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

Abstract

Wire crossing angle affects the stability of circular fine wire frames. Anatomical atlases document safe ‘corridors’ to avoid neurovascular structures, although this may limit crossing angle. In the distal tibia the furthest posteriolateral safe corridor described is through the fibula. The present study describes a new and safe ‘retro-fibular’ corridor for wire placement in the distal tibia that provides a greater crossing angle. Two different methods of wire insertion are considered to determine which provides greater protection to neurovascular structures.

A dissection based study of 20 embalmed lower limbs divided into two groups. 1.8mm wires were inserted at increments along the tibia, from posterolateral to antero-medial, at 30–45 degrees to the sagittal plane. In the first group wires were placed against the posterior surface of the fibula and ‘stepped’ medially onto the tibia. In the second wires were inserted midway between the border of the fibula and tendoachilles. Standard dissection techniques were used to identify the path of wires and distance from neurovascular structures.

In group one distal tibial wires avoided the posterior tibial neurovascular bundle (mean distance 21.7mm) although passed close to the peroneal artery (mean distance 1.2mm). In group two both the posterior tibial and peroneal structures were avoided (mean distances 15.5mm and 7.1mm respectively). Comparison of the two groups shows a significant difference (p< 0.001).

Retrofibular wire placement is safe in the distal quarter of the tibia and facilitates an optimal crossing angle, although is not described in standard atlases. Insertion of wires mid-way between the posteromedial border of the fibula and the tendoachilles appears the most reliable technique.