An evaluation of the measurement properties of the Olerud Molander Ankle Score in adults with an ankle fracture

Objectives The aim of this study is to evaluate the measurement properties of the Olerud Molander Ankle Score in adults with an ankle fracture. Methods Patients completed outcome measure questionnaires at baseline, six, 10-and 16-weeks postinjury as part of an ongoing clinical trial on ankle fracture rehabilitation. The internal consistency, convergent validity, structural validity and interpretability of the Olerud Molander Ankle Score was assessed. This was achieved through using the respective analysis methods of Cronbach's alpha, correlation coefficients, principal component analysis, evaluation of floor and ceiling scores and estimation of the minimally important change using anchor-based methods. Results The Olerud Molander Ankle Score showed adequate convergent validity against hypotheses set in relation to scores of comparator instruments. Principal component analysis demonstrated that the measure has two subscales: ankle function and ankle symptoms. The internal consistency of the measure and the ankle function subscale was sufficient, but inconclusive for the ankle symptoms subscale. There were no floor and ceiling effects present within the scores and the estimated minimally important change was 9.7 points. Conclusion The Olerud Molander Ankle Score demonstrates sufficient measurement properties and is likely to be primarily measuring the construct of patient reported function following ankle fracture. Further research should evaluate the relevance of other domains to individuals recovering from and ankle fracture, such as social participation and psychological wellbeing. The development of a core outcome set would be advantageous to standardise outcome measurement collection in this area. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of Chartered Society of Physiotherapy. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).