Change in Trabecular Bone Score (TBS) With Antiresorptive Therapy Does Not Predict Fracture in Women: The Manitoba BMD Cohort

Bone mineral density (BMD) and trabecular bone score (TBS), along with additional clinical risk factors, can be used to identify individuals at high fracture risk. Whether change in TBS in untreated or treated women independently affects fracture risk is unclear. Using the Manitoba (Canada) DXA Registry containing all BMD results for the population we identified 9044 women age ≥40 years with two consecutive DXA scans and who were not receiving osteoporosis treatment at baseline (baseline mean age 62 ± 10 years). We examined BMD and TBS change, osteoporosis treatment, and incident major osteoporotic fractures (MOFs) for each individual. Over a mean of 7.7 years follow‐up, 770 women developed an incident MOF. During the interval between the two DXA scans (mean, 4.1 years), 5083 women initiated osteoporosis treatment (bisphosphonate use 80%) whereas 3961 women did not receive any osteoporosis treatment. Larger gains in both BMD and TBS were seen in women with greater adherence to osteoporosis medication (p for trend <0.001), and the magnitude of the increase was consistently greater for BMD than for TBS. Among treated women there was greater antifracture effect for each SD increase in total hip BMD change (fracture decrease 20%; 95% CI, 13% to 26%; p < 0.001), femoral neck BMD change (19%; 95% CI, 12% to 26%; p < 0.001), and lumbar spine BMD change (9%; 95% CI, 0% to 17%; p = 0.049). In contrast, change in TBS did not predict fractures in women who initiated osteoporosis treatment (p = 0.10). Among untreated women neither change in BMD or TBS predicted fractures. We conclude that, unlike antiresorptive treatment–related changes in BMD, change in lumbar spine TBS is not a useful indicator of fracture risk irrespective of osteoporosis treatment. © 2016 American Society for Bone and Mineral Research.     

Bone microarchitecture assessed by TBS predicts osteoporotic fractures independent of bone density: the Manitoba study

The measurement of BMD by dual‐energy X‐ray absorptiometry (DXA) is the “gold standard” for diagnosing osteoporosis but does not directly reflect deterioration in bone microarchitecture. The trabecular bone score (TBS), a novel gray‐level texture measurement that can be extracted from DXA images, correlates with 3D parameters of bone microarchitecture. Our aim was to evaluate the ability of lumbar spine TBS to predict future clinical osteoporotic fractures. A total of 29,407 women 50 years of age or older at the time of baseline hip and spine DXA were identified from a database containing all clinical results for the Province of Manitoba, Canada. Health service records were assessed for the incidence of nontraumatic osteoporotic fracture codes subsequent to BMD testing (mean follow‐up 4.7 years). Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Osteoporotic fractures were identified in 1668 (5.7%) women, including 439 (1.5%) spine and 293 (1.0%) hip fractures. Significantly lower spine TBS and BMD were identified in women with major osteoporotic, spine, and hip fractures (all p < 0.0001). Spine TBS and BMD predicted fractures equally well, and the combination was superior to either measurement alone (p < 0.001). Spine TBS predicts osteoporotic fractures and provides information that is independent of spine and hip BMD. Combining the TBS trabecular texture index with BMD incrementally improves fracture prediction in postmenopausal women. © 2011 American Society for Bone and Mineral Research     

Clinical Factors Associated With Trabecular Bone Score

Dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD) is the reference standard for diagnosing osteoporosis but does not directly reflect deterioration in bone microarchitecture. The trabecular bone score (TBS), a novel grey-level texture measurement that can be extracted from DXA images, predicts osteoporotic fractures independent of BMD. Our aim was to identify clinical factors that are associated with baseline lumbar spine TBS. In total, 29,407 women ≥50 yr at the time of baseline hip and spine DXA were identified from a database containing all clinical results for the Province of Manitoba, Canada. Lumbar spine TBS was derived for each spine DXA examination blinded to clinical parameters and outcomes. Multiple linear regression and logistic regression (lowest vs highest tertile) was used to define the sensitivity of TBS to other risk factors associated with osteoporosis. Only a small component of the TBS measurement (7–11%) could be explained from BMD measurements. In multiple linear regression and logistic regression models, reduced lumbar spine TBS was associated with recent glucocorticoid use, prior major fracture, rheumatoid arthritis, chronic obstructive pulmonary disease, high alcohol intake, and higher body mass index. In contrast, recent osteoporosis therapy was associated with a significantly lower likelihood for reduced TBS. Similar findings were seen after adjustment for lumbar spine or femoral neck BMD. In conclusion, lumbar spine TBS is strongly associated with many of the risk factors that are predictive of osteoporotic fractures. Further work is needed to determine whether lumbar spine TBS can replace some of the clinical risk factors currently used in fracture risk assessment.     

