Clinical usefulness of the Ottawa Ankle Rules in the overweight and obese population following an acute ankle injury: A prospective cross-sectional study.

Objective: The aim of this study was to determine the clinical usefulness of the Ottawa Ankle Rules (OAR) in overweight and obese patients compared to the general population.

Methods: In this prospective cross-sectional study, 935 adult patients (453 female, 482 male; mean age = 57.2 ± 20.9) admitted to the emergency department following an acute ankle injury (<3 days) secondary to low energy-trauma were included. All the patients were examined based on a standardized protocol, including age, Body-Mass Index (BMI), OAR, and presence of ankle fracture. As accuracy indicators, sensitivity, specificity, positive and negative predictive values of OAR were calculated.

Results: Of all patients, 790 (84.5%) were normal weighted, 107 (11.5%) were overweight, and 38 (4%) were obese. While OAR was negative in 58.8% of patients, 41.2% of patients met OAR. The sensitivity of OAR in the normal weighted population was significantly higher than obese and overweight groups (P < 0.01). The specificity of OAR in the normal weighted population was significantly lower than overweight and obese groups (P < 0.01). The accuracy of OAR in the overweight group was 82.7% and significantly higher compared with the normal weighted population (62.8%) (P < 0.01).

Conclusion: We do not recommend OAR as a screening tool to be used safely in patients with higher BMI because of its lower sensitivity in this population. In this specific patient population, these rules should be implemented carefully, and radiography should be evaluated meticulously not to miss a fracture.

Level Of Evidence: Level IV, Cross Sectional Study.