Preoperative MRI-based vertebral bone quality (VBQ) score assessment in patients undergoing lumbar spinal fusion

BACKGROUND CONTEXTThe importance of bone status assessment in spine surgery is well recognized. The current gold standard for assessing bone mineral density is dual-energy X-ray absorptiometry (DEXA). However, DEXA has been shown to overestimate BMD in patients with spinal degenerative disease and obesity. Consequently, alternative radiographic measurements using data routinely gathered during preoperative evaluation have been explored for the evaluation of bone quality and fracture risk. Opportunistic quantitative computed tomography (QCT) and more recently, the MRI-based vertebral bone quality (VBQ) score, have both been shown to correlate with DEXA T-scores and predict osteoporotic fractures. However, to date the direct association between VBQ and QCT has not been studied.PURPOSEThe objective of this study was to evaluate the correlation between VBQ and spine QCT BMD measurements and assess whether the recently described novel VBQ score can predict the presence of osteopenia/osteoporosis diagnosed with QCT.STUDY DESIGN/SETTINGCross-sectional study using retrospectively collected data.PATIENT SAMPLEPatients undergoing lumbar fusion from 2014-2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs were included.OUTCOME MEASURESCorrelation of the VBQ score with BMD measured by QCT, and association between VBQ score and presence of osteopenia/osteoporosis.METHODSAsynchronous QCT measurements were performed. The average L1-L2 BMD was calculated and patients were categorized as either normal BMD (>120 mg/cm³) or osteopenic/osteoporotic (≤120 mg/cm³). The VBQ score was calculated by dividing the median signal intensity of the L1-L4 vertebral bodies by the signal intensity of the cerebrospinal fluid on midsagittal T1-weighted MRI images. Inter-observer reliability testing of the VBQ measurements was performed. Demographic data and the VBQ score were compared between the normal and osteopenic/osteoporotic group. To determine the area-under-curve (AUC) of the VBQ score as a predictor of osteopenia/osteoporosis receiver operating characteristic (ROC) analysis was performed. VBQ scores were compared with QCT BMD using the Pearson's correlation.RESULTSA total of 198 patients (53% female) were included. The mean age was 62 years and the mean BMI was 28.2 kg/m². The inter-observer reliability of the VBQ measurements was excellent (ICC of 0.90). When comparing the patients with normal QCT BMD to those with osteopenia/osteoporosis, the patients with osteopenia/osteoporosis were significantly older (64.9 vs. 56.7 years, p<.0001). The osteopenic/osteoporotic group had significantly higher VBQ scores (2.6 vs. 2.2, p<.0001). The VBQ score showed a statistically significant negative correlation with QCT BMD (correlation coefficient = -0.358, 95% CI -0.473 - -0.23, p<.001). Using a VBQ score cutoff value of 2.388, the categorical VBQ score yielded a sensitivity of 74.3% and a specificity of 57.0% with an AUC of 0.7079 to differentiate patients with osteopenia/osteoporosis and with normal BMD.CONCLUSIONSWe found that the VBQ score showed moderate diagnostic ability to differentiate patients with normal BMD versus osteopenic/osteoporotic BMD based on QCT. VBQ may be an interesting adjunct to clinically performed bone density measurements in the future.     

MRI-based vertebral bone quality score effectively reflects bone quality in patients with osteoporotic vertebral compressive fractures

Objective

The present study is aimed to validate the ability of the vertebral bone quality (VBQ) score to evaluate bone quality in patients with osteoporotic vertebral compression fractures (OVCF) and to compare it with the ability of T-score by DXA. In addition, the sensitivity of VBQ score with cerebrospinal fluid (CSF) of L2 and L3 segments as baseline is evaluated.

Methods

196 inpatients were collected and assigned into OVCF and Non-OVCF groups, respectively. For each patient, the VBQ score was calculated by the signal intensity of the L1–L4 vertebral bodies and CSF at L3 or L2 level from T1-weighted MRIs, while T-score from DXA was also obtained. The VBQ and T-score was compared between OVCF and non-OVCF groups, and among age groups. The OVCF ORs by VBQ score and T-score were calculated using logistic regression.

