Story Highlights•Girls four to eight times more likely than boys to injure anterior cruciate ligament
• Doctors suspect anatomy, hormones, muscle-use differences may be factors
• Rehab focuses on different ways to jump, land, to prevent re-injury
By Judy Fortin
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(CNN) -- First she heard the pop, then she felt the pain. Sixteen-year-old Lindsey Robinson tore the anterior cruciate ligament, or ACL, in her knee during the last game of the 2005 soccer season. She's been sidelined ever since.
"I was rolling on the ground," Lindsey says. "I couldn't feel the bottom half of my knee. It freaked me out."
Lindsey's story is becoming more common. Several of her teammates have torn the same knee ligament. "We often compare scars during practice," Lindsey says with a laugh. (Watch how more girls are being sidelined )
An estimated 150,000 Americans suffer ACL injuries each year in the United States. A growing number of them are female athletes.
Orthopedic surgeon John Xerogeanes (pronounced Zer ROY ans) says girls are four to eight times more likely than boys to injure the ACL. Last year, he recalls, "I reconstructed ACLs for just four male high school soccer players, compared to 25 girls." He expects to see more young female athletes on the operating table.
"We know that there is a huge increase in ACL injuries when you compare female athletes to male athletes," says Dr. Xerogeanes, who is the head of sports medicine at the Emory Orthopaedic and Spine Center in Atlanta, Georgia. "We've looked at a million different things in terms of size of the pelvis, angulation of the knees, hormones and the way girls fire their muscles when they land. We're not exactly sure why this happens."
Twenty years ago, injuries like Lindsey's would be career-ending, but thanks to advances in arthroscopic surgery and specialized physical therapy, doctors are able to get the majority of athletes back to the same level of playing.
In Lindsey's case, an initial surgery (done by another surgeon) to repair the damage was unsuccessful. She endured a second operation last fall and has undergone months of rehabilitation. "My rehab was really slow," says Lindsey. "The first few weeks, it really hit me that I wouldn't be playing soccer for a long time."
Part of the reason is that healing takes time. The ACL is located behind the knee cap. It connects the thigh bone to the leg bone. "It's basically a rubber band," explains Xerogeanes. "If you don't have it, your bones will separate and you'll fall over." (Interactive: Inside the knee )
Xerogeanes says knee braces and physical therapy don't help repair an ACL tear. The ligament must be replaced in order to restore proper function. He recommends surgery for almost all of his young patients. "When people are older they may say, 'I'm going to do activity modification rather than surgery,'" says Xerogeanes. "For young people, this is not a good viable option because they will not modify their activities and they will injure other structures in their knee because the ACL doesn't work."
Xerogeanes says full recovery from ACL surgery can take eight to 10 months. In his center, doctors and trainers are taking a new look at the role of rehabilitation.
As part of her program, Lindsey is being retrained how to jump and land and contract her muscles correctly. She's worked for months with certified athletic trainer Forrest Pecha. "This is more than the standard physical therapy," Pecha says. "We focus on the prevention of re-injury."
"What I'm trying to achieve is proper biomechanical function so all the muscles are firing properly," he explains. "We have them do lower extremity exercises like mini-squat-jumps and lunge walks."
Xerogeanes is hoping the conditioning can improve on something that may not come naturally. "When female athletes land, they tend to land stiffed legged with their knees coming together a little bit, versus male athletes who tend to land and bend their knees with their knee straight in front of them." He says helping athletes with this type of training is leading to an overall decrease in knee injuries.
"I'm feeling the burn," Lindsey complains to Pecha as he urges her to do more squats and deep knee bends. The sessions are tough, but Lindsey believes the hard work is paying off. She's hoping to be back on a soccer field by June and she predicts, "I'll be a smarter player. I'll do my exercises before practices and games."
Judy Fortin is a CNN Medical News correspondent.
Lindsey Robinson works at rehabilitating her knee after surgery to repair a torn anterior cruciate ligament, as trainer Forrest Pecha looks on.
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