Abstract: BACKGROUND: At present, anterior cervical discectomy and fusion is the “gold standard” for treatment of cervical spondylosis. The cervical zero-notch anterior interbody fusion cage is gradually being promoted and applied in clinical practice, with good clinical efficacy and imaging results.  
OBJECTIVE: To evaluate the mid-term outcome of cervical spondylotic myelopathy treated with variable-angle zero-notch anterior interbody fusion system.
METHODS:  Totally 81 patients with cervical spondylotic myelopathy treated in First Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2015 to January 2018 were included in this study. Among them, 42 patients received anterior cervical discectomy and decompression and fusion using variable-angle zero-notch anterior interbody fusion system (trial group); 39 patients received anterior cervical discectomy and decompression and fusion using traditional titanium plate-cage system (control group). Visual Analog Scale score, Japanese Orthopaedic Association score, Cobb-C angle and Cobb-S angle of cervical spine, interbody fusion, and complications were compared between the two groups. The protocols were approved by the Ethics Committee of First Affiliated Hospital of Guangzhou University of Chinese Medicine (approval No. JY2020199).  
RESULTS AND CONCLUSION: (1) Visual Analog Scale score and Japanese Orthopaedic Association score were significantly improved after surgery compared with those before surgery in both groups (P < 0.05). No significant differences in Visual Analog Scale score and Japanese Orthopaedic Association score were detected between the two groups (P > 0.05). (2) Cobb-S angle was significantly improved at 3 days and 30 months after surgery compared with that before surgery in both groups (P < 0.05). Cobb-C angle was significantly improved at 3 days after surgery compared with that before surgery in the trial group (P < 0.05). Cobb-C angle was significantly improved at 3 days and 30 months after surgery compared with that before surgery in the control group (P < 0.05). (3) The rate of complete fusion was 98% in the trial group and 100% in the control group. (4) The rate of the fusion cage sinking in the trial group was higher than that in the control group (24%, 3%, P < 0.05); the incidence of postoperative dysphagia was lower than that in the control group (2%, 38%, P < 0.05); and the incidence of adjacent intervertebral disc degeneration was lower than that in the control group (2%, 18%, P < 0.05). (5) The results have shown that variable-angle zero-notch anterior interbody fusion system for cervical spondylotic myelopathy can effectively improve the symptoms and reduce postoperative complications. However, the incidence of fusion cage sinking was higher than that of traditional titanium plate-cage system. The change of the overall curvature of the cervical spine needs long-term observation and follow-up. The mid-term efficacy of the operation is generally good.

Key words: anterior cervical discectomy and fusion, variable-angle zero-notch anterior interbody fusion system, cervical spondylotic myelopathy, mid-term efficacy, imaging evaluation, complications, cervical curvature, bone tissue engineering