There are many causes of knee pain, in addition to the knee itself, you should also pay attention to your hip and lumbar spine problems. This is because there is a nerve in the hip called the obturator nerve in the innervation of the hip joint at the same time there are branches of the innervation of the same side of the knee joint, so hip joint lesions (such as necrosis of the femoral head, etc.) can produce the same side of the knee joint region of the pain or discomfort, and even to the knee symptoms as the main complaint. Clinically, we also often encounter such a situation, in the treatment of patients with lumbar spinal stenosis found that the pain is mainly from the hip or knee joint, while the treatment of hip or knee joint lesions found that the pain is mainly from the lumbar spinal stenosis. Therefore, knee pain should not be ignored in the examination of the hip and lumbar spine.