A growing number of U.S. athletes are getting operations to repair torn knee ligaments, and a new study suggests injury rates are highest and rising fastest among teen girls. Researchers focused on surgery for a common knee injury known as an anterior cruciate ligament (ACL) tear, which has long been linked to intense participation in sports like basketball and soccer which require constant pivoting as well as contact sports like football.
The study of private insurance data for 148 million U.S. residents found that overall, the average annual ACL surgery rate climbed 22 percent from 2002 to 2014, when it reached 75 procedures for every 100,000 people. For teen girls, however, the average annual knee surgery rate rose by 59 percent during the study period to 269 procedures for every 100,000 people. “Although there are proven ACL injury prevention programs available, they are not being widely adopted, particularly among young women,” said lead study author Mackenzie Herzog of the University of North Carolina at Chapel Hill.
Because the proportion of teens getting surgery within a year of an ACL injury remained steady during the study period, the surge in procedures is likely due to an increase in injuries and not a shift toward more aggressive treatment, Herzog said by email. While the study didn’t examine why more injuries are happening, Herzog points to a few trends in youth sports that may be contributing to the problem.
“There are likely multiple factors contributing to the increase, including increased participation due to broader promotion of physical activity to improve health and adolescents participating in athletics more frequently and more intensely,” Herzog said. “Two particular trends that concern us are increased trends toward year-round sports participation at a young age and the tendency to specialize in one sport early.”
For teen boys, the average annual knee surgery rate climbed 44 percent during the study period to end at 212 procedures for every 100,000 people, researchers report in JAMA Pediatrics. Surgery rates also rose faster for women than for men, although adult male athletes still had more procedures. By the end of the study, 87 men and 61 women out of every 100,000 people had ACL surgery each year.
The study has several limitations, including the lack of data on what sports people played, how often they participated in practices and competitions and any individual characteristics or medical conditions that might influence the odds of ACL injuries. For young female athletes, the rise in injuries may be due at least in part to a new generation of women coming of age after the 1972 passage of Title IX, a U.S. law giving women the same right to participate in education and school sports as their male counterparts. Before the law took effect, women had far fewer opportunities to participate in sports.
“I think that the reason for the increased incidence of ACL tears and subsequent surgery in women is absolutely because more women and girls are playing sports,” said Dr. Elizabeth Gardner of Yale University School of Medicine in New Haven, Connecticut. “As this is really the second generation after Title IX, the intensity of training for women’s sports is also increasing dramatically,” Gardner, who wasn’t involved in the study, said by email.
Cross-training programs that include exercises to improve strength, balance, coordination and muscle control can help prevent ACL tears, Dr. Devin Peterson, a researcher at McMaster University in Hamilton, Ontario, who wasn’t involved in the study, said by email.
