Search

Poor bone quality and low bone mineral density (BMD) have been previously tied to higher rates of postoperative mechanical complications in patients undergoing spinal fusion. These include higher rates of proximal junctional kyphosis, screw pullout, pseudoarthrosis, and interbody subsidence. For these reasons, accurate preoperative assessment of a patient's underlying bone quality is paramount for all elective procedures. Dual-energy X-ray absorptiometry (DXA) is currently considered to be the gold standard for assessing BMD. However, a growing body of research has suggested that in vivo assessments of BMD using DXA are inaccurate and have, at best, moderate correlations to postoperative mechanical complications. Consequently, there have been investigations into using alternative methods for assessing in vivo bone quality, including using computed tomography (CT) and magnetic resonance imaging (MRI) volumes that are commonly obtained as part of surgical evaluation. Here we review the data regarding the accuracy of DXA for the evaluation of spine bone quality and describe the alternative imaging modalities currently under investigation. [ABSTRACT FROM AUTHOR]

Poor bone quality is a known risk factor for hardware failure and adjacent segment disease after lumbar fusion. One new method of analyzing bone quality is the vertebral bone quality (VBQ) score, which can be obtained from preoperative lumbar magnetic resonance imaging (MRI) scans. We decided to evaluate whether patients' VBQ scores were associated with reoperation after lumbar fusion. We queried records of patients who underwent elective lumbar fusion for degenerative conditions between 2012 and 2017. Patients who required reoperations after lumbar fusions because of symptomatic hardware failure or adjacent segment disease were combined into a case group and compared with a matched control group. Of the 46 patients who underwent elective lumbar fusions and required reoperation, 30 met the inclusion criteria. A 2:1 control group of 60 individually age-, body mass index–, and sex-matched patients who did not require reoperation was then created. The reoperation group had significantly lower degrees of postoperative lumbar lordosis. There were no significant differences regarding other spinopelvic parameters, adjacent Pfirrmann scores, or dual energy x-ray absorptiometry (DXA) T scores. There was, however, a significant difference in VBQ scores between the groups, with the reoperation group having a higher VBQ score. This study found that bone quality, according to the VBQ score rather than the DXA T score, is an important risk factor for reoperation after lumbar fusion surgery. Therefore, this MRI-based tool may be used to assist surgeons in preoperative planning for spine surgeries with the goal of reducing the risk of requiring reoperation. [ABSTRACT FROM AUTHOR]

Background: Current evidence suggests that dual-energy x-ray absorptiometry (DXA) scans, the conventional method defining osteoporosis, is underutilized and, when used, may underestimate patient risk for skeletal fragility. It has recently been suggested that other imaging modalities may better estimate bone quality, such as the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score which also may assess vertebral compression fracture risk in patients with spine metastases.Purpose: To evaluate whether VBQ score is predictive of fragility fractures in a population with pre-existing low bone density and at high-risk for fracture.Study Design/setting: Retrospective single-center cohort.Patient Sample: Patients followed at a metabolic bone clinic for osteopenia and/or osteoporosis.Outcome Measures: Radiographically-documented new-onset fragility fracture.Methods: Patients with a DXA and MRI scans at the time of consultation and ≥2-year follow-up were included. Details were gathered about patient demographics, health history, current medication use, and serological studies of kidney function and bone turnover. For each patient, VBQ score was calculated using T1-weighted lumbar MRI images. Univariable and multivariable analyses were used to identify the independent predictors of a new fragility fracture. To support the construct validity of VBQ, patient VBQ scores were compared to those in a cohort of 45 healthy adults.Results: Seventy-two (39.1%) study participants suffered fragility fractures, the occurrence of which was associated with higher VBQ score (3.50 vs. 3.01; p<.001), chronic glucocorticoid use (30.6% vs. 15.2%; p=.014), and a history of prior fragility fracture (36.1% vs. 21.4%; p=.030). Mean VBQ score across all patients in the study cohort was significantly higher than the mean VBQ score in the healthy controls (p<.001). In multivariable analysis, new-onset fracture was independently associated with history of prior fracture (OR=6.94; 95% confidence interval [2.48-19.40]; p<.001), higher VBQ score (OR=2.40 per point; [1.30-4.44]; p=.003), higher body mass index (OR=1.09 per kg/m²; [1.01-1.17]; p=.03), and chronic glucocorticoid use (OR=2.89; [1.03-8.17]; p=0.043). Notably, DXA bone mineral density (BMD) was not found to be significantly predictive of new-onset fractures in the multivariable analysis (p=.081).Conclusions: Here we demonstrate the novel, MRI-derived VBQ score is both an independent predictor of fragility fracture in at-risk patients and a superior predictor of fracture risk than DXA-measured BMD. Given the frequency with which MRIs are obtained by patients undergoing spine surgery consultation, we believe the VBQ score could be a valuable tool for estimating bone quality in order to optimize the management of these patients. [ABSTRACT FROM AUTHOR]

Good bone quality is key in avoiding a multitude of afflictions, including osteoporotic fragility fractures and poor outcomes after spine surgery. In patients undergoing instrumented spine fusion, bone quality often dictates screw pullout strength, insertional torque, and vertebral body loading properties. While dual-energy X-ray absorptiometry (DEXA) screening is the current method of assessing bone mineral density, the majority of patients do not have DEXA measurements available before undergoing surgical instrumentation. To create a simple magnetic resonance imaging (MRI)-based score to evaluate bone quality and evaluate the degree to which it correlates with conventional DEXA scores. Retrospective cohort. Patients ≥18 years of age undergoing spine surgery for degenerative conditions between 2013 and 2018. Correlation of the vertebral bone quality (VBQ) score with DEXA T-scores, and association between VBQ score and presence of osteopenia/osteoporosis. Using noncontrast T1-weighted MRIs of the lumbar spine, the novel VBQ score was calculated for each patient. DEXA T-scores of the femoral neck and total hip were obtained and were compared with patient VBQ scores using linear regression and Pearson's correlation. Among 68 patients included in this study, 37 were found to have osteopenia/osteoporosis (T-score < −1.0) based on DEXA. A greater VBQ score was significantly associated with the presence of osteopenia/osteoporosis with a predictive accuracy of 81%. VBQ scores correlated moderately with femoral neck T-scores, the lowest overall T-scores of each patient, and correlated fairly with total hip T-scores. This is the first study to correlate the novel VBQ score obtained from MRIs with DEXA T-score. We found this score to be a significant predictor of healthy versus osteopenic/osteoporotic bone with an accuracy of 81%, and found that VBQ score was moderately correlated with femoral neck and overall lowest T-score. [ABSTRACT FROM AUTHOR]