Results

OVCF group was significantly different to the non-OVCF group in the T-score (− 2.9 vs. − 0.7) and VBQ score (4.0 vs. 3.5). VBQ score and T-score in patient aged 60–79 years old could indicate the bone quality, but only T-score in patients aged 50–59 years old. OVCF are associated with both higher VBQ score and lower T-score. The VBQ scores calculated by L2 CSF and L3 CSF were similar.

Conclusions

The VBQ score is an effective indicator of bone quality in OVCF patients and comparable to T-score, particularly in people over 60 years old. The VBQ score is not sensitive to CSF of different segments as a baseline.

     

Patient physiology influences the MRI-based vertebral bone quality score

BACKGROUND CONTEXTOsteoporosis is a critical issue affecting postmenopausal women and the aging population. A novel magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score has been proposed as a method to identify poor bone quality and predict fragility fractures. The diagnostic accuracy of this tool is not well understood.PURPOSETo examine the ability of VBQ to predict osteoporosis and osteopenia, its correlation with dual-energy x-ray absorptiometry (DEXA), and the influence of patient-specific factors upon the score.STUDY DESIGNRetrospective cohort study.PATIENT SAMPLEPatients over the age of 18 with a DEXA scan and noncontrast, T1-weighted MRI of the lumbar spine completed within a 2-year period.OUTCOME MEASURESArea-under-curve (AUC) values of the VBQ score predicting osteopenia and osteoporosis when controlling for patient characteristics.METHODSPatients with noncontrast, T1-weighted MRIs of the lumbar spine and DEXA scans completed within a 2-year time frame were retrospectively reviewed. Patient demographics and medical risk factors for osteoporosis were identified and compared. VBQ scores were measured by two trained researchers and interrater reliability was calculated. Patients were separated into three groups defined by lowest DEXA T-score: Healthy Bone, Osteopenia, and Osteoporosis. analysis of variance, Kruskal-Wallis test, chi-square, t tests, Mann-Whitney U tests, and multivariate linear regression were performed to examine the relationship between patient characteristics, DEXA t-scores, and VBQ scores. Receiver operating characteristic analysis and AUC values were generated for the prediction of osteopenia and osteoporosis.RESULTSA total of 156 patients were included for analysis. Sufficient inter-rater reliability was determined for VBQ measures (intraclass correlation coefficient: 0.81). Most patients were female (83%), postmenopausal (81%), and had hyperlipidemia (64%). Patients with hyperlipidemia and healthy bone density by DEXA had elevated baseline VBQ scores (p<.001) reflective of values seen in osteopenia and osteoporosis. The AUC of the VBQ score predicting osteopenia and osteoporosis changed to be more concordant with DEXA results after controlling for hyperlipidemia (AUC=0.72, 0.70 vs. AUC=0.88, 0.89; p<.001). Sub-analysis of hyperlipidemia subtypes revealed that elevated high-density lipoprotein is associated with elevated VBQ scores.CONCLUSIONSHyperlipidemia increased the MRI-based VBQ score in our healthy bone population. The high signal intensities resembled values seen in osteopenia and osteoporosis, suggesting that physiologic variables which impact bone composition may influence the VBQ score. Specifically, elevated high-density lipoprotein may contribute to this. The microarchitectural changes and the clinical implications of these factors need further exploration.     

The utility of lumbar spine trabecular bone score and femoral neck bone mineral density for identifying asymptomatic vertebral fractures in well-compensated type 2 diabetic patients

Summary

The objective of the study was to evaluate the usefulness of trabecular bone score (TBS) and bone mineral density (BMD) for identifying vertebral fractures (VFx) in well-compensated type 2 diabetic (T2D) patients. TBS and femoral neck BMD below certain cutoffs may be useful for identifying VFx in well-compensated T2D patients.

