Assessing bone impairment in ankylosing spondylitis (AS) using the trabecular bone score (TBS) and high-resolution peripheral quantitative computed tomography (HR-pQCT).

OBJECTIVES: To compare bone quality using the trabecular bone score (TBS) and bone microarchitecture in the distal tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT) in ankylosing spondylitis (AS) patients and healthy controls (HC). METHODS: Areal bone mineral density (aBMD) and TBS (TBS iNsight software) were evaluated using DXA (Hologic, QDR 4500); while volumetric bone mineral density (vBMD) and bone microarchitecture were analyzed in the distal tibia using HR-pQCT (Scanco) in 73 male patients with AS and 52 age-matched HC. RESULTS: AS patients were a mean 41.6 ±â€¯7.9 years old and had a mean disease duration of 16.4 ±â€¯8.6 y, with a mean mSASSS 25.6 ±â€¯16.4. No difference was observed in lumbar spine aBMD in AS patients and HC (p = 0.112), but total hip BMD (p = 0.011) and TBS (p < 0.001) were lower in AS patients. In the distal tibia, reduced trabecular volumetric density [Tb.vBMD (p < 0.006)] and structural alterations - trabecular thickness (Tb.Th), p = 0.044 and trabecular separation (Tb.Sp), p = 0.039 - were observed in AS patients relative to controls. Further analysis comparing TBS < 1.310 and TBS ≥ 1.310 in AS patients revealed a higher mean body mass index [BMI] (p = 0.010), lower tibia cortical vBMD [Ct.vBMD] (p = 0.007), lower tibia cortical thickness [Ct.Th]: (p = 0.048) in the former group. On logistic regression analysis, BMI (OR = 1.27; 95%IC = 1.08-1.50, p = 0.005), (VF 4.65; 1.13-19.1, p = 0.033) and tibial Ct.vBMD (0.98; 0.97-1.00, p = 0.007) were associated with a lower TBS (<1.310). CONCLUSIONS: The present study demonstrates that TBS and HR-pQCT imaging are important technologies evaluating bone impairment in AS patients. Moreover, in these patients vertebral fractures were associated with lower TBS.

A Randomized Trial of Zoledronic Acid to Prevent Bone Loss in the First Year after Kidney Transplantation.

BACKGROUND: Bone and mineral disorders commonly affect kidney transplant (KTx) recipients and have been associated with a high risk of fracture. Bisphosphonates may prevent or treat bone loss in such patients, but there is concern that these drugs might induce adynamic bone disease (ABD). METHODS: In an open label, randomized trial to assess the safety and efficacy of zoledronate for preventing bone loss in the first year after kidney transplant, we randomized 34 patients before transplant to receive zoledronate or no treatment. We used dual-energy x-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and bone biopsies to evaluate changes in bone in the 32 evaluable participants between the time of KTx and 12 months post-transplant. RESULTS: Both groups of patients experienced decreased bone turnover after KTx, but zoledronate itself did not affect this outcome. Unlike previous studies, DXA showed no post-transplant bone loss in either group; we instead observed an increase of bone mineral density in both lumbar spine and total hip sites, with a significant positive effect of zoledronate. However, bone biopsies showed post-transplant impairment of trabecular connectivity (and no benefit from zoledronate); HR-pQCT detected trabecular bone loss at the peripheral skeleton, which zoledronate partially attenuated. CONCLUSIONS: Current immunosuppressive regimens do not contribute to post-transplant central skeleton trabecular bone loss, and zoledronate does not induce ABD. Because fractures in transplant recipients are most commonly peripheral fractures, clinicians should consider bisphosphonate use in patients at high fracture risk who have evidence of significantly low bone mass at these sites at the time of KTx.

Association of moderate/severe vertebral fractures with reduced trabecular volumetric bone density in older women and reduced areal femoral neck bone density in older men from the community: A cross-sectional study (SPAH).

