Anterior cervical discectomy and fusion can restore cervical sagittal alignment in degenerative cervical disease

The purpose of this study was to evaluate its effect on the restoration and maintenance of cervical sagittal alignment in usual cervical degenerative diseases without preoperative sagittal malalignment.

We retrospectively evaluated 108 patients who were diagnosed with degenerative cervical disease and underwent ACDF (allograft and plating) with > 1-year follow-up. For radiographic evaluation, we analysed segmental and C2-7 cervical lordosis, disc height, C2-7 sagittal vertical axis (SVA), T1 slope, and T1 slope minus C2-7 lordosis (T1S - CL) in lateral X-ray. Clinical assessment was based on arm VAS, neck VAS, and NDI scores. Correlation analysis was performed across the pre-post-changes in radiological parameters. Correlations between the changes in radiological and clinical parameters at final follow-up were also analysed.

C2-7 lordosis was 7.13° preoperatively and increased to 13.06° (p < 0.001) and maintained at 10.08° at final follow-up (p = 0.007). Segmental lordosis increased from 0.66° to 8.33° and maintained at 5.19° (p < 0.001). Segmental disc height was 4.67 mm preoperatively (increased to 7.13 mm postoperatively and decreased to 5.74 mm at final follow-up) (p < 0.001). SVA distance (31.53 mm to 30.02 mm) (p = 0.750) and T1 slope (30.03° to 31.37°) did not show meaningful change after surgery. Increase in segmental lordosis was correlated to an increase in C2-7 lordosis (p < 0.001). C2-7 SVA change correlated with both the T1 slope change (p < 0.001) and T1S - CL (p = 0.012). Change in SVA was correlated to a change in segmental lordosis and T1 slope (p = 0.003, p = 0.014). Clinical outcomes did not correlate with radiological findings.

ACDF for the treatment of degenerative cervical disease without preoperative deformity was effective in restoring cervical sagittal alignment. Improvement of segmental lordosis related to an improvement in C2-7 lordosis and SVA. Radiological sagittal alignment did not show any relation with clinical outcomes in usual degenerative cases.