Introduction

In T2D, the prevalence of VFx is increased, especially in poorly compensated and complicated diabetic patients. The possibility of predicting the fracture risk in T2D patients by measuring BMD and TBS, an indirect parameter of bone quality, is under debate. Therefore, the objective was to evaluate the usefulness of TBS and BMD for identifying VFx in well-compensated T2D patients.

Methods

Ninety-nine T2D postmenopausal women in good metabolic control (glycosylated haemoglobin 6.8?±?0.7 %) and 107 control subjects without T2D were evaluated. In all subjects, we evaluated the following: the BMD at the lumbar spine (LS) and the femoral neck (FN); the TBS by dual X-ray absorptiometry; and VFx by radiography. In T2D subjects, the presence of diabetic retinopathy, neuropathy, and nephropathy was evaluated.

Results

T2D subjects had increased VFx prevalence (34.3 %) as compared to controls (18.7 %) (p?=?0.01). T2D subjects presented higher BMD (LS ?0.8?±?1.44, FN ?1.06?±?1.08), as compared to controls (LS ?1.39?±?1.28, p?=?0.002; FN ?1.45?±?0.91, p?=?0.006, respectively). TBS was not different between diabetics and controls. In fractured T2D patients, LS-BMD, FN-BMD, and TBS were reduced (?1.2?±?1.44; ?1.44?±?1.04; 1.072?±?0.15) and the prevalence of retinopathy (15.4 %) was increased than in nonfractured T2D subjects (?0.59?±?1.4, p?=?0.035; ?0.87?±?1.05, p?=?0.005; 1.159?±?0.15, p?=?0.006; 1.8 %, p?=?0.04, respectively). The combination of TBS ≤1.130 and FN-BMD less than ?1.0 had the best diagnostic accuracy for detecting T2D fractured patients (SP 73.8 %, SN 63.6 %, NPV 78.9 %, PPV 56.8 %).

Conclusions

TBS and FN-BMD below certain cutoffs may be useful for identifying VFx in well-compensated T2D patients.

     

Lumbar spine bone density in argentine children

It has been demonstrated that bone mineral density (BMD) in children and adolescents is influenced by individual height. The aim of the present work was to introduce a formula to include height in the BMD analysis. Postero-anterior (PA) (L2–L4) and lateral (L2–L3) lumbar BMD was assessed by dual X-ray absorptiometry (DXA) in 433 and 393, respectively, healthy Caucasian females from 2 to 20 years of age. A complete medical examination including weight, height, and Tanner puberal stage was performed in all the subjects. Bone age was assessed by left wrist radiographs and analyzed by the TW2 method to insure that it was within 1 year of chronological age. Bone mineral density adjusted for height (BMD_corr=BMC/projected area × height), was calculated for each individual. As analyzed by Tanner stage, both PA and lateral BMD increased up to stage 3, and there were no significant differences among stages 3–5. Results of BMD_corr variations related to Tanner stage suggested that the increase in lateral BMD before puberty might be related to height. PA BMD_corr increased up to Tanner stage 3, and there were no differences among stages 3–5. The BMD_CORR approach can be used to get a more reliable analysis of BMD studies in children and adolescents. This study was presented in part at the 16th Annual Meeting of the American Society for Bone and Mineral Research, Kansas City, Missouri, September, 1994 This study has been supported by a grant from the Metabolic Research Foundation, Buenos Aires, Argentina     

Added value of trabecular bone score over bone mineral density for identification of vertebral fractures in patients with areal bone mineral density in the non-osteoporotic range

Summary

Detection of patients with vertebral fracture is similar for areal bone mineral density (aBMD) and trabecular bone score (TBS) in patients with non-vertebral fracture. In non-osteoporotic patients, TBS adds information to lumbar spine aBMD and is related to an index of spine deterioration.

