Which Measuring Method Is Better for Reflecting Subtalar Joint Stiffness?

Background/Objectives: A standard method for the measurement of subtalar joint motion has yet to be developed. This study aimed to determine which of the two methods (AMA and modified McBride) for the measurement of subtalar joint motion better reflects subtalar joint stiffness. Methods: We evaluated the intraobserver and interobserver reliability and validity of the two methods in the normal group (n = 50) and the patient group (n = 90; 30 with normal hindfoot, 30 with ankle joint pathology, and 30 with subtalar joint pathology). We assessed the intraclass correlation coefficient (ICC) and receiver operating characteristic (ROC) curve for statistical analysis. Results: In the normal group, the intraobserver reproducibility and interobserver reliability of the AMA method were better than those of the modified McBride method. In the hindfoot patient group, both methods showed excellent interobserver reliability (ICC > 0.75). The results of the ROC curve also indicated that the modified McBride method (AUC: 0.919, 0.813) was better than the AMA method (AUC: 0.715, 0.749) in reflecting subtalar joint stiffness. Conclusions: In patients with subtalar joint lesions, the modified McBride method had a relatively better validity and was more appropriate than the AMA method for measuring the stiffness of the subtalar joint.