STRUCTURES AT RISK DURING RETROFIBULAR WIRE PLACEMENT IN THE DISTAL TIBIA: A QUANTITATIVE CADAVERIC STUDY

Abstract

Introduction: An important factor affecting the stability of circular fine wire frames is the wire crossing angle, where an angle of 90 degrees confers optimal stability. Safe anatomical ‘corridors’ have been described to avoid neurovascular structures, but often limit the crossing angle. In the distal tibia the posterior tibial artery and tibial nerve wind medially facilitating safe placement of a posterior to anterior ‘retrofibular’ wire. The present study aims to identify structures at risk during ‘retrofibular’ wire placement and determine the level at which this can be used safely.

Methods: A dissection based study of 10 embalmed lower limbs. Wires of 1.8mm diameter were inserted at increments along the tibia. These were placed against the posterior surface of the fibula and ‘stepped’ medially past the posteromedial border onto the tibia. Wires were introduced from posterior to anterior, between 30 degrees and 45 degrees to the sagittal plane. This angle is estimated, reproducing clinical practice. Standard dissection techniques were used to identify the path of wires and distance from neurovascular structures.

Results: In the distal quarter of the tibia wires avoided the posterior tibial neurovascular bundle (mean distance 21.7mm) although passed close to the peroneal artery (mean distance 1.2 mm). Of the 30 wires placed in the distal tibia, 29 (97%) passed through the leg without damage to any neurovascular structures. Anterior tendons were tethered by 13% of wires placed in the distal quarter of the tibia.

Discussion: Retrofibular wire placement facilitates an optimal crossing angle, although is not described in standard atlases. Use in the lower quarter of the tibia does not threaten the posterior tibial neurovascular bundle. However, peroneal artery injury is a possibility. The clinical significance of peroneal artery injury at this level is unclear but should be considered when using this technique.