Lying down and lifting the leg bone ringing, is a normal physiological phenomenon. Because when a person stands, the pelvis and hip muscles and tendons are relatively tense. Upper limb trunk, head weight is relatively large, the human body to maintain standing when the hip joint depression and femoral head combined very closely to meet the human body’s stable lower limb movement. But once lying down, the pelvis and ligaments around the hip joint will become relatively relaxed, and when doing lying leg lifting action, the leg is equivalent to a lever, the fulcrum of the lever is the hip joint. This will cause the hip joint to shift back and forth, and the surrounding soft tissues do not have enough tension to bind the femoral head, which will cause the femoral head to produce sudden sliding in the hip joint, causing the leg to have a ringing sound.