Necrosis of the femoral head 4-word self-test refers to the 4-word test, which is a common orthopedic examination maneuver. Positive results are not only seen in patients with necrosis of the femoral head, but also in sacroiliac joint lesions, ankylosing spondylitis, knee diseases, etc. The 4-word test is performed in the same position as the 4-word test. The 4-word test is to keep the examinee lying down, one leg straight, the other leg knee and hip flexion, the heel is placed in the knee of the straightened leg, constituting a 4-word, the examiner then fixes the hip and presses down the flexed knee, if the patient’s flexed knee can not contact with the bed surface or there is pain in the hip during the process of downward compression, then it will be a positive manifestation. Patients suspected of femoral head necrosis should go to the hospital in time to improve the CT, MRI and other tests in a timely manner, after a clear diagnosis and timely treatment.