The purpose of functional exercise for patients with femoral head necrosis is to prevent tissue adhesion, muscle atrophy, joint stiffness, improve the nutritional blood supply and functional status of the joint, and remodel the necrotic femoral head. The common pain of femoral head necrosis is pain in the hip during weight bearing or activity, and sometimes the pain can radiate to the knee and inner thigh. Pain in the groin area is the most common symptom of hip joint involvement, often accompanied by difficulty in walking and standing up. The hip joint is limited in internal rotation and often remains in a mildly flexed and externally rotated position due to the relaxation of the joint capsule in this position, which reduces intra-articular pressure and makes the patient feel comfortable. However, maintaining this position for a long time may lead to contracture and stiffness of the soft tissues around the joint, decreased mobility of the hip joint and atrophy of the muscles around the joint. Therefore, patients with R osteonecrosis should pay special attention to the exercise of the hip joint to prevent joint ankylosis caused by being in a relatively comfortable flexion and external rotation position for a long time. The hip joint has six degrees of freedom of movement, namely flexion and extension, internal and abduction, internal rotation and external rotation. The most important of these functions are flexion and extension and abduction. Rehabilitation exercises should focus on flexion and extension, abduction and internal rotation. (1) hip flexion and extension exercises, 10-15 each time, 3-5 groups per day, hip flexion should exceed 90° to maintain function; (2) hip abduction training, lying or standing outward leg swing, 10-15 each time, 3-5 groups per day, to prevent contracture of the iliopsoas muscle; (3) the physiological function of internal rotation is not as important as the first two, after the flexion and extension and abduction training in place, internal rotation function can often be maintained to some extent. By following the above methods, the progression of femoral head necrosis can be delayed and the occurrence of deformity and femoral head collapse can be reduced. Long-term exercise can also reduce pain, delay the age of hip replacement, and improve the success rate of surgery and surgical results once joint replacement is needed. Functional exercise should follow the following methods and principles: (1) Functional exercise should be carried out under the guidance of professionals after the pain is relieved and the condition is stable after treatment; (2) Gradual and consistent; (3) When the pain is aggravated during functional exercise, the amount of exercise can be reduced or analgesic drugs can be taken, and the amount of exercise can be increased gradually after the pain is relieved or reduced; (4) Active exercise is the main method; (5) Commonly used (5) The common exercise methods are non-weight-bearing activities, such as cycling, swimming, etc. (5) Commonly used exercise methods are non-weight-bearing activities, such as cycling, swimming, etc. Those who are not allowed to do so can exercise in bed.