Changes in bone density and microarchitecture in adolescents undergoing a first kidney transplantation: a prospective study.

PURPOSE: Mineral bone disorder associated with chronic kidney disease (CKD-MBD) frequently persists after kidney transplantation (KTx), being due to pre-existing CKD-MBD, immunosuppressive therapies, and post-KTx hypophosphatemia. This study aimed to evaluate bone biomarkers and microarchitecture using high resolution peripheral quantitative computed tomography (HR-pQCT) at the time of KTx and 6 months thereafter and to compare these results with those of matched healthy controls (HC). METHODS: This study presented the single-center subgroup of patients aged between 10 and 18 years included in the prospective "Bone Microarchitecture in the Transplant Patient" study (TRANSOS-NCT02729142). Patients undergoing a first KTx were matched (1:2) with HC from the "Vitamin D, Bones, Nutritional and Cardiovascular Status" cohort (VITADOS) on sex, pubertal stage, and age. RESULTS: At a median (interquartile range, IQR) age of 15 [13; 16] years, 19 patients (6 girls, 7 pre-emptive KTx, 7 steroid-sparing immunosuppressive strategies) underwent a first KTx, with a median [IQR] parathyroid hormone level of 1.9 [1.4; 2.9] the upper limit of normal (ULN). Higher total and trabecular bone densities, along with superior trabecular microarchitecture, were observed at KTx compared to HC. Six months post-KTx, patients had significantly impaired trabecular parameters at the radius, while results were not significantly different at the weight-bearing tibia, neither cortical parameters at both sites. Six months post-KTx, 6 (32%) patients still present with metabolic acidosis, 10 (53%) persistent hyperparathyroidism (always < 2 ULN), and 5 (26%) elevated FGF23 levels; 11 (58%) received phosphate supplementation. CONCLUSIONS: Bone density and microarchitecture at the time of KTx were superior compared to HC, but radial trabecular bone microarchitecture impairment observed 6 months post-KTx may reflect subtle albeit present post-KTx CKD-MBD. What is Known? • Mineral bone disorder associated with chronic kidney disease (CKD-MBD) frequently persists after kidney transplantation (KTx) and is associated with morbidity. However, biochemical parameters and dual X-ray absorptiometry (DXA) are poor predictors of the underlying bone disease. What is new? • The present study on 19 adolescent KTx recipients with adequate CKD-MBD control at the time of KTx reveals no significant bone disease compared to matched healthy controls. Microarchitecture impairment observes 6 months post-KTx may reflect subtle, albeit present, post-KTx CKD-MBD.

Bone turnover, areal BMD, and bone microarchitecture by second-generation high-resolution peripheral quantitative computed tomography in transfusion-dependent thalassemia.

Thalassemic osteopathy includes low bone mass and impaired bone microarchitecture. We aimed to evaluate the prevalence and determinants of bone quantity (osteoporosis) and quality (microarchitecture) in a cohort of adult patients with transfusion-dependent thalassemia (TDT). Patients with TDT (n = 63) and age- and BMI-matched controls (n = 63) were recruited in the study. Areal bone mineral density (BMD) was measured using DXA Hologic scanner. P1NP and ß-CTX were estimated by electrochemiluminescence assay. Bone geometry and volumetric BMD (vBMD) were estimated by second-generation high-resolution peripheral quantitative computed tomography. Bone turnover marker ß-CTX was significantly lower in the TDT group, but there was no difference in P1NP levels. Low bone mass (Z ≤ -2) was present in greater proportion of patients both at lumbar spine (LS) (54 vs 0%; p = .001) and femoral neck (FN) (33 vs 8%; p = .001). Hypogonadism was associated with low BMD at FN (OR 10.0; 95% CI, 1.2-86; p = .01) and low hemoglobin with low BMD at LS (OR 1.58; 95% CI, 0.96-2.60; p = .07). The mean trabecular bone score was also significantly lower in patients compared with controls (1.261 ± 0.072 vs 1.389 ± 0.058). Total, cortical and trabecular vBMD were significantly lower in cases than controls. The trabecular number and cortical thickness were significantly lower and trabecular separation higher in cases than controls. Adults with TDT have significantly lower areal, cortical and trabecular vBMD. The bone microarchitecture is also significantly impaired in terms of lower number and wider spacing of trabeculae as well as lower cortical thickness and area at both radius and tibia.

Association between bone microarchitecture and sarcopenia in postmenopausal women with type 2 diabetes.

