Context: Few population-based studies have examined the incidence of meniscal injuries, and limited information is available on the influence of patient's demographic and occupational factors.Objective: To examine the incidence of meniscal injuries and the influence of demographic and occupational factors among active-duty US service members between 1998 and 2006.Design: Cohort study. Setting: Using the International Classification of Diseases (9th revision) codes 836.0 (medial meniscus), 836.1 (lateral meniscus), and 836.2 (meniscus unspecified), we extracted injury data from the Defense Medical Surveillance System to identify all acute meniscal injuries among active-duty military personnel.Patients or Other Participants: Active-duty military personnel serving in all branches of military service during the study period.Main Outcome Measure(s): Incidence rate (IR) per 1000 person-years at risk and crude and adjusted rates by strata for age, sex, race, rank, and service.Results: During the study period, 100201 acute meniscal injuries and 12115606 person-years at risk for injury were documented. The overall IR was 8.27 (95% confidence interval [CI] = 8.22, 8.32) per 1000 person-years. Main effects were noted for all demographic and occupational variables (P< .001), indicating that age, sex, race, rank, and service were associated with the incidence of meniscal injuries. Men were almost 20% more likely to experience an acute meniscal injury than were women (incidence rate ratio = 1.18, 95% CI = 1.15, 1.20). The rate of meniscal injury increased with age; those older than 40 years of age experienced injuries more than 4 times as often as those under 20 years of age (incidence rate ratio = 4.25, 95% CI=4.08,4.42).Conclusions: The incidence of meniscal injury was substantially higher in this study than in previously reported studies. Male sex, increasing age, and service in the Army or Marine Corps were factors associated with meniscal injuries.Key Words: knee injuries, lower extremity injuries, military athletes, injury epidemiology Key Points• To our knowledge, this is the largest population-based study to examine the incidence of meniscal tears within a physically active population that is at elevated risk of sport-and training-related knee injuries. • The overall incidence rate for meniscal injury was more than 10 times that previously documented in civilian populations.• Factors associated with a greater incidence of meniscal injury were male sex, increasing age, and Army or Marine Corps service.
