Comparison between 3-level and 4-level anterior cervical discectomy and fusion in the treatment of cervical spondylotic myelopathy: A meta-analysis

Objective: Our objective is to estimate the clinical effectiveness of 3-level and 4-level anterior cervical discectomy and fusion (ACDF) in the management of cervical spondylotic myelopathy (CSM).Methods: We conducted a thorough search in English databases. We gathered the data on surgical variables and complications to contrast the clinical effectiveness between 3-level and 4-level. We utilized RevMan 5.3 and STATA 12.0 to analyze the data.Results: Finally, eight studies met inclusion criteria of this study. Our findings indicated that operation time [p for heterogeneity = 0.23, I-2 = 32 %, p<0.00001, OR =-24.93, 95%CI (-32.39,-17.49)], blood loss [p for heterogeneity = 0.33, I-2 = 10 %, p<0.00001, OR =-60.87, 95%CI (-85.43,-36.32)] and the total number of complications [p for heterogeneity = 0.36, I-2 = 0 %, p = 0.004, OR = 0.37, 95%CI (0.18,0.72)] in 3-level ACDF were significantly less than in 4-level ACDF. No marked difference was found in hospital stay, revision rate, fusion rate, the number of readmissions, infection, hematoma, or pseudarthrosis between 3-level and 4-level ACDF.Conclusions: It is easy to understand that performing 4-level needs more operation time and blood loss. No obvious discrepancy was found with regard to the subgroups of complications between the two procedures, yet 4-level procedures had a more number of complications.