Development and validation of the Copenhagen Ankle Range of Motion Scale

INTRODUCTION: It would be advantageous if patients could self-report ankle range of motion (ROM). This study aimed to develop the Copenhagen Ankle Range of Motion Scale (CARS).

METHODS: After input from healthcare professionals and patients, a pictorial questionnaire was developed to report ankle dorsiflexion with a straight knee and a flexed knee and ankle plantiflexion. CARS outcomes were compared to goniometer measurements made by a nurse and a doctor. Reliability, interclass correlation coefficients (ICC), agreements and correlations were calculated.

RESULTS: A total of 102 patients were enrolled. ICCs for goniometer measurements by a nurse and a doctor were 0.66-0.77. There was good agreement between the pictorial choices made by doctors and nurses, with a weighted kappa between 0.63 and 0.71. Agreement between CARS measures and the mean of goniometer measures by the two observers showed a weighted kappa of 0.32-0.5, and Pearson correlation coefficients between patient selections and the mean goniometer measurement were 0.53-0.56.

CONCLUSIONS: CARS can be used to obtain an indication of ankle ROM without the patient's physical attendance and can standardise estimates of ankle ROM in clinical practice. It was not possible to calculate the tool's sensitivity, specificity and positive/negative predictive values. Further development with patient involvement may improve the validity of CARS version 2.0.

FUNDING: None.

TRIAL REGISTRATION: Not relevant.