Predictive value of the VBQ score for internal fixation failure after PLIF and determinants of its cutoff value

Background: Vertebral bone quality (VBQ), which critically influences spinal fusion outcomes, can be quantitatively assessed by the VBQ score—a radiation-free metric sensitive to marrow fat changes and increasingly used to predict postoperative complications such as implant failure. The study was aimed to evaluate the predictive value of the VBQ score for internal fixation failure after PLIF, and to explore factors influencing VBQ cut-off value. Objectives: This study aimed to evaluate the predictive value of VBQ score for internal fixation failure (IFF) after posterior lumbar interbody fusion (PLIF), and to explore factors influencing VBQ cutoff value. Methods: A retrospective study was conducted on patients who underwent PLIF at Chinese People’s Liberation Army General Hospital from January 2017 to December 2022. IFF requiring revision was used as the endpoint. Predictive performance was assessed using the receiver operating characteristic (ROC) curve and Youden index to determine the cutoff value. Logistic regression analyses were used to identify influencing factors. Pearson correlation was used to assess associations. Results: A total of 256 patients were included in this study, with a mean age of 68.73 ± 6.32 years, and 74% were female. Sixty-seven patients experienced IFF, while 189 did not. The mean VBQ score was significantly higher in the IFF group compared to the nonfailure group (3.62 ± 0.46 vs. 2.97 ± 0.43, p < 0.001). Receiver operating characteristic curve analysis revealed that the VBQ score had good predictive value for IFF, with an area under the curve of 0.859 (95% confidence interval: 0.81–0.91). The optimal cutoff value was 3.3, with a sensitivity of 77.6% and specificity of 79.9%. Multivariate analysis confirmed that the VBQ cutoff value was not affected by demographic variables. VBQ score was associated with gender, chronic disease, and IFF. Conclusions: VBQ score is an excellent screening tool for predicting internal fixation failure following PLIF, which can provide a key basis for preoperative intervention in high-risk patients.