Understanding the knee's complex biomechanics, and how to get ahead of lacrosse's ACL problem
This article appears in the October issue of Lacrosse Magazine, a special sports science and safety edition.
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"This is a life-altering injury."
Those are the words of Dr. Richard Hinton, physician for the U.S. women's team and a member of US Lacrosse's Sports Science and Safety Committee, when discussing anterior cruciate ligament (ACL) knee injuries.
"ACL injuries are the leading cause of game and practice missed time by lacrosse athletes," said Hinton, who performs more than 100 ACL reconstructions annually as director of MedStar Sports Medicine in Baltimore.
One of four major ligaments in the knee, the ACL's primary role is to stabilize the knee when turning or planting. Basically, it connects the thighbone (femur) to the shinbone (tibia).
For most of life's common, everyday activities — walking, bending or climbing — the ligament serves us well. But the added stress of sports that involve sudden stops and changes in direction can increase the risk of injury.
"The knee has very complex biomechanics, and there are any number of places where the knee joint can fail when it is overstressed," Hinton said. "There's a greater potential for injury associated with jump, cut, twist, turn sports."
The American Orthopaedic Society for Sports Medicine estimates there are 150,000 ACL injuries annually in the U.S.
Statistics also indicate females are at higher risk than males for ACL injuries in some sports, but studies have not shown any significant difference between men's and women's lacrosse.
"We see a lot of injuries that just don't make sense," said Justin Cooper, a physical therapist, who specializes in post-operative rehabilitation and injury prevention at Baltimore's MedStar Harbor Hospital Sports Medicine Clinic. "An athlete does something 1,000 times with no injury, then the next time, tears the ACL. Why that time?"
Through the early 1980s, just one-third of people that suffered ACL tears opted for surgery. Most simply modified their activities and focused on rehab. Conversely, nearly 100 percent of today's ACL tears result in surgery, a statistic driven by athletes who want to return to competition.
More than 90 percent of these surgical procedures result in excellent clinical outcomes — a mechanical, stable knee is restored. But research indicates less than 70 percent of athletes who sustain an ACL injury return to the same level of play. "Surgery is not a perfect solution, but it does provide the best option to return to lacrosse," Hinton said. "We have a problem here that we don't have a great answer for yet."
Hinton tells ACL patients that even in best-case scenario, surgery won't provide them with a better knee ligament than the one with which they were born. That's why US Lacrosse has invested in research on ACL injury prevention — with focus on the athlete and his or her personal characteristics, rather than on the environment. The days of evaluating ACL injury risk based on artificial playing surfaces as opposed natural grass fields, for example, are long past. "Preventing these injuries is a much better answer than operating on them," Hinton said.
Hinton cited landing techniques as an example, noting that athletes must be trained to "land soft and land stacked." Proper mechanics and posture allow the body to absorb energy so that it is not being transferred to the ACL. Hip strength, core strength and coordination also affect susceptibility to injury.
A current pilot study funded by US Lacrosse will identify the most effective exercises to reduce ACL injuries among high school players. It incorporates a 20-minute warm-up of dynamic exercises. While still in the preliminary stages, the data collected could help players, coaches and athletic trainers implement a warm-up routine that more effectively reduces injury risk.
US Lacrosse plans to release an instructional video series on ACL injury prevention practices by the end of the year.
"There's still a disconnect between the gravity and seriousness of this injury and what the public thinks about it," Hinton said. "Despite our best efforts, it still happens."