Table 2. Wang classification system of atlantoaxial dislocations.

Type	Description	Diagnosis	Incidence (%)	Treatment
I	Instability	Reducible in dynamic X-rays	52.2	Posterior fusion procedure
II	Reducible	Reducible with skeletal traction under general anesthesia	17.7	Posterior fusion procedure
III	Irreducible	Irreducible with skeletal traction under general anesthesia	29.6	Transorally released anteriorly before posterior fusion
IV	Bony dislocations	Dislocations with bony anomalies that are visualized by reconstructive computed tomography scan	0.4	Transoral odontoidectomy