Introduction

Vertebral fractures (VFs) are more predictive of future fracture than aBMD. The number and severity of VFs are related to microarchitecture deterioration. TBS has been shown to be related to microarchitecture. The study aimed at evaluating TBS in the prediction of the presence and severity of VFs.

Methods

Patients were selected from a Fracture Liaison Service (FLS): aBMD and vertebral fracture assessment (VFA) were assessed after the fracture, using dual-energy X-ray-absorptiometry (DXA). VFs were classified using Genant's semiquantitative method and severity, using the spinal deformity index (SDI). TBS was obtained after analysis of DXA scans. Performance of TBS and aBMD was assessed using areas under the curves (AUCs).

Results

A total of 362 patients (77.3 % women; mean age 74.3?±?11.7 years) were analysed. Prevalence of VFs was 36.7 %, and 189 patients (52.2 %) were osteoporotic. Performance of TBS was similar to lumbar spine (LS) aBMD and hip aBMD for the identification of patients with VFs. In the population with aBMD in the non-osteoporotic range (n?=?173), AUC of TBS for the discrimination of VFs was higher than the AUC of LS aBMD (0.670 vs 0.541, p?=?0.035) but not of hip aBMD; there was a negative correlation between TBS and SDI (r?=??0.31; p?<?0.0001).

Conclusion

Detection of patients with vertebral fracture is similar for aBMD and TBS in patients with non-vertebral fracture. In patients with aBMD in the non-osteoporotic range, TBS adds information to lumbar spine aBMD alone and is related to an index of spine deterioration.     

骨小梁评分在2型糖尿病患者中评价骨质量的应用

目的探讨骨小梁评分(trabecular bone score,TBS)在评价2型糖尿病患者骨质量中的应用。方法回顾性分析128例2型糖尿病患者和64例非糖尿病患者的腰椎骨密度(bone mineral density,BMD)图像,通过骨小梁评分软件(TBS i Nsight software)计算得出骨小梁评分,分析两组患者的骨密度、骨小梁评分差异,并分析骨小梁评分和骨密度、年龄、体重的关系。结果和非糖尿病组相比,2型糖尿病患者组腰椎BMD升高(0.9103±0.1742 vs 0.8382±0.1422,P=0.005),TBS降低(1.2787±0.122 vs 1.3166±0.1016,P=0.033),在排除年龄、体重、骨密度的干扰后差异依然有统计学意义(P=0.008);相关性分析方面发现TBS和年龄呈负相关(r=-0.395,P0.001),和体质量指数呈负相关(r=-0.270,P0.001); TBS和腰椎BMD呈正相关,非糖尿病患者比糖尿病患者的相关性更强(r=0.563,P0.001 vs r=0.766,P0.001)。结论在2型糖尿病患者中骨小梁评分降低,这和2型糖尿病患者骨折风险增高的事实相符合,骨小梁评分可能成为评估2型糖尿病患者骨质量的指标。     

Experimental validation of DXA and MRI-based bone density measurement by ash-method

Different methods have been established for bone density measurements such as dual energy X-ray absorptiometry (DXA), quantitative computertomography (QCT), and scintigraphy (VQ-Scan). There are hints that magnetic resonance imaging (MRI) might become a new option for the evaluation of bone density. The aim of this study was to investigate correlations between MRI vs. DXA and MRI vs. mineral content of lumbar vertebrae. Data were obtained from ten lumbar vertebral bodies of cattles. The T-1 MRI-sequences SE, PS, and the T-2 Sequence STIR were used for analysis. Total pixel numbers and a pixel per area ratio were determined. Values were compared to DXA-measurements, to the wet weight, and to separated measurements of the spongious, trabecular, and total mineral content of the vertebral body after ashing. We found correlations between DXA (g/vertebral body) vs. mineral content by ash-method (0.918; p < 0.01), DXA vs. MRI (SE-sequence) (-0.872; p < 0.01), and MRI (SE-sequence) vs. mineral content (0.775; p < 0.01). No correlations were found between PS- or STIR-sequences and the ash-method. This study shows that the determination of the bone mineral content of vertebrae is possible applying MRI in the T1-weighted SE-sequence. Without radiation, the MRI provides additionally early detection of trabecular lesions, fractures, and deformities at the spine, without other diagnostic procedures becoming necessary.     

