Background/Purpose: Obesity and knee injury, including anterior cruciate ligament (ACL) rupture, are strong risk factors for the development of knee osteoarthritis. Identifying participant and post-injury characteristics that are associated with obesity after knee injury may help target at risk populations for weight management interventions. The purpose of this study is to examine factors associated with overweight or obesity in athletes 5 years after ACL injury.

Methods: We analyzed data from the Delaware-Oslo ACL Cohort Study, a longitudinal cohort study of athletes after acute ACL rupture from the United States (n=150) and Norway (n=150). Inclusion criteria were sustaining a unilateral ACL rupture confirmed by MRI and regularly participating in level I/II sports prior to injury. Those with bilateral injuries or significant concomitant injuries were excluded. The outcome of interest was overweight or obesity at the 5-year follow-up. Body mass index (BMI) was calculated from self-reported height and weight, and categorized as Normal (BMI <25 kg/m²) or Overweight/Obese (BMI ≥ 25kg/m²). Exposures of interest were age (at enrollment), sex, surgical status (ACL reconstruction vs. non-operative rehabilitation), and self-reported knee function at 2-year follow-up (IKDC, International Knee Documentation Committee Subjective Knee Form). We evaluated the association between the exposures and the outcome using odds ratios with 95% confidence intervals from logistic regression, mutually adjusting for the other exposures, as well as baseline BMI, country (US vs. Norway).

Results: Of 300 participants enrolled in the study, 215 (72%) completed the 5-year follow up (mean baseline age 27.4 ± 10.1 years, baseline BMI 24.3 ± 3.5 kg/m², 48% women). At 5 years, 49% of the athletes were overweight or obese. Athletes who were older age at baseline, women, and received non-operative treatment had lower odds of being overweight or obese at 5-year follow-up, adjusting for baseline BMI and country (Table). Self-reported knee function at 2-year follow-up was not associated with being overweight or obese at 5-year follow-up.

Conclusion: Athletes who received non-operative treatment, women, and older athletes were less likely to be overweight or obese at 5-year follow-up. Those who undergo ACL reconstruction, men, and younger athletes may be appropriate targets for weight management interventions to prevent weight gain. Further research is needed to confirm these results and evaluate why those who undergo ACL reconstruction have higher odds of being overweight or obese at long-term follow-up.