A new study in Pediatrics, the journal for the American Academy of Pediatrics, found that anterior cruciate ligament injuries are on the rise, and girls are more likely to get this injury than their male friends.
In the U.S. study, girls playing the same sport as boys are 2.5 to 6.2 times more likely to have an ACL injury than boys. In a Norwegian study, girls ages 10-19 had a 76 in 100,000 chance of tearing their ACL; boys in that same age range had a 47 in 100,000 chance of the same injury.
About 70 percent of these injuries happen when there is no contact with another player at all.
Usually, you feel a pop in the knee and then see swelling, says Dr. Randall Schultz, an orthopedic surgeon with Texas Orthopedics. Sometimes it will hurt; other times, the pain might not be that bad.
It's not something you have to go to the emergency room for, he says, but you should see a doctor the next day or after the weekend to see what's going on and what needs to be done. In the meantime, put ice on it and use crutches to try to stay off it, Schultz says.
Sports where kids stop suddenly and turn a different direction usually are the common offenders: soccer, gymnastics, volleyball and basketball. Boys also saw problems in football. Locally, doctors see all of these, plus cheerleading and dance.
The risk goes up for girls once they hit age 12 or 13 and for boys around age 14 or 15.
Why? Puberty. This is the time when kids grow faster and their bodies can't always keep up, which is especially true in the leg's tibia and femur bones. For girls, hormones also make the ligaments more lax. In boys, the testosterone surge actually helps them increase muscular power and control, allowing them to handle the rapid skeletal growth better.
The number of kids with ACL injuries is on the rise because more kids are focusing on one sport intensely all year with few breaks. This is very different from the old habit of kids playing a variety of sports with time off in between seasons.
The treatment now is also different. It used to be that you would keep the knee immobile, but now ACL tears require surgery to replace them. After the surgery, athletes usually have six months of rehabilitation exercises before they can return to sports.
An ACL injury can have long-lasting effects, however. Athletes who had an ACL injury are 10 times more likely to have early-onset degenerative knee osteoarthritis than those who never had an ACL injury.
"I have daughters that play sports. I'm worried about it," Schultz says.
A study of athletes older than 18 with an ACL injury found that only about half returned to the level of performance they had achieved before the injury.
Once you have an ACL injury, you also are 15 percent more likely to have another, a study showed.