Bone microarchitecture, as assessed using high-resolution peripheral quantitative computed tomography, is adversely affected in postmenopausal women with type 2 diabetes mellitus having sarcopenia/sarcopenic obesity while areal bone mineral density does not differ between those with and without sarcopenia. PURPOSE: Type 2 diabetes (T2D) increases the risk of sarcopenia, which independently contributes to bone fragility. We aimed to explore the association between sarcopenia/sarcopenic obesity and bone quality using second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) in T2D. METHODS: We analyzed the baseline participant characteristics of an ongoing randomized clinical pilot trial (CTRI/2022/02/039978). Postmenopausal women (≥ 50 years) with T2D and high risk of fragility fractures were included. Areal BMD (aBMD), trabecular bone score (TBS), and body composition were measured using DXA. Bone microarchitecture was assessed at distal radius/distal tibia using HR-pQCT. Muscle strength was estimated using dominant handgrip strength (HGS). Sarcopenia was defined as low HGS (< 18.0 kg) and low appendicular skeletal muscle index (ASMI) (< 4.61 kg/m2). Probable sarcopenia was defined as low HGS with normal ASMI. Sarcopenic obesity was classified as co-existence of sarcopenia and obesity (BMI ≥ 25.0 kg/m2). RESULTS: We recruited 129 postmenopausal women (mean age 64.2 ± 6.7 years). Participants were categorized into four mutually exclusive groups: group A (normal HGS and ASMI, n = 17), group B (probable sarcopenia, n = 77), group C (non-obese sarcopenia, n = 18), and group D (obese sarcopenia, n = 18). The four groups did not differ significantly with regard to baseline characteristics, fracture prevalence, HbA1c, aBMD, and TBS. However, HR-pQCT-derived volumetric BMD and cortical/trabecular microarchitecture were significantly poorer in group C/group D than in group A/group B. CONCLUSIONS: Bone quality rather than bone density (quantity) is adversely affected in T2D postmenopausal women with sarcopenia/sarcopenic obesity, which could increase the fracture risk in this patient sub-population.

HR-pQCT cross-calibration using standard vs. Laplace-Hamming binarization approach.

High-resolution peripheral quantitative computed tomography (HR-pQCT) has emerged as a powerful imaging technique for characterizing bone microarchitecture in the human peripheral skeleton. The second-generation HR-pQCT scanner provides improved spatial resolution and a shorter scan time. However, the transition from the first-generation (XCTI) to second-generation HR-pQCT scanners (XCTII) poses challenges for longitudinal studies, multi-center trials, and comparison to historical data. Cross-calibration, an established approach for determining relationships between measurements obtained from different devices, can bridge this gap and enable the utilization and comparison of legacy data. The goal of this study was to establish cross-calibration equations to estimate XCTII measurements from XCTI data, using both the standard and Laplace-Hamming (LH) binarization approaches. Thirty-six volunteers (26-85 yr) were recruited and their radii and tibiae were scanned on both XCTI and XCTII scanners. XCTI images were analyzed using the manufacturer's standard protocol. XCTII images were analyzed twice: using the manufacturer's standard protocol and the LH segmentation approach previously developed and validated by our team. Linear regression analysis was used to establish cross-calibration equations. Results demonstrated strong correlations between XCTI and XCTII density and geometry outcomes. For most microstructural outcomes, although there were considerable differences in absolute values, correlations between measurements obtained from different scanners were strong, allowing for accurate cross-calibration estimations. For some microstructural outcomes with a higher sensitivity to spatial resolution (eg, trabecular thickness, cortical pore diameter), XCTII standard protocol resulted in poor correlations between the scanners, while our LH approach improved these correlations and decreased the difference in absolute values and the proportional bias for other measurements. For these reasons and due to the improved accuracy of our LH approach compared with the standard approach, as established in our previous study, we propose that investigators should use the LH approach for analyzing XCTII scans, particularly when comparing to XCTI data.

Identification of Osteosarcopenia by High-Resolution Peripheral Quantitative Computed Tomography.

Osteosarcopenia is a prevalent geriatric disease with a significantly increased risk of adverse outcomes than osteoporosis or sarcopenia alone. Identification of older adults with osteosarcopenia using High-Resolution Peripheral Quantitative Computed Tomography (HR-pQCT) could allow better clinical decision making. This study aimed to explore the feasibility of HR-pQCT to differentiate osteoporosis, sarcopenia, and osteosarcopenia in older adults, with a primary outcome to derive a model to distinguish older adults with osteosarcopenia from those with low bone mineral density only, and to examine important HR-pQCT parameters associated with osteosarcopenia. This was a cross-sectional study involving 628 community-dwelling Chinese adults aged ≥ 40. Subjects were assessed by dual energy X-ray absorptiometry (DXA) for osteopenia/osteoporosis and sarcopenia using the Asian Working Group for Sarcopenia definition; then grouped into healthy, osteopenia/osteoporosis, sarcopenia, and osteosarcopenia groups. A series of regression analyses and other statistical tests were performed to derive the model. HR-pQCT showed the ability to discriminate older adults with osteosarcopenia from those with osteopenia/osteoporosis only. Cross-validation of our derived model correctly classified 77.0% of the cases with good diagnostic power and showed a sensitivity of 76.0% and specificity of 77.6% (Youden index = 0.54; AUC = 0.79, p < 0.001). Analysis showed trabecular volumetric bone density and cortical periosteal perimeter were important and sensitive parameters in discriminating osteosarcopenia from osteopenia/osteoporosis subjects. These findings demonstrated that HR-pQCT is a viable and effective screening method for differentiating osteosarcopenia from low bone mineral density alone without the need to carry out multiple assessments for osteosarcopenia, especially for case-finding purposes. This could facilitate the decision of a follow-up and the management of these frail older adults to ensure they receive timely therapeutic interventions to minimise the associated risks.

