UF Study: Female Knee Injuries More Likely Because Of Bone Structure

December 7, 1999

GAINESVILLE — Men and women have significantly different skeletal structures in their legs, making women much more likely than men to experience sports-related knee injuries, according to a new University of Florida study.

The study looked specifically at injuries to the anterior cruciate ligament, better known as the ACL. That type of injury is three to four times more common in female athletes than in male athletes, according to Randy Dick, the senior assistant director of health and safety for the National Collegiate Athletic Association.

“This means we have to start looking at female athletes specifically to decrease their incidence of injuries rather than making comparisons to male injuries,” said Jeff Bauer, an assistant professor in UF’s department of exercise and sport sciences. “This probably has ramifications on other types of injuries as well.”

ACL injuries affect about 100,000 people each year in the United States, and about half of them undergo reconstructive surgery at a total cost of nearly $1 billion, Bauer said.

Bauer, along with Tony Falsetti, an associate professor in UF’s department of anthropology, and graduate students Mark Tillman and Kendra Smith, studied 200 human skeletons in the Smithsonian Museum of Natural History, taking 28 measurements of the pelvis, femur (upper leg), patella (kneecap) and tibia (lower leg). Fifty of the skeletons were black males, 50 were white males, 50 were black females and 50 were white females. There were significant differences between all four groups in all of the measurements except those of the patella, the size of which has not been linked to ACL injuries.

In general, though, women had a much smaller knee joint surface than men, which may make them more susceptible to knee injury, Bauer said. It is difficult to speculate on the likelihood of ACL injuries to black athletes vs. white athletes, because no prior studies had addressed that question, Bauer said.

The study was presented at this year’s meeting of the American College of Sports Medicine.

The finding that race and gender affect how people sustain injuries could lead to important changes in training techniques for women and minorities, Bauer said. Muscle strength and activation patterns differ between genders, and different skeletal shapes and sizes contribute to slight differences in movements, Bauer said. The incidence of injury might be reduced if training took those factors into account, he said.

“We need to look at male and female athletes as different groups and not get so hung up on the comparisons,” Bauer said. “Nobody is going to compare the way I play basketball with the way Shaquille O’Neal plays basketball, but that’s basically what you’re doing when you compare male and female ACL injury rates.”

Bauer and Falsetti plan on trying to get the prosthetic industry to take into account the differences in skeletal measurements between genders and races, Bauer said. Currently, knee joint replacements come in three sizes — small, medium and large — and are designed to mimic the knee joint of a white male. That means females and minorities who need knee joint replacements aren’t getting a new knee that meets their specific skeletal requirements, Bauer said.

“Knee joint replacements aren’t optimized for ethnicity or gender,” Bauer said. “The requirements might be very different for a black female or a black male, but most of it is sized and designed around the knee of a white male.”

Despite the study’s findings, Dick, who tracks injuries for the NCAA, says that women shouldn’t shy away from exercise. “There are a lot of positive benefits to exercise,” he said. “This doesn’t mean that women shouldn’t be exercising, just because they may be more likely than men to be injured.”

Bauer agreed.

“It’s wonderful that women are getting more involved in sports,” he said. “We don’t want them to get hurt, so we’re trying to develop better ways to prevent injuries.”