Seeking the sex factor in knee pain

New research into the cause of joint injuries hopes to uncover the underlying difference in injury rates between men and women and may even break down some of the gender barriers in sport science along the way.

Part of a larger study funded by the Canadian Institutes for Health Research to examine sex influences on musculoskeletal health across the lifespan, an interdisciplinary team of U of C researchers is examining differences between the sexes when it comes to sports injuries and aims to find out why females have five to 15 times the number of knee injuries as males and tend to develop osteoarthritis more frequently. “When we announced this study there was considerable resistance from some people who thought that by examining the differences between men and women and their risk for joint injuries, we would somehow be undermining the perception of women as elite athletes,” said Dr. David Hart, the principal researcher from the Alberta Bone and Joint Health Institute. “Nothing could be farther from the truth.”Dr. Barbara Loitz-Ramage from the U of C Faculty of Medicine’s McCaig Centre for Joint Injury and Arthritis Research said their goal is to identify root causes of joint injuries to help decrease the higher injury rates among females.”Knee injuries can be devastating to young athletes. A torn ACL [anterior cruciate ligament] can side-line a young woman for months and take her from being extremely active, to being much more sedentary. It also likely predisposes her to early joint degeneration,” Loitz-Ramage said. “We hope that through this research we can understand the issues, provide some answers and develop interventions to lower or eliminate the risk in females.”Hart, Loitz-Ramage and Dr. Darren Stefanyshyn and Sang Kyoong Park from the Faculty of Kinesiology will conduct several studies on women between the ages of 18 and 40 to test various theories about why such a dramatic difference in injury rates exists.Similar to how joints become looser during pregnancy, the researchers want to determine if joint laxity in women who aren’t pregnant also varies during the menstrual cycle. “One of the things we are trying to discover is whether or not the changes in hormone levels during a woman’s menstrual cycle affect the laxity of the joints, thereby increasing the injury risk in some way,” Loitz-Ramage said. “There seems to be some anecdotal information connecting the two but we won’t know for sure until we do this research,” she said.The research is part of a growing movement to understand the physiological differences that may increase the incidence of injury among female athletes, looking at many issues including why there is a spike in the number of knee injuries suffered by adolescent girls.”There is an epidemiological spike around the age of 16 that you don’t see in the male population and we’d like to know why,” Hart said.In addition, the team is hoping to figure out whether joint hypermobility syndrome-double jointedness-is a possible culprit when it comes to sport injury or early onset osteoarthritis.”Double jointedness, or joint hypermobility syndrome, used to be called benign joint hypermobility syndrome,” Loitz-Ramage said. “Clinicians now believe that the condition may not be as benign as we thought. We’d like to see if it’s a genetic trait and what relationship this has to the whole joint health puzzle.”The team is hoping to recruit more than 100 women to take part in various studies over the next two years.(Source: University of Calgary: August 2006).