Simplified S1 Vertebral Bone Quality Score Predicts Screw Loosening in Patients with Lumbar Spondylolisthesis

Objective

Investigate whether S1 vertebral bone quality (VBQ) score serves as a viable substitute for the traditional VBQ score in predicting screw loosening in patients undergoing transforaminal lumbar interbody fusion (TLIF) for lumbar spondylolisthesis using quantitative computed tomography (QCT) as a standard reference.

Methods

We reviewed 165 patients undergoing single-segment TLIF for lumbar spondylolisthesis at our center from 2012 to 2021. Demographic and radiographic data were collected. To determine the independent factors affecting pedicle screw loosening, univariate analysis and multivariate logistic regression were conducted. Receiver operating characteristic analysis was carried out to assess the predictive ability.

Results

16.3% of patients experienced screw loosening at a minimum of 24 months of follow-up. Statistically significant differences in the 2 groups were observed in surgery level (L5–S1), traditional VBQ, S1 VBQ, and QCT values. QCT values, traditional VBQ score, and the S1 VBQ score were independent risk factors for screw loosening. The receiver operating characteristic analysis showed that area under the curve (AUC) of QCT was 0.839 (95% confidence interval [CI]: 0.771–0.907) and the cut-off value was 119 (sensitivity: 85.2% and specificity: 76.8%); AUC of VBQ scores was 0.787 (95% CI: 0.699–0.875) and the cut-off value was 3.585 (sensitivity: 88.9% and specificity: 69.6%), while AUC of S1 VBQ score was 0.823 (95% CI: 0.739–0.908) and the cut-off value was 3.72 (sensitivity: 81.5% and specificity: 76.8%).

Conclusions

The elevated S1 VBQ score was identified as an independent risk factor for screw loosening and exhibits greater predictive capability compared to the traditional VBQ score in forecasting screw loosening following TLIF for lumbar spondylolisthesis.