Effects of zoledronate versus placebo on spine bone mineral density and microarchitecture assessed by the trabecular bone score in postmenopausal women with osteoporosis: A three‐year study

The trabecular bone score (TBS) is an index of bone microarchitectural texture calculated from anteroposterior dual‐energy X‐ray absorptiometry (DXA) scans of the lumbar spine (LS) that predicts fracture risk, independent of bone mineral density (BMD). The aim of this study was to compare the effects of yearly intravenous zoledronate (ZOL) versus placebo (PLB) on LS BMD and TBS in postmenopausal women with osteoporosis. Changes in TBS were assessed in the subset of 107 patients recruited at the Department of Osteoporosis of the University Hospital of Berne, Switzerland, who were included in the HORIZON trial. All subjects received adequate calcium and vitamin D3. In these patients randomly assigned to either ZOL (n = 54) or PLB (n = 53) for 3 years, BMD was measured by DXA and TBS assessed by TBS iNsight (v1.9) at baseline and 6, 12, 24, and 36 months after treatment initiation. Baseline characteristics (mean ± SD) were similar between groups in terms of age, 76.8 ± 5.0 years; body mass index (BMI), 24.5 ± 3.6 kg/m²; TBS, 1.178 ± 0.1 but for LS T‐score (ZOL–2.9 ± 1.5 versus PLB–2.1 ± 1.5). Changes in LS BMD were significantly greater with ZOL than with PLB at all time points (p < 0.0001 for all), reaching +9.58% versus +1.38% at month 36. Change in TBS was significantly greater with ZOL than with PLB as of month 24, reaching +1.41 versus–0.49% at month 36; p = 0.031, respectively. LS BMD and TBS were weakly correlated (r = 0.20) and there were no correlations between changes in BMD and TBS from baseline at any visit. In postmenopausal women with osteoporosis, once‐yearly intravenous ZOL therapy significantly increased LS BMD relative to PLB over 3 years and TBS as of 2 years. © 2013 American Society for Bone and Mineral Research.     

非骨密度DXA测量对骨折风险的预测——骨小梁评分（TBS）：ISCD 2015官方共识（第四部分）

DXA测量骨密度(BMD)是诊断和治疗骨质疏松症的金标准,但是BMD只能解释60%～80%的骨强度,除BMD外还有众多其他骨骼特征与骨强度和骨折风险相关。且可以通过先进的影像技术获得这些骨骼特征。但是与传统的DXA相比较,这些技术的费用较高且获取不易。因此,在标准DXA测量基础和临床风险因素上,发展能够提升骨折预测的非侵入性检查技术来满足临床实践要求是一个重要的挑战。为此,骨小梁评分(trabecular bone score),一个从腰椎DXA图像衍生而来的灰阶结构指数被研究出来。ISCD专题工作组的目的是复习相关证据并提出如何在临床工作中使用TBS的建议。在临床中应用TBS来进行骨折风险评估、指导治疗、治疗监测和使用,以及在关于更高骨折风险的情况下如何使用TBS被一一列出。我们通过专家组对工作组的建议和证据进行了仔细的评审后推出了此官方立场。     

Spine Trabecular Bone Score Subsequent to Bone Mineral Density Improves Fracture Discrimination in Women

Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is used to diagnose osteoporosis and assess fracture risk. However, DXA cannot evaluate trabecular microarchitecture. This study used a novel software program (TBS iNsight; Med-Imaps, Geneva, Switzerland) to estimate bone texture (trabecular bone score [TBS]) from standard spine DXA images. We hypothesized that TBS assessment would differentiate women with low trauma fracture from those without. In this study, TBS was performed blinded to fracture status on existing research DXA lumbar spine (LS) images from 429 women. Mean participant age was 71.3 yr, and 158 had prior fractures. The correlation between LS BMD and TBS was low (r = 0.28), suggesting these parameters reflect different bone properties. Age- and body mass index–adjusted odds ratios (ORs) ranged from 1.36 to 1.63 for LS or hip BMD in discriminating women with low trauma nonvertebral and vertebral fractures. TBS demonstrated ORs from 2.46 to 2.49 for these respective fractures; these remained significant after lowest BMD T-score adjustment (OR = 2.38 and 2.44). Seventy-three percent of all fractures occurred in women without osteoporosis (BMD T-score > −2.5); 72% of these women had a TBS score below the median, thereby appropriately classified them as being at increased risk. In conclusion, TBS assessment enhances DXA by evaluating trabecular pattern and identifying individuals with vertebral or low trauma fracture. TBS identifies 66–70% of women with fracture who were not classified with osteoporosis by BMD alone.     

Ethnicity and Fracture Risk Stratification from Trabecular Bone Score in Canadian Women: The Manitoba BMD Registry

Lumbar spine Trabecular Bone Score (TBS), a grey-level texture measure derived from spine dual-energy x-ray absorptiometry (DXA) images, is a bone mineral density (BMD)-independent risk factor for fracture. An unresolved and controversial question is whether there are ethnic differences that affect the utility of TBS for fracture risk assessment. The current analysis examined whether self-identified ethnicity (White, Asian, Black) in women age 40 years and older referred for DXA testing affected fracture risk stratification from TBS using a large clinical registry. The study population comprised 63,078 White women, 1,915 Asian women and 329 Black women (n=329) with mean follow up 9.0±5.2 years. There were between group differences in BMI (Black>White>Asian), lumbar spine fat percentage (Asian>White>Black) and lumbar spine tissue thickness (Black>White>Asian). Despite this, lumbar spine TBS was not significantly different between the subgroups, though there was a significant difference in lumbar spine and total hip BMD (Black >White>Asian). TBS provided significant stratification for MOF and any fracture for all ethnicity subgroups, and for hip fracture in White and Asian subgroups (insufficient numbers for analysis in Black women). No significant difference in White vs. Asian or White vs. Black women were identified using a Bonferroni adjusted p-value. In summary, we found that lumbar spine TBS measurements were similar among White, Asian and Black women referred for DXA assessment in Manitoba, Canada. TBS and BMD measurements significantly stratified fracture risk in all three populations without a meaningful difference between groups. This suggests that TBS does not need to be used differently in White vs. non-White populations.     

Prevalence of low bone mineral density in a low‐income inner‐city population

Bone mineral density (BMD) is an important factor linked to bone health. Little is known of the prevalence of low BMD and its associated risk factors in an urban underserved population. Between 2001 and 2004, we recruited 338 subjects who completed drug use and medical history questionnaires, underwent hormonal measurements, and underwent whole‐body dual‐energy X‐ray absorptiometry (DXA) for evaluation of BMD and body composition. Of these, 132 subjects had site‐specific DXA (lumbar spine and hip) performed. Osteoporosis was defined as a T‐score of –2.5 or less for men 50 years of age and older and postmenopausal women and a Z‐score of –2.0 or less in men younger than 50 years of age and premenopausal women at either the lumbar spine, total hip, or femoral neck, according to National Osteoporosis Foundation (NOF) guidelines. The cohort consisted of mostly African‐American, middle‐aged people with a high prevalence of illicit drug use, 50% HIV⁺, and 39% hepatitis C⁺. Osteoporosis was identified in 22% of subjects (24 men, 5 women), with the majority of cases (90%) attributable to osteoporosis at the lumbar spine. Osteoporosis was more common in men than in women. Lower whole‐body BMD among women was associated with multiple risk factors, but only with lower lean mass among men. Osteoporosis was highly prevalent in men, mainly at the spine. The risk factors for bone loss in this population need to be further clarified. Screening men for osteoporosis starting at age 50 might be warranted in this population given the multiple risk factors and the unexpectedly high prevalence of low BMD. © 2011 American Society for Bone and Mineral Research.     

