Preventing Girls' Knee Injuries During Sports

Girls kicking and throwing balls, running up and down a field or court and lifting weights to keep muscles strong are common sights today on school grounds and in gymnasiums. Millions of kids participate in competitive play each year, including 69 percent of girls ages 8 to 17 who take part in organized sports, according to research by the Women’s Sports Foundation. There’s a downside to all the activity, particularly girls’ knee injuries.

“The number of knee injuries in girls keep going up,” said  John Zvijac, M.D., orthopedic surgeon with Miami Orthopedics & Sports Medicine Institute.“Women are much more engaged in sports these days – nearly all leagues have women’s involvement.”

Dr. Zvijac is a founding member of the medical advisory team for Miami-Dade Public Schools’ Athletic Program.  Half of the patients he sees in his office are younger than 18. Dr. Zvijac and his Miami Orthopedics & Sports Medicine Institute colleagues also provide medical treatment to professional athletes at certain organizations, such as the Miami Dolphins and Miami HEAT.

Why Girls are More Prone to Knee Injuries

Dr. Zvijac says there are several reasons why knee injuries occur in girls:

1. Anatomy – Girls’ hips grow wider after puberty, which sometimes results in a larger angle at the knee – a condition more commonly known as knock-knees. Compared to males, females also have a narrower notch where the ACL attaches to the femur. These differences may impact mechanics, such as limiting the space in and around girls’ knees that allow the ACL to move, according to the American Academy of Orthopaedic Surgeons. While anatomic risk factors in girls cannot be changed, understand and building exercises to address them are important for injury recovery and prevention, doctors say.
2. Biomechanics – Forces on the knees that come with the ways girls are built are also something causes knee injuries, Dr. Zvijac says. By watching videos of female athletes in motion, sports medicine researchers documented in a study published in the American Journal of Sports Medicine how girls run more upright, land with their knees buckled inward, place weight on a single leg during certain movements and tilt their torso away from their center of mass.  Women’s hip-to-feet ratio causes them to be more “knock kneed” than boys, putting more stress on the knees and the ACL in particular, Dr. Zvijac says. These neuromuscular risk factors can be modified through strength training, he adds.
3. Muscle imbalances – The hamstring, quadricep, buttock and hip muscles in girl athletes can usually benefit from being strengthened, Dr. Zvijac says. When these muscles are strong, they can work in conjunction with each other to take pressure off the knees. Ways to overcome the muscle imbalances include learning how to land properly and techniques for proper “cuts” that don’t force hyperextension of the knee, he says.
4. Hormones – The role girls’ hormones play in knee injuries has been an increasing focus of sports medicine research. Estrogen in girls during adolescence makes ligaments more lax, Dr. Zvijac says. And hormonal fluctuations during the month contribute to injury risk. Girls are more susceptible to injury during the first half of the menstrual cycle, just before ovulation, according to Dr. Zvijac.

Common Knee Injuries in Girls

There are a couple of knee injuries most common in girls, Dr. Zvijac says.

• Patellofemoral pain syndrome, a condition that happens when the knee cap turns inward, is the is the most common cause of knee pain in young athletes, Dr. Zvijac said. It can be caused by overuse, injury or a kneecap that is not properly aligned, he says. The syndrome often results from activities – like running, jumping and squatting – that cause pressure or friction on the cartilage behind the kneecap. Because the injury doesn’t show up on an X-ray, Nearly all cases get better with strengthening and rehab that help reduce contact forces on the knee cap and provide symptom relief, he said.
• An ACL tear is more concerning and the most devastating knee injury in girls, Dr. Zvijac says. This ligament located behind the kneecap and attached to the femur (thighbone) and the tibia (shinbone) stabilizes the joint when the knee twists and prevents the tibia from sliding forward. “ACL injuries are four to five times more common in girls than in boys participating in similar sports,” Dr. Zvijac said. “The injury is usually the result of a non-contact action, such as a forceful landing or twist.” While most ACL tears are season-ending injuries, surgery and a few months of physical therapy allow for recovery, he adds.

ACL Injury Prevention

Despite the odds, there are steps girls can take to stay injury-free. Doctors recommend neuromuscular strengthening exercises that focus on building strength in the leg and core muscles and improving balance and landing techniques. Squats, lunges and jumping and balancing exercises are good choices.

“Weight training and strengthening are preventive measures women can take to prevent knee injuries,” Dr. Zvijac says. “We know that time allocated in the off-season to weight and strength training can have a great benefit. Pilates and other types of exercise that involve good muscle resistance are also helpful.”

To help girls avoid season-ending knee injuries, an ACL Injury Prevention Program is available to young athletes at Miami Orthopedics & Sports Medicine Institute. The six-week program involves an initial assessment at which each athlete is evaluated for neuromuscular strength and mobility. Based on the results, a plan of exercises designed for each person’s specific sport are prescribed, focusing on strengthening specific areas that need addressing.

“Movements that focus on the neuromuscular component of knee mechanics result in an improvement in balance which ultimately helps fend off injury,” Dr. Zvijac said.

While balancing successful competitive play with staying injury free can be a challenge for young athletes, Dr. Zvijac says it can help avoid painful and sometimes debilitating conditions in the future, such as arthritis and osteoporosis.

“By helping these young ladies prevent injury to their ACLs now, it’s our hope the maintenance they need to do to keep their knees strong will become part of their life going forward,” he said.