Validated Method for Measuring Functional Range of Motion in Patients with Ankle Arthritis

Abstract

Background: Total range of motion between the tibia and the floor is an important outcome measure following ankle surgery. However, there is wide variation in its measurement: from clinical evaluation, to radiographic metrics, and gait analysis. The purpose of this study was to present and validate a simple, standardized technique for measurement of functional total range of motion between the tibia and the floor using a digital goniometer. Methods: Institutional review board approval was obtained. Forty-six ankles from 33 participants were recruited into 2 groups: Group 1 (healthy controls) comprised 20 ankles from 10 participants. None had any musculoskeletal or neurologic pathology. Group 2 (ankle osteoarthritis) comprised 25 ankles from 23 patients. Ankle pathology had been treated with ankle arthrodesis (n = 5), total ankle replacement (n = 6), and nonoperative treatment (n = 14). Measurement was performed by 2 testers according to a standardized protocol developed for the Total Ankle Replacement Versus Arthrodesis (TARVA) randomized controlled trial. Intra- and interrater reliability was calculated using intraclass correlation coefficients (ICCs). Results: Group 1 (healthy controls): the median difference for all measurements within an observer was 1.5 (interquartile range [IQR] 0.7-2.5) degrees, and the intraclass coefficients (ICCs) for inter- and intrarater total ankle range of motion were excellent: 0.95 (95% confidence interval [CI] 0.91-0.97, P