Comparison of the Predictive Roles of CT- and MRI-Based Pedicle Regional Osteoporosis Status Measurements for Pedicle Screw Loosening After Posterior Lumbar Interbody Fusion

Study DesignRetrospective Study.ObjectivesTo compare the efficacy of pedicle Hounsfield unit (HU) values and pedicle bone quality (PBQ) scores in predicting pedicle screw loosening (PSL) after posterior lumbar interbody fusion (PLIF) in elderly patients and to identify the most discriminative bone mineral density (BMD) assessment indicator.MethodsThis retrospective analysis included 275 consecutive patients who underwent PLIF. L1 and pedicle HU values were obtained from CT scans, whereas vertebral bone quality (VBQ) and PBQ scores were obtained from MRI. Logistic regression analysis determined factors associated with PSL. Receiver-operating characteristic curve analysis was conducted to assess the predictive value of pedicle HU and PBQ score for PSL and to additionally compare their predictive value with that of L1 HU value and VBQ score.ResultsThe PSL rate was 20.36% (56/275). The loosening group demonstrated a higher postoperative low-back pain visual analog scale score (P < 0.05), lower L1 (P < 0.001) and pedicle HU values (P < 0.001) and higher VBQ (P < 0.001) and PBQ scores (P < 0.001) than the non-loosening group. The logistic regression analysis identified L1 (OR = 0.98, 95% CI = 0.97-0.99, P < 0.001) and pedicle HU values (OR = 0.99, 95% CI = 0.98-0.99, P < 0.001) and VBQ (OR = 2.81, 95% CI = 1.43-5.52, P = 0.003) and PBQ scores (OR = 3.85, 95% CI = 2.03-7.32, P < 0.001) as independent predictors of PSL. The area under the curve for L1 and pedicle HU values and VBQ and PBQ scores were 0.751, 0.766, 0.684, and 0.702, respectively. The optimal pedicle HU cut-off for predicting PSL was 106.32 (sensitivity: 78.49%; specificity: 75.00%).ConclusionsPedicle HU values exhibited a relatively higher predictive performance for PSL compared with the PBQ score and served as the most discriminative BMD indicator in patients who underwent PLIF. Measuring the pedicle HU value preoperatively help surgeons to select a more appropriate surgical plan and is expected to improve the patient outcomes.