The ACL is a major ligament in the knee that provides stability to the front of the knee joint and keeps the lower leg from sliding too far forward.
There are several theories why females are more prone to these injuries than males, according to Dr. Stephen Cord, but no one knows for sure. One of the more prevalent theories is that in females, the quadriceps muscle (thigh) is stronger than the hamstring muscle (back of the leg, connecting to the buttocks). This creates a natural tendency for the knee to want to twist or turn, which can result in an ACL injury.
Also, a woman's pelvis is wider than a man's, causing her to be more knock-kneed. So the woman's ACL has to pass through a smaller space than a man's, whose knees angle more outward.
ACL injuries can result from contact activities such as a direct hit to the knee during a game of soccer, or they can be the result of a non-contact activity such as a quick stop or turn during a basketball game. According to a recent report published by six major professional associations including the American Academy of Orthopedic Surgeons, the non-contact ACL injury rate is two to 10 times higher in female athletes than in their male counterparts. High-risk sports include basketball, field hockey, lacrosse, skiing and soccer.
There are measures that can help prevent an ACL injury. Greg Sherwood, retired public-school athletic director, started a weight-training program in 1992 in the junior high and high schools that continues today.
According to Cord, his practice has seen a marked decrease in the number of ACL injuries in young female athletes since that time.
"The earlier the better - fifth or sixth grade - before starting organized sports in junior high," Cord advised for weight training.
Weight training helps to balance the quadriceps/hamstring ratio and has been the single most effective preventative measure found to date to help a young athlete, and particularly a young female athlete, continue with an active lifestyle for many years to come.
Stretching, agility training and balancing exercises also can help.
Usually in the case of an ACL tear, the athlete will feel or hear a pop, and then the knee will swell up almost immediately.
"It is important to go to an orthopedic surgeon that is trained in sports injury if an injury occurs, or even if you think you might have one," said Cord. "Many West Texas people say, iWalk it off,' but if you feel or hear that pop, have someone check it for you."
Macey Sheumaker, a 2006 high school graduate and an avid basketball player, had just such an experience two years ago.
Sheumaker jumped at the net, and when she came down on her knee, she said, "Something just popped. It didn't hurt that bad, but my knee felt loose, like it wasn't attached." Her team's trainer looked at it and immediately referred her to her physician. Sheumaker went to Cord for an examination, and an MRI confirmed an ACL tear.
There are different treatment regimens, but surgery is necessary in about 95 percent of the cases -- especially for the young person who wants to continue participating in sports, according to Cord.
Without surgery, youngsters may develop early degenerative arthritis, trick knee or torn cartilage in the knee joint, Cord said.
The recovery process for an ACL injury typically takes at least four to six months, and for the professional college athlete, it may take a year to return to normal. In almost every case, recovery involves physical therapy.
"Therapy is really hard because it's things you don't normally do (during a basketball workout)," Sheumaker said.
Cord worked with Sheumaker's trainer and designed a workout program for her that included additional weight lifting, bicycling, stair-stepping and knee bends. Nine months later, she was back on the court again, and she finished up her senior year of basketball at Trinity this year.
Sheumaker plans to play basketball at college in the fall and said, other than a little tendonitis and sensitivity to changes in the weather, she feels no long-term effects from her injury.