A Retrospective Radiographic Analysis of Cervical Sagittal Alignment After Posterior C1–2 Fusion: Conventional Surgery Versus Minimally Invasive Surgery

Objective: Minimally invasive surgery (MIS) techniques, which were initially used for the lumbar spine, are now being increasingly used for the cervical spine as well. This study compared the outcomes of posterior C1–2 fusion performed via MIS versus conventional surgery, as well as the changes in radiologic parameters after surgery.Methods: This study compared patients who underwent MIS and conventional surgery for atlantoaxial instability using Harm technique with interlaminar fusion and miniplate to maximize bone fusion between February 2012 and January 2021. Demographic characteristics and radiologic parameters were analyzed preoperatively, immediately postoperatively, and at 2 years postoperatively.Results: The study included 17 patients with more than 2 years of postoperative follow-up, including 7 patients who underwent MIS. Statistically significant differences were found between the 2 groups at the postoperative and intraoperative C1–2 angles (p=0.027 and p=0.001, respectively). There were no significant differences between the preoperative and 2-year postoperative C1–2 angles, or in the radiologic parameters between the MIS and conventional surgery groups. Both groups showed significant positive correlations between the C1–7 angle and T1 slope angle at 2 years postoperatively.Conclusion: The MIS and conventional surgery groups exhibited comparable surgical outcomes, suggesting the potential of MIS as an alternative treatment option. Nevertheless, finding the ideal C1–2 angle remains a challenge, because an inadequate angle can cause subaxial kyphosis.