Applying Full Spectrum Analysis to a Raman Spectroscopic Assessment of Fracture Toughness of Human Cortical Bone.

Makowski AJ, Granke M, Ayala OD, Uppuganti S, Mahadevan-Jansen A, Nyman JS
Appl Spectrosc. 2017 71 (10): 2385-2394

PMID: 28708001 · PMCID: PMC5561524 · DOI:10.1177/0003702817718149

A decline in the inherent quality of bone tissue is a † Equal contributors contributor to the age-related increase in fracture risk. Although this is well-known, the important biochemical factors of bone quality have yet to be identified using Raman spectroscopy (RS), a nondestructive, inelastic light-scattering technique. To identify potential RS predictors of fracture risk, we applied principal component analysis (PCA) to 558 Raman spectra (370-1720 cm) of human cortical bone acquired from 62 female and male donors (nine spectra each) spanning adulthood (age range = 21-101 years). Spectra were analyzed prior to R-curve, nonlinear fracture mechanics that delineate crack initiation (K) from crack growth toughness (K). The traditional νphosphate peak per amide I peak (mineral-to-matrix ratio) weakly correlated with K (r = 0.341, p = 0.0067) and overall crack growth toughness (J-int: r = 0.331, p = 0.0086). Sub-peak ratios of the amide I band that are related to the secondary structure of type 1 collagen did not correlate with the fracture toughness properties. In the full spectrum analysis, one principal component (PC5) correlated with all of the mechanical properties (K: r = - 0.467, K: r = - 0.375, and J-int: r = - 0.428; p < 0.0067). More importantly, when known predictors of fracture toughness, namely age and/or volumetric bone mineral density (vBMD), were included in general linear models as covariates, several PCs helped explain 45.0% (PC5) to 48.5% (PC7), 31.4% (PC6), and 25.8% (PC7) of the variance in K, K, and J-int, respectively. Deriving spectral features from full spectrum analysis may improve the ability of RS, a clinically viable technology, to assess fracture risk.

MeSH Terms (13)

Adult Aged Aged, 80 and over Bone Density Collagen Cortical Bone Female Fractures, Bone Humans Male Middle Aged Spectrum Analysis, Raman Young Adult

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