If a patient has pelvic malalignment, it is often caused by the following reasons: 1. It may be caused by congenital malformation of the lower limbs. If the patient has congenital hip dislocation, it often causes excessive anterior tilting of the pelvis, and sometimes the presence of congenital hip dislocation on one side may cause one side of the pelvis to drop, that is, high and low. 2. It may be caused by severe lower limb deformity acquired later in life. The pelvic malalignment caused by severe osteoarthritis acquired later in life, resulting in shortening or deformity of one lower limb, may also cause pelvic malalignment, which can cause both anterior pelvic tilt and pelvic collapse on one side. 3, may be caused by spine related diseases. If the patient has scoliosis, or special lesions of the lumbosacral region, such as excessive forward protrusion of the lumbar protrusion and excessive backward protrusion of the sacral protrusion, it may cause a series of pelvic malformations.