General Session: Innovative Technologies II - Hall F

Presented by: P. Passias

Author(s):

P. Passias(1), C. Wang(1), G. Poorman(1), S. Horn(1), F. Segreto(1), C. Bortz(1), C. Varlotta(1), D. Ge(1), B. Diebo(2), S. Wang(3)

(1) New York University Langone Orthopedic Hospital, Division of Spinal Surgery, New York, NY, United States
(2) SUNY Downstate Medical Center, Department of Orthopaedic Surgery, Brooklyn, NY, United States
(3) Peking University Third Hospital, Beijing, China

Abstract

Introduction: Patients with atlantoaxial dislocation (atlantodens interval >5mm; AAD) first undergo a trial of reduction with cervical traction intraoperatively. If reduction fails, transoral anterior atlantoaxial dislocation can be performed prior to posterior fixation (fixed irreducible AAD patients). The effect of this management on cervical sagittal alignment has not been well characterized and compared with patients who have reducible AAD who only require posterior fixation (fixed reducible AAD patients). The aim of this study was to compare cervical alignment changes in patients with fixed irreducible and fixed reducible AAD after surgical treatment.

Methods: Retrospective review of prospectively-collected preoperative and 6-month postoperative sagittal cervical spine radiograph alignment parameters from a single institution. Patients were categorized by whether they had fixed irreducible vs fixed reducible AAD. Fixed irreducible patients differed from fixed reducible patients in that they received transoral anterior releases prior to posterior fixation. Baseline and postoperative cervical radiographic measurements were compared using Student's t-tests (McGregor's slope, C2-C7, T1 Slope, T1 CL. cSVA, and C1-C2).

Results: 25 patients were included (17 fixed irreducible, mean age 52.1, 53% female; 9 fixed reducible, mean age 47.1, 13% female). Fixed irreducible patients had higher baseline T1slope - cervical lordosis mismatch (7.06° vs. -2.63°) and 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°, p=0.020) with relatively decrease in T1 slope compared to fixed reducible AAD patients, although this value didn't meet statistical significance (5.5° vs. 0.52°, p=0.177). Fixed reducible AAD patients had no statistically significant changes in sagittal profile after surgery.

Conclusions: Transoral anterior release prior to posterior fixation results in focal sagittal realignment of the upper cervical spine. Furthermore, these patients undergo reciprocal compensatory changes in the subaxial spine and cerviocothoracic junction compared with fixed reducible AAD patients. Thus transoral release plays a role in restoring the overall sagittal cervical alignment in otherwise fixed irreducible AAD patients.