Analysis of sagittal alignment parameters following anterior cervical hybrid decompression and fusion of multilevel cervical Spondylotic myelopathy

BACKGROUND: To investigate the relationships between sagittal parameters and health-related quality of life (HRQOL) scores following anterior cervical hybrid decompression and fusion (ACHDF) of multilevel cervical spondylotic myelopathy (CSM) and to study the impact of the T1 slope (T1 s). METHODS: In total, 42 patients with complete radiographic measurements following ACHDF in the Spine Surgery Department of the First Affiliated Hospital of Fujian Medical University from August 2014 to January 2017 were retrospectively analysed. Radiographic measurements included C2–7 lordosis, T1 s, C2–7 sagittal vertical axis (SVA), cervical tilting and cranial tilting. The neck disability index (NDI) was used to evaluate the HRQOL. Spearman’s correlation coefficients were calculated between pairs of cervical sagittal parameters and NDI scores. RESULTS: Preoperative NDI scores were correlated with preoperative T1 s (r = 0.413); follow-up NDI scores were correlated with follow-up T1 s (r = 0.534). The regression analysis indicated that a preoperative T1 s value of 42.36° corresponded to a preoperative NDI score of 25 (r(2) = 0.171, P < 0.001). A follow-up T1 s value of 48.61° corresponded to a follow-up NDI score of 25 (r(2) = 0.421, P < 0.01). The differences in C2–7 SVA and cranial tilting before and after the operation were statistically significant (P < 0.05). CONCLUSION: This study showed that the sagittal balance of the cervical vertebrae changed significantly after ACHDF, showing a forward trend. The sagittal parameters after ACHDF were related to clinical prognosis. An excessive T1 s can be considered a risk factor. The T1 s could provide a reference value to determine the correction of the sagittal balance of the cervical spine.