Revisiting the Treatment Algorithm for Atlantoaxial Dislocation After 10 Years: A Multicenter Study With Mid-to-long-term Follow-up.

STUDY DESIGN

A multicenter retrospective cohort study.

OBJECTIVE

To overcome the limitations of former single-center strategy studies, an updated classification guiding surgical management of Atlantoaxial dislocation (AAD) is proposed in this study based on a large multicenter retrospective cohort study with mid-to-long-term follow-up.

SUMMARY OF BACKGROUND DATA

AAD is the most prevalent disorder affecting the craniovertebral junction, often leading to myelopathy and impairment of cranial nerve function, which can result in significant morbidity or even mortality. Although the treatment algorithm we previously proposed for these diseases in 2013 has been widely adopted, its effectiveness and safety in multicenter settings have yet to be thoroughly evaluated.

METHODS

Patients with AAD who underwent surgical treatment were recruited from eight tertiary spine centers in eight provinces (two northeastern, two southwestern, one northwestern, one southeastern, and two central) across China between January 2011 and December 2021. Patient classification, surgical procedure, postoperative recovery progress, and occurrence of complications of the patients were collected and analyzed.

RESULTS

In total, 2354 patients were included. Type I and type II constituted most patients (76.0%). For type III AAD, our goal was conversion to type II, first using posterior intra-articular release (212/523 patients, 40.5%), and if failed, transoral release (311/523 patients, 59.5%). For type IV, we also attempted conversion to type II, using posterior or transoral osteotomy (37/42 patients, 88.1%). Transoral and transnasal odontoidectomy was the last resort for decompression for patients whose AAD could not be reduced despite all efforts (5/42 patients, 11.9%). At an average follow-up of 5.3 years, 85.9% of patients achieved complete anatomical AAD reduction, and 98.8% demonstrated clinical or radiological signs of solid fusion.

CONCLUSIONS

The classification system of AAD was updated. Advancements have been made in the management of irreducible and bony AAD, and the transoral release and odontoidectomy procedures were required by less AAD patients.