Clinical atlantoaxial subluxation is more common, the main reasons are as follows: 1, trauma, such as excessive cervical rotation, resulting in dislocation of the ligaments and joint capsule on both sides, the appearance of the dentate process and the two lateral blocks are not equal to each other is known as the atlantoaxial subluxation; 2, we must exclude atlantoaxial subluxation leading to the dentate process and the two lateral blocks are not equal to each other, is it due to congenital factors. If the imaging performance for the atlanto-dentate gap is not equal, but the patient does not have any clinical symptoms, such as neck discomfort, most of the consideration may be congenital factors, such patients can continue to observe; 3, there is a history of trauma and imaging performance for the dentate process on both sides of the block is not equal, and the patient has symptoms of neck pain, will be considered to traumatic atlantoaxial joints caused by half dislocation; 4, infectious factors, such as the child due to the ligamentous structure of poor development, upper respiratory tract infections resulting in localized atlantoaxial joints. Infection factors such as children due to ligamentous structure development is not good, upper respiratory tract infection leads to local synovial inflammation, edema; 5, local septic infection, imaging manifestation of the dentate process and the two lateral blocks are not equal, this case is relatively more common in children, the patient will have upper respiratory tract infection symptoms, as well as the symptoms of neck pain; the specific which factors need to be based on different cases to the spine surgery clinic, to determine what kind of factors lead to atlantoaxial joint subluxation.