Early postoperative factors associated with pseudoarthrosis at 24 months following anterior cervical discectomy and fusion

Pseudoarthrosis after anterior cervical discectomy and fusion (ACDF) may lead to clinical deterioration and revision surgery. This study aimed to evaluate early risk factors to determine their associations with pseudoarthrosis at 24 months following ACDF. Patients who underwent ACDF for degenerative cervical spine disease at a single institution were retrospectively analyzed. Pseudoarthrosis was defined as ISM (interspinous motion) ≥ 1 mm at 24 months after ACDF. Among segments with ISM ≥ 1 mm at 6 months postoperatively, we conducted multivariate logistic regression analysis, including patients' baseline clinical factors and radiological variables measured at 6 months, to identify those associated with pseudoarthrosis. We also determined the optimal ISM cutoff at 6 months for the identification of pseudoarthrosis at 24 months. Pseudoarthrosis occurred in 21 of 120 segments (17.5%). In multivariate analysis, ISM at 6 months was independently associated with pseudoarthrosis (odds ratio 2.81; 95% confidence interval 1.08-7.28; P = .033). Receiver operating characteristic analysis determined the optimal ISM cutoff at 6 months for identifying pseudoarthrosis is 4.0 mm (sensitivity 74%, specificity 95%). ISM cutoff of 4.0 mm at 6 months postoperatively can effectively identify pseudoarthrosis at 24 months. Early identification of patients at high risk for pseudoarthrosis may facilitate tailored follow-up and timely interventions, potentially optimizing clinical outcomes. Large-scale, prospective validation is warranted.