BACKGROUND: Many vertebral fractures (VF) occur in individuals classified by DXA as being at low risk of fragility fractures. The aim of this study was to verify the association between VF and peripheral bone microarchitecture and strength parameters (SP) using, in addition to DXA, high-resolution peripheral quantitative computed tomography (HR-pQCT) and axial bone microarchitecture using the trabecular bone score (TBS). STUDY DESIGN: Cross-sectional study of 276 community-dwelling subjects aged ≥65 years from the SPAH study cohort. METHODS: Lateral DXA scans of the spine were analyzed to assess VF. HR-pQCT was performed at the radius and tibia. TBS was determined using DXA. RESULTS: VF was observed in 42.6% of women and 28% of men. At the tibia, women with moderate/severe VF had lower volumetric bone density (vBMD), trabecular number (Tb.N), and SP, and higher trabecular separation (Tb.Sp); and men with VF had lower Tb.N and SP, and higher Tb.Sp. At the radius, women with moderate/severe VF had lower vBMD, trabecular and cortical thickness and SP; and men with VF had lower trabecular vBMD and SP. No associations between TBS and VF were observed in either gender. Logistic regression analysis revealed that trabecular vBMD at the tibia in women (OR:0.980, 95%CI:0.963-0.997, p = 0.022) and femoral neck aBMD in men (OR:0.445, 95%CI:0.212-0.935, p = 0.033) were independently associated with VF. CONCLUSION: HR-pQCT images detected differences in bone microstructure in older women with VF independent of aBMD and TBS by DXA, and HR-pQCT could be a useful tool to assess fracture risk. In men, femoral neck aBMD was associated with VF, and DXA continues to be an important tool for predicting VF.

The relationship between estimated bone strength by finite element analysis at the peripheral skeleton to areal BMD and trabecular bone score at lumbar spine.

Bone strength, estimated by finite element (FE) analysis based on high resolution peripheral quantitative computed tomography (HR-pQCT) images is an important contributor to understanding risk of fracture. However, it is a peripheral device and cannot be evaluated in vivo at lumbar spine L1-L4. The aim of this study was to investigate if the axial bone quality can be predicted by strength measurements of peripheral bone. Peripheral bone microarchitecture, areal bone mineral density (aBMD) and trabecular bone score (TBS) were measured in adults individuals (n = 262, 60 years and older; 63% women). Stiffness and failure load were estimated by FE analysis at HR-pQCT images at radius and tibia. Areal BMD and TBS were measured by dual energy X-ray absorptiometry (DXA) at L1-L4. Correlations between peripheral and axial data were estimated for each gender adjusted by age, weight, and height. Areal BMD L1-L4 resulted in weak to moderate significant correlations with stiffness and failure load at radius (women: R2 = 0.178, p < 0.05 and R2 = 0.187, p < 0.001, respectively; men: R2 = 0.454 and R2 = 0.451, p < 0.001, respectively) and at tibia (women: R2 = 0.211 and R2 = 0.216, p < 0.001, respectively; men: R2 = 0.488 and R2 = 0.502, p < 0.001, respectively). TBS showed a very weak or no correlation with stiffness and failure load at radius (women: R2 = 0.148 and R2 = 0.150, p < 0.05, respectively; men: R2 = 0.108 and R2 = 0.106, p < 0.05, respectively) and at tibia (women: R2 = 0.146 and R2 = 0.150, p < 0.05, respectively; men: R2 = 0.072 and R2 = 0.078, respectively). These data suggest that aBMD L1-L4 was better explained by peripheral bone strength characteristics than the TBS, mainly in men and tibia is generally the site with a better relationship.

Cortical bone density and thickness alterations by high-resolution peripheral quantitative computed tomography: association with vertebral fractures in primary Sjögren's syndrome.

OBJECTIVES: To evaluate volumetric BMD (vBMD), microarchitecture and strength and vertebral fractures (VFs) in primary SS (pSS). METHODS: We evaluated 71 female pSS patients and 71 gender-, age-, and race-matched controls. Clinical data including risk factors for osteoporosis (OP) and fractures were collected through a standardized protocol. Areal BMD and VFs were analysed by DXA. Bone microarchitecture, vBMD and bone strength were assessed by high-resolution peripheral quantitative CT (HR-pQCT), a non-invasive method. RESULTS: pSS patients and controls were comparable for age, BMI, calcium intake, smoking, menopause, sedentary lifestyle and family history of fractures (P > 0.05). OP or low BMD for the patient's age (33.8 vs 5.6%; P < 0.0001) and VFs (19.7 vs 5.6%; P = 0.043) were more frequent in patients than controls. HR-pQCT showed deterioration of cortical and trabecular components and strength at the radius, and of cortical components and strength at the tibia (P < 0.05) in patients compared with controls. pSS patients and controls were also analysed by multivariate analysis adjusted for age, ethnicity, prednisone use, weight and height, which showed that the pSS group had lower values of cortical vBMD, cortical thickness and apparent modulus (P < 0.05) at the radius and cortical vBMD and apparent modulus (P < 0.05) at the tibia. Patients with VFs had more cortical bone deterioration (cortical vBMD/cortical thickness) at the tibia compared with patients without VFs (P < 0.05). CONCLUSIONS: This study was the first to assess bone microarchitecture in pSS and demonstrated that cortical deterioration is the most important abnormality observed in pSS patients with VFs. This novel finding shows that this compartment contributes to vertebral fragility, suggesting that this non-invasive evaluation may be useful in the clinical practice.