Josie Berg-Hammond

Josie Berg-Hammond, 24, suffered an ACL tear when she was 11, and corrective surgery was delayed for two years because she was still growing. Berg-Hammond, who says her knee still hurts every day, does yoga in her Logan Square apartment in Chicago on Aug. 14. (Scott Strazzante/Tribune Photo)

Eleven-year-old Josie Berg-Hammond was running sideways in gym class when her right knee popped and buckled. She had torn a ligament, but surgery was delayed for two years because she was still growing.

As the preteen waited for the operation on her anterior cruciate ligament, or ACL, she was encouraged to remain active. But her unstable knee kept giving out. Now, more than a decade after surgery, Berg-Hammond says she has constant pain in her knee.

"It hurts to walk and to do any sort of physical activity," said Berg-Hammond, 24, of Chicago, who never dreamed her childhood mishap might have lifelong consequences.

Once considered an adult injury, ACL tears are occurring more often in the legs of elementary and middle school-age children, orthopedic specialists report. The increase, which stems in part from better diagnostic tools and a dramatic increase in children playing competitive, organized sports, has created a vexing problem: What's the best way to fix it?

For years doctors have advised delaying surgery until the bones are done growing, usually around age 14 for girls and 16 for boys. In the meantime, children were prescribed physical therapy and encouraged to remain active while using a knee brace, with the exception of cutting, pivoting and contact sports.

But postponing surgery hasn't worked very well, in part because it's difficult to keep children from further damaging the knee while they wait — in some cases for years. Athletic youngsters often must stop playing sports they love, a loss that can lead to depression and affect a child's identity and friendships.

"It's very difficult to have a condition where there isn't a clear, favored treatment," said Dr. Mininder Kocher, associate director of the division of sports medicine at Boston Children's Hospital and one of the country's busiest pediatric ACL surgeons. "The kids who tear them young are good athletes; they were strong enough or had good enough technique to generate that force in the knee."

Kocher, also a professor of orthopedic surgery at Harvard Medical School, has helped pioneer novel surgeries for children that bypass the growing areas of the leg bones or are designed to minimize damage to the area. Though Kocher's published data show low failure rates among his young patients, nobody knows what the long-term outcomes will be.

The ACL, which connects the thigh bones and shinbones inside the knee joint, is a crucial stabilizer during sports like basketball, football, soccer and lacrosse. Its job is to protect the knee from shifting, rotating and hyperextending as an athlete runs, jumps or lands. An easy way to tear the ligament involves simultaneously decelerating and twisting.

In adults, surgery isn't always necessary, especially for those with sedentary lifestyles. Though skiing and soccer might be out, it's possible to walk, run and even play tennis with a fully torn ACL.

Risks are higher for children because it's hard to get them to modify their activity. A study published last year in The American Journal of Sports Medicine found that young athletes who delay surgery five months or more have a higher chance of suffering a secondary knee injury. Waiting can lead to progressive damage to other parts of the knee, including the meniscus and cartilage, multiple studies show.

"It's almost like having a ticking time bomb in the child's knee," Kocher said. "The damage can happen in free play or recess, not just travel soccer."

When 12-year-old Hugh Besl of Cincinnati suffered an ACL tear during a lacrosse game in April, multiple doctors recommended intense rehab with the hope of stabilizing the knee. If that didn't work, then surgery might be an option, the family was told.

As time went on, however, and Hugh's knee remained unstable, the Besls opted for surgery at Boston Children's Hospital with Kocher, who operated Aug. 9. The decision was based on what might be best for Hugh in the long run, said his mother, Anne.

"At first you think, wow, he can't play sports," she said. "Then you think, wow, he's 12 and already hurt something major. What will he be like when he's 30?"

Added Hugh, who loves soccer, baseball, lacrosse, snowboarding and basketball: "I really just want to be able to play outside with my friends."

Though official statistics are scarce, orthopedic specialists estimate that thousands of children and teens are tearing their ACLs each year. Researchers at Children's Hospital of Philadelphia found a 400 percent increase in youth ACL injuries over the last decade, according to findings presented at the American Academy of Pediatrics 2011 annual meeting. Girls have up to eight times the risk of an ACL tear as boys, though no one knows exactly why.

Traditional surgery on the ACL requires tunneling into parts of the leg bone. In children, these areas are still growing; the drilling can risk stunting development or creating deformities that are difficult to correct.

As a result, some physicians still tell parents it's better to wait. Orthopedic surgeon Victor Romano of West Suburban Medical Center in Oak Park encourages children to be as active as possible between the injury and surgery, as long as the sports don't require pivoting and cutting.

"I give them a brace, and if the knee feels safe and doesn't give out, I'll let them play," said Romano, the team doctor for Fenwick High School and Dominican University.