Figure 4. Injury rates for select conditions (concussions, ankle ligament sprains, and anterior cruciate ligament injuries) for games and practices combined for 15 sports, National Collegiate Athletic Association, 1988–1989 through 2003–2004. Ankle ligament sprains time trend P = .68. Average annual change = −0.1% (95% confidence interval = −0.8, 0.5). Anterior cruciate ligament (ACL) injury time trend P = .02. Average annual change = 1.3% (95% confidence interval = 0.2, 2.4). Concussion time trend P < .01. Average annual change = 7.0% (95% confidence interval = 5.4, 8.7) .