Tobacco use and increased risk of ACL and meniscus injury and surgical intervention: a matched-cohort study of 3 million patients

Abstract Meniscus and anterior cruciate ligament (ACL) tears are among the most common knee injuries, yet little is known about whether tobacco use affects their incidence, need for subsequent surgery, or postoperative hospital length of stay (LOS). We retrospectively analyzed a Humana claims database of over 8 million patients from 2007–2017 using ICD-9/ICD-10 codes, identifying 3,310,668 patients with and without tobacco use disorder matched 1:1 by age and comorbidities. Logistic regression calculated odds ratios (OR) for injury and surgery, and Welch’s t-test assessed LOS differences, with significance set at p < 0.05. Tobacco users had greater incidence and odds of meniscus tear (4.25% vs. 3.97%; OR 1.07, 95% CI 1.06–1.09, p < 0.0001) and ACL injury (0.48% vs. 0.42%; OR 1.15, 95% CI 1.11–1.19, p < 0.0001). Among patients with meniscal injury, tobacco users had modestly greater odds of subsequent surgical repair (OR 1.18, 95% CI 1.07–1.31, p = 0.001); the increase in ACL reconstruction was not statistically significant (OR 1.07, 95% CI 0.99–1.16, p = 0.09). Tobacco users also had longer postoperative LOS. These findings indicate tobacco use is associated with increased incidence of meniscus and ACL injury and, for meniscus tear, increased odds of subsequent surgery, though the retrospective, claims-based design limits conclusions to associations rather than causation.