Explanatory Variables for Adult Patients' Self-Reported Recovery After Acute Lateral Ankle Sprain

Background Longitudinal research on musculoskeletal disorders often makes use of a single measure of recovery, despite the large variation in reported recovery that exists. Patients with an acute ankle sprain often experience no pain or functional disability following treatment, yet report not being fully recovered, or vice versa. Objective The purpose of this study was to find explanatory variables for reporting recovery by analyzing the extent to which different outcomes (eg, pain intensity) were associated with recovery and how baseline scores of different variables influence this association in adult patients after acute lateral ankle sprain. Design This was a cohort study based on data collected in a randomized controlled trial (RCT). Methods This study was constructed within the framework of an RCT. One hundred two patients who incurred an acute ankle sprain were included. Recovery, pain intensity, giving way of the ankle, and Ankle Function Score (AFS) were assessed during the RCT at baseline and at 4 weeks, 8 weeks, 3 months, and 12 months postinjury. Mean differences were calculated between baseline and follow-up. Associations were calculated using linear mixed models, and the influence of baseline scores on these associations was determined using linear regression with interaction. Results Associations were found between recovery and the mean differences of pain during running on flat and rough surfaces (4 and 8 weeks, 3 months) and between recovery and the mean difference of giving way of the ankle during walking on a rough surface (8 weeks, 3 months). Limitations This study used data collected from an RCT. Therefore, the study was limited to the outcomes measured in that trial, and some explanatory factors easily could have been missed. Conclusions This study is the first to identify explanatory variables for reporting recovery in adults after ankle sprain. Pain intensity and giving way of the ankle measured during high ankle load activities make it easier to measure and to generalize recovery in this population and should be the primary outcome measures of interest. This study indicates the huge need to reach consensus about primary outcome measures for research in patients sustaining ankle sprains.