What is the Early Fate of the Adjacent Segmental Angles Following a Single-level Anterior Cervical Discectomy Fusion for Degenerative Pathology?

Abstract

Retrospective case series study. This study aims to investigate adjacent segmental angle changes postsingle-level anterior cervical discectomy and fusion (ACDF). Anterior cervical fusion's impact on adjacent levels and global cervical alignment remains insufficiently understood, with potential implications for surgical planning and radiographic outcomes. A single-center retrospective analysis of consecutive patients undergoing single-level ACDF for degenerative pathology was conducted. Preoperative and 12-month postoperative lateral cervical plain radiographs were evaluated. Measured parameters included pre and postoperative C2-C7 lordosis, segmental lordosis of the fusion and adjacent levels, T1-slope, occipito-C2 angle (O-C2), and C2-C7 sagittal vertical axis. Patients were stratified by operative level. Univariate and multivariate analyses were performed. Seventy patients were included (18 C4-C5, 35 C5-C6, and 17 C6-C7 operative levels). No significant changes were observed in any of the measured parameters at the C4-C5 level. Likewise, at the C5-C6 level, there were no clinically significant changes in any parameters. At the C6-C7 level, significant alterations in segmental angles were observed. At this level, the ACDF procedure led to an overall loss of lordosis of 3.48 degrees with an associated lordotic change in the supra- and infra-adjacent levels, which preferentially favored change at the supra-adjacent level (4.83 degrees of lordosis response) compared with the infra-adjacent level (3.52 degrees of lordotic response). This study suggests that preoperative cervical lordosis may influence adjacent segmental angles after single-level ACDF procedures, offering crucial insights for future research and preoperative planning. Understanding these dynamics is crucial for preserving cervical lordosis and managing adjacent segment disease. Level IV.