The reason for MRI normal knee discomfort for two years may be a smaller lesion. MRI is an imaging test that has a higher probability of detecting soft tissue injuries or lesions only, especially for head, abdominal and spinal cord lesions than CT. However, the examination of smaller lesions, bone or bone cortex is sometimes not clear. Knee discomfort for two years, but the MRI did not see obvious lesions, may be due to the knee joint at the bone cortex has a slight lesion, the MRI examination due to the lesion is small from the image can not see clearly. MRI normal knee discomfort for two years should go to a regular hospital, by the doctor according to the symptoms, signs and auxiliary examination to determine the specific cause of the disease, according to the cause of the disease to give the correct treatment.