A comparison of fracture discrimination using calcaneal quantitative ultrasound and dual X-ray absorptiometry in women with a history of fracture at sites other than the spine and hip

The aim of this study was to determine whether calcaneal quantitative ultrasound can discriminate between women with and those without fragility fracture at (1) the wrist or (2) at sites other than the spine, hip, or forearm, as well as axial DXA measurements of BMD can. The study population consisted of 342 postmenopausal Caucasian women who were placed into one of three groups: (1) healthy women with no clinical risk factors for osteoporosis (n = 240); (2) women with a history of atraumatic fracture at the wrist (n = 50); (3) women with a history of atraumatic fracture at a skeletal site other than the spine, hip, or wrist (n = 52). Subjects had DXA measurements of the lumbar spine (LS), femoral neck (FN), and total hip (THIP), and calcaneal broadband ultrasound attenuation (BUA) and speed of sound (SOS) measurements on the Hologic Sahara (s) and Osteometer DTUone (d). Z-scores were calculated using the mean and SD obtained from the healthy postmenopausal group. All the BMD and QUS variables were significantly reduced in women reporting a fracture of the wrist or at a site other than the spine, hip, or forearm. When the group of women with a history of wrist fracture were compared with the postmenopausal controls, age-adjusted logistic regression yielded odds ratios associated with a 1 SD decrease, that were significant for both BMD and QUS, averaging 2.2. The AUC values ranged from 0.65 for FN BMD to 0.75 for BUAd. BMD and QUS measurements were also significantly reduced in women reporting a skeletal fracture at a site other than the spine, hip, or wrist, and odds ratios for BMD and QUS were significant, averaging 1.7. BMD and QUS showed similar fracture discriminatory abilities that were not significantly different from one another. In conclusion, calcaneal QUS can discriminate between women with and those without fracture at the wrist or at sites other than the spine, hip, or forearm as well as axial DXA measurements of BMD can.     

Post-fracture Risk Assessment: Target the Centrally Sited Fractures First! A Substudy of NoFRACT

The location of osteoporotic fragility fractures adds crucial information to post-fracture risk estimation. Triaging patients according to fracture site for secondary fracture prevention can therefore be of interest to prioritize patients considering the high imminent fracture risk. The objectives of this cross-sectional study were therefore to explore potential differences between central (vertebral, hip, proximal humerus, pelvis) and peripheral (forearm, ankle, other) fractures. This substudy of the Norwegian Capture the Fracture Initiative (NoFRACT) included 495 women and 119 men ≥50 years with fragility fractures. They had bone mineral density (BMD) of the femoral neck, total hip, and lumbar spine assessed using dual-energy X-ray absorptiometry (DXA), trabecular bone score (TBS) calculated, concomitantly vertebral fracture assessment (VFA) with semiquantitative grading of vertebral fractures (SQ1–SQ3), and a questionnaire concerning risk factors for fractures was answered. Patients with central fractures exhibited lower BMD of the femoral neck (765 versus 827 mg/cm²), total hip (800 versus 876 mg/cm²), and lumbar spine (1024 versus 1062 mg/cm²); lower mean TBS (1.24 versus 1.28); and a higher proportion of SQ1-SQ3 fractures (52.0% versus 27.7%), SQ2–SQ3 fractures (36.8% versus 13.4%), and SQ3 fractures (21.5% versus 2.2%) than patients with peripheral fractures (all p < 0.05). All analyses were adjusted for sex, age, and body mass index (BMI); and the analyses of TBS and SQ1–SQ3 fracture prevalence was additionally adjusted for BMD). In conclusion, patients with central fragility fractures revealed lower femoral neck BMD, lower TBS, and higher prevalence of vertebral fractures on VFA than the patients with peripheral fractures. This suggests that patients with central fragility fractures exhibit more severe deterioration of bone structure, translating into a higher risk of subsequent fragility fractures and therefore they should get the highest priority in secondary fracture prevention, although attention to peripheral fractures should still not be diminished. © 2019 American Society for Bone and Mineral Research. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.     

