ACL injuries in young female athletes

Laird Harrison | Disclosures

An Epidemic of ACL Injuries
In the mid-1990s, Bert R. Mandelbaum, MD, realized that his practice at the Santa Monica Orthopaedic and Sports Medicine Group in Santa Monica, California, was changing.
“I saw a flip,” he says. “My practice had been about 80% male and 20% female. And then it went to 80% female and 20% male.”
Over in Ohio, renowned knee surgeon and orthopedic sports medicine specialist Frank Noyes, MD, was noticing something similar at the University of Cincinnati and among Olympic soccer players. The number of anterior cruciate ligament (ACL) injuries had more than tripled among National Collegiate Athletic Association (NCAA) soccer players from 1990 to 2000.[1] Researchers crunched the numbers and confirmed what the surgeons had noticed: Women suffer ACL injuries at 4-10 times the rate of men.[1]
Noyes, Mandelbaum, and others like them investigated this phenomenon. They found the cause, devised preventive exercise programs to address the situation, proved that the programs work, and shared them with the world. But their work has hardly staunched the tide of athletic knee injuries, leaving them groping for a next act. “We feel that it’s a very unmet need,” Noyes says.
Noyes estimates the incidence of ACL injuries in the United States at 300,000 per year. And the injuries can be devastating. One study found that only 44% of athletes are able to return to competition after ACL surgery.[2]
While men still suffer the majority of ACL injuries, the incidence of such injuries has risen as more people — particularly more women — participate in sports.[3] From the 1981-1982 school year to the 2012-2013 school year, the NCAA added 3071 women’s sports teams and 749 men’s sports teams to its roster, with the highest growth in women’s soccer.[3]

Diagnosing the Problem
Noyes has some theories about why women, especially teenage girls, are blowing out their ACLs. “I observed that the way they moved in jumping and landing and cutting, the so-called ‘wiggle-wobble knee,’ made it apparent that there were balance and control issues that made them vulnerable to knee injuries,” he says.
But not every female athlete is suffering this way. “I noticed that Olympic volleyball players had really good knee control,” Noyes says. The reason, he theorizes, is the plyometric training that volleyball players do. “They jumped off mattresses,” he observes.
To confirm the theory, his team videotaped men and women, injured athletes and noninjured athletes, as they jumped onto force plates that measured the impact of their landing. The investigators found significant differences. Among the most striking: Women — and people who had suffered knee injuries — were more likely to land harder, with their knees less flexed and more valgus.
In 1994, Noyes and colleagues at the Cincinnati SportsMedicine Research and Education Foundation, of which Noyes is President, began to develop Sportsmetrics™, a program of exercises aimed at reducing the risk for injuries. They were able to show that the training can change biomechanical metrics, such as the distance between the athlete’s knees when landing from a jump.
A few years later, at a meeting of the American Orthopaedic Society for Sports Medicine, Mandelbaum and others who had noticed the trend toward knee injury watched hours of video showing athletes getting injured. They too noticed the awkward landings of the athletes who hurt their knees.
“I was the national team physician for US men’s soccer and I felt it was my duty to put together a program,” Mandelbaum says. Soon the Santa Monica Sports Medicine Foundation, of which he is Director, was testing the Prevent Injury Enhance Performance (PEP) program, which consists of a warm-up, stretching, strengthening, plyometrics, and sport-specific agilities to address potential deficits in the strength and coordination of the stabilizing muscles around the knee joint.
New Programs Focus on Prevention
Around the world, other regimens were cropping up as well, and they have proliferated. Sue Barber-Westin, Director of Clinical and Applied Research at the Cincinnati Foundation, counted 50 of them in a recent literature review.[4]
Many of these regimens have proved themselves in clinical trials, in which some teams do the exercises and other teams stick to their usual warm-ups. Noyes and Barber-Westin showed that Sportsmetrics reduced the risk for noncontact ACL injuries by 88%-100% in soccer, basketball, and volleyball.[4-12]

