Background Over two million sports-related knee injuries present to US emergency departments annually. Knee injuries frequently require costly surgical repair, and knee sprains are one of the most common injuries in athletes. Thus, understanding injury patterns across the age spectrum is important to identify areas for prevention.

Methods Knee sprain and athlete exposure (AE) data were collected for 20 sports using the High School Reporting Information Online database for high school athletes and the National Collegiate Athletic Association Injury Surveillance Program for college athletes during the 2009/10–2014/15 acdemic years. We report knee sprain rates per 10,000 AEs and rate ratios with 95% confidence intervals (RR; CI).

Results The knee sprain rate was higher in college (1.03) than high school (0.35; RR = 2.46, 95% CI: = 2.31–2.61). Sports with the highest rates in college were men’s wrestling (1.21), men’s football (0.66), and women’s soccer (0.61); the highest in high school were boys’ football (0.35), girls’ soccer (0.26), and girls’ gymnastics (0.23). In gender-comparable sports, females had higher rates than males (college RR = 1.70, 95% CI: = 1.40–2.07; high school RR = 2.21, 95% CI: = 1.97–2.48); college men had higher rates of torn cartilage (RR = 4.19, 95% CI: = 3.19–5.51) and PCL injuries (RR = 29.51, 95% CI: = 19.64–44.34) than high school boys; and college women had higher rates of ACL (RR = 2.30, 95% CI: = 1.86–2.85) and PCL (RR = 2.99, 95% CI: = 1.52–5.88) injuries than high school girls. A larger percentage of females in college required surgery (43.0%) vs. high school (34.9%). Player contact was the most common injury mechanism across age groups (55.0% each).

Conclusions In gender-comparable sports, females at both age levels had higher knee injury rates than males. College athletes had higher knee injury rates than high school athletes, perhaps due to level of play or biological differences. Both sex and age should be considered when developing targeted injury prevention efforts.