Publications by authors named "Nicolas Vilayphiou"

Background: Joint space assessment for rheumatoid arthritis (RA) by ordinal conventional radiographic scales is susceptible to floor and ceiling effects. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides superior resolution, and may detect earlier changes. The goal of this work was to compare existing 3D methods to calculate joint space width (JSW) metrics in human metacarpophalangeal (MCP) joints with HR-pQCT and reach consensus for future studies.

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Objective: Assessment of calcaneus microstructure using high-resolution peripheral quantitative computed tomography (HR-pQCT) might be used to improve fracture risk predictions or to assess responses to pharmacological and physical interventions. To develop a standard clinical protocol for the calcaneus, we validated calcaneus trabecular microstructure measured by HR-pQCT against 'gold-standard' micro-CT measurements.

Methods: Ten human cadaveric feet were scanned in situ using HR-pQCT (isotropic 82μm voxel size) at 100, 150 and 200ms integration times, and at 100ms integration time following removal of the calcaneus from the foot (ex vivo).

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Risk for premature osteoporosis is a major health concern in astronauts and cosmonauts; the reversibility of the bone lost at the weight-bearing bone sites is not established, although it is suspected to take longer than the mission length. The bone three-dimensional structure and strength that could be uniquely affected by weightlessness is currently unknown. Our objective is to evaluate bone mass, microarchitecture, and strength of weight-bearing and non-weight-bearing bone in 13 cosmonauts before and for 12 months after a 4-month to 6-month sojourn in the International Space Station (ISS).

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Fractures of the distal section of the radius (Colles' fractures) occur earlier in life than other osteoporotic fractures. Therefore, they can be interpreted as a warning signal for later, more deleterious fractures of vertebral bodies or the femoral neck. In the past decade, the advent of HR-pQCT allowed a detailed architectural analysis of the distal radius and an automated but time-consuming estimation of its strength with linear micro-finite element (μFE) analysis.

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The high resolution peripheral computed tomography (HR-pQCT) technique has seen recent developments with regard to the assessment of cortical porosity. In this study, we investigated the role of cortical porosity on bone strength in a large cohort of women. The distal radius and distal tibia were scanned by HR-pQCT.

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Sclerostin is predominantly expressed by osteocytes. Serum sclerostin levels are positively correlated with areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) and bone microarchitecture assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) in small studies. We assessed the relation of serum sclerostin levels with aBMD and microarchitectural parameters based on HR-pQCT in 1134 men aged 20 to 87 years using multivariable models adjusted for confounders (age, body size, lifestyle, comorbidities, hormones regulating bone metabolism, muscle mass and strength).

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Context: Abdominal aortic calcification (AAC) is an indicator of cardiovascular risk, especially in the diseases characterized by insulin resistance such as type 2 diabetes. Osteocalcin is a bone-secreted hormone that favors insulin sensitivity and insulin secretion.

Objectives: We investigated whether total serum osteocalcin level at baseline is associated with AAC progression and 10-year all-cause mortality in elderly men.

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Obesity is associated with higher areal bone density (aBMD) but its protective effect on the risk of fracture is controversial. We aimed to analyze bone microarchitecture and biomechanical properties in obese (OB) postmenopausal French women compared with normal weight (NW) women. A matched case-control study from the Os des Femmes de Lyon (OFELY) cohort was conducted in 63 OB women (body mass index [BMI] > 30, mean age 69 ± 8 years) age-matched with 126 NW women (19 ≤ BMI ≤ 25).

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The aim was to study the association between bone microarchitecture and muscle mass and strength in older men. Volumetric bone mineral density (vBMD) and bone microarchitecture were assessed in 810 men aged ≥60 years at the distal radius by high-resolution peripheral computed tomography (HR-pQCT). Areal bone mineral density (aBMD) and appendicular muscle mass (ASM) were assessed by dual-energy X-ray absorptiometry (DXA).

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We used high-resolution quantitative computed tomography to study the microarchitecture of bone in patients with chronic kidney disease on dialysis. We compared bone characteristics in 56 maintenance hemodialysis (21 women, 14 post-menopausal) and 23 peritoneal dialysis patients (9 women, 6 post-menopausal) to 79 healthy men and women from two cohorts matched for age, body mass index, gender, and menopausal status. All underwent dual-energy X-ray absorptiometry of the spine and hip to measure areal bone mineral density, and high-resolution peripheral quantitative computed tomography of the radius and tibia to measure volumetric bone mineral density and microarchitecture.

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Objectives: Rheumatoid arthritis is characterized by an early inflammatory related periarticular osteopenia. A new high resolution direct digital X-ray device has been recently developed to provide bone texture analysis which is designed to assess changes in trabecular bone architecture. For the first time, we have evaluated trabecular bone texture impairment in rheumatoid arthritis patients compared to healthy controls.

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Objectives: High resolution peripheral quantitative tomography (HR-pQCT) is used more widely to assess microarchitecture, but we are lacking comparisons between HR-pQCT and histomorphometry, which is considered the gold standard. They have only been assessed on different anatomical regions. The purpose of our study was to assess the microarchitecture and the relative contribution of cortical and trabecular bone in hip fracture with this 3D imaging technique, compared with the 2D histomorphometry.

