But out of 100 athletes who had reconstructive surgery on their anterior cruciate ligament, or ACL, researchers found female and older players were less likely than younger men and boys to get back in the game.

And by seven years out, 12 of the athletes had undergone a second ACL surgery on the same or opposite knee.

"The good news is, you can get back to a sport like soccer after an ACL reconstruction," said Dr. Robert Brophy, an orthopedic surgeon from the Washington University School of Medicine in St. Louis, who led the study.

But athletes who've had an ACL tear, he added, "need to have a sense of the fact that they're going to be at risk for future injury."

The ACL, located in the middle of the knee joint, is most commonly injured during sports that require jumping or quick changes in direction, or when the knee gets overextended.

Female athletes are known to be at higher risk of ACL tears. Regardless of gender, those are typically thought of as season-ending injuries because rehab takes months of working to regain strength and range of motion.

For the new study, Brophy and his colleagues interviewed 100 soccer players who'd undergone surgery to repair a torn ACL in 2002 or 2003.

At the time of surgery, those athletes ranged in age from 11 to 53 years and included high school and college players as well as recreational athletes. Forty-five of them were female.

After surgery, 72 of the athletes returned to playing soccer, usually after a year or so, with most reaching their pre-injury level of play. That included 42 male athletes and 30 female athletes who said they'd gone back to the sport.

People who were younger at the time of injury were more likely to return to the field.

Seven years after surgery, 36 out of the 100 initial athletes were still playing soccer, the researchers reported in The American Journal of Sports Medicine. By then, nine female athletes and three males reported having had another ACL surgery.

The American Orthopaedic Society for Sports Medicine estimates there are about 150,000 ACL injuries in the U.S. every year.

Brophy said there are many reasons why athletes may never return to their sport of choice after an ACL tear. They may not get their conditioning back to where it once was, or they may feel okay running but have trouble with the type of knee function required for soccer or football.

In addition, "they may be afraid of re-injury or feel like it's not worth the risk," he told Reuters Health.

That may be especially true for older athletes, he said.

"Life demands may make the rehabilitation more challenging and more difficult to get through, as well as make it more difficult to say, ''(It's) worth it to go back and play.'"

SOURCE: bit.ly/NToCq9 The American Journal of Sports Medicine, online September 21, 2012.

• A Permanent Economic Emergency