Contribution of mineral to bone structural behavior and tissue mechanical properties.

Autor:	Donnelly, Eve, Chen, Dan X., Boskey, Adele L., Baker, Shefford P., van der Meulen, Marjolein C. H.
Předmět:	MINERALS in the body BONES TISSUE mechanics VITAMIN D CALCIUM in the body BONE physiology RESEARCH NEAR infrared spectroscopy BONE growth ANIMAL experimentation RESEARCH methodology EVALUATION research MEDICAL cooperation RATS OSTEOPOROSIS COMPARATIVE studies TENSILE strength RESEARCH funding BONE density CALCIUM EXTRACELLULAR space WEIGHT-bearing (Orthopedics) KINEMATICS PHYSIOLOGY
Zdroj:	Calcified Tissue International; Nov2010, Vol. 87 Issue 5, p450-460, 11p, 3 Charts, 4 Graphs
Abstrakt:	Bone geometry and tissue material properties jointly govern whole-bone structural behavior. While the role of geometry in structural behavior is well characterized, the contribution of the tissue material properties is less clear, partially due to the multiple tissue constituents and hierarchical levels at which these properties can be characterized. Our objective was to elucidate the contribution of the mineral phase to bone mechanical properties across multiple length scales, from the tissue material level to the structural level. Vitamin D and calcium deficiency in 6-week-old male rats was employed as a model of reduced mineral content with minimal collagen changes. The structural properties of the humeri were measured in three-point bending and related to the mineral content and geometry from microcomputed tomography. Whole-cortex and local bone tissue properties were examined with infrared (IR) spectroscopy, Raman spectroscopy, and nanoindentation to understand the role of altered mineral content on the constituent material behavior. Structural stiffness (-47%) and strength (-50%) were reduced in vitamin D-deficient (-D) humeri relative to controls. Moment of inertia (-38%), tissue mineral density (TMD, -9%), periosteal mineralization (-28%), and IR mineral:matrix ratio (-19%) were reduced in -D cortices. Thus, both decreased tissue mineral content and changes in cortical geometry contributed to impaired skeletal load-bearing function. In fact, 97% of the variability in humeral strength was explained by moment of inertia, TMD, and IR mineral:matrix ratio. The strong relationships between structural properties and cortical material composition demonstrate a critical role of the microscale material behavior in skeletal load-bearing performance. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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