Relationship Between Sagittal Balance and Axial Symptoms in Patients with Cervical Spondylotic Myelopathy Treated with Anterior Cervical Discectomy and Fusion.

Purpose: The purpose of this study was to investigate the sagittal balance of the cervical spine and the clinical outcomes of anterior cervical discectomy and fusion (ACDF) for the treatment of cervical spondylotic myelopathy and to explore whether sagittal balance is related to the incidence of postoperative axial symptoms. Methods: Sixty-seven consecutive patients who underwent ACDF for the treatment of cervical spondylotic myelopathy from January 2014 to December 2016 were enrolled in our study. Sagittal balance parameters (global lordotic angle, segmented lordotic angle, T1 slope, and C2-7 sagittal vertical axis [C2-7 SVA] were recorded in the preoperative period and at 1 month, 3 months, and 1 year postoperatively. Clinical outcomes (JOA and NDI scores) and incidence of axial symptoms were also evaluated before and after surgery. Subgroup analysis included 20 patients with preoperative abnormal sagittal balance group (C2-7 SVA larger than 20 mm), and these patients were divided into two groups, namely axial symptom group and nonaxial symptom group. Result : The sagittal balance parameters (global lordotic angle, segmented lordotic angle, and TI slope) and the clinical outcomes after surgery significantly improved. The subgroup analysis within the preoperative abnormal sagittal balance group showed significant differences in postoperative and change in C2-7 SVA between patients with and without postoperative axial symptoms. Conclusion: ACDF can be applied to restore the sagittal alignment of the cervical spine and effectively improve clinical outcomes for the treatment of cervical spondylotic myelopathy. Sagittal balance improvement may be associated with the low incidence of postoperative axial symptoms for patients with abnormal cervical sagittal balance before surgery.