Long and short legs are generally due to the following reasons: 1) Hip pain caused by localized necrosis of the femoral head, after severe pain, the affected side will be affected by weight-bearing and activities, tilted to the non-painful side, and long and short legs will appear. 2) Severe femoral head collapse or changes in the hip joint gap, then there can be obvious changes in the gap, and the limbs are not equal in length. 3) The pain is caused by the pain in the hip joint, and the limbs are not equal in length. 4) The pain in the hip joint is caused by the pain in the hip joint. After checking clearly, the treatment of long and short legs needs to be chosen according to different reasons. If the poor posture is caused by simple pain or soft tissue condition, it can be avoided by analgesia, activating blood circulation and improving posture after relieving the pain, thus avoiding the situation of long and short legs. If there has been collapse of the femoral head necrosis or changes in the joint space, replacement surgery is needed for treatment.