MTX Osteopathy Versus Osteoporosis Including Response to Treatment Data-A Retrospective Single Center Study Including 172 Patients.

MTX is an effective and widely used immunomodulatory drug for rheumatoid diseases. MTX osteopathy is a very rare and specific side effect, characterized by stress fractures at multiple locations in the lower extremity, hampering the patient's mobility by pain and loss of function. In clinical practice, osteoporosis and MTX osteopathy are repeatedly confused and a comparative workup is needed to clarity it's specifics. Furthermore, specific treatment options for MTX osteopathy need to be established. We compared patients suffering from MTX osteopathy to patients with osteoporosis (OPO). Patients underwent an extensive clinical workup including blood sampling, bone mineral density measurements, high-resolution peripheral quantitative computed tomography and muscular performance testing. Furthermore, treatment regimes in MTX osteopathy were compared with respect to regain of mobility and pain reduction. 83 patients with MTX osteopathy and 89 with OPO were included. Patients with MTX osteopathy did exhibit fractures predominantly at the lower extremity and pain scores were significantly higher (MTX: 6.75 ± 1.86 vs. OPO: 3.62 ± 2.95, p < 0.0001). MTX-caused mobility restriction was successfully reduced by treatment only if MTX was discontinued (pre-treatment: 2.16 ± 1.19 vs. post-treatment: 1.04 ± 0.87, p < 0.0001). Most mobility gain was achieved by involving anabolic treatment (anabolic: 2.1 ± 1.02 vs. antiresorptive: 1.09 ± 0.94, p < 0.05). In summary, MTX osteopathy is characterized by distinct lower extremity stress fractures leading to severe pain and immobility. Discontinuation of MTX is essential to enable treatment success and involving anabolic treatment seems to be more effectively in mobility regain as antiresorptive treatment alone.

Erosion regression in patients with rheumatoid arthritis after upadacitinib-a pilot study using high resolution peripheral quantitative computed tomography.

OBJECTIVES: To evaluate whether inhibition of Janus kinases (JAK) 1 could lead to erosion repair on high-resolution peripheral quantitative computer tomography (HR-pQCT) in patients with active rheumatoid arthritis (RA). METHODS: This was a prospective, non-randomized pilot study. We enrolled 20 adult patients with active RA with ≥1 bone erosion on HR-pQCT. They were given upadacitinib 15 mg once daily for 24 weeks. HR-pQCT of the metacarpophalangeal joint was performed at baseline and 24-week. The serum bone biomarkers level was evaluated before and after treatment. Twenty age-and-sex matched RA patients from another study treated with conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) were included as active controls. RESULTS: Nineteen patients in the upadacitinib group completed the study procedures. After 24 weeks, despite similar improvement in disease activity, a reversed trend in the mean erosion volume change on HR-pQCT was observed comparing the upadacitinib and active control group (upadacitinib group: -0.23 ± 3.26mm3 vs control group: 1.32 ± 6.05mm3, p= 0.131). A greater proportion of erosions in the upadacitinib group demonstrated regression (27% vs 12%, p= 0.085). Using general estimating equation (GEE), the use of upadacitinib was significantly associated with erosion regression (OR: 3.61, 95% CI: 1.00-13.00, p= 0.049) after adjusting for the difference in disease duration. The serum levels of bone resorption markers reduced after upadacitinib treatment. No new safety signal was noted. CONCLUSION: Despite a similar improvement in RA disease activity after upadacitinib compared with csDMARDs, a differential regression of erosion on HR-pQCT was observed in patients received upadacitinib. The potential role of JAK1 inhibition in erosion repair should be investigated.

Bone microarchitecture and strength assessed by HRpQCT in individuals with type 2 diabetes and prediabetes: the Maastricht study.

Type 2 diabetes (T2D) is a prevalent disease and has been associated with an increased fracture risk despite normal or even higher areal BMD. The aim of this study was to estimate the association between glucose metabolism status (GMS) and measurements of glycemic control with HRpQCT parameters of bone microarchitecture and strength. Participants of the Maastricht study who underwent an HRpQCT scan at the distal radius and tibia were included. GMS was determined by use of an oral glucose tolerance test and grouped into a normal glucose metabolism (NGM), prediabetes, or T2D. Linear regression models were used, stratified by sex with multiple adjustments. This study incorporated cross-sectional data from 1400 (796 [56.9%] NGM, 228 [16.3%] prediabetes, and 376 [26.9%] T2D) men and 1415 (1014 [71.7%] NGM, 211 [14.9%] prediabetes, and 190 [13.4%] T2D) women. The mean age was 59.8 ± 8.6 and 57.6 ± 9.0 yr for men and women, respectively. After adjustment, T2D was associated with a higher total BMD measured by HRpQCT and cortical thickness, and a smaller total and trabecular area in men and women compared with NGM. In women, T2D was additionally associated with a higher stiffness and failure load at the radius. Results were more pronounced at the distal radius than at the distal tibia. To conclude, these findings suggest that in this cohort of Maastricht study participants, total and trabecular bone area are smaller, but bone microarchitecture, density, and bone strength assessed by HRpQCT are not impaired in individuals with T2D.

