Comparing the Prognostic Utility of Vertebral and Endplate Bone Quality Scores for Cage Subsidence Following...

Cage subsidence following anterior cervical discectomy and fusion (ACDF) is linked with poor bone quality. MRI-derived bone quality scores have been shown to provide valuable insights into postoperative complication risk; however, the optimal MRI-based metric for predicting cage subsidence remains unclear. This study aims to compare the predictive value of different MRI-derived bone quality measures for cage subsidence following ACDF.

Patients undergoing single-level ACDF between October 2012 and September 2022 at our institution with at least 6 months of radiographic follow-up were retrospectively evaluated. T1 preoperative MRI scans were used to measure mean, median, and segmental vertebral bone quality (VBQ) scores, and upper, lower, and average endplate bone quality (EBQ) scores. Postoperative and follow-up X-rays were used to identify cage subsidence.

Fifty-six patients met the inclusion criteria; 26 developed cage subsidence and 30 did not. Age, sex, surgical indication, cage type, and clinical setting were similar between groups. Mean disc space loss was significantly greater in the subsidence group (3.99 mm vs. 0.37 mm; p < 0.001). All bone quality scores were significantly higher in the subsidence group across all metrics. Mean VBQ (OR = 14.22), segmental VBQ (OR = 8.23), and lower EBQ (OR = 5.54) were strong predictors of subsidence (p < 0.001). ROC analysis showed excellent discrimination for mean VBQ (AUC = 0.821), segmental VBQ (AUC = 0.817), and median VBQ (AUC = 0.817). Interobserver reliability was high for all bone quality metrics (ICC 0.836-0.925).

MRI-derived bone quality metrics, particularly VBQ and lower endplate EBQ scores, are strong predictors of cage subsidence following single-level ACDF. These findings reinforce the clinical utility of preoperative MRI as a non-invasive, radiation-free tool for assessing vertebral bone integrity. Incorporating VBQ and EBQ assessments into surgical planning may enhance risk stratification and optimize postoperative outcomes in patients undergoing cervical fusion.