title: Finite element analysis performed on radius and tibia HR-pQCT images and fragility fractures at all sites in men.
abstract: 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. A principal component (PC) analysis (PCA) was used to study the association of synthetic PCs with fracture by computing their odds ratio (OR [95%CI]) per SD change. Specific associations with vertebral fracture (n = 100), and nonvertebral fracture (n = 85) were also computed. At both sites, areal and volumetric BMD, cortical thickness and trabecular number, separation, and distribution were significantly worse in cases than in controls, with differences ranging from -6% to 15%. µFE-derived stiffness and failure load were 8% to 9% lower in fractures (p < .01). No difference in load distribution was found between the two groups. After adjustment for aBMD, only differences of µFE-derived stresses, stiffness, and failure load at the tibia remained significant (p < .05). PCA resulted in defining 4 independent PCs, explaining 83% of the total variability of bone characteristics. Nonvertebral fractures were associated with PC1, reflecting bone quantity and strength at the radius (tibia) with OR = 1.64 [1.27-2.12] (2.21 [1.60-3.04]), and with PC2, defined by trabecular microarchitecture, with OR = 1.27 [1.00-1.61]. Severe vertebral fractures were associated with PC1, with OR = 1.56 [1.16-2.09] (2.21 [1.59-3.07]), and with PC2, with OR = 1.55 [1.17-2.06] (1.45 [1.06-1.98]). In conclusion, microarchitecture and biomechanical properties derived from µFE were associated with all types of fractures in men, showing that radius and tibia mechanical properties were relatively representative of distant bone site properties.
authors.affiliation: INSERM Research Unit 831 and Université de Lyon, Lyon, France. nicolas.vilayphiou@inserm.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vilayphiou
authors.forename: Stephanie
authors.initials: S
authors.lastname: Boutroy
authors.forename: Pawel
authors.initials: P
authors.lastname: Szulc
authors.forename: Bert
authors.initials: B
authors.lastname: van Rietbergen
authors.forename: Francoise
authors.initials: F
authors.lastname: Munoz
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Delmas
authors.forename: Roland
authors.initials: R
authors.lastname: Chapurlat
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D015519:Bone Density; D020342:Finite Element Analysis; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D025341:Principal Component Analysis; D011884:Radius / Q000000981:diagnostic imaging* / Q000473:pathology*; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D013314:Stress, Mechanical; D013977:Tibia / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D055815:Young Adult