Trabecular and cortical bone microarchitecture using high-resolution peripheral quantitative computed tomographic imaging in diabetic peripheral neuropathy.

CONTEXT: Type 2 Diabetes Mellitus (T2D) is associated with an increased risk of fragility fracture despite normal areal bone mineral density (BMD). The contribution of diabetic peripheral neuropathy (PN) to volumetric BMD (vBMD) and bone microarchitecture in T2D is not explored. OBJECTIVE: To assess vBMD and microarchitectural properties of bone using high-resolution peripheral quantitative computed tomography (HR-pQCT) in patients of T2D with or without PN. DESIGN: This is a cross-sectional study of patients of T2D divided into two groups [patients with T2D without PN (Group A) and T2D with PN (Group B)]. All patients underwent clinical examination, biochemical evaluation, dual-energy X-ray absorptiometry (DXA), and HR-pQCT of the radius and tibia. RESULTS: A total of 296 patients were included in the study [Group A (n = 98), Group B (n = 198)]. HR-pQCT demonstrated a significant difference in total vBMD[mg/cm3] at tibia (291.6 ± 61.8 vs. 268.2 ± 63.0; p-0.003); cortical vBMD[mg/cm3] at tibia [912.5 (863.3, 962.4) vs. 853.8 (795.3, 913.2) p-0.000], among groups A and B respectively. Among the microarchitecture parameters, there was a significant difference in cortical porosity at the tibia (2.5% ±1.7% vs. 3%±1.7%; p-0.004), trabecular number[mm-1] at the tibia [1.080 (0.896, 1.237) vs. 1.140 (0.983, 1.286), p-0.045] and trabecular thickness[mm] at the radius [0.228 (0.217, 0.247) Vs. 0.238 (0.224, 0.253); p-0.006], among groups A and B respectively. CONCLUSION: Despite comparable areal BMD, T2D patients with PN have diminished vBMD and deteriorated skeletal microarchitecture, compared to those without PN.

Real-world efficacy of a teriparatide biosimilar (RGB-10) compared with reference teriparatide on bone mineral density, trabecular bone score, and bone parameters assessed using quantitative ultrasound, 3D-SHAPER® and high-resolution peripheral computer tomography in postmenopausal women with osteoporosis and very high fracture risk.

A retrospective analysis comparing a teriparatide biosimilar (RGB-10) with reference teriparatide for osteoporosis treatment in postmenopausal women at high fracture risk found them to be therapeutically equivalent. Both provided significant improvements in lumber spine BMD, TBS, and other parameters of bone health, assessed using multiple diagnostic methods. PURPOSE: To compare the therapeutic efficacy of a teriparatide biosimilar (RGB-10) with reference teriparatide for the treatment of osteoporosis in postmenopausal women at very high fracture risk. METHODS: A retrospective analysis of 25 postmenopausal female patients treated for osteoporosis with RGB-10 for 24 months and a matched cohort of 25 patients treated with reference teriparatide. The following outcomes were assessed at baseline, 12 and 24 months: bone mineral density (BMD) at the lumbar spine, femoral neck and total hip using dual-energy x-ray absorptiometry (DXA) and integral, trabecular and cortical volumetric and surface BMD using 3D-SHAPER® imaging, trabecular bone score (TBS), quantitative ultrasound (QUS) measurements, and high-resolution peripheral quantitative computed tomography (HRpQCT) imaging of the radius and tibia. RESULTS: No significant differences were observed between treatment groups in any of the measured parameters of BMD or bone health at baseline as well as in any timepoint when assessed using these various diagnostic methods. Both compounds provided equivalent significant improvements from baseline in measures of osteoporosis and fracture risk. CONCLUSION: The results of the analysis demonstrate the therapeutic equivalence of the teriparatide biosimilar (RGB-10) to reference teriparatide for the treatment of osteoporosis in postmenopausal women at very high risk of fracture.

A Randomized Controlled Trial on the Effect of Luseogliflozin on Bone Microarchitecture Evaluated Using HR-pQCT in Elderly Type 2 Diabetes.

INTRODUCTION: Bone fragility is a critical issue in the treatment of elderly people with type 2 diabetes (T2D). In the Canagliflozin Cardiovascular Assessment Study, the subjects with T2D who were treated with canagliflozin showed a significant increase in fracture events compared to a placebo group as early as 12 weeks post-initiation. In addition, it has been unclear whether sodium-glucose co-transporter 2 (SGLT2) inhibitors promote bone fragility. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to prospectively evaluate the short-term effect of the SGLT2 inhibitor luseogliflozin on bone strength and microarchitecture in elderly people with T2D. METHODS: This was a single-center, randomized, open-label, active-controlled pilot trial for ≥ 60-year-old Japanese individuals with T2D without osteoporosis. A total of 22 subjects (seven women and 15 men) were randomly assigned to a Lusefi group (added luseogliflozin 2.5 mg) or a control group (added metformin 500 mg) and treated for 48 weeks. We used the second-generation HR-pQCT (Xtreme CT II®, Scanco Medical, Brüttisellen, Switzerland) before and 48 weeks after the treatment to evaluate the subjects' bone microarchitecture and estimate their bone strength. RESULTS: Twenty subjects (Lusefi group, n = 9; control group, n = 11) completed the study, with no fracture events. As the primary outcome, the 48-week changes in the bone strength (stiffness and failure load) estimated by micro-finite element analysis were not significantly different between the groups. As the secondary outcome, the changes in all of the cortical/trabecular microarchitectural parameters at the radius and tibia from baseline to 48 weeks were not significantly different between the groups. CONCLUSIONS: In the pilot trial, we observed no negative effect of 48-week luseogliflozin treatment on bone microarchitecture or bone strength in elderly people with T2D. TRIAL REGISTRATION: UMIN-CTR no. 000036202 and jRCT 071180061.