Effect of concomitant vitamin D deficiency or insufficiency on lumbar spine volumetric bone mineral density and trabecular bone score in primary hyperparathyroidism

Summary

Lower vitamin D and higher parathyroid hormone (PTH) levels are associated with higher volumetric BMD and bone strength at the lumbar spine as measured by central quantitative computed tomography in primary hyperparathyroidism (PHPT), but there are no differences in bone microarchitecture as measured by trabecular bone score (TBS).

Introduction

The purpose of this study was to evaluate the association between 25-hydroxyvitamin D (25OHD) and volumetric bone mineral density (vBMD) and the TBS at the lumbar spine (LS) in PHPT.

Methods

This is a cross-sectional analysis of PHPT patients with and without low 25OHD. We measured vBMD with quantitative computed tomography (cQCT) and TBS by dual-energy X-ray absorptiometry (DXA) at the LS in 52 and 88 participants, respectively.

Results

In the cQCT cohort, those with lower vitamin D (<20 vs. 20-29 vs. ≥30 ng/ml) tended to be younger (p?=?0.05), were less likely to use vitamin D supplementation (p?<?0.01), and had better renal function (p?=?0.03). Those with 25OHD <20 ng/ml had 80 and 126 % higher serum PTH levels respectively vs. those with 25OHD 20–29 ng/ml (p?=?0.002) and 25OHD ≥30 ng/ml (p?<?0.0001). Covariate-adjusted integral and trabecular vBMD were higher in those with 25OHD 20–29 vs. those with 25OHD ≥30 ng/ml, but those with 25OHD <20 did not differ. Because there were few participants with 25OHD deficiency, we also compared those with vitamin D <30 vs. ≥30 ng/ml. Covariate-adjusted integral and trabecular vBMD were 23 and 30 % higher respectively (both p?<?0.05) in those with vitamin D <30 vs. ≥30 ng/ml. TBS was in the partially degraded range but did not differ by vitamin D status.

Conclusion

In mild PHPT, lower 25OHD is associated with higher PTH, but vitamin D deficiency and insufficiency using current clinical thresholds did not adversely affect lumbar spine skeletal health in PHPT. Further work is needed to determine if higher vBMD in those with lower vitamin D is due to an anabolic effect of PTH.

     

Lateral bone density variations in the scoliotic spine

Adolescent Idiopathic Scoliosis (AIS) is the most common deformity of the spine, affecting 2–4% of the population. Previous studies have shown that the vertebrae in scoliotic spines undergo abnormal shape changes, however there has been little exploration of how scoliosis affects bone density distribution within the vertebrae.In this study, existing CT scans of 53 female idiopathic scoliosis patients with right-sided main thoracic curves were used to measure the lateral (right to left) bone density profile at mid-height through each vertebral body. Five key bone density profile measures were identified from each normalized bone density distribution, and multiple regression analysis was performed to explore the relationship between bone density distribution and patient demographics (age, height, weight, body mass index (BMI), skeletal maturity, time since Menarche, vertebral level, and scoliosis curve severity).Results showed a marked convex/concave asymmetry in bone density for vertebral levels at or near the apex of the scoliotic curve. At the apical vertebra, mean bone density at the left side (concave) cortical shell was 23.5% higher than for the right (convex) cortical shell, and cancellous bone density along the central 60% of the lateral path from convex to concave increased by 13.8%. The centre of mass of the bone density profile at the thoracic curve apex was located 53.8% of the distance along the lateral path, indicating a shift of nearly 4% toward the concavity of the deformity. These lateral bone density gradients tapered off when moving away from the apical vertebra. Multi-linear regressions showed that the right cortical shell peak bone density is significantly correlated with skeletal maturity, with each Risser increment corresponding to an increase in mineral equivalent bone density of 4–5%. There were also statistically significant relationships between patient height, weight and BMI, and the gradient of cancellous bone density along the central 60% of the lateral path. Bone density gradient is positively correlated with weight, and negatively correlated with height and BMI, such that at the apical vertebra, a unit decrease in BMI corresponds to an almost 100% increase in bone density gradient.     

