A standardised computed tomography measurement method for distal fibular rotation.

Abstract

The aim of the study is to identify an ideal location to measure fibular rotation in the ankle joint using axial computed tomography (CT) scans. Another objective was to detect the average fibular rotation in the uninjured ankle joint in a large cohort. Standardised axial CT with coronal/sagittal reconstructions was performed in healthy ankle joints. Three investigators performed the measurements. In the axial view, each investigator appointed the ideal location to measure the angle of fibular rotation with the use of reference lines either 4, 6, 8 or 10mm distal from the talar joint line. Inter- and intraobserver reliability, as well as the intraclass correlation coefficient, were determined. CT scans of one hundred individuals-78 males and 22 females-were analysed. The most common locations for measuring the fibular rotation were in 31% of cases 4mm and in 51% of cases 6mm distal the talar joint line. The external rotation of the fibula averaged 8.42° ± 4.86° (range 0°-26°). The intraclass coefficient correlations (ICC) for interrater and intrarater reliability were 0.75. The results of the study demonstrate a reproducible location to measure the fibular rotation in the ankle joint. The most convenient location to measure fibular rotation with a high reliability was 6mm distal to the talar joint line.