Cross-sectional size, shape, and estimated strength of the tibia, fibula and second metatarsal in female collegiate-level cross-country runners and soccer players.

Bone stress injuries (BSIs) frequently occur in the leg and foot long bones of female distance runners. A potential means of preventing BSIs is to participate in multidirectional sports when younger to build a more robust skeleton. The current cross-sectional study compared differences in tibia, fibula, and second metatarsal diaphysis size, shape, and strength between female collegiate-level athletes specialized in cross-country running (RUN, n = 16) and soccer (SOC, n = 16). Assessments were performed using high-resolution peripheral quantitative computed tomography and outcomes corrected for measures at the radius diaphysis to control for selection bias and systemic differences between groups. The tibia in SOC had a 7.5 % larger total area than RUN, with a 29.4 % greater minimum second moment of area (IMIN) and 8.2 % greater estimated failure load (all p ≤ 0.02). Tibial values in SOC exceeded reference data indicating positive adaptation. In contrast, values in RUN were similar to reference data suggesting running induced limited tibial adaptation. RUN did have a larger ratio between their maximum second moment of area (IMAX) and IMIN than both SOC and reference values. This suggests the unidirectional loading associated with running altered tibial shape with material distributed more in the anteroposterior (IMAX) direction as opposed to the mediolateral (IMIN) direction. Comparatively, SOC had a similar IMAX/IMIN ratio to reference data suggesting the larger tibia in SOC resulted from multiplane adaptation. In addition to enhanced size and strength of their tibia, SOC had enhanced structure and strength of their fibula and second metatarsal. At both sites, polar moment of inertia was approximately 25 % larger in SOC compared to RUN (all p = 0.03). These data support calls for young female athletes to delay specialization in running and participate in multidirectional sports, like soccer, to build a more robust skeleton that is potentially more protected against BSIs.

Association between changes in serum bone metabolism markers and bone microarchitecture changes during basic combat training - The ARMI study.

IMPORTANCE: U.S. Army Basic Combat Training (BCT) improves tibial volumetric bone mineral density (BMD) and structure in most, but not all soldiers. Few studies have investigated whether changes in serum bone biomarkers during BCT are associated with changes in tibial BMD and bone structure following BCT. OBJECTIVE: To characterize bone biomarker changes during BCT and to investigate the relationship between changes in bone biomarkers and changes in tibial BMD and bone structure. METHODS: We enrolled 235 trainees entering BCT in this ten-week prospective observational study. Trainees provided fasted blood samples and questionnaires weekly throughout BCT. Procollagen type 1 N-terminal propeptide (PINP) and C-terminal telopeptide of type 1 collagen (CTX) were measured by enzyme-linked immunoabsorbent assays every two weeks during BCT. We evaluated body composition and mass via dual-energy X-ray absorptiometry and bone structure, microarchitecture, and mineral density at the distal tibia via high-resolution peripheral quantitative computed tomography at baseline and post-BCT. RESULTS: Both male (n = 110) and female trainees (n = 125) were young (20.9 ± 3.7 and 20.7 ± 4.3 years, respectively), with normal to overweight BMIs (25.2 ± 4.1 and 24.2 ± 3.6 kg/m2, respectively). In female trainees, PINP increased during and post-BCT compared to baseline, with the greatest increase in PINP at week four (45.4 % ± 49.6, p < 0.0001), whereas there were no changes in CTX. PINP also increased in male trainees, but only at weeks two and four (21.9 % ± 24.5, p = 0.0027 and 35.9 % ± 35.8, p < 0.0001, respectively). Unlike female trainees, in males, CTX was lower than baseline at weeks four, eight, and post-BCT. The change in PINP from baseline to week four of BCT was positively associated with changes in tibial BMD, Tb.BMD, Tb.Th, Tb.BV/TV, Ct.Th, Ct.Ar, and Ct.Po from the baseline to post-BCT. CONCLUSION: The bone formation marker PINP increases during U.S. Army BCT, especially during the first four weeks. Increases in PINP, but not CTX, were correlated with improved BMD and bone structure in the distal tibia.

Evaluation of bone density and microarchitecture in adult patients with X-linked hypophosphatemic rickets: A pilot longitudinal study.

