A Leg Up

$1 Million NIH Grant Fuels Knee Research

A $1 million grant from the National Institutes of Health will help a team of researchers at The University of North Carolina at Greensboro investigate the role of hormones in females' knee injuries.

Young, physically active females have a far greater risk – two to nine times greater, according to studies – of suffering a torn anterior cruciate ligament (ACL) than males with a similar activity level. Hormones are one of the factors thought to contribute to that disparity.

Dr. Sandra Shultz, an associate professor in the Department of Exercise and Sport Science, will lead the three-year study. In research conducted with an earlier NIH grant with Dr. David Perrin, they found that knee laxity, the looseness of the joint, changes for some females as sex hormones fluctuate across the menstrual cycle.

"Having observed these changes, we want to know how they affect the knee during sports," Shultz said. "Do we see greater displacement in the joint? Do we see muscles working harder to stabilize the joint? An increase in laxity could be something the body can compensate for very well, or it could increase the risk of an injury."

Researchers will collect data in the Applied Neuromechanics Research Laboratory in the university's School of Health and Human Performance, of which Perrin is the dean.

The project will explore how laxity, both in females compared to males and among females across the menstrual cycle, affects the knee during the weight-bearing activities common in sports. Not all females experience substantial changes in knee laxity, so a secondary goal is to determine whether key hormone tests can predict those changes.

Along with Perrin, three other UNCG faculty members – Dr. Randy Schmitz and Dr. Laurie Wideman in the Department of Kinesiology (formerly Exercise and Sport Science), and Dr. Beverly Levine in the Department of Public Health Education – also are study investigators. The team includes research assistant Dr. Yohei Shimokochi, and doctoral students Yum Nguyen and Jennifer Merkle.

An athlete with a torn ACL faces a lengthy and grueling rehabilitation, and may never regain her previous level of performance. Later in life, she becomes more likely to suffer early onset osteoarthritis. Shultz hopes her research leads to more effective strategies to prevent these injuries.

"We know that preventative training programs work," Shultz said. "We just don't know what exactly we're targeting at this point. If we can identify risk factors for ACL injury, then we can be more effective in our training programs."

They plan to enroll 100 physically active subjects – 75 normally menstruating females (i.e. not taking birth control hormones) and 25 males – between the ages of 18 and 30. The males will serve as a control group, because they do not experience substantial variations in hormones and knee laxity from one day to the next.

During the first two months of the study, each female will undergo daily blood and knee laxity tests for six days following menses, and eight - ten days following ovulation to determine the days of her menstrual cycle when knee laxity is at its minimum and maximum.

Participants will undergo neuromuscular and biomechanical tests twice during the third month. The females will be tested on the days of least and greatest knee laxity. These tests will shed light on whether greater laxity results in greater instability and, therefore, greater risk of injury.

For more information about the study or to volunteer, please contact Dr. Sandra Shultz at (336) 334-3027 or sjshultz@uncg.edu.