Ankle sprains are common injuries that may lead to long-term morbidity. Individuals with obesity are at increased risk for ankle sprains; however, prognostic associations between body mass index (BMI) and recovery are less well understood. This study investigated whether BMI status affects recovery from ankle sprains.

We included individuals≥16 years old with grade 1 or 2 ankle sprains who sought emergency department treatment in Kingston, Ontario, Canada. Height in centimeters and weight in kilograms were measured at baseline by using a height rod and a standard medical column scale, respectively. BMI was calculated and categorized as non-overweight,<25.0kg/m²; overweight, 25.0–29.9kg/m²; and obese,≥30kg/m². Recovery was assessed at 1, 3 and 6 months post-injury by the Foot and Ankle Outcome Score (FAOS). Continuous FAOS and binary recovery status were compared by BMI group at each assessment using a repeated measures linear mixed effects model and logistic regression, respectively.

In total, 504 individuals were recruited and 6-month follow-up data were collected for 80%. We observed no significant differences in recovery at 1 and 3 months post-injury. At 6 months, between 53% and 66% of the participants were considered to have recovered according to the FAOS. The mean difference in unadjusted FAOS between participants classified as obese and non-overweight was −23.02 (95% confidence interval, −38.99 to −7.05) but decreased after adjusting for confounders. The odds ratio for recovery was 0.60 (0.37–0.97) before adjustment and 0.74 (0.43–1.29) after adjustment. Six-month recovery was significantly lower for participants with obesity than non-overweight participants on the FAOS Pain and Function in Daily Living subscales but were not clinically meaningful.

All BMI groups showed improvements from ankle sprain over time. However, at 6 months, a sizeable proportion of the participants had not fully recovered particularly among individuals classified as obese. The findings suggest that individuals with obesity may benefit from specialized interventions focused on symptom management and functional activity.