Bone marrow fat composition as a novel imaging biomarker in postmenopausal women with prevalent fragility fractures

The goal of this magnetic resonance (MR) imaging study was to quantify vertebral bone marrow fat content and composition in diabetic and nondiabetic postmenopausal women with fragility fractures and to compare them with nonfracture controls with and without type 2 diabetes mellitus. Sixty‐nine postmenopausal women (mean age 63 ± 5 years) were recruited. Thirty‐six patients (47.8%) had spinal and/or peripheral fragility fractures. Seventeen fracture patients were diabetic. Thirty‐three women (52.2%) were nonfracture controls. Sixteen women were diabetic nonfracture controls. To quantify vertebral bone marrow fat content and composition, patients underwent MR spectroscopy (MRS) of the lumbar spine at 3 Tesla. Bone mineral density (BMD) was determined by dual‐energy X‐ray absorptiometry (DXA) of the hip and lumbar spine (LS) and quantitative computed tomography (QCT) of the LS. To evaluate associations of vertebral marrow fat content and composition with spinal and/or peripheral fragility fractures and diabetes, we used linear regression models adjusted for age, race, and spine volumetric bone mineral density (vBMD) by QCT. At the LS, nondiabetic and diabetic fracture patients had lower vBMD than controls and diabetics without fractures (p = 0.018; p = 0.005). However, areal bone mineral density (aBMD) by DXA did not differ between fracture and nonfracture patients. After adjustment for age, race, and spinal vBMD, the prevalence of fragility fractures was associated with ?1.7% lower unsaturation levels (confidence interval [CI] ?2.8% to ?0.5%, p = 0.005) and +2.9% higher saturation levels (CI 0.5% to 5.3%, p = 0.017). Diabetes was associated with ?1.3% (CI –2.3% to ?0.2%, p = 0.018) lower unsaturation and +3.3% (CI 1.1% to 5.4%, p = 0.004) higher saturation levels. Diabetics with fractures had the lowest marrow unsaturation and highest saturation. There were no associations of marrow fat content with diabetes or fracture. Our results suggest that altered bone marrow fat composition is linked with fragility fractures and diabetes. MRS of spinal bone marrow fat may therefore serve as a novel tool for BMD‐independent fracture risk assessment.     

Trabecular bone score (TBS): available knowledge,clinical relevance,and future prospects

The diagnosis of osteoporosis rests on areal bone mineral density (BMD) measurement using DXA. Cancellous bone microarchitecture is a key determinant of bone strength but cannot be measured using DXA. To meet the need for a clinical tool capable of assessing bone microarchitecture, the TBS was developed. The TBS is a texture parameter that evaluates pixel gray-level variations in DXA images of the lumbar spine. The TBS variations may reflect bone microarchitecture. We explain the general principles used to compute the TBS, and we report the correlations between TBS and microarchitectural parameters. Several limitations of the TBS as it is used now are pointed out. We discuss data from currently available clinical studies on the ability of the TBS to identify patients with fractures and to evaluate the fracture risk. We conclude that this new index emphasizes the failure of the BMD T-score to fully capture the fragility fracture risk. However, although microarchitecture may influence the TBS, today, to the best of our understanding, there is no sufficient evidence that a TBS measurement provides reliable information on the status of the bone microarchitecture for a given patient. The TBS depends on gray-level variations and in a projectional image obtained in vivo, these variations can have many causes. Nevertheless, as clinical studies suggest that the TBS predicts the risk of fracture even after adjustment for BMD, we are encouraged to learn more about this score. Additional studies will have to be performed to assess the advantages and limitations of the TBS, in order to ensure that it is used appropriately in clinical practice.     