“It definitely works,” Barber-Westin says. “You can see in 6 weeks that you really can change these dangerous movement programs that you see in female athletes.”
PEP achieved similar success, reducing the risk for ACL injuries by 82% in soccer alone.[4]
But the success of a program depends partly on the outcome measured. The HarmoKnee Preventive Training Program, developed by Swedish researchers, reduced the combined incidence of all types of acute knee injuries, including contact injuries, by 90% in soccer.[13] And exercises developed by researchers at the Norwegian University of Sport and Physical Education in Oslo, Norway, reduced the combined risk for lower extremity injuries in team handball by 47%.[14]
Other programs have reduced injuries in male athletes as well. Mandelbaum went on to help develop FIFA11+, a program for soccer’s governing body, the Fédération Internationale de Football Association (FIFA), which cut overall injuries — not just knee injuries — roughly in half for male soccer players.[15]
The number of competing programs can be bewildering. But they have a lot in common.[4] They train athletes to land softly on the forefoot and roll back to the rearfoot, engaging the knee and flexing their hips on landing and when making lateral cutting maneuvers. They demonstrate how to avoid excessive genu valgum (“knock knee”) on landing, squatting, and running.
Most of the programs also feature jumping exercises (plyometrics), as well as hamstring, gluteus medius, core, and hip abductor strength exercises aimed at correcting imbalances.[4]
“Soccer athletes are quad-dominant,” says Holly Silvers, MPT, who worked with Mandelbaum on the PEP and FIFA programs. “They don’t use their hip adductors a lot. And if the quad pulls against the ACL, if they don’t have enough hamstring co-contraction, that creates an imbalance.”
Some of the programs include stretching exercises; others don’t.
The programs work differently, and their developers are each ready with arguments for why theirs is the best. For example, Sportsmetrics differs from most of the other programs in offering a six-week program of training for 90 minutes, three times a week at the beginning of the season. The Cincinnati foundation certifies instructors in the program.
In contrast, most other programs are based on participation throughout the season — for example, as a 15-minute warm-up before practices. Barber-Westin argues that repeating the exercises multiple times per week will lead to poor compliance. “The athletes get bored,” she says.
Holly Silvers has the opposite perspective. If athletes don’t keep up the exercises, they become less effective over time, she says. “The reality is you lose compliance,” she notes. “If you abandon them, you get recidivism. There is a benefit to continuous development over the season.”
To prevent boredom, the FIFA11+ program offers 3 levels of some exercises so that athletes can challenge themselves to improve.
Will Athletes Take ACL Prevention Seriously?
The debate about compliance gets at the key problem facing all knee injury prevention programs: Not enough athletes are doing them.
“We’re doing a study to try to get a handle on how many clubs are implementing injury prevention,” Mandelbaum says. “So far, the numbers are extremely disappointing.”
It’s not as if these experts haven’t tried to spread the word. “We’ve been preaching this for 15 years,” says Frank Noyes.
Dozens of journal articles have shown the efficacy of the knee injury prevention programs, and lay publications, such as Sports Illustrated and the New York Times, have reported on them. “It’s not that people don’t know the information,” says Bert Mandelbaum. “It’s that people don’t pick up the information.”
Lately professional organizations have started getting on board. In April, the American Academy of Pediatrics endorsed neuromuscular training for young athletes to prevent ACL injuries.[16] It also published a list of resources for these programs[17] and a report on diagnosing and treating ACL injuries.[18]
Noyes has heard that other organizations are working on similar statements. But it’s not doctors — but rather coaches, trainers, parents, and the athletes themselves — who need convincing.
“Part of it is the nature of athletics today, and part of it is human nature,” says Noyes. “If you have a 15- or 16-year-old daughter and she participates in soccer, would she rather go to a summer skill camp to learn how to manage the ball and learn how to do all the skills for six weeks, or is she going to take a six-week performance neuromuscular training camp?”
Experts offer these tips to physicians who want to help reduce knee injuries:
• Reach out to trainers and coaches in your community;
• Make the argument that the programs will not only prevent injuries but also enhance athlete performance; and
• Point out that the training programs don’t take extra time, because they can replace traditional warm-ups, such as toe-touches, that have not been shown to reduce injury.
Consciousness-raising is a slow process, but statistics suggest that even convincing one team to undertake these exercises can save several athletes from physical and emotional pain and loss of fitness.

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