September 2015

Profiling for ACL injury prevention: Biomechanics identify risk subtypes

In the moment: Sports medicine

9ITMsports_iStock3269604-copyBy P.K. Daniel

Although existing anterior cruciate ligament (ACL) injury prevention programs have been successful at reducing the incidence of ACL injury, a new study suggests that tailoring interventions based on four risk profile subtypes could be more effective.

A team of researchers hailing from Australia, Greece, and the US analyzed a large cohort of high school female athletes during an unanticipated cutting task and identified high-risk profiles based on observed biomechanical characteristics associated with ACL injury.

“Recent reports indicate that targeted neuromuscular training to identified deficits can further enhance the effectiveness of neuromuscular training aimed to prevent injury,” said study co-author Greg Myer, PhD, associate professor of pediatrics and director of research and the Human Performance Laboratory in the Division of Sports Medicine at Cincinnati Children’s Hospital Medical Center in Ohio.

The study, epublished in August in Medicine & Science in Sports & Exercise, analyzed trunk and lower extremity 3D kinetics and kinematics during cutting in 721 female athletes. Approximately 40% showed no biomechanical deficits and were deemed low risk. Nearly a quarter (24%) presented with a combination of high quadriceps and leg dominance deficits. The third most prevalent profile (22%) had a combination of trunk and leg dominance deficits and, to a lesser extent, ligament dominance deficits. The last category (14%) demonstrated only very high ligament dominance deficits. With the exception of the last profile, the current analysis indicates that risk profiles consist of a combination of biomechanical deficits.

Much of the previous research on ACL injury risk has focused on jump-landing mechanics. Myer said he and his coauthors focused on the unanticipated cutting task as a means of fleshing out all risk factors.

“While the drop vertical jump continues to be our most sensitive and specific task to identify deficits related to ACL injury risk, we need to continue to develop more sports-related tasks that can support risk identification,” he said.

Amy Beth Hopkins, MPT, owner of Your Personal Best Physical Therapy in Austin, TX, agreed with that approach.

“In improving our identification of higher risk athletes, we need to analyze cutting movements and biomechanical discrepancies,” she said.

However, Holly Silvers, MPT, a researcher in the University of Delaware’s Biomechanics and Movement Science Program in Newark and a researcher at the Santa Monica Sports Medicine Foundation/Institute for Sports Sciences in Los Angeles, cautioned against overdependence on categorization systems when matching patients with interventions.

“We have to be very, very careful in overly compartmentalizing or overly specializing with respect to injury prevention,” Silvers said. “We’re going to lose people who are presenting one way and may have other deficits that could be underlying. They may not reveal themselves overtly.”

Cynthia LaBella, MD, associate professor of pediatrics at Northwestern University’s Feinberg School of Medicine, and medical director for the Institute for Sports Medicine at the Ann & Robert H. Lurie Children’s Hospital of Chicago, thinks there are benefits to tailoring ACL injury prevention.

“Individuals often differ regarding the collection of neuromuscular factors that need to be addressed,” LaBella said.

An important question, however, is how the tailored information can be integrated into existing generic prevention programs.

“One possibility is for program instructors to undergo more comprehensive training such that they are able to identify individual needs,” LaBella said. “If class size can be kept small, this allows the instructor to keep a close eye on all participants and make individual adjustments.”

But Silvers questioned the feasibility, compliance, and applicability of tailoring ACL injury prevention programs in a team setting.

“How do you introduce that implementation to a team?” said Silvers, who helped create FIFA 11+, an injury prevention program designed for soccer players aged 14 years and older that has been associated with significant reductions in lower extremity injury rates. “It would be very difficult.”

Sources:

Pappas E, Shiyko MP, Ford KR, Myer GD, Hewett TE. Biomechanical deficit profiles associated with ACL injury risk in female athletes. Med Sci Sports Exerc 2015 Aug 7. [Epub ahead of print]

Soligard T, Myklebust G, Steffen K, et al. Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial. BMJ 2008;337:a2469.

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