Introduction: Patients with atlantoaxial dislocation (atlantodens interval >5mm) first undergo trial of reduction with cervical traction intraoperatively. If reduction fails, transoral anterior atlantoaxial dislocation can be performed prior to posterior fixation (fixed AAD patients). The effects of this management on cervical sagittal alignment has not been well characterized and compared with patients who have flexible AAD who only require posterior fixation (flexible AAD patients)
Methods: Retrospective review of preoperative and 6 month postoperative sagittal cervical spine radiographs from a single institution. Patients were categorized by whether they had fixed vs. flexible AAD. Baseline and postoperative cervical radiographic measurements were compared using t-tests (McGregor’s slope, C2-C7, T1 Slope, T1 CL. cSVA, and C1-C2).
Results: 25 patients were included (17 fixed, mean age 52.1, 53% F; 9 flexible, mean age 47.1, 13% F). Flexible patients had higher baseline T1slope – cervical lordosis mismatch (7.06 vs. -2.63). Fixed AAD patients were surgically realigned with respect to C1-C2 (-25.4 vs -15.0). This resulted in higher postoperative C2-C7 lordosis (-28.38 vs. -14.53) with significant decrease in T1 slope compared to AAI patients (5.5 vs. 0.52). Flexible AAD patients had no change in sagittal profile with surgery. all p<0.05.
Conclusions: Transoral anterior release prior to posterior fixation results in focal sagittal realignment of upper cervical spine. Furthermore, these patients undergo reciprocal compensatory changes in the subaxial spine and cerviocothoracic junction compared with flexible AAD patients. This transoral release plays a role in restoring the overall sagittal cervical alignment in otherwise irreducible fixed AAD patients.
Patient Care: This data gives surgeons treating AAD information concerning the repercussions on sagittal alignment after certain procedures.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of transoral anterior release, 2) Discuss, in small groups, differences in treatment of fixed irreducible vs reducible atlantoaxial dislocations., 3) Identify an effective treatment AAD.