X-linked Hypophosphatemia (XLH) is the most common type of inherited rickets. Although the clinical features are well characterized, bone structure, mineralization, and biomechanical properties are poorly known. Our aim was to analyze bone properties in the appendicular and axial skeleton of adults with XLH. In this observational case-control study, each affected patient (N = 14; 9 females; age 50 ± 15 years) was matched by sex, age and body mass index to a minimum of two healthy controls (N = 34). Dual-energy X-ray Absorptiometry (DXA) analyses revealed that areal bone mineral density (aBMD) was higher in XLH patients at the lumbar spine (Z score mean difference = +2.47 SD, P value = 1.4 × 10-3). Trabecular Bone Score was also higher at the lumbar spine (P value = 1.0 × 10-4). High Resolution peripheral Quantitative Computed Tomography (HRpQCT) demonstrated that bone cross-sectional area was larger at the distal radius (P value = 6 × 10-3). Total and trabecular volumetric BMD were lower at both sites. Trabecular bone volume fraction was also lower with fewer trabecular numbers at both sites. However, bone strength evaluated by micro-finite element analyzes revealed unaffected bone stiffness and maximum failure load. Evaluation of bone mineralization with aBMD by DXA at the distal radius correlated with vBMD by HRpQCT measurements at both sites. PTH levels were inversely correlated with trabecular vBMD and BV/TV at the tibia. We then followed a subset of nine patients (median follow-up of 4 years) and reassessed HRpQCT. At the tibia, we observed a greater decrease than expected from an age and sex standardized normal population in total and cortical vBMD as well as a trabecularization of the cortical compartment. In conclusion, in adult patients with XLH, bone mineral density is high at the axial skeleton but low at the appendicular skeleton. With time, microarchitectural alterations worsen. We propose that noninvasive evaluation methods of bone mineralization such as DXA including the radius should be part of the management of XLH patients. Larger studies are needed to evaluate the clinical significance of BMD changes in XLH patients under conventional or targeted therapies.

Bone and muscle differences in children and adolescents with type 1 diabetes: The mediating role of physical activity.

Children with type 1 diabetes (T1D) experience an increased risk of fracture, which may be related to altered bone development. We aimed to assess differences in bone, muscle and physical activity (PA), and explore if better muscle and PA measures would mitigate bone differences between children and adolescents with T1D and typically developing peers (TDP). We matched 56 children and adolescents with T1D (mean age 11.9 yrs) and 56 TDP (11.5 yrs) by sex and maturity from 171 participants with T1D and 66 TDP (6-17 yrs). We assessed the distal radius and tibia with high-resolution peripheral quantitative computed tomography (HR-pQCT), and the radius and tibia shaft bone and muscle with pQCT. We also measured muscle function from force-related measures in neuromuscular performance tests (push-up, grip test, countermovement and long jump). We compared PA based on questionnaire scores and accelerometers between groups. Bone, muscle, and neuromuscular performance measures were compared using MANOVA. We used mediation to explore the role of PA and muscle in bone differences. Children and adolescents with T1D had 6-10 % lower trabecular density, bone volume fraction, thickness and number at both distal radius and tibia, and 11 % higher trabecular separation at the distal radius than TDP. They also had 3-16 % higher cortical and tissue mineral density, and cortical thickness at the distal radius, 5-7 % higher cortical density and 1-3 % higher muscle density at both shaft sites compared to TDP. PA mediated the between-group difference in trabecular number (indirect effect -0.04) at the distal radius. Children and adolescents with T1D had lower trabecular bone density and deficits in trabecular micro-architecture, but higher cortical bone density and thickness at the radius and tibia compared to TDP. They engaged in less PA but had comparable muscle measures to those of TDP. PA participation may assist in mitigating deficit in trabecular number observed in children and adolescents with T1D.

Statistical investigation of interdependence of trabecular microarchitectural parameters from micro-computed tomography.

Standard microarchitectural analysis of bone using micro-computed tomography produces a large number of parameters that quantify the structure of the trabecular network. Analyses that perform statistical tests on many parameters are at elevated risk of making Type I errors. However, when multiple testing correction procedures are applied, the risk of Type II errors is elevated if the parameters being tested are strongly correlated. In this article, we argue that four commonly used trabecular microarchitectural parameters (thickness, separation, number, and bone volume fraction) are interdependent and describe only two independent properties of the trabecular network. We first derive theoretical relationships between the parameters based on their geometric definitions. Then, we analyze these relationships with an aggregated in vivo dataset with 2987 images from 1434 participants and a synthetically generated dataset with 144 images using principal component analysis (PCA) and linear regression analysis. With PCA, when trabecular thickness, separation, number, and bone volume fraction are combined, we find that 92 % to 97 % of the total variance in the data is explained by the first two principal components. With linear regressions, we find high coefficients of determination (0.827-0.994) and fitted coefficients within expected ranges. These findings suggest that to maximize statistical power in future studies, only two of trabecular thickness, separation, number and bone volume fraction should be used for statistical testing.

Impaired bone mineral density and microarchitecture in female adolescents with IgE-mediated cow's milk allergy.

