Validated Method for Measuring Functional Range of Motion in Patients With Ankle Arthritis.
Thornton J., Sabah S., Segaren N., Cullen N., Singh D., Goldberg A.
BackgroundTotal 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.MethodsInstitutional 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).ResultsGroup 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 < .001) and 0.942 (95% CI 0.859-0.977, P < .001), respectively. Group 2 (ankle osteoarthritis): the median difference for all measurements within an observer was 0.6 (IQR 0.2-1.3) degrees, and the ICCs for inter- and intrarater total ankle range of motion were excellent: 0.99 (95% CI 0.97-1.0), P < .001) and 0.99 (95% CI 0.96-1.0), P < .001), respectively.ConclusionThis technique provided a reliable, standardized method for measurement of total functional range of motion between the tibia and the floor. The technique required no special equipment or training. It provided a valid functional assessment for patients with or without ankle osteoarthritis, including those who had undergone operative treatment.Level of evidenceLevel II, prospective comparative study.