Validation and comparative evaluation of four osteoporosis risk indexes in Moroccan menopausal women

Introduction Measuring bone mineral density (BMD) is a widely accepted strategy for identifying subjects with an increased risk of fracture. However, because of limited availability of BMD technology in some communities and cost considerations, it has been proposed that BMD measurements be targeted to subjects with risk factors for osteoporosis. Recently, many risk assessment indices have been developed to identify women who are more likely to have low BMD and thus undergo BMD testing. The objective of this study was to compare the performance of four risk indices for osteoporosis in white women in Morocco. Methods We analysed in an epidemiological cross-sectional study the records for 986 postmenopausal white Moroccan women seen at an out-patient rheumatology centre. Four osteoporosis risk index scores were compared to bone density T-scores. The ability of each risk index to identify women with low BMD (T-score<−2.0) or osteoporosis (T<−2.5) was evaluated. Results Using an Osteoporosis Self-Assessment Tool (OST) score<2 to recommend DXA referral, we found that sensitivity ranged from 61% at the lumbar spine to 85% at the total hip to detect BMD T-scores of −2.5, and specificity ranged from 62% at the lumbar spine to 67% at the total hip. The negative predictive value was high at all skeletal sites (79–98%), demonstrating the usefulness of the OST to identify patients who have normal BMD and should not receive DXA testing. All risk indices performed similarly and showed better results in identifying women with osteoporosis or low BMD based on hip measurement. Conclusions This is the first study that validated several risk osteoporosis indexes in Moroccan women. The performance of these risk indices among women in Morocco was similar to that reported earlier for other samples in Asian countries, the US, and Belgium. The OST and other risk indices are effective and efficient tools to help target high-risk women for DXA measurement.     

Trabecular Bone Score (TBS) in Primary Hyperparathyroidism (PHPT): A Useful Tool?

Primary Hyperparathyroidism (PHPT) often leads to bone loss, even in its asymptomatic presentations. Trabecular Bone Score (TBS) is a method to assess the trabecular bone structure of the spine. This study aimed to evaluate TBS measurements combined with Dual X-ray Absorptiometry (DXA) values in the search for more accurate bone fragility risk assessment among PHPT patients. From 2017 to 2019, patients diagnosed with PHPT (n = 64), before surgery, were invited to participate in this study. Bone mineral density (BMD) by DXA at the lumbar spine, total hip, femoral neck, distal third radius, and TBS were determined in patients and controls (n = 63). The vertebral fracture was defined using the Genant method in vertebral images by DXA and vertebral fracture assessment (VFA). Patients and controls did not differ in age, sex, menopausal status, or body mass index (BMI). The PHPT patients presented significantly lower BMD values than the controls in all sites evaluated. The TBS measurements were also statistically lower in PHPT patients than controls (mean TBS PHPT = 1.233 vs TBS controls = 1.280, p = 0.044). Osteoporosis was observed in 50% of PHPT patients and 26.6% of controls (p = 0.02). However, lumbar spine T-Score < -2.5 was observed only in 21.8% of PHPT patients. Vertebral fractures were detected in nine individuals (14%) from the PHPT group and four (6.3%) in the controls (p = 0.24). The TBS area under the curve (AUC) was higher than DXA AUC in all sites, for vertebral fracture assessment. The TBS AUC was significant in the PHPT group (0.75, 95% CI 0.62 - 0.88, p = 0.02) and not significant in the DXA analysis. The ROC curve showed that TBS values < 1.187 are associated with a significantly higher risk of vertebral fracture among PHPT patients (p = 0.02). The TBS used as a complement to DXA measurements is a useful tool which may better assess fragility risk among PHPT patients.     

Evaluation of the Potential Use of Trabecular Bone Score to Complement Bone Mineral Density in the Diagnosis of Osteoporosis: A Preliminary Spine BMD–Matched,Case-Control Study

The trabecular bone score (TBS) is a new parameter that is determined from gray-level analysis of dual-energy X-ray absorptiometry (DXA) images. It relies on the mean thickness and volume fraction of trabecular bone microarchitecture. This was a preliminary case-control study to evaluate the potential diagnostic value of TBS as a complement to bone mineral density (BMD), by comparing postmenopausal women with and without fractures. The sample consisted of 45 women with osteoporotic fractures (5 hip fractures, 20 vertebral fractures, and 20 other types of fracture) and 155 women without a fracture. Stratification was performed, taking into account each type of fracture (except hip), and women with and without fractures were matched for age and spine BMD. BMD and TBS were measured at the total spine. TBS measured at the total spine revealed a significant difference between the fracture and age– and spine BMD–matched nonfracture group, when considering all types of fractures and vertebral fractures. In these cases, the diagnostic value of the combination of BMD and TBS likely will be higher compared with that of BMD alone. TBS, as evaluated from standard DXA scans directly, potentially complements BMD in the detection of osteoporotic fractures. Prospective studies are necessary to fully evaluate the potential role of TBS as a complementary risk factor for fracture.     

