Cervical Vertebral Bone Quality Score Independently Predicts Zero-Profile Cage Subsidence After Single-Level Anterior Cervical Discectomy and Fusion

Abstract

ObjectiveThis is the first study to evaluate the predictive value of the cervical vertebral bone quality (VBQ) score on zero-profile cage (ZPC) subsidence after anterior cervical discectomy and fusion (ACDF) using the HU value of computed tomography (CT) as the reference. MethodsA total of 89 patients with at least 1 year of follow-up who underwent single-level ACDF with ZPC were retrospectively and consecutively included. VBQ and HU value were determined from preoperative T1-weighted MRI and CT. Subsidence was defined as ≥2 mm of migration of the cage into the superior or inferior endplate or both using lateral cervical spine radiography. The results were subjected to statistical analysis. ResultsSubsidence was observed among 16 of the 89 study patients (Subsidence rate:18.0%). The mean VBQ score was 2.94±0.820 for patients with subsidence and 2.33±0.814 for patients without subsidence. The multivariable analysis demonstrated that only an increased VBQ score (OR:1.823, 95%CI: 0.918,3.620, p=0.001) was associated with an increased rate of cage subsidence. There was a significant and moderate correlation between HU and VBQ (r = -0.507, P < 0.001). Using receiver operating characteristic curves, the area under the curve (AUC) was 0.785, and the most appropriate threshold of VBQ was 2.68 (sensitivity 72.7%, specificity 82.1%). ConclusionsThe VBQ score may be a valuable tool for independently predicting zero-profile cage subsidence after single-level ACDF.