Cervical Flexion Osteotomy through One-Stage Posterior-Anterior-Posterior Approach for Cervical Extension Deformity in Ankylosing Spondylitis: A Novel Surgical Technique.

The present study was to introduce a new surgical technique of cervical flexionosteotomy, with an emphasis on the clinical and radiographic outcomes. Two male patients aged 45 and 21 years presented with cervical extension deformity in ankylosing spondylitis (AS). Both patients exhibited upward deviation of the forward gaze. The chin brow vertical angle (CBVA) were 15° upward and 5° downward, respectively; and the sagittal vertical axis (SVA) were-13.2mm and 195.7mm, respectively. Aposterior transverse release was performed at C7 -T1 , exposing the theca and C8 nerve roots to facilitate closure of theosteotomy site. Then, an anterior closing-wedgeosteotomy of C7 -T1 was performed followed with anterior internal fixation with a locking plate to prevent any translation. After closure and anterior fixation, patients were returned to the proneposition, and posterior screw-rod instrumentation was used for further stabilization. The follow-up periods were 20 and 10 months, respectively. At the last follow-up, CBVA and SVA of Patient 1 were 14° downwardand -12.6mm; and CBVA and SVA of Patient 2 were 1° downward and 75.6mm respectively, indicating the visual angle and sagittal balance were significantly improved. No intraoperative or postoperative complications were encountered. Full-spine radiographs of each patient at the last visit confirmed successfulbony union. The present study was the first report introducing a novel flexion osteotomy for cervical extension deformity in AS through a posterior-anterior-posterior approach inone-stage. The improved forward gaze and no complications demonstrated the effectiveness and safety of the novel technique, suggesting that it might provide a more feasible method for the correction of cervical extension deformity.