What injury occurs 200,000 times each year and costs half a billion dollars annually? It’s the same injury that affects women eight times as frequently as men and has been the cause of countless athletic careers ending prematurely. It is also the condition that sidelined Tom Brady and Wes Welker in consecutive seasons.

That’s right — I’m talking about ruptures of the anterior cruciate ligament.

The ACL is the most important ligament in the knee. It holds the thigh to the leg and allows the kind of rapid cutting motions that are crucial for athletes. Without a functioning ACL, athletes feel their knees buckle under stress and may be more likely to develop arthritis.

ACL injuries are much more common in women. This may be because women tend to land using their thigh muscles rather than their hamstrings to stabilize themselves. It’s called being “quad dominant.” This causes uneven forces across the knee and explains why 4 out of 5 ACL injuries occur with no contact.

Researchers like Tim Hewett at Cincinnati Children’s Hospital have taken their understanding of ACL injuries one step further — to the point of predicting what athletes may go on to injure their ACL. Hewett’s research team uses video cameras to assess athletes as they jump and land, allowing them to calculate the angles and forces across the knee that would predispose an athlete to an ACL injury.

Even better, they have been moving forward and perfecting a program that allows physicians to train athletes to prevent ACL injuries. In clinical trials, athletes who had gone through an ACL prevention program were up to 84 percent less likely to be injured.

These programs involve improving an athlete’s jumping mechanics, strength and their balance. Agility training and sports specific exercises are important components. Many programs are designed to be done by an entire team for 15 minutes before practice. Most important, they work.

Many professional and Olympic teams are already including these programs in their schedules. College teams are catching on, especially in sports that see a lot of ACL injuries, like soccer and basketball.

Programs typically start 6 to 8 weeks before the season, and involve exercises three days a week. Athletes go through training on techniques of jumping, fundamentals training and finally work on performance to increase their strength, explosiveness and jump height.

An ACL prevention program would have helped Alice, a college soccer player who I saw recently. Alice injured her ACL for the fifth time. She has already had each knee reconstructed twice. Despite her challenges, Alice has always kept a good attitude and focused on the work she needed to do to get back.

But last week I saw the effects of her injuries wearing on Alice. She was in tears even before hearing that she had ruptured her ACL graft. “I just don’t know if I can go through the surgery and rehab again,” she said. “Sometimes knowing what is ahead makes things even harder.”

If Alice had gone through the ACL training program, she might have prevented that first injury. With a stronger knee, each of the ruptures that followed might have been avoided. Fifteen minutes of ACL prevention training seems a small price to pay for a career without these devastating surgeries. Millions of athletes like Alice could be helped by ACL injury prevention programs.

Maine athletes can learn more about ACL injury prevention by talking to their sports medicine specialist, or by checking out http://www.stopsportsinjuries.org

Dr. James Glazer is a sports medicine physician for Coastal Orthopedics and Sports Medicine in Freeport. He serves as a consultant for the Portland Pirates and the U.S. Ski Team.