STRUCTURES AT RISK DURING TIBIALIS ANTERIOR TENDON TRANSFER FIXATION.

Abstract

Introduction: Tibialis anterior tendon transfer (TATT) is a common procedure for recurrence in clubfeet treated with the Ponseti method. Fixation usually includes passing the tendon through a drill hole in the lateral cuneiform using sutures brought out through the plantar aspect of the foot. Drilling of the tunnel and passing the sutures holds potential for neurovascular damage. We performed a cadaver study to evaluate plantar nerve structures at risk during TATT.

Method: TATT was performed to the lateral cuneiform in fresh frozen adult cadaver limbs. In 3 feet, the drill hole was made perpendicular to the surface of the lateral cuneiform (group A), in 3 feet, the drill hole was perpendicular to the weight bearing surface of the foot (group B), in 3 feet, the drill was directed at 15 degrees in the frontal and sagital planes (group C) and in another 3 feet the drill was aimed at the middle of the foot (group D). The tendon sutures were pulled through the plantar aspect using two Keith needles aimed in the same direction as the drill hole. A layered dissection was performed. The distance from the drill hole to the nearest nerve or nerve branch was measured. Keith needles were passed 20 times per foot. With each pass, damage to nerve structures was noted.

Results: In group A, the drill was in proximity to the medial plantar nerve at a mean distance of 1.7mm (1–3mm). The bifurcation of the nerve trunk was found more proximally at a mean distance of 5mm (2–9mm). In group B, the drill was found to be close to the lateral plantar nerve branches at a mean distance of 0.3mm (0–1mm) with a mean distance to the bifurcation of 25.3mm (16–37mm). The drill hole in group C was at a mean distance of 1.7mm (0–3mm) to the lateral plantar nerve bifurcation and at a distance of 1mm to the lateral nerve branch in one case. In group D, the drill exited in the middle of the plantar aspect at a mean distance of 7.7mm (5–11mm) from the medial nerve branch and 13mm (10–18mm) from the bifurcation of the medial nerve and at a mean distance of 4.3mm (3–6mm) from the lateral nerve branch and 14.7mm (11–19mm) from the lateral nerve bifurcation.

Passing the Keith needles resulted in hitting a nerve structure 12 times in group A, 20 times in group B, 6 times in group C and once in group D.

Conclusion: In TATT, the drill hole should be aimed at the middle of the foot in the transverse and longitudinal planes. This results in a maximum distance to both the lateral and medial nerve. A blunt Keith needle might allow a safer passing of the sutures to avoid damage to nerves and vessels.