Atlantoaxial asymmetry is commonly known as atlantoaxial subluxation and atlantoaxial instability. 1. Atlantoaxial subluxation refers to the atlantoaxial vertebrae dislocated forward and backward, or the gap on both sides of the atlantoaxial teeth is asymmetrical, which leads to neck, shoulder and upper limb pain, or even quadriplegia, respiratory anesthesia, and in serious cases, it can also be life-threatening. It is mainly caused by atlantoaxial periarthritis, trauma, occupational habits, congenital variants of atlantoaxial vertebrae and/or defects of transverse and pterygoid ligaments. 2. Radiographs show asymmetry of the gap between the atlas and the atlantoaxial blocks on both sides or loss of joint space on one side, with the atlas favoring one side. If atlantoaxial joint asymmetry is found in the examination, it is recommended to consult the doctor in time and take standardized treatment under the doctor’s guidance.