Intraobserver and Interobserver Reliability of Three Classification Systems for Hallux Rigidus

Background There are more than ten classification systems currently used in the staging of hallux rigidus. This results in confusion and inconsistency with radiographic interpretation and treatment. The reliability of hallux rigidus classification systems has not yet been tested. We sought to evaluate the intraobserver and interobserver reliabilities of three commonly used classifications for hallux rigidus. Methods Twenty-one plain radiograph sets were presented to ten American College of Foot and Ankle Surgeons board-certified foot and ankle surgeons. Each physician classified each radiograph based on clinical experience and knowledge according to the Regnauld, Roukis, and Hattrup and Johnson classification systems. The two-way mixed single-measure consistency intraclass correlation coefficient was used to calculate intrarater and interrater reliabilities. Results The mean ± SD intrarater reliability of individual sets for the Roukis (0.62 ± 0.19) and Hattrup and Johnson (0.62 ± 0.28) classification systems was fair to good and for the Regnauld system bordered between fair to good and poor (0.43 ± 0.24). The interrater reliability of the mean classification was excellent for all three classification systems. Conclusions Reliable and reproducible classification systems are essential for treatment and prognostic implications in hallux rigidus. Herein, the Roukis classification system had the best intrarater reliability. Although there are various classification systems for hallux rigidus, the present results indicate that the three classification systems evaluated show reliability and reproducibility.