Epidemiology of Isolated Meniscus Tears in Young Athletes

OBJECTIVES: Meniscus tears are common in athletic populations; however, there are few studies of the epidemiology of meniscal tears in a stable knee, and particularly tears in young populations. The purpose of this study was to define the incidence of isolated meniscus tears and to determine demographic and athletic risk factors. METHODS: A longitudinal cohort study was performed to determine the incidence and characteristics of isolated meniscus tears at the United States Military Academy between 2005 and 2012. Injuries identified in the Cadet Illness and Injury Tracking System (CIITS) were confirmed by clinic, surgical, and radiographic data for inclusion. Cooper's classification was used to localize meniscus tears. Incidence rates (IR) per 1000 person-years and per 1000 athlete-exposures (AE) were determined for sport and level of competition. Demographic, injury characteristic and time loss data were also evaluated. RESULTS: There were 79 instances of meniscus tears in stable knees in a cohort of 9086 subjects from 2005-2012. Of these, 68 (86%) were in males and 11 (14%) in females. Right (40) and Left (39) knees were equally affected. The lateral meniscus (70%) was torn at a greater rate than medial meniscus (30%). Body mass index (BMI) of the meniscus injured population was 25.7 vs. 24.6 for the uninjured cohort (p less than .05). BMI was also greater in subjects with lateral (26.4) vs. medial (23.9) meniscus tears (p less than .05). The average time lost from activity was 102 days. Surgically managed injuries lost 112.7 days vs. 36.1 for non-operative cases (p less than .05). Of the operative cases, repairs lost 150.8 days vs. 101.0 for debridement (p less than .05). There was no significant difference in time lost from medial (90.9 days) vs. lateral (106.9 days) injuries. The greatest percentages of meniscus tears were found in football (19%), wrestling (13%) and rugby (9%) activities. Military combative training accounted for 5% of meniscus tears. The IR per 1000 AE for intercollegiate athletes was greatest in wrestling (0.157) and rugby (0.150). This was mirrored in the intramural population with rates of 0.125 and 0.138 respectively. Rates per AE in football were lower at 0.045 and 0.062 for intercollegiate and intramural competition. CONCLUSION: Isolated meniscus tears are relatively common in young athletes and cause significant loss of time from athletic pursuits with meniscus repair causing greater loss than debridement. Lateral meniscus tears are more prevalent in this population. A significantly greater BMI was seen in those with vs. without isolated meniscus tear in this cohort, and between those with lateral vs. medial meniscus tear among the injured. Wrestling and rugby carry the greatest risk of meniscus injury per exposure at both the intercollegiate and intramural level of competition.