Four months after hip replacement surgery, leg lifting may be related to surgical damage to peripheral nerves and postoperative disuse atrophy, etc. Generally, medication and physical therapy can be given. 1. Surgical damage to peripheral nerves: nerve damage may be caused during surgery, resulting in the body’s innervation of the muscles and joints of the lower limbs being affected, which is often manifested as difficulty in lifting the leg or weakness. Nerve damage mostly occurs in hip arthroplasty where the surgical approach is posterior lateral approach, and the sciatic nerve is the most likely to be damaged. Nutritional nerve drugs such as methylcobalamin and vitamin B1 should be used under doctor’s guidance to minimize the damage and improve the prognosis. 2. Postoperative wasting atrophy: If the patients can not carry out muscle strength training, joint activities, weight bearing exercises and other rehabilitation training in a timely manner after the operation, the lower limb muscle strength can be insufficient, resulting in wasting atrophy, which can lead to the inability to lift the leg. It is recommended that patients actively carry out rehabilitation training for lower limbs under the guidance of doctors, and gradually increase the amount of training to restore muscle strength and lower limb mobility as soon as possible. If you can’t lift your leg after hip replacement surgery, we suggest you go to the hospital in time, describe your condition to the doctor in detail, improve the X-ray, electromyography and other tests, and then standardize the treatment under the doctor’s guidance after the diagnosis is clear.