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  • 1
    ISSN: 1432-0827
    Keywords: Key words: Quantitative ultrasound — Bone mineral density — Collagen abnormalities — Ehlers-Danlos syndrome — Systemic sclerosis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. There is little information concerning how the mutation of collagen affects bone mineralization and the assessment of bone properties. To estimate these influences, we performed ultrasonic assessments of the calcaneus and bone mineral density (BMD) measurements of the hip and lumbar spine. Females with diseases related to the mutation of collagen [Ehlers-Danlos syndrome (EDS) type III and systemic sclerosis (SSc)] participated in this study. We compared the broadband ultrasound attenuation (BUA and UBI-4), the average transit time through the heel (TTH), and a multiple factor index (UBI-4T) with control subjects matched on age, race, and menstrual status. Both groups of patients had BMD of the spine (L2–L4) within the normal range for their age and sex (for EDS: n = 23, 1.14 ± 0.14 g/cm2 and z-score = 0.37; for SSc: n = 15, 0.98 ± 0.15 g/cm2 and z-score = 0.20). EDS and SSc subjects had lower BMD of the femoral neck (FN) compared with controls (for EDS: 0.91 ± 0.13 g/cm2, z-score =−0.41, P= 0.025; for SSc 0.67 ± 0.13 g/cm2, z-score =−0.92, P= 0.006). Subjects with EDS and SSc also had lower BUA values (P= 0.051–0.001) compared with controls. After adjusting for body weight, height, and the level of physical activity, the difference in FN BMD between EDS or SSc and controls became marginal (EDS: P= 0.072; SSc: P= 0.086). However, the significant difference for BUA between subjects and controls remained for EDS (P= 0.008), and disappeared for SSc (0.70) after adjusting for weight, height, level of physical activity, and BMD. These results suggest that the abnormalities of collagen may impact on bone mass measurements differently depending on skeletal site, modality of the assessment, and the source and nature of collagen defects. To determine whether collagen properties influence QUS, proper models in vivo and in vitro should be used.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 38 (2000), S. 333-338 
    ISSN: 1741-0444
    Keywords: Biomechanics ; Cortical bone ; Young's modulus ; Anisotropy ; Elasticity ; Ultrasonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The anisotropy of Young's modulus in human cortical bone was determined for all spatial directions by performing coordinate rotations of a 6 by 6 elastic stiffness matrix. The elastic stiffness coefficients were determined experimentally from ultrasonic velocity measurements on 96 samples of normal cortical bone removed from the right tibia of eight human cadavers. The following measured values were used for our analysis: c 11 =19.5 GPa, c 22 =20.1 GPa, c 33 =30.9 GPa, c 44 =5.72 GPa, c 55 =5.17 GPa, c 66 =4.05 GPa, c 23 =12.5 GPa. The remaining coefficients were determined by assuming that the specimens possessed at least an orthorhombic elastic symmetry, and further assuming that c 13 =c 23 , c 12 =c 11 –2c 66 . Our analysis revealed a substantial anisotropy in Young's modulus in the plane containing the long axis of the tibia, with maxima of 20.9 GPa parallel to the long axis, and minima of 11.8 GPa perpendicular to this axis. A less pronounced anisotropy was observed in the plane perpendicular to the long axis of the tibia. To display our results for the full three-dimensional anisotropy of cortical bone, a closed surface was used to represent Young's modulus in all spatial directions.
    Type of Medium: Electronic Resource
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