Movement patterns predict risk of ACL tear, but targeted training may aid prevention

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Rheumawire

Mar 17, 2004

Movement patterns predict risk of ACL tear, but targeted training may

aid prevention

San Francisco, CA - Altered movement patterns of female athletes

increase risk of noncontact injuries to the anterior cruciate ligament

(NC-ACL) [1], but targeted prevention programs that incorporate

neuromuscular training may help female athletes lower their risk [2],

according to 2 studies presented at the 71st annual meeting of the

American Academy of Orthopaedic Surgery.

A third study, however, found that a knee-ligament-injury prevention had

no effect on NC-ACL risk.

Dr Bing Yu (University of North Carolina, Chapel Hill) and colleagues

looked at 30 male and 30 female recreational athletes between the ages

of 18 and 30. They found that altered movement patternsspecifically,

excessive movements at the knee jointare responsible for elevated risk

of NC-ACL injuries in women. They used a stochastic modeling paradigm to

determine how motion patterns affect risk of noncontact ACL.

The study found that lower-extremity motor control is a risk factor for

NC-ACL in stop-jump movements and that a hard or awkward landing alone

may not cause injury.

Now Yu and colleagues are following 400 freshmen in the Naval Academy

and plan to recruit the same from the US Military Academy at West Point

and the Air Force Academy to see how and when players are injured.

" We hope our studies can provide a solid scientific basis for clinicians

to develop strategies to prevent NC-ACL injuries, " Yu says.

In a related study, Dr E Hewett (Cincinnati Children's Hospital,

OH) found that targeted neuromuscular training improves performance and

lower-extremity biomechanics among female athletes.

Specifically, they found that being valgus at the knee (knock-kneed)

predicts ACL injury among female athletes.

They used targeted training based on this imbalance, including using an

unstable surface to control knee joints and using the hip to control the

knee as well as strengthening helper muscles. Athletes trained 3 times a

week for 6 weeks.

" We are making them better athletes, that is without a doubt, " Hewett

says. " Neuromuscular training can improve measures of performance, which

is what kids, coaches, and parents are interested in, [and] these

changes can take you from a nonstarter to a starter. "

In addition, the training program exacted desirable biomechanical

changes during a landing, and the rate and degree of valgus also

decreased among athletes who participated in the training program,

compared with controls.

Dr P Pfeiffer (Boise State University, ID) and colleagues

conducted a 2-year study of a knee-ligament-strengthening regimen. The

study included 1439 female athletes from 112 athletic teams at 15

schools. Participants trained via jumping and landing programs that

included double- and single-leg-jump hops and agility drills.

There was a low yield of injuries overall in both the athletes who

participated in the training program and those who did not. Among the

1439 teens in his study, a total of 6 NC-ACL injuries were reported3 in

the intervention group and 3 in the control group.

" Our program had no effect, either positive or negative, on risk of

NC-ACL injury in the subject pool, " Pfeiffer says. " But coaches say that

the girls felt that their performance improved. "

It could be that the program we developed is not sufficient in

magnitude, " Pfeiffer says. Another reason that the training program did

not reduce injury may be related to the age of the athletes, as it may

be necessary to start these training programs in younger athletes.

" If exercise programs can be designed to reduce knee injuries in female

athletes, they will be better accepted if they require a reasonable

amount of training time, such as 20 to 30 minutes, 2 to 3 times per

week. If we can't come up with something that's going to work in that

length of time, we may have to come up with a completely different

approach to this problem, " he says.

" ACL tears occur with alarming frequency in young female athletes, " says

Dr Letha (University of Georgia, Athens).

" One in 10 female collegiate athletes tear their ACL and so do 1 in 100

high school girls who participate in sports that involve jumping,

cutting, pivoting, or changing direction, such as basketball,

volleyball, and soccer, " she says.

" The implications will last a lifetime and influence mobility, " she

says.

Each year, $1 billion is spent on reconstructing this injury, and this

figure does not include the care for resulting secondary arthritis, she

says.

Mann

Sources

1. Garrett Jr WE, Yu Bing, and Kirkendall D. Presentation: Gender

differences in motion pattern and risk for ACL injuries in stop-jump

task. San Francisco, CA: American Academy of Orthopaedic Surgeons: 2004

meeting; March 10-14, 2004:Paper no 13.

2. Hewett TE, Myer GD, Ford KR. Presentation: Neuromuscular training

improves performance and lower extremity biomechanics in female

athletes. San Francisco, CA: American Academy of Orthopaedic Surgeons:

2004 meeting; March 10-14, 2004:Paper no 12.

I'll tell you where to go!

Mayo Clinic in Rochester

http://www.mayoclinic.org/rochester

s Hopkins Medicine

http://www.hopkinsmedicine.org