A study of cervical sagittal parameters change after two modus of anterior cervicalsurgery in cervical myelopathy

Objective To analyze cervical sagittal parameters change after anterior cervical discectomy fusion (ACDF) and anterior cervical corpectomy fusion (ACCF) in cervical myelopathy. Methods 80 patients with cervical myelopathy who underwent anterior cervical surgery between March 2013 and October 2014 were analyzed in this study. 44 patients (24 males, 20 females) were operated by ACDF, with an average age of 59.5±4.26 years old and 36 patients (20 males, 16 females) were operated by ACCF, with an average age of 62.5±3.85 years old. Japanese Orthopaedic Association (JOA) scores, visual analogue scale(VAS) and neck disability index (NDI) were obtained in all patients preoperatively, 6 months after surgery and at the latest follow-up. Standing radiographs of cervical spine, CT (3D) and MR were obtained preoperatively, 6 months after surgery and at the latest follow-up. Cervical sagittal parameters were assessed with the following 3 parameters: C2-7 Cobb angle, C2-7 sagittal vertical axis(C2-7 SVA) and T1-Slope. Results All the patients were followed up from 18 to 26 months, with the average time of 22 months. The group of ACDF: JOA scores, VAS scores and NDI scores changed from 8.1±1.4, 5.8±1.2, 22.2±5.9 to 13.2±1.8, 1.5±1.4, 10.5±4.8. The group of ACCF: JOA scores, VAS scores and NDI scores changed from 7.3±1.6, 4.9±1.5, 24.2±4.3 to 13.9±1.1, 1.7±1.2, 11.3±4.2. There was no significant difference of JOA scores, VAS scores and NDI scoresbetween two group (t=1.544, 0.887, 1.666;P=0.134, 0.382, 0.107). The group of ACDF: C2-7 Cobb angle, C2-7 SVA and T1-Slope angle changed from 17.5°±4.7°, 20.3±9.3 mm, 35.2°±8.6° to 29.5°±5.2°, 11.2±8.6 mm, 28.7°±8.2°. The group of ACCF: C2-7 Cobb angle, C2-7 SVA and T1-Slope angle changed from 16.8°±5.1°, 19.5±8.6 mm, 34.6°±9.1° to 25.3°±4.2°, 15.7±9.2 mm, 30.3°±7.9°, with significant difference between the two group (t=2.75, 2.45, 2.34; P=0.039, 0.045, 0.043). The changes of T1-Slope angle in ACDF group were more significantly (P 25°) was decreased significantly. Compared with patients who had high T1-Slope preoperatively, the C2-7 Cobb in the patients with low T1-Slope was increased significantly. Conclusion Good curative effect could be achieved by ACDF and ACCF in cervical myelopathy. Both surgical methods can maintain the curvature of the cervical alignment and improve the sagittal balance parameters of the cervical alignment. Consideringthe cervical sagittal balance, the ACDF is more suitable for the patient with high T1-Slope angle preoperatively. Key words: Cervical spondylosis; Cervical vertebrae; Surgical procedures, operative