Comparison of sagittal parameters for anterior cervical discectomy and fusion, hybrid surgery, and total disc replacement for three levels of cervical spondylosis

Purpose: To analyze sagittal balance of the cervical spine after three operative methods for three consecutive levels. Methods: A retrospective case selection and observational study was performed from December 2012 to December 2015: 20 patients underwent anterior cervical discectomy and fusion, 22 patients underwent hybrid surgery (HS), and 20 patients underwent total disc replacement (TDR). Perioperative parameters, clinical outcomes, and preoperative and postoperative sagittal parameters were recorded. Results: Clinical outcomes improved. Fusion and hybrid groups were associated with more postoperative focal lordosis than the TDR group (no significant difference). The postoperative C2-7 sagittal vertical axis (SVA) was greater in the TDR group (no significant difference). In the fusion group, the postoperative C2-7 SVA was highly correlated with the preoperative C2-7 SVA and postoperative C7 slope (C7SL). Postoperative C2-7 lordosis (C2-7L) was highly correlated with the preoperative C2-7 SVA and preoperative and postoperative C7SL. In the hybrid group, postoperative C2-7L was highly correlated with preoperative C2-7L, preoperative and postoperative focal lordosis, and C7SL. In the TDR group, the postoperative C2-7 SVA was highly correlated with the preoperative C2-7 SVA and postoperative C7 slope. The postoperative C2-7 SVA was also negatively correlated with postoperative C2-7L and focal lordosis. Postoperative C2-7L was highly correlated with postoperative focal lordosis. Conclusions: For three or more levels of cervical degenerative disease, good clinical outcomes can be achieved. TDR may not be a good choice for large preoperative C2-7 SVA. HS provides good cervical range of motion and restores cervical lordosis and C2-7 SVA.