A Study Of MRI-based Vertebral Bone Quality Score In Predicting Pedicle Screw Loosening In Lumbar Degenerative Diseases

Objective: To investigate a new MRI-based Vertebral bone quality(VBQ)method to predict pedicle screw loosening after Posterior lumbar inter-body fusion(PLIF).Methods: From June 2018 to October 2021,the patients,who is over50-years old and underwent PLIF surgery for lumbar degenerative diseases(LDDs),were retrospectively analyzed,and the follow-up was ≥ 12 months.174 patients were included,57 of them were males,and 117 were females,with a mean age of 63.5 ± 7.8(50-81)years.The VBQ score is calculated by delineating the designated region of interest(ROI) on the non-contrast T1-weighted phase of MRI.Additionally,a dual-energy X-ray absorptiometry(DXA)was undergone to record L1-4,and the lowest bone mineral density(BMD)and T score.The patients were divided into loosening and non-loosening groups based on the presence or absence of a radiolucent zone on the last follow-up imaging. The demographic data(sex,age,body mass index),health status(hypertension,diabetes,smoking,and alcohol history),surgical data(fusion level,lowest instrumented vertebra),preoperative and last follow-up clinical data(visual analogue score of pain,Oswestry dysfunction index),sagittal alignment parameters,etc.were recorded,the comparison was conduct after which.Multivariate regression analysis was included for data with a statistical P<0.05 to identify independent risk factors for screw loosening.Establish the Receiver-operating characteristic curve of VBQ scoring subjects and establish the VBQ scoring threshold for loosening screws.Results: For the 174 patients,the mean follow-up was 14.6 months(12-37),and the median follow-up screw loosening was ten months(8; 18).Among them,52 cases were included in the loosening group,and 122 cases were included in the non-loosening group,and 83 screws were loose by 9.18%(83/904).There were no significances in gender,body mass index,health history,etc.,between the two groups(P>0.05).For bone quality assessment,the lowest BMD in the loosening group was lower than the non-loosening group(0.81±0.1 vs.0.86±0.1,P=0.028),and the lowest T score was not different(P<0.05).Conversely,the VBQ score in the loosening group was higher than that of the non-loosening group(3.1±0.5 vs.2.8±0.4,P<0.001).The VBQ score was analyzed using the ROC curve,and the AUC for predictive power was 0.744.The sensitivity was 76.9%,the specificity was 64.8%,and the VBQ threshold reflecting screw loosening was 2.87.In multivariate regression analysis,fixed to SI(OR=3.78;95% CI [1.63-8.79];p=0.002),VBQ score(OR=1.02 per point;95% CI [1.01-1.03];p<0.001)as an independent risk factor for screw loosening.Conclusion: VBQ scores,as an independent risk factor for screw loosening after lumbar fusion,provide a new non-invasive solution for assessing bone quality when planning surgery before surgery.