Evaluation of Cervical Vertebral Bone Quality Score in Predicting Risk of Cage Subsidence After Single-Level Anterior Cervical Discectomy and Fusion

Study Design: Retrospective cohort study. Objectives: The objectives of this study are to (1) measure the association between Cervical Vertebral Bone Quality (C-VBQ) score and subsidence after anterior cervical discectomy and fusion (ACDF), (2) determine whether there is a clinically relevant cutoff for predicting risk, and (3) determine whether ACDF cage construct configuration impacts the utility of C-VBQ. Summary of Background Data: Cage subsidence after ACDF can be influenced by patient factors such as age, medical history, cage construct material, and bone quality. Prior research suggests that the recently introduced C-VBQ score, an MRI-based measure of trabecular bone, can precisely predict postoperative subsidence risk. There is no prior research investigating whether cage construct configuration, known to impact subsidence risk, can affect the utility of C-VBQ score. Methods: One hundred seventeen patients undergoing single-level ACDF for degenerative pathology between 2019 and 2023 were included. C-VBQ was calculated at C2–C7 from preoperative T1-weighted MRI images. Radiographic subsidence was defined as collapse of the interbody cage by greater than one-third of cage height. Receiver operating characteristic (ROC) curves were generated for C-VBQ and subsidence between cage configurations. Inferential and descriptive statistics were performed. Results: Radiographic subsidence was present in 22 patients (19%). Mean C-VBQ score was significantly higher in the subsidence group ( P <0.001). A higher C-VBQ demonstrated greater odds of developing subsidence (OR=15.26, P <0.001). A C-VBQ score of ≥2.59 was 60% sensitive and 82% specific in detecting subsidence (AUC=0.747, P <0.001). C-VBQ score was most predictive with allograft (AUC=0.906, P <0.001), with a score of 2.44 demonstrating 100% sensitivity and 67% specificity, and least predictive with PEEK cage-plate constructs (AUC=0.625, P =0.360). Conclusions: Preoperative C-VBQ score is effective in predicting cage subsidence risk after ACDF surgery. It demonstrates the greatest utility in patients implanted with allograft cage-plate constructs and is least predictive in those with PEEK configurations.