Importance of bone mineral density in instrumented spine fusions

The effect of equivalent mineral density on pedicular screw fixation strength was investigated. The equivalent mineral density of human vertebral bodies was correlated highly with the pullout force of Kluger screws (r2 = 0.61, P less than 0.02). A moderate to high correlation existed between density and vertical force (r2 = 0.42 for Kluger screws, r2 = 0.55 for Steffee screws, P less than 0.02). In calf vertebral bodies of higher density (146 +/- 14 mg/cc), the forces were significantly higher than in the human vertebral bodies (P less than 0.05). Human lumbosacral spines were instrumented with three different fixators: Steffee plates, AO fixateur interne, and Kluger fixateur interne. Of five specimens with a mean density of 88 +/- 11 mg/cc, one screw loosened. More than one screw loosened in six specimens with a mean density of 63 +/- 12 mg/cc, and no screw loosened in four specimens with a mean density of 114 +/- 38 mg/cc. Measurement of equivalent mineral density correlates with the fixation strength of the intrapedicular screws in vitro and should be considered in patients with signs of osteopenia before using pedicular screws for spinal fusions. It is also concluded that calf spines are a good model for testing implants because they tend to focus failure processes in the implant rather than in the implant-bone interface.     

Identification of rheumatoid arthritis patients with vertebral fractures using bone mineral density and trabecular bone score

The aim of this study was to test bone mineral density (BMD), trabecular bone score (TBS), and their combination, for detection of rheumatoid arthritis (RA) patients with vertebral fractures (VFs). One hundred eighty-five women aged 56.0 ± 13.5 yr, with RA since 15.5 ± 9.9 yr were studied. Lumbar spine, total hip, and femoral neck BMD were assessed by dual-energy X-ray absorptiometry (DXA). TBS was calculated from anteroposterior image of lumbar spine BMD. VFs from T4 to L4 were evaluated using Vertebral Fracture Assessment software on DXA device. The proportions of patients with VF and T-scores ≤-2.5 were only 24.2%, 21.2%, and 33.3% at lumbar spine, total hip, and femoral neck, respectively. T-scores were significantly lower in patients with VF than in patients without VF, the largest difference being observed at femoral neck (p=0.0001). TBS was significantly lower in patients with VF vs without VF (p=0.0001). The areas under the curves were 0.621, 0.704, 0.703, 0.719, and 0.727 for lumbar spine BMD, TBS, lumbar spine BMD+TBS, total hip BMD, and femoral neck BMD, respectively. The threshold of 1.173 for TBS had the best sensitivity (63%) and specificity (74%). TBS measured at the lumbar spine has a better discrimination value than lumbar spine BMD, and similar to femoral neck BMD, for prediction of presence of VF in patients with RA. In RA subjects with osteopenia, the proportion of patients with VF was higher in the lowest tertile of TBS when compared with the highest tertile. In this population, at low risk according to BMD, TBS could help to detect patients with VF.     

