The lateral atlantoaxial joint surface is tilted in the sagittal plane or occipito-atlanto-axial joints are asymmetric. Each of the case may result in atlantoaxial dislocation.

寰枢外侧关节面在矢状面上倾斜，枕骨髁、寰椎、枢椎关节发育不对称，可能是导致寰枢椎脱位的另外原因。