Changes of cervical sagittal balance after anteriorcervical discectomy and fusion

English Keywords:Cervical spondylosis  Anterior cervical discectomy and fusion  Fusion segments  Sagittal balance

English Abstract:

  【Abstract】 Objectives: To explore the changes of cervical sagittal balance after anterior cervical discectomy and fusion. Methods: A total of 326 patients with lower cervical spondylosis, who underwent anterior cervical discectomy and fusion in spinal surgery department of Shanghai East Hospital from January 2012 to December 2016 were reviewed, including 175 males and 151 females, and aging from 34 to 81 years old(average, 56.0± 9.4 years old). The follow-up time was 12 to 30 months, with an average of 18.5±6.4 months. According to the fusion segment, patients were divided into four groups: 69 cases in single segment fusion group, 85 cases in double segments fusion group, 90 cases in three segments fusion group, 82 cases in four segments fusion group. Radiographic parameters on cervical spine X-ray, clinical scores before surgery and at 12 months after surgery were recorded: occiput-C2 angle(C0-2 Cobb), C2-7 Cobb, C2-7 sagittal vertical axis(C2-7 SVA) and T1 slope(T1S), Japanese Orthopaedic Association(JOA) and visual analog scale(VAS) scores. The changes of sagittal parameters and scores from preoperation to 12 months after surgery were calculated and compared among the four groups by using one-way-ANOVA. Pearson analysis was employed to explore the correlation of sagittal parameters before surgery and 12 months after surgery. Results: There was no significant difference of general data among the four groups. From preoperation to 12 months after surgery in single segment fusion group, C0-2 Cobb decreased from 21.07°±8.21° to 20.92°±5.99°(P=0.888), C2-7 Cobb increased from 15.29°±8.64° to 17.69°±11.25°(P=0.125), C2-7 SVA decreased from 20.94±10.77mm to 20.61±10.23mm(P=0.839), T1S increased from 23.02°±8.64° to 24.05°±9.35°(P=0.450); in two segments fusion group, C0-2 Cobb increased from 20.38°±7.49° to 24.20°±7.96°(P=0.000), C2-7 Cobb increased from 13.04°±8.07° to 15.85°±10.53°(P=0.003), C2-7 SVA increased from 18.57±11.88mm to 23.73±9.87mm(P=0.000), T1S increased from 24.28°±6.71° to 28.65°±7.64°(P=0.000); in three segments fusion group, C0-2 Cobb increased from 16.76°±6.24° to 20.54°±6.58°(P=0.000), C2-7 Cobb increased from 11.46°±7.83° to 15.12°±10.42°(P=0.001), C2-7 SVA increased from 19.36±8.40mm to 25.25±12.20mm(P=0.000), T1S increased from 26.56°±9.47° to 30.39°±7.31°(P=0.000); in four segments fusion group, C0-2 Cobb increased from 15.44°±6.50° to 18.39°±6.26°(P=0.000), C2-7 Cobb increased from 11.54°±8.30° to 19.61°±5.53°(P=0.001), C2-7 SVA increased from 22.39±12.60mm to 27.68±11.17mm(P=0.000), T1S increased from 24.70°±6.30° to 31.22°±6.45°(P=0.000). T1S had positive relationship with C2-7 Cobb and C2-7 SVA, C2-7 Cobb had negative relationship with C2-7 SVA in each group before and 12 months after operation. The changes of C0-2 Cobb, C2-7 Cobb, C2-7 SVA and T1S had significant differences among the four groups(P=0.000, 0.013, 0.001, 0.000). Conclusions: The cervical sagittal balance changed with no significant difference after single-segment ACDF, two- and long-segments ACDF changed cervical sagittal balance significantly, but lower cervical sagittal alignment maintained dynamic stability.