Thoracic bone mineral density measured by quantitative computed tomography in patients undergoing spine surgery

BACKGROUND CONTEXTThe thoracic spine is a common location for vertebral fractures as well as instrumentation failure after long spinal fusion procedures. The association between those complications and bone mineral density (BMD) are well recognized. Due to the overlying sternum and ribs in the thoracic spine, projectional BMD assessment tools such as dual energy x-ray absorptiometry (DXA) are limited to the lumbar spine. Quantitative computed tomography circumvents several shortcomings of DXA and allows for level-specific BMD measurements. Studies comprehensively quantifying BMD of the entire thoracic spine in patients undergoing spine surgery are limited.PURPOSEThe objective of this study was: (1) to assess the reliability of thoracic QCT measurements, (2) to determine possible level-specific BMD variation throughout the thoracic spine and (3) to assess the correlation between BMDs of the T1-T12 spinal levels.STUDY DESIGN/SETTINGCross-sectional observation study.PATIENT SAMPLEPatients undergoing spine surgery from 2016–2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study.OUTCOME MEASURESThe outcome measure was BMD measured by QCT.METHODSPatients undergoing spine surgery from 2016–2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study. Subjects with previous instrumentation at any thoracic level, concurrent vertebral fractures, a Cobb angle of more than 20 degrees, or incomplete thoracic spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of T1-T12 were performed. To assess inter- and intra-observer reliability, a validation study was performed on 120 vertebrae in 10 randomly selected patients. The interclass correlation coefficient (ICC) was calculated. A pairwise comparison of BMD was conducted and correlations between each thoracic level were evaluated. The statistical significance level was set at p<.05.RESULTS60 patients (men, 51.7%) met inclusion criteria. The study population was 90% Caucasian with a mean age of 62.2 years and a mean BMI of 30.2 kg/m². The inter- and intra-observer reliability of the thoracic QCT measurements was excellent (ICC of 0.97 and 0.97, respectively). The trabecular BMD was highest in the upper thoracic spine and decreased in the caudal direction (T1 = 182.3 mg/cm³, T2 = 168.1 mg/cm³, T3 = 163.5 mg/cm³, T4 = 164.7 mg/cm³, T5 = 161.4 mg/cm³, T6 = 152.5 mg/cm³, T7 = 143.5 mg/cm³, T8 = 141.3 mg/cm³, T9 = 143.5 mg/cm³, T10 = 145.1 mg/cm³, T11 = 145.3 mg/cm³, T12 = 133.6 mg/cm³). The BMD of all thoracic levels cranial to T6 was statistically higher than the BMD of all levels caudal to T6 (p < .001). Nonetheless, significant correlations in BMD among all measured thoracic levels were observed, with a Pearson's correlation coefficient ranging from 0.74 to 0.97.CONCLUSIONSThere is significant regional BMD variation in the thoracic spine depending on spinal level. This BMD variation might contribute to several clinically relevant phenomena. First, vertebral fractures occur most commonly at the thoracolumbar junction including T12. In addition to mechanical reasons, these fractures might be partially attributed to thoracic BMD that is lowest at T12. Second, the optimal upper instrumented vertebra (UIV) for stopping long fusions to the sacrum and pelvis is controversial. The BMD of surgically relevant upper thoracic stopping points (T2-T4) was significantly higher than the BMD of lower thoracic stopping points (T10-T12). Besides stress concentration at the relatively mobile lower thoracic segments, the low BMD at these levels might contribute to previously suggested higher rates of junctional failures with short fusions.     

The Waterlow score for risk assessment in surgical patients

Introduction

Perioperative scoring systems aim to predict outcome following surgery and are used in preoperative counselling to guide management and to facilitate internal or external audit. The Waterlow score is used prospectively in many UK hospitals to stratify the risk of decubitus ulcer development. The primary aim of this study was to assess the potential value of this existing scoring system in the prediction of mortality and morbidity in a general surgical and vascular cohort.

Methods

A total of 101 consecutive moderate to high risk emergency and elective surgical patients were identified through a single institution database. The preoperative Waterlow score and outcome data pertaining to that admission were collected. The discriminatory power of the Waterlow score was compared against that of the American Society of Anesthesiologists (ASA) grade and the Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM).

