By Tom Keppeler, Knee1 Staff
For many years, orthopedic surgeons have suspected that a link exists between a woman's chemical make-up and her risk of ankle and knee injuries. Now, a University of Vermont professor seeks to prove it.
The rate of leg injuries among female players in the National Collegiate Athletic Association (NCAA) in sports such as lacrosse, soccer, field hockey, and basketball is drastically higher than that of males playing similar sports. Dr. Frank Noyes of Cincinnati Sportsmedicine and Orthopaedic Center, has suggested that the female anatomy puts the lower part of the leg at an angle that increases the risk of injury. Others have suggested the higher knee-injury rates of female athletes may be due to differences in their muscular structure. Many have suggested that estrogen causes ligaments to become lax when the hormone is at its peak (just before ovulation), but no definitive study has proven this hunch.
Dr. Bruce Beynnon, Ph.D., a professor at the University of Vermont, is investigating whether it is true that estrogen plays a factor in female leg injuries. "Women are more estrogen dependent than men," Beynnon told Knee1. "It obviously affects bone health; the real question is whether it affects joint health." In the study, Beynnon and his staff will draw blood from the female participants at five points during their menstrual cycle. The blood will be analyzed for the presence of estradiol, a type of estrogen responsible for collagen production. The participants will then perform a number of exercises so that the researchers can determine their strength, neuromuscular function, and joint laxity.
What athletes and trainers may do with this research, however, remains to be determined. Should estrogen level be determined to be a risk factor for injury, management of the hormone to prevent such ailments—a highly controversial topic—often becomes the next issue. "There is a camp of individuals that agree it is a risk factor, and believe we should therefore put female athletes on birth control," Beynnon says. "It quickly becomes a very controversial, hot topic." Others have suggested less drastic methods, such as strengthening the muscles around the knee to tighten it, as well as abstaining from competition on high-risk days. Beynnon, however, says he tries to ignore the possible outcomes from the research; he instead focuses on getting the raw data necessary to come to a conclusion on the topic. "I just want to know the answer with respect to the question," he says. "Then, we'll try to figure out what to do. [Jumping to conclusions] only biases you."
Beynnon has also begun a study into which of the suspected pre-disposing conditions (estrogen level, lower leg alignment, joint laxity, muscular development) plays the largest part in female knee and ankle injuries. To do this, he hopes to measure each of the factors in 1,000 female athletes and track them for injuries sustained over a number of years. Beynnon has already registered 300 female athletes—from both high-school and collegiate levels—in the study. "There may be no one thing that you can point to," says Beynnon. "The injury may also be sport-specific, and the prevention may involve both sport-specific training and other things. This is yet to be determined."