Abstract
BACKGROUND: Anterior cervical discectomy and fusion (ACDF) is a standard surgical procedure for treating degenerative cervical disc diseases. However, the differences between autograft and allografts in terms of early-stage fusion and bone morphology remain largely unclear. This study aimed to provide a comprehensive analysis of the fusion process via quantitative computed tomography (CT)-based three-dimensional (3D) reconstruction, focusing on the differences between autografts and allografts and their impact on clinical outcomes. METHODS: A retrospective analysis was conducted on 134 patients who underwent single- or two-level ACDF with polyetheretherketone (PEEK) cages filled with either autografts (n=80) or allografts (n=54). Fusion volume and osteogenic morphology were assessed at 3, 6, 12, and 24 months postoperatively via CT-based 3D reconstruction. Fusion morphology was classified into stalactite, hourglass, and columnar patterns. Clinical outcomes were evaluated with the neck pain visual analog scale (VAS) and modified Japanese Orthopaedic Association (mJOA) scores, while radiographic parameters included cervical sagittal vertical axis (cSVA), C2-7 lordosis, segmental height, and subsidence. RESULTS: At 3 and 6 months, the autograft group, as compared to the allograft group, exhibited significantly higher fusion volumes (3 months: the autograft group 185.04±92.67 mm(3) vs. the allograft group 143.54±60.41 mm(3); 6 months: the autograft group 270.03±96.15 mm(3) vs. the allograft group 213.42±114.08 mm(3)) and fusion rates (3 months: the autograft group 11.2% vs. the allograft group 0%; 6 months: the autograft group 46.9% vs. the allograft group 23.8%), and superior osteogenic morphology (P<0.05). By 12 and 24 months, the fusion rates were similar between groups, but the autograft group demonstrated a more structured fusion morphology, with a higher prevalence of columnar fusion patterns. Larger early fusion volumes were associated with better intervertebral height maintenance, reduced subsidence, and greater pain relief. The absence of postoperative cervical collar use did not negatively impact fusion progression, likely due to the stability provided by advanced implant designs. CONCLUSIONS: Quantitative CT-based 3D reconstruction offers a highly precise and dynamic approach for assessing bone fusion in ACDF, enabling detailed visualization of fusion morphology and volume over time. These findings indicate that autografts promote earlier and more robust osteogenesis, leading to superior early clinical outcomes. These results emphasize the importance of graft selection and suggest that advanced 3D imaging techniques should be integrated into clinical practice to enhance fusion evaluation and optimize patient recovery.