A novel nomogram model to predict the risk factors for C5 palsy following anterior controllable antedisplacement and fusion for cervical ossification of the posterior longitudinal ligament: a retrospective study

BACKGROUND: C5 palsy is a common and clinically significant complication following cervical decompression surgery. However, the relationship between this complication and the novel surgical technique, anterior controllable antedisplacement and fusion (ACAF), remains underexplored. PURPOSE: This study aimed to investigate the incidence and independent risk factors of C5 palsy in patients with cervical ossification of the posterior longitudinal ligament (C-OPLL) after ACAF, with the goal of facilitating early prevention and improving clinical outcomes. METHODS: We conducted a retrospective review of all patients with C-OPLL who underwent ACAF at our institution between June 2018 and December 2020. Independent risk factors for postoperative C5 palsy were identified using binary logistic regression analysis. Cutoff values for significant predictors were determined via receiver operating characteristic (ROC) curve analysis to support clinical diagnosis. RESULTS: Among the 275 included patients, 12 (4.36%) developed C5 palsy. The median age was 51.0 years in the non-C5 palsy group and 56.5 years in the C5 palsy group. Significant differences (P < 0.05) were observed in the maximum stenosis rate at the C4-5 spinal canal (MSRSC), preoperative spinal cord rotation angle (SCRA), left/right narrowest distance between the vertebral body and articular process at C5 (NDVA), and postoperative distance of dura mater beyond the facet joint (DDF). Binary logistic regression identified preoperative SCRA, NDVA, and postoperative DDF as independent risk factors for C5 palsy (P < 0.05). The combined diagnostic model showed the largest area under the curve (AUC), with sensitivity and specificity both exceeding 90%, demonstrating strong predictive performance. A nomogram was developed based on these independent predictors. CONCLUSIONS: This study established preoperative SCRA, NDVA, and postoperative DDF as independent risk factors for C5 palsy following ACAF and proposed a clinically applicable nomogram for risk prediction. To reduce the incidence of C5 palsy, we recommend performing slow and symmetric antedisplacement of the vertebral-OPLL complex combined with appropriate foraminotomy during ACAF. Future studies should assess the generalizability of these risk factors to other decompressive techniques for C-OPLL.