A retrospective study to reveal the effect of surgical correction of cervical kyphosis on thoraco-lumbo-pelvic sagittal alignment

Purpose Recent studies suggest that cervical lordosis is influenced by thoracic kyphosis and that T1 slope is a key factor determining cervical sagittal alignment. However, no previous study has investigated the influence of cervical kyphosis correction on the remaining spinopelvic balance. The purpose of this study is to assess the effect of surgical correction of cervical kyphosis on thoraco-lumbo-pelvic alignment. Methods Fifty-five patients who underwent ≥2 level cervical fusions for cervical radiculopathy or myelopathy were included. All patients had regional or global cervical kyphosis, which was surgically corrected into lordosis. Radiographic measurements were made using whole spine standing lateral radigraphs pre- and postoperatively to analyze various sagittal parameters. The visual analogue scale (VAS) for neck pain and the neck disability index (NDI) were calculated. The paired t test was used to compare pre- and post-operative radiographic measures and functional scores. Correlations between changes in cervical sagittal parameters and those of other sagittal parameters were analyzed by Pearson’s correlation method. Results Preoperative kyphosis (11.4° ± 8.3°) was corrected into lordosis (−9.3° ± 8.1°). The average fusion levels were 3.3 ± 1.0. With increasing C2–C7 lordosis after surgery (from −3.4° ± 10.0° to −15° ± 7.9°), C0–C2 lordosis decreased significantly (from −34.6° ± 8.2° to −27.7° ± 8.0°) ( P