.0 mm). A 3.5-mm threshold for each category was used because this represented a multiple of the diameter of the interlocking screws. Mean ± SD and ranges are reported for structures at high and intermediate risk for injury.

Proximally, the deltoid ligament (ten of ten), posterior tibial tendon (eight of ten), and saphenous vein (six of ten) were at high or intermediate risk for injury consistently. At the middle screw, the medial dorsal cutaneous nerve and the medial marginal vein were at high or intermediate risk in ten and eight specimens, respectively. At the distal interlocking screw, the medial dorsal cutaneous nerve was at high risk for injury in all ten specimens.

There is high and intermediate risk to many musculotendinous and neurovascular structures when performing percutaneous interlocking screws in a medial column nail. These findings serve to educate surgeons of the anatomical considerations they must have when performing medial column nailing for reconstruction of Charcot's foot.