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Areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) identifies 20% of men who will sustain fragility fractures. Thus we need better fracture predictors in men. We assessed the association between the low-trauma prevalent fractures and bone microarchitecture assessed at the distal radius and tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT) in 920 men aged 50 years of older.

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Few studies have investigated bone microarchitecture and biomechanical properties in men. This study assessed in vivo both aspects in a population of 185 men (aged 71 ± 10 years) with prevalent fragility fractures, compared to 185 controls matched for age, height, and weight, from the Structure of the Aging Men's Bones (STRAMBO) cohort. In this case-control study, areal BMD (aBMD) was measured by DXA, bone microarchitecture was assessed by high resolution (HR)-pQCT, and finite element (µFE) analysis was based on HR-pQCT images of distal radius and tibia.

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Bone damage in children with chronic kidney disease (CKD) is a challenge for pediatric nephrologists. Areal measurements of bone mineral density (BMD) by dual x-ray absorptiometry (DXA) have been routinely performed to assess bone mass but recent international guidelines have concluded that DXA was of less value in CKD. The aim of this study is to evaluate bone quality in CKD children using new bone imaging techniques in a pilot cross-sectional single-center study.

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The ability of a vertebra to carry load after an initial deformation and the determinants of this postfracture load-bearing capacity are critical but poorly understood. This study aimed to determine the mechanical behavior of vertebrae after simulated mild fracture and to identify the determinants of this postfracture behavior. Twenty-one human L(3) vertebrae were analyzed for bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) and for microarchitecture by micro-computed tomography (µCT).

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Bone microarchitecture can be studied noninvasively using high-resolution peripheral quantitative computed tomography (HR-pQCT). However, this technique is not widely available, so more simple techniques may be useful. BMA is a new 2D high-resolution digital X-ray device, allowing for bone texture analysis with a fractal parameter (H(mean)).

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Low bone mineral density (BMD) is a strong risk factor for vertebral fracture risk in osteoporosis. However, many fractures occur in people with moderately decreased or normal BMD. Our aim was to assess the contributions of trabecular microarchitecture and its heterogeneity to the mechanical behavior of human lumbar vertebrae.

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Objectives: A new high-resolution peripheral quantitative CT (HR-pQCT) system allows for in vivo assessment of bone microarchitecture and volumetric bone mineral density (vBMD) with an 82 microm isotropic resolution. With this device, the microarchitecture impairment was evaluated in patients with rheumatoid arthritis (RA) in comparison with healthy controls and measured the erosion volume at metacarpal heads (MCPs).

Methods: In this cross-sectional study, the reproducibility was first assessed by 3 HR-pQCT exams with repositioning in 14 patients with late RA and 14 healthy subjects.

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Few data concern the relationship between bone turnover and microarchitecture in men. We investigated the association between levels of biochemical markers of bone turnover (BTM) and bone microarchitecture in 1149 men aged 19 to 85 years. Bone microarchitecture was assessed by high-resolution peripheral quantitative computed tomography at the distal radius and tibia.

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The deposition of calcium oxalate crystals in the kidney and bone is a hallmark of primary hyperoxaluria type 1 (PH1). We report here an evaluation of the bone status of 12 PH1 children based on bone biomarkers [parathyroid hormone, vitamin D, fibroblast growth factor 23 (FGF23)] and radiological assessments (skeletal age, three-dimensional high-resolution peripheral quantitative computed tomography, HR-pQCT) carried out within the framework of a cross-sectional single-center study. The controls consisted of healthy and children with chronic kidney disease already enrolled in local bone and mineral metabolism studies.

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Assessment of bone strength at the radius by micro-finite element analysis (muFEA) has already been associated with wrist fractures. In this study, the analysis has been extended to the distal tibia, and to a larger group of subjects to examine the association with several types of fragility fractures. We have compared muFEA based on in vivo HR-pQCT measurements of BMD and microarchitecture at the radius and tibia, in a case-control study involving 101 women with prevalent fragility fracture and 101 age-matched controls, from the OFELY cohort.

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Bone fragility is a complication of chronic kidney disease (CKD). The aim of this study was to assess whether volumetric bone mineral density (vBMD) and microarchitecture could be impaired early in the course of CKD. Bone microarchitecture was examined with a noninvasive 3D imaging technique [high-resolution peripheral quantitative computed tomography (HR-pQCT)] at the tibia and radius in 70 stage II-IV CKD patients older than 50 years of age; controls belonged to two cohorts of healthy subjects comparable for age and gender (OFELY cohort in women and STRAMBO cohort in men).

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Bone damage because of chronic kidney disease (CKD) represents a daily challenge for nephrologists. The impact of CKD on bone health may be immediate (serum phosphocalcic disturbances) or delayed (bone fractures and vascular calcifications). Histomorphometry remains the gold standard to evaluate bone, but it is rarely performed in clinical practice.

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