This study compared the bone parameters of adolescents with persistent cow's milk allergy (CMA) with those of healthy adolescents. Adolescents with CMA had compromised bone parameters (lower bone mineral density, impaired trabecular microarchitecture, and lower bone strength). Partial exclusion diet was associated with better bone parameters than total exclusion diet. BACKGROUND: Persistent immunoglobulin E (IgE)-mediated cow's milk allergy (CMA) may impair bone parameters and increase the risk of fractures. High-resolution peripheral quantitative computed tomography (HR-pQCT) is a novel methodology that not only assesses trabecular and cortical bone compartments and volumetric density measurements, but also evaluates bone microarchitecture and estimates biomechanical properties through finite element analysis (FEA). Both HR-pQCT and bone strength parameters derived from FEA have shown a strong correlation with fracture risk. PURPOSE: To assess the bone density, microarchitecture, and bone strength of adolescents with persistent IgE-mediated CMA (IgE-CMA). METHODS: This was an observational, cross-sectional study with female adolescents with persistent IgE-CMA and healthy control participants matched by female sex and sexual maturation. Bone parameters were assessed by areal bone mineral density (aBMD) through dual-energy X-ray absorptiometry (DXA), bone microarchitecture by HR-pQCT at the radius and tibia, and laboratory markers related to bone metabolism. RESULTS: The median age of adolescents with persistent IgE-CMA (n = 26) was 13.0 years (interquartile range (IQR) 11.4-14.7) and of healthy control participants (n = 28) was 13.6 years (IQR 11.9-14.9). Adolescents with IgE-CMA ingested 27.4% less calcium (p = 0.012) and 28.8% less phosphorus (p = 0.009) than controls. Adolescents with IgE-CMA had lower bone mineral content (BMC) (38.83 g vs. 44.50 g) and aBMD (0.796 g/cm2 vs. 0.872 g/cm2) at lumbar spine, and lower BMC (1.11 kg vs. 1.27 kg) and aBMD (0.823 g/cm2 vs. 0.877 g/cm2) at total body less head (TBLH) (p < 0.05). However, Z-scores BMC and Z-scores aBMD at lumbar spine and TBLH, when adjusted for Z-score height/age, were not significantly different between the groups. Moreover, CMA adolescents had lower bone strength at the distal tibia (S 169 kN/mm vs. 194 kN/mm; F Load 8030 N vs. 9223 N) (p < 0.05). Pairing of groups by the presence of menarche showed compromised parameters at the tibia-lower total volumetric BMD (Tt.vBMD) (293.9 mg HA/cm3 vs. 325.9 mg HA/cm3) and trabecular vBMD (Tb.vBMD) (170.8 mg HA/cm3 vs. 192.2 mg HA/cm3), along with lower cortical thickness (Ct.th) (1.02 mm vs. 1.16 mm) and bone strength (S 174 kN vs. 210 kN; F Load 8301 N vs. 9950 N)-and at the radius (S 61 kN/mm vs. 71 kN/mm; F Load 2920 N vs. 3398 N) (p < 0.05) among adolescents with IgE-CMA. Adolescents with IgE-CMA on a total exclusion diet (n = 12) showed greater impairment of bone features than those on a partial exclusion diet (n = 14), with lower lumbar spine Z-score BMC (- 0.65 vs. 0.18; p = 0.013), lumbar spine trabecular bone score (TBS) (1.268 vs. 1.383; p = 0.005), Z-score TBS (0.03 vs. 1.14; p = 0.020), TBLH Z-score BMC (- 1.17 vs. - 0.35; p = 0.012), TBLH Z-score aBMD (- 1.13 vs. - 0.33; p = 0.027), Tt.vBMD at the tibia (259.0 mg HA/cm3 vs. 298.7 mg HA/cm3; p = 0.021), Ct.th at the tibia (0.77 mm vs. 1.04 mm; p = 0.015) and Ct.th at the radius (0.16 mm vs. 0.56 mm; p = 0.033). CONCLUSION: Adolescents with persistent IgE-CMA had lower aBMD and compromised microarchitecture (impaired trabecular microarchitecture and lower bone strength). Adolescents on a partial exclusion diet had better bone parameters than those on a total exclusion diet.

Long-term Pegvisomant Therapy of Acromegaly: Effects on Bone Density, Turnover and Microstructure Using HRpQCT.

Context: Fracture rate is increased in patients with active acromegaly and those in remission. Abnormalities of bone microstructure are present in patients with active disease and persist despite biochemical control after surgery. Effects of treatment with the GH receptor antagonist pegvisomant on bone microstructure were unknown. Methods: We studied 25 patients with acromegaly (15 men, 10 women). In 20, we evaluated areal bone mineral density (BMD) by dual-energy X-ray absorptiometry and bone turnover markers (BTMs) longitudinally, before and during pegvisomant treatment. After long-term pegvisomant in 17, we cross-sectionally assessed volumetric BMD, microarchitecture, stiffness, and failure load of the distal radius and tibia using high-resolution peripheral quantitative computed tomography (HRpQCT) and compared these results to those of healthy controls and 2 comparison groups of nonpegvisomant-treated acromegaly patients, remission, and active disease, matched for other therapies and characteristics. Results: In the longitudinal study, areal BMD improved at the lumbar spine but decreased at the hip in men after a median ∼7 years of pegvisomant. In the cross-sectional study, patients on a median ∼9 years of pegvisomant had significantly larger bones, lower trabecular and cortical volumetric density, and disrupted trabecular microarchitecture compared to healthy controls. Microstructure was similar in the pegvisomant and acromegaly comparison groups. BTMs were lowered, then stable over time. Conclusion: In this, the first study to examine bone microstructure in pegvisomant-treated acromegaly, we found deficits in volumetric BMD and microarchitecture of the peripheral skeleton. BTM levels remained stable with long-term therapy. Deficits in bone quality identified by HRpQCT may play a role in the pathogenesis of fragility in treated acromegaly.

