Raman assessment of bone quality.
BACKGROUND
Progress in the diagnosis and prediction of fragility fractures depends on improvements to the understating of the compositional contributors of bone quality to mechanical competence. Raman spectroscopy has been used to evaluate alterations to bone composition associated with aging, disease, or injury.


OBJECTIVE
In this survey we will (1) review the use of Raman-based compositional measures of bone quality, including mineral-to-matrix ratio, carbonate-to-phosphate ratio, collagen quality, and crystallinity; (2) review literature correlating Raman spectra with biomechanical and other physiochemical measurements and with bone health; and (3) discuss prospects for ex vivo and in vivo human subject measurements.


METHODS
ISI Web of Science was searched for references to bone Raman spectroscopy in peer-reviewed journals. Papers from other topics have been excluded from this review, including those on pharmaceutical topics, dental tissue, tissue engineering, stem cells, and implant integration.


RESULTS
Raman spectra have been reported for human and animal bone as a function of age, biomechanical status, pathology, and other quality parameters. Current literature supports the use of mineral-to-matrix ratio, carbonate-to-phosphate ratio, and mineral crystallinity as measures of bone quality. Discrepancies between reports arise from the use of band intensity ratios rather than true composition ratios, primarily as a result of differing collagen band selections.


CONCLUSIONS
Raman spectroscopy shows promise for evaluating the compositional contributors of bone quality in ex vivo specimens, although further validation is still needed. Methodology for noninvasive in vivo assessments is still under development.
University of Michigan, Ann Arbor, MI, USA, mdmorris@umich.edu.
Michael D
MD
Morris
Gurjit S
GS
Mandair
D015502:Absorptiometry, Photon; D000818:Animals; D015519:Bone Density / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology; D001842:Bone and Bones / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D050723:Fractures, Bone / Q000503:physiopathology; D006801:Humans; D010024:Osteoporosis / Q000175:diagnosis / Q000503:physiopathology; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods