Dynamic Varus and the Development of Iliotibial Band Syndrome.

CONTEXT:   Although the risk of osteoarthritis development after acute knee injury has been widely studied, the long-term consequences of knee overuse injury are not well understood.

OBJECTIVE:   To identify the relationship between gait-related risk factors associated with osteoarthritis and the development of iliotibial band syndrome (ITBS) in members of a single University Army Reserve Officers' Training Corps unit.

DESIGN:   Prospective cohort study.

SETTING:   Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS:   Sixty-eight cadets undergoing standardized physical fitness training.

INTERVENTION(S):   Three-dimensional lower extremity kinematics (240 Hz) and kinetics (960 Hz) were collected for 3 bilateral trials during shod running at 4.0 m/s ± 10%. Injury tracking was conducted for 7 months of training.

MAIN OUTCOME MEASURE(S):   Biomechanical variables, including varus thrust and knee-adduction moment, were compared between the injured and control groups.

RESULTS:   Twenty-six cadets with no history of overuse injury served as the control group, whereas 6 cadets (7 limbs) who developed ITBS that required them to modify their training program or seek medical care (or both) served as the injured group. Maximum varus velocity was higher ( P = .006) and occurred sooner during stance ( P = .04) in the injured group than in the control group, indicating greater varus thrust. Maximum knee-varus angle and maximum knee-adduction moment were higher ( P = .02 and P = .002, respectively) and vertical stiffness was lower ( P = .03) in the injured group.

CONCLUSIONS:   Measures of dynamic varus stability appeared to be altered in individuals who developed ITBS. Biomechanical knee variables previously identified as increasing the risk for knee osteoarthritis were also associated with the development of ITBS in healthy adults.