The management of irreducible atlantoaxial dislocation associated is challenging. Direct posterior distraction technique we proposed in 2010 could achieve satisfactory reduction. In 2020, we modified this technique and proposed a posterior intra-articular distraction technique. The intra-articular distraction technique could theoretically achieve satisfactory reduction and fusion. However, its superiority has not been proven. Therefore, we design a prospective study to compare the reduction rate and fusion rate of different strategies.

Inclusion Criteria:

CT indicated atlantoaxial dislocation Agree with the operation plan Agree to be followed up

Exclusion Criteria:

The pathology is traumatic or RA Underwent operations in occipital-cervical region before With mortal diseases Without ability to sign papers

18-70, exclude traumatic, RA and previous surgery.