Noninvasive Assessment of Skeletal Microstructure and Estimated Bone Strength in Hypoparathyroidism

In hypoparathyroidism, areal bone mineral density (BMD) by dual‐energy X‐ray absorptiometry (DXA) is above average, and skeletal indices by bone biopsy are abnormal. We used high‐resolution peripheral quantitative computed tomography (HRpQCT) and finite element analyses (FEA) to further investigate skeletal microstructure and estimated bone strength. We studied 60 hypoparathyroid subjects on conventional therapy using DXA, HRpQCT, and FEA of the distal radius and tibia compared with normative controls from the Canadian Multicentre Osteoporosis Study. In hypoparathyroid women and men, areal BMD was above average at the lumbar spine and hip sites by DXA; radial BMD was also above average in hypoparathyroid women. Using HRpQCT, cortical volumetric BMD was increased in the hypoparathyroid cohort compared with controls at both the radius and tibia. Cortical porosity was reduced at both sites in pre‐ and postmenopausal women and at the tibia in young men with a downward trend at the radius in men. At the tibia, trabecular number was increased in premenopausal women and men and trabecular thickness was lower in women. Ultimate stress and failure load at both sites for the hypoparathyroid subjects were similar to controls. Using a linear regression model, at both radius and tibia, each increment in age decreased ultimate stress and failure load, whereas each increment in duration of hypoparathyroidism increased these same indices. These results provide additional evidence for the critical role of parathyroid hormone in regulating skeletal microstructure. Longer disease duration may mitigate the adverse effects of age on estimated bone strength in hypoparathyroidism. © 2015 American Society for Bone and Mineral Research.     

Bone Microarchitecture Assessed by HR‐pQCT as Predictor of Fracture Risk in Postmenopausal Women: The OFELY Study

Several cross‐sectional studies have shown that impairment of bone microarchitecture contributes to skeletal fragility. The aim of this study was to prospectively investigate the prediction of fracture (Fx) by bone microarchitecture assessed by high‐resolution peripheral computed tomography (HR‐ pQCT) in postmenopausal women. We measured microarchitecture at the distal radius and tibia with HR‐pQCT in the OFELY study, in addition to areal BMD with dual‐energy X‐ray absorptiometry (DXA) in 589 women, mean ± SD age 68 ± 9 years. During a median [IQ] 9.4 [1.0] years of follow‐up, 135 women sustained an incident fragility Fx, including 81 women with a major osteoporotic Fx (MOP Fx). After adjustment for age, women who sustained Fx had significantly lower total and trabecular volumetric densities (vBMD) at both sites, cortical parameters (area and thickness at the radius, vBMD at the tibia), trabecular number (Tb.N), connectivity density (Conn.D), stiffness, and estimated failure load at both sites, compared with control women. After adjustment for age, current smoking, falls, prior Fx, use of osteoporosis‐related drugs, and total hip BMD, each quartile decrease of several baseline values of bone microarchitecture at the radius was associated with significant change of the risk of Fx (HR of 1.39 for Tb.BMD [p = 0.001], 1.32 for Tb.N [p = 0.01], 0.76 for Tb.Sp.SD [p = 0.01], 1.49 [p = 0.01] for Conn.D, and 1.27 for stiffness [p = 0.02]). At the tibia, the association remained significant for stiffness and failure load in the multivariate model for all fragility Fx and for Tt.BMD, stiffness, and failure load for MOP Fx. We conclude that impairment of bone microarchitecture—essentially in the trabecular compartment of the radius—predict the occurrence of incident fracture in postmenopausal women. This assessment may play an important role in identifying women at high risk of fracture who could not be adequately detected by BMD measurement alone, to benefit from a therapeutic intervention. © 2017 American Society for Bone and Mineral Research.     

