Influence of Q-angle on lower-extremity running kinematics

Study Design: Two-group posttest-only comparison. Objective: To assess the influence of the Q-angle on the 3-dimensional lowe r-extremity kinematics during running. Background: An excessive Q-angle has been implicated in the development of knee injuries by altering the lower-extremity locomotion kinematics. Previo us investigations using 2-dimensional analyses during walking did not suppo rt this hypothesis. Methods and Measures: We hypothesized that individuals with Q-angles more t han 15 degrees would display an increase in rearfoot eversion and tibial in ternal rotation during running. Thirty-two nonimpaired subjects (men: n = 1 6, mean age = 22 +/- 3 years; women: n = 16, mean age = 23 +/- 3 years) ran over ground, and 3-dimensional kinematic data were collected from the righ t lower extremity. Subjects with a Q-angle of 15 degrees or less comprised the low-Q-angle group, whereas those with Q-angles of more than 15 degrees comprised the highQ-angle group. Segment and joint maximum angles and the t imes when the maxima occurred during stance were measured. Results: The Q-angle magnitude did not increase the maximum segment or join t angles during running. The groups displayed similar maximum angles for re arfoot eversion (low Q-angle, -15.5 +/- 5.0 degrees; high Q-angle, -15.6 +/ - 6.6 degrees) and tibial internal rotation (low Q-angle, -8.8 +/- 4.8 degr ees; high Q-angle, -6.8 +/- 5.1 degrees). The high-Q-angle group (39.5 +/- 16.3%) achieved maximum tibial internal rotation later in the stance phase than the low-Q-angle group (28.8 +/- 10.7%). Conclusions: In support of the previous investigations involving Q-angle in fluences on kinematics, our study did not reveal any differences between gr oups in maximum joint or segment angles. The kinematic information did reve al that the high-Q-angle group displayed an increase in time to maximum tib ial internal rotation. The impact of this single factor on producing knee i njury is unknown.