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Comparison of Hounsfield Unit Value and Vertebral Bone Quality Score in Predicting Cage Subsidence After Zero-P
Hong-Yu Pu1, Jin-Zhou Wang2, Jian-Wei Guo3
1Department of Orthopaedic Surgery, Fushun People's Hospital, Zigong.
Background:
This study compared the predictive performance of the Hounsfield unit (HU) value and vertebral bone quality (VBQ) score based on cage subsidence after anterior cervical discectomy and Zero-P fusion.
Materials And Methods:
We conducted a retrospective analysis of 104 patients who underwent Zero-P fusion surgery for cervical spondylosis in our hospital. Before surgery, the VBQ of each patient's C2-C7 vertebral body was measured by cervical magnetic resonance imaging, while the HU value was measured by cervical computed tomography. The maximum loss distance of vertebral height was measured immediately after surgery and at final follow-up. Patients were divided into a subsidence group (≥3 mm) and a non-subsidence group (<3 mm). Single-factor analysis was used to preliminarily determine the risk factors for Zero-P cage (ZPC) subsidence. For variables with statistical differences, logistic regression was further used for multivariate analysis to determine independent risk factors. Receiver operating characteristic (ROC) and area under the curve (AUC) were used to evaluate the ability of VBQ score and HU value to predict ZPC subsidence.
Results:
Interbody ZPC subsidence was observed in 20 of 104 patients. Significant differences in HU value and VBQ score were found between the two groups. HU value (odds ratio [OR]=0.987, 95% CI 0.978-0.997, P=0.006) and VBQ score (OR=4.462, 95% CI 1.721-11.373, P=0.002) were independent risk factors for ZPC subsidence. On the ROC curve, the AUC of VBQ score was 0.776 (95% CI 0.669-0.883), and the optimal threshold of VBQ score was 3.860 (sensitivity: 60.0%, specificity: 86.9%). The AUC of HU was 0.757 (95% CI 0.645-0.869), and the optimal threshold of HU value was 298.44 (sensitivity: 60.7%, specificity: 90.0%). The AUC of HU value and VBQ score showed no statistical difference, whereas the AUC of the joint index of HU value and VBQ score was 0.833, which was higher than that of the single indicator, and the difference was statistically significant (P<0.05).
Conclusion:
Higher VBQ score and lower HU value are independent predictors of ZPC subsidence in patients following Zero-P fusion. The joint index of HU value and VBQ score is more predictive of Zero-P fusion than a single indicator.