Results

The inpatient mortality rate was 17% and the 30-day morbidity rate was 29%. A statistically significant association was demonstrated between the preoperative Waterlow score and inpatient mortality (p<0.0001) and 30-day morbidity (p=0.0002). Using a threshold Waterlow score of 20 to dichotomise risk, accuracies of 0.84 and 0.76 for prediction of mortality and morbidity were demonstrated. In comparison with P-POSSUM, the preoperative Waterlow score performed well on receiver operating characteristic analysis. With respect to mortality, the area under the curve was 0.81 (0.80–0.85) and for morbidity it was 0.72 (0.69–0.76). The ASA grade achieved a similar level of discrimination.

Conclusions

The Waterlow score is collected routinely by nursing staff in many hospitals and might therefore be an attractive means of predicting postoperative morbidity and mortality. It might also function to stratify perioperative risk for comparison of surgical outcome data. A prospective study comparing these risk prediction scores is required to support these findings.     

Clinical utility of spine bone density in elderly women.

It is common clinical practice to obtain a bone density measurement at both the hip and spine to evaluate osteoporosis. With aging, degenerative changes in the lumbar spine may elevate the bone mineral density (BMD) results giving false assurances that the fracture risk at the spine is low. We examined the association of spine osteoarthritis and bone mineral density in 1082 community-dwelling ambulatory older women aged 50-96 years who participated in a 1992-1996 osteoporosis research clinic visit. The BMD was measured at the hip and posteroanterior (PA) and lateral lumbar spine using dual energy X-ray absorptiometry (DXA). Spine osteoarthritis was identified on the PA lumbar spine DXA images by a musculoskeletal radiologist. Forty percent of women had evidence of spine osteoarthritis (OA). Women with spine OA had a mean age of 77.4 yr (95% confidence interval [CI]: 76.5-78.2), were significantly older than women without spine OA (mean age, 66.8 yr; 95% CI: 65.9-67.7), and were more likely to have prevalent radiographic fractures (14.2% vs. 9.5%; p<0.05). Age-adjusted BMD at the femoral neck, total hip, PA spine, and lateral spine was significantly higher in women with spine OA. Women with spine OA were more likely to have osteoporosis by the World Health Organization classification at the femoral neck and total hip than those without spine OA, but less likely based on the PA spine (14.4% vs. 24.5%). Despite higher BMD levels, women with OA of the lumbar spine had higher prevalence of osteoporosis at the hip and more radiographic vertebral fractures. In elderly women 65 yr and older who are likely to have spine OA, the DXA measurement of the spine may not be useful in assessing fracture risk, and DXA of the hip is recommended for identification of osteoporosis.     

腰椎骨质增生患者不同部位骨密度检查的临床分析

目的探讨骨质增生对不同部位骨密度测定的影响。方法以本院就诊有明确骨质增生的患者为研究对象(试验组),将无骨质增生患者作对照(对照组)。首先比较两组年龄、性别构成、髋部和腰椎骨密度T值、骨量分布情况的差别,然后将两组腰椎T值和髋部T值进行组内相关性分析。结果①试验组腰椎T值显著高于髋部T值,差异有统计学意义(P<0.01);对照组腰椎T值与髋部T值比较,差异无统计学意义(P>0.05)。②试验组髋部骨量与腰椎骨量差异显著,差异有统计学意义(P<0.05);对照组髋部骨量与腰椎骨量比较,差异无统计学意义(P>0.05)。③试验组腰椎正位T值与髋部T值存在正相关(r=0.657,P<0.01);对照组腰椎正位T值与髋部T值也存在正相关(r=0.968,P<0.01)。结论髋部骨密度检查可提高腰椎骨质增生患者骨质疏松的检出率。     

Vertebral bone quality score predicts fragility fractures independently of bone mineral density

BackgroundCurrent 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.PurposeTo 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/SettingRetrospective single-center cohort.Patient SamplePatients followed at a metabolic bone clinic for osteopenia and/or osteoporosis.Outcome MeasuresRadiographically-documented new-onset fragility fracture.MethodsPatients 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.ResultsSeventy-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).ConclusionsHere 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.