Anterior cervical discectomy and fusion may be more effective than anterior cervical corpectomy and fusion for the treatment of cervical spondylotic myelopathy

Various different approaches have been applied to decompressive surgery of the cervical spine, such as multilevel discectomy, corpectomy, laminectomy with/without fusion, laminoplasty, and laminectomy [21,37]. Both approaches (anterior and posterior approaches) could contribute to the achievement of sufficient decompression of the spinal cord to improve clinical outcomes of CSM patients [38,39]. Anterior approach appears to be more suitable when the pathologies of anterior involve only 1 or 2 vertebral body levels, while if more than 2 levels usually proceed using an posterior approach clinically [40]. Additionally, cervical lordosis can be improved by both approaches, whereas anterior approaches present a relatively better overall correction for its higher probability of achieving release and distraction [41]. The present meta-analysis was mainly conducted to assess the efficacy and safety of anterior approaches (ACDF and ACCF) for managing CSM. Importantly, we discovered that the safety of ACDF was significantly superior as compared to ACCF with regard to the operation time, blood loss as well as hospitals time. Results in our study suggested that CSM patients received ACDF treatment showed less operative blood loss than those treated with ACCF. It has also been evidenced that as compared to ACCF, ACDF caused less blood loss as well as greater ameliorations in cervical lordosis and segmental height with better clinical outcomes [13]. Previous literature has described that the difference may probably due to the more invasive surgical approach of ACDF which was involved in removing a vertebral body [9,19]. We also found that the operation time of ACDF was obviously shorter than that of ACCF. Published studies suggested that ACCF was involved in the removal of about 15 ~ 19 mm of the anterior midline trough in the vertebral body down to the posterior longitudinal ligament, with elimination of the upper and lower adjacent discs; while ACDF was only associated with the excision of the affected intervertebral disc tissue [21,42]. So the ACCF was a complex procedure performed with technically more time consuming and challenging than ACDF. Our results was in line with a previous study confirming that ACCF had more operation time and blood loss compared to ACDF, and ACCF was inferior to ACDF in terms of segmental angle improvement and C2-7 angle improvement [23]. Furthermore, CSM patients in the ACDF group experienced shorter hospital time than those in the ACCF group. A potential explanation may be that patients receiving ACCF in the treatment of CSM may suffer from more serious spinal cord injury than patients undergoing ACDF, and ACDF was also suggested to be with less intraoperative blood loss; thus patients recover faster after ACDF surgery [23,43,44]. Multilevel ACDF may be related with high rates of fusion. The technique has well documented to be effective and safe for treating multilevel CSM resulting in less intraoperative blood loss, shorter operative times and shorter hospital stays for patients [21,38]. Consistent with our findings, Hwang et al. demonstrated that in multilevel cervical degenerative disc disease, multilevel discectomy and cage fusion with plate fixation is superior to corpectomy and struct graft fusion with plate fixation in terms of the absence of construct failures and donor site complications, along with shorter hospital stay [45]. However, we found no evident differences in the fusion rate, preoperative JOA scores and postoperative JOA scores in both groups, suggesting that there was no strong difference in the efficiency between ACCF and ACDF in the treatment of CSM.

Several limitations in this study should also be acknowledged. First, owing to the small sample size, there may be certain selection bias in our results. Second, despite the rigorous study design, the observer might be influenced by environmental factors, psychological factors, physical factors, theory and clinical experience, which may lead to bias in results. Third, original data from the selected studies was failed to be obtained in the present study that may limit further estimation of potential difference of the efficacy and safety between ACDF and ACCF in the treatment of CSM; thus limiting the clinical value of our study. Finally and importantly, ten in thirteen included articles were from China, which might affect the credibility and reliability of our results, and restricted the wide application of our findings.