The risk for a cruciate ligament injury of the knee in adolescents and young adults: a population-based cohort study of 46 500 people with a 9 year follow-up

<jats:sec><jats:title>Objectives:</jats:title><jats:p>The knee joint is the most common site for injury among younger people, the injury often resulting in expensive (surgical) treatment, long-term rehabilitation and permanent functional impairment and disability.</jats:p></jats:sec><jats:sec><jats:title>Methods:</jats:title><jats:p>We investigated the incidence and risk factors for a major knee-ligament injury in an adolescent Finnish population. A population-based cohort of 46 472 adolescents was followed for an average of 9 years. All patients hospitalised with the diagnosis of anterior or posterior cruciate ligament injury (ACL or PCL injury) were included in the analysis.</jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p>265 (0.6%) people (194 male and 71 female subjects) from the total cohort of 46 472 were treated for a cruciate ligament injury of the knee during the follow-up period, giving an injury incidence of 60.9 (95% CI 53.6 to 68.2) per 100 000 person-years. When the socioeconomic, health and lifestyle background variables were taken into account, the adjusted hazard ratio for a cruciate ligament injury of the knee was 8.5 (95% CI 4.3 to 16.4) for female and 4.0 (95% CI 2.7 to 6.1) for male subjects who participated in organised sports ⩾4 times/week.</jats:p></jats:sec><jats:sec><jats:title>Conclusions:</jats:title><jats:p>The general risk for a cruciate ligament injury of the knee is relatively low among adolescents and young adults, but participation in organised sports increases the risk significantly. The risk is especially high in active young women. Preventive measures should be adopted to decrease the short-term and long-term burden of these severe injuries.</jats:p></jats:sec>