Anatomic considerations for retrograde fibular medullary screw insertion: a cadaveric study.

Abstract

A retrograde fibular medullary screw may be utilized in certain fractures about the ankle. The purpose of this study is to investigate the anatomic considerations of a retrograde medullary screw inserted from a lateral starting point to nearby anatomic structures about the distal fibula. Ten fresh-frozen cadaveric lower extremities were utilized. A 1.6-mmKirschner wire was inserted into the distal fibula from a far-lateral starting point. A 3.2-mm cannulated drill bit was then inserted over the Kirschner wire. After placement of the drill bit, dissection of the lateral ankle was undertaken. The proximity of nearby anatomic structures to the drill bit was measured using calipers. A 4.5-mm cortical screw was then inserted using fluoroscopic guidance. Measurements were then taken again to assess the relationship of the screw head to adjacent structures. Mean distance from drill bit to nearby structures is as follows: Peroneus longus tendon 4.56mm, peroneus brevis tendon 6.62mm, sural nerve 4.13mm, superior peroneal retinaculum 7.52mm, inferior peroneal retinaculum 6.61mm, anterior talofibular ligament (ATFL) 6.1mm, calcaneofibular ligament (CFL) 6.7mm. Average distance from 4.5-mm screw head to nearby structures is as follows: peroneus longus tendon 6.79mm, peroneus brevis tendon 6.73mm, ATFL 4.16mm, CFL 5.14mm, lateral talar process 9.41mm. Retrograde medullary fibular screw fixation may be safely carried out through a lateral start point. Anatomic structures about the lateral ankle are nearby but not immediately adjacent to the drill bit.