Vascular function and skeletal fragility: a study of tonometry, brachial hemodynamics, and bone microarchitecture.

Osteoporosis and cardiovascular disease frequently occur together in older adults; however, a causal relationship between these 2 common conditions has not been established. By the time clinical cardiovascular disease develops, it is often too late to test whether vascular dysfunction developed before or after the onset of osteoporosis. Therefore, we assessed the association of vascular function, measured by tonometry and brachial hemodynamic testing, with bone density, microarchitecture, and strength, measured by HR-pQCT, in 1391 individuals in the Framingham Heart Study. We hypothesized that decreased vascular function (pulse wave velocity, primary pressure wave, brachial pulse pressure, baseline flow amplitude, and brachial flow velocity) contributes to deficits in bone density, microarchitecture and strength, particularly in cortical bone, which is less protected from excessive blood flow pulsatility than the trabecular compartment. We found that individuals with increased carotid-femoral pulse wave velocity had lower cortical volumetric bone mineral density (tibia: -0.21 [-0.26, -0.15] standardized beta [95% CI], radius: -0.20 [-0.26, -0.15]), lower cortical thickness (tibia: -0.09 [-0.15, -0.04], radius: -0.07 [-0.12, -0.01]) and increased cortical porosity (tibia: 0.20 [0.15, 0.25], radius: 0.21 [0.15, 0.27]). However, these associations did not persist after adjustment for age, sex, height, and weight. These results suggest that vascular dysfunction with aging may not be an etiologic mechanism that contributes to the co-occurrence of osteoporosis and cardiovascular disease in older adults. Further study employing longitudinal measures of HR-pQCT parameters is needed to fully elucidate the link between vascular function and bone health.

Osteoporosis and heart disease are both medical conditions that commonly develop in older age. It is not known whether abnormal functioning of blood vessels contributes to the development of bone fragility with aging. In this study, we investigated the relationship between impaired blood vessel function and bone density and micro-structure in a group of 1391 people enrolled in the Framingham Heart Study. Blood vessel function was measured using specialized tools to assess blood flow and pressure. Bone density and micro-structure were measured using advanced imaging called HR-pQCT. We found that people with impaired blood vessel function tended to have lower bone density and worse deterioration in bone micro-structure. However, once we statistically controlled for age and sex and other confounders, we did not find any association between blood vessel function and bone measures. Overall, our results showed that older adults with impaired blood vessel function do not exhibit greater deterioration in the skeleton.

Rapid bone microarchitecture decline in older men with high bone turnover-the prospective STRAMBO study.

Older men with high bone turnover have faster bone loss. We assessed the link between the baseline levels of bone turnover markers (BTMs) and the prospectively assessed bone microarchitecture decline in men. In 825 men aged 60-87 yr, we measured the serum osteocalcin (OC), bone alkaline phosphatase (BAP), N-terminal propeptide of type I procollagen (PINP), and C-terminal telopeptide of type I collagen (CTX-I), and urinary total deoxypyridinoline (tDPD). Bone microarchitecture and strength (distal radius and distal tibia) were estimated by high-resolution pQCT (XtremeCT, Scanco Medical) at baseline and then after 4 and 8 yr. Thirty-seven men took medications affecting bone metabolism. Statistical models were adjusted for age and BMI. At the distal radius, the decrease in the total bone mineral density (Tt.BMD), cortical BMD (Ct.BMD), cortical thickness (Ct.Thd), and cortical area (Ct.Ar) and failure load was faster in the highest vs the lowest CTX-I quartile (failure load: -0.94 vs -0.31% yr-1, P < .001). Patterns were similar for distal tibia. At the distal tibia, bone decline (Tt.BMD, Ct.Thd, Ct.Ar, Ct.BMD, and failure load) was faster in the highest vs the lowest tDPD quartile. At each skeletal site, the rate of decrease in Tb.BMD differed between the extreme OC quartiles (P < .001). Men in the highest BAP quartile had a faster loss of Tt.BMD, Tb.BMD, reaction force, and failure load vs the lowest quartile. The link between PINP and bone decline was poor. The BTM score is the sum of the nos. of the quartiles for each BTM. Men in the highest quartile of the score had a faster loss of cortical bone and bone strength vs the lowest quartile. Thus, in the older men followed prospectively for 8 yr, the rate of decline in bone microarchitecture and estimated bone strength was 50%-215% greater in men with high bone turnover (highest quartile, CTX-I above the median) compared to the men with low bone turnover (lowest quartile, CTX-I below the median).