Varus/valgus and internal/external rotational knee joint stiffness in males and females

"The purpose of this investigation was to establish day to day reliability of varus/valgus and internal/external rotational stiffness measures and then compare stiffnesses between males and females. Twenty healthy college students underwent varus/valgus (non-weightbearing) and internal/external (non-weight and weightbearing) applied torques to 10, and 5 Nm, respectively. Ten subjects returned a second day to establish reliability measures. Stiffness constants were calculated for each displacement created by a .5 Nm incrementally applied torque. Results revealed mean female stiffness was significantly less than males for valgus, varus, and weightbearing external rotational stiffness. Interactions demonstrated that female knees were less stiff during initial loading. Female knee joint stiffness increased to equal male stiffness during internal rotation, external rotation, and weightbearing internal rotation. These results suggest that with respect to males, females are in different joint positions as loads are applied, potentially causing a need for alternate strategies to control joint orientation. "--Abstract from author supplied metadata