Clinical Outcomes Following Three- and Four-Level Anterior Cervical Discectomy and Fusion: A Systematic Review and...

Study Design/SettingSystematic review and meta-analysis.ObjectivesAnterior cervical discectomy and fusion (ACDF) is a well-established treatment for degenerative cervical pathology. Although outcomes following 1- and 2-level ACDF are favorable, increasing construct length has been associated with worse outcomes. Despite this, 3- and 4-level ACDF are often grouped as "multilevel" constructs, though emerging evidence suggests 4-level ACDF may carry greater risk. This study systematically reviewed the literature and performed a meta-analysis comparing outcomes between 3- and 4-level ACDF.MethodsA systematic search of MEDLINE, Embase, and Cochrane databases was performed per PRISMA guidelines. Studies reporting outcomes following three- or four-level ACDF were included. Complex etiology and registry-based studies were excluded. Analysis included patient-reported outcomes, perioperative characteristics, and postoperative fusion and complication rates. Data were synthesized, and random-effects meta-analysis was performed using Cohen's d for continuous outcomes and log odds ratios for dichotomous outcomes.ResultsBoth 3- and 4-level ACDF improved pain, disability, and neurologic function. Meta-analysis showed 4-level ACDF had less improvement in axial neck pain, with similar arm pain improvement. Fusion rates were lower with 4-level ACDF. Perioperative outcomes favored 3-level constructs, with 4-level ACDF associated with longer operative time, greater blood loss, and longer hospital stay. No significant differences were observed in complication or revision rates, though confidence intervals were wide.ConclusionsBoth procedures improved pain and function. However, 4-level ACDF showed less neck pain improvement, lower fusion rates, and greater perioperative morbidity. Meta-analysis reveals clinically meaningful differences that should inform surgical planning and patient counseling.