Comparative Outcomes of 1-Level vs. 2-Level Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-Analysis

Background/Objectives: Cervical spine disease requiring surgical intervention is a major cause of disability. Anterior cervical discectomy and fusion (ACDF) is a well-established procedure for treating cervical pathology; however, there remains no consensus on whether 1-level versus 2-level ACDF yields comparable outcomes. This study compares 1-level versus 2-level ACDF by evaluating surgery-related and postoperative outcomes, radiographic parameters, and patient-reported outcome measures (PROMs). Methods: PubMed, Embase, Scopus, and Cochrane Library were searched through 10 July 2024. Studies comparing 1-level with 2-level ACDF were included. Data on operating room (OR) time, estimated blood loss (EBL), length of hospital stay (LOS), complications, and PROMs, including Neck Disability Index (NDI) and Visual Analogue Scale (VAS) for neck and arm pain, were extracted. Results: Thirteen studies met our inclusion criteria, comprising 2091 patients (1078 undergoing 1-level and 1013 2-level ACDF). No statistically significant differences were observed in EBL or LOS between the cohorts. However, the 2-level ACDF group showed significantly longer OR times (p-value < 0.001) and higher odds of developing dysphagia (p-value = 0.05). Patients undergoing 2-level ACDF showed greater correction in cervical lordosis. Both cohorts reported similar statistically and clinically significant improvements in VAS neck and NDI scores at final follow-up. There was no difference in adjacent segment disease or revision surgery at final follow-up. Conclusions: Both 1-level and 2-level ACDF improve clinical and radiographic outcomes. The choice should be tailored to the patient’s pathology and anatomy while considering the higher dysphagia risk with additional fusion levels. This study highlights the importance of individualized surgical planning to optimize postoperative outcomes while minimizing complications.