Paper 248
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Study reports female ACL injuriescaused while landing from jump
ORLANDO, Fla.--Research presented here today suggests that gender differences in anterior cruciate ligament (ACL) injuries may be related to landing from a jump. The study found that women expose their knee joints to higher forces per pound of bodyweight when landing from a jump than men do. This is caused by less knee flexion during impact which causes increased knee joint pressure.
Twenty people with no prior knee injuries (10 males and 10 females with an average age of 28.5 years) were matched for similar heights in size and jumps by the researchers. With regular activity levels ranging from recreational to competitive sports, participants performed different jumps from different heights. Reflective markers were placed on the right side of the body at six key sites to track jump reactions.
"Women appear to jump and land in a more hazardous position than men," said study author Edward M. Wojtys, MD, professor of orthopaedic surgery, University of Michigan at Ann Arbor, Mich. "This position may contribute to the very high rate of serious knee injuries in women."
The largest gender difference in knee angles occurred at the lowest jump height of 20 centimeters. Women consistently landed with a straighter leg than men. By increasing the bend angle of the knees, women can reduce the strain on their knees, Dr. Wojtys reported at the 67th annual meeting of the American Academy of Orthopaedic Surgeons.
The researchers agreed training programs that teach proper landing methods or basic injury prevention techniques should be adopted to help female athletes. "Adopting preventative training programs that focus on building hamstring strength is crucial," Dr. Wojtys said. "We need to implement these programs right now."
According to 1998 injury statistics from the U.S. Consumer Product Safety Commission, more than 81,600 people injured their knee playing soccer, and 225,800 sustained knee injuries in basketball--considered two high risk sports for ACL injury in females.
An estimated 660,000 Americans injure their ACL each year. Nearly 70 percent of these injuries are sports-related.
Co-authors, all from the University of Michigan, Ann Arbor, Mich., are Laura J. Huston, MS, senior research associate with the section of orthopaedic surgery; Brady Vibert, medical student; and James A. Ashton-Miller, PhD, senior research scientist with the department of mechanical engineering and applied mechanics, and department of biomedical engineering, and the Institute of Gerontology.
In the first year of the United Nations-declared Bone and Joint Decade (2000-2010) (http://www.boneandjointdecade.org), the Academy is holding its annual meeting at the Orange County Convention Center, Orlando, March 15-19, 2000.
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