Relationship between alterations of cervical sagittal parameters and clinical outcomes after cervical anterior discectomy and fusion

Abstract

Objective To explore the relationships between the alterations of cervical sagittal parameters and clinical outcomes after anterior cervical discectomy and fusion (ACDF). Methods From January 2010 to December 2015, a total of 227 patients with cervical spondylosis who undelwent ACDF in Dongfang Hospital affiliated Tongji University were analyzed in this study. There were 109 male and 118 female, with an average age of 52.2±10.7 years (ranged from 34 to 78 years). The average duration of follow-up after revision surgery was (21.1±9.0) months (12-60 months). Comparing with Japanese 0rthopaedic Association (JOA) score and its improvement rate (IR), visual analogue scale (VAS) scores and neck disability index (NDI) between pre-operation and 1 year follow-up. Cervical alignment was assessed with the following 3 parameters: T1 slope (T1S), Cobb's angle of C2 to C7 and C2-7 sagittal vertical axis (SVA). And compared the changes of sagittal parameters and clinical efficacy. Results At 1 year follow-up, T1S was increased from 25.4°±8.5° to 27.9°±8.2°, Cobb's angle was increased from 12.7°±8.5° to 15.3°±9.5°, SVA was increased from (21.0±12.3) mm to (24.30±11.4) mm, and the differences were statistical significant (P<0.001). JOA score was increased from (8.5±4.0) points to (13.0±2.4) points at 1 year follow-up, however, VAS score was decreased from 2.7±1.8 points to 0.2±0.4 points, and NDI was decreased from 48.2%±8.2% to 27.1%±11.1%, and the differences were statistical significant (P<0.001). Preoperatively, T1S had positive correlations with both Cobb's angle and SVA before operation (r=0.311, 0.213; P=0.000, 0.001), but Cobb's angle had negative correlation with SVA (r=-0.246, P=0.000). At 1 year follow-up, T1S had positive correlations with Cobb's angle and SVA (r=0.390, 0.392; P=0.000, 0.000), and Cobb's angle had negative correlation with SVA (r=-0.131, P=0.048). At 1 year after operation, the change value of Cobb's angle had positive correlation with the change of JOA (r=0.294, P=0.000), but negative correlation with the change of NDI (r=-0.141, P=0.034). Conclusion ACDF is effective in the treatment of cervical spondylosis which the cervical sagittal alignment remains relatively stable, and there were significant correlation between the alteration of cervical sagittal parameters and clinical outcomes after ACDF. Key words: Cervical spondylosis; Spinal fusion; X-Rays; Treatment outcome