TBS在监测及诊断骨质疏松方面的应用价值

利用DXA（dual energy X-ray absorptiometry,双能X线吸收法）测得的单位面积骨密度值（areal bone mineral density,BMD）是诊断骨质疏松的金标准。骨质疏松患者骨量减少的同时通常存在骨微结构的退化,表现为骨小梁数量减少、间距增加以及骨小梁间连接性下降,而BMD仅能显示骨量的变化,不能提供关于骨结构的信息。因此,仅靠BMD来诊断或排除骨质疏松是不全面的。骨小梁分数（trabecular bone score,TBS）是一种可由DXA图像获得的反映图像上灰阶变化的结构参数,能有效评估骨的微结构、描述骨的质量。本文将从TBS的检测方法、与其他检测骨折风险指标之间的关系以及TBS的有效性和不足等方面来介绍TBS在监测及诊断骨质疏松方面的应用价值。     

Comparison between T-score-based diagnosis of osteoporosis and specific skeletal site measurements: prognostic value for predicting fracture risk.

T-score-based diagnosis of osteoporosis might lead to diagnostic misclassification when using multiple-site bone mineral density (BMD) measurements. To compare the diagnostic concordance of T-score-based diagnosis of osteoporosis among different skeletal sites and its correlation to osteoporotic fracture, we studied 1200 postmenopausal women with (441) and without (759) fragility fracture after measuring BMD at the femoral neck, Ward's triangle, trochanter, and spine. Agreement rates of T-score-based diagnosis of osteoporosis were statistically different between pairs of measurements taken at different skeletal sites (McNemar test, p < 0.001). Fragility fractures poorly matched T-score-based diagnosis of osteoporosis (Cohen and Younden indexes <0.4). Technique inaccuracies support these discrepancies as also shown by the large range of T-score values (from -2 to -3) with similar abilities to predict fractures by ROC curve area comparison. Concordance rates between T-score and fragility fracture diagnosis of osteoporosis (marginal homogeneity test, p < 0.001) were also different across the various measurement sites. Our data show that the T-score leads to diagnostic inconsistencies among different skeletal sites and low concordance with fragility fracture based diagnosis of osteoporosis. Integration of the T-score with multiple risk assessment from clinical sources should be tested to better diagnose osteoporosis and related fracture risk.     

Clinical Utility of Using Lumbar Spine Trabecular Bone Score to Adjust Fracture Probability: The Manitoba BMD Cohort

Decreased lumbar spine trabecular bone score (TBS), a dual‐energy X‐ray absorptiometry (DXA)‐derived image texture measurement, is a risk factor for major osteoporotic fracture (MOF) and hip fracture (HF) independent of 10‐year fracture probability estimated using FRAX. We determined how often applying the TBS adjustment to fracture probability altered treatment qualification. Using a population‐based registry containing all clinical DXA results for Manitoba, Canada, we identified 34,316 women with baseline spine and hip DXA, FRAX‐based fracture probability measurements (computed with femoral neck bone mineral density), lumbar spine TBS, and minimum 5 years of observation (mean 8.7 years). Population‐based health services data were used to identify incident non‐traumatic MOF and HF in 3503 and 945 women, respectively. Baseline MOF and HF probabilities were estimated using FRAX before and after applying the TBS adjustment. Risk recategorization was assessed using net reclassification improvement (NRI) for individual FRAX‐based intervention criteria and three national clinical practice guidelines (CPGs) (US National Osteoporosis Foundation, Osteoporosis Canada, and UK National Osteoporosis Guideline Group). Overall, proportions of women reclassified with the TBS adjustment to FRAX were small (less than 5%) with more than 90% of the reclassification occurring close to the intervention threshold. For women close to an intervention cut‐off reclassification, rates ranged from 9.0% to 17.9% and were <1% otherwise. There was a small but significant improvement in overall NRI for all individual FRAX‐based intervention criteria (range 0.007 to 0.018) and all three national CPGs (range 0.008 to 0.011). NRI was larger in women below age 65 years (up to 0.056 for hip fracture). In summary, a small but significant improvement in MOF and HF risk assessment was found by using lumbar spine TBS to adjust FRAX probability. An improvement in risk reclassification was observed for CPGs from three different countries, with almost all of the benefit found in individuals close to an intervention threshold. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone and Mineral Research.