The quadriceps angle: a review of the literature.

Previous investigations of the quadriceps (Q) angle and its relationship to knee disorders have yielded equivocal results. The purpose of this paper is to present a review of the current literature on the Q angle and to examine the differences in Q angles when measured: 1) under differing measurement protocols; 2) between asymptomatic and symptomatic populations; 3) between male and female samples; and 4) from side to side within subjects. Little scientific evidence exists to support the commonly held assumptions that Q angles are larger in symptomatic vs. asymptomatic or that they are equal in the right vs. left lower limb. However, larger mean values are consistently observed in groups of young adult females vs. young adult males.