Walking with splayed legs, standing in a resting position, wearing high heels for a long time, sitting cross-legged, kneeling, squatting, etc., will exert outward force on the knee joint, and this force will pull the knee The lateral collateral ligament of the joint, if this happens for a long time, will lead to the laxity of the lateral collateral ligament of the knee joint.
The medial and lateral collateral ligaments of the knee joint are structures that stabilize the medial and lateral angles of the knee joint. When the lateral collateral ligament is loose, the greater force of the medial collateral ligament will pull the tibia of the calf to rotate inward, forming knee varum, or O-leg.