Artificial disc replacement versus anterior decompression and fusion for multilevel cervical degenerative disc disease: A meta-analysis of direct comparative studies

Background: Multilevel cervical degenerative disc disease (MDDD) is a prevalent medical disorder characterized by deterioration occurring in two or more segments of the cervical spine. The optimal surgical technique for MDDD remains controversial. Aim: To compare cervical disc replacement (CDR) and Anterior cervical discectomy and fusion (ACDF) for the treatment of MDDD with respect to radiological outcomes, pain, re-operation rates and complications. Methods: In October 2022, we searched the Cochrane Library, Scopus, Web of Science, and PubMed databases using an advanced search strategy for studies that recruited MDDD patients and treated them using CDR and ACDF. We excluded studies including patients below 18 years or single-level cervical degenerative disc disease, non-English studies, case report, animal studies, non-full text study (abstract only) or letter to the editor. Results: 15 papers were included with 2897 patients in total; 1212 had CDF and 1685 had CDR. Age ranged from 44 to 60 and the body mass index varied from 24 to 29. ROM of C2-C7 (cervical ROM) was higher after CDR than after ACDF (MD 13.42, 95%CI 8.86,18.19], p=0.09). A decreased incidence of ASD was seen following CDR compared to ACDF ([RR] = 0.56, 95% CI [0.47, 0.65], p< 0.001). There was no statistically significant difference in the overall success rate (RR 1.33, 95% CI [0.98,1.81], p=0.07). The incidence of NDI success rate was higher after CDR than after ACDF (RR 1.23, 95%CI [1.15,1.32], p