MRI-based pedicle bone quality score: a superior predictor over vertebral bone quality score for pedicle screw loosening following transforaminal lumbar interbody fusion.

PURPOSE: Pedicle screw loosening (PSL) is a significant complication in transforaminal lumbar interbody fusion (TLIF), often associated with poor bone quality. This study evaluates the predictive value of MRI-based pedicle bone quality (PBQ) and vertebral body quality (VBQ) scores for PSL, hypothesizing that PBQ is a stronger predictor than VBQ.

METHODS

This retrospective cohort study analyzed 394 patients who underwent TLIF between January 2018 and January 2021. Preoperative PBQ and VBQ scores were derived from sagittal T1-weighted MRI images. The primary outcome measure was PSL, which was evaluated in accordance with established radiographic criteria. Secondary outcomes included fusion rates and patient-reported outcomes. Statistical analyses included receiver operating characteristic curves to determine predictive accuracy and multivariate logistic regression to identify other risk factors for PSL.

RESULTS

PBQ demonstrated superior predictive performance for PSL relative to VBQ, with higher sensitivity (75.93% vs. 50.00%) and specificity (92.31% vs. 87.06%). In addition, PBQ yielded higher positive predictive value (78.85% vs. 59.34%) and negative predictive value (91.03% vs. 82.18%). The discriminative ability of PBQ was further supported by a larger area under the ROC curve (0.894, 95% CI: 0.856-0.932) compared with VBQ (0.722, 95% CI: 0.664-0.781). Independent risk factors associated with PSL included advanced age, lower hip bone mineral density T-scores, longer fusion constructs, and reduced fusion rates. Furthermore, patients who developed PSL reported significantly higher postoperative back pain scores.

CONCLUSION

MRI-derived PBQ and VBQ scores independently predict PSL, with PBQ demonstrating superior performance. Incorporating PBQ into preoperative planning may improve surgical decision-making and potentially enhance outcomes in patients with reduced bone strength. Additionally, lower hip BMD T-scores, reduced fusion rates, longer fusion constructs, and advanced age were identified as significant risk factors for PSL.