Table 2.

A list of secondary Raman metrics along with their method of determination.

Metric	Measurement	Method	Characterization	Ref
Pentosidine	Peak at 1305 cm−1 or 1362 cm−1/amide I	Likely PI ratio	Pentosidine to matrix ratio increased in the cortical bone of rats following thyroparathyroidectomy (TPTx) and partial nephrectomy (Nx) compared to TPTx only rats	129
	Band at ~1495 cm−1/CH2-wag	IA ratio	Ratio increased implying diabetic mice had greater pentosidine (p = 0.017) content on the periosteal surface as compared to non-diabetic mice; propagation toughness correlated inversely with pentosidine (diabetic: r = −0.97, p = 0.001 and non-diabetic: r = −0.94, p = 0.005)a	130
CML	Band at ~1150 cm−1/CH2-wag	IA ratio	Diabetic mice had greater carboxymethyllysine (CML) (p = 0.003) content compared to non-diabetic mice; propagation toughness correlated inversely with CML (diabetic: r = −0.99, p < 0.001 and non-diabetic: r = −0.94, p = 0.005)a	130
Proline hydroxylation	Hyp/Pro	PI ratio	Ratio significantly increased (by ~10%) in the osteolytic samples than healthy controls	131
Lipid content	Band at ~1298 cm−1/amide III	IA ratio	Analyzing iliac crest biopsies, relative lipid content was lower in older tissue than in youngest tissue (near active osteoblasts), irrespective of menopausal status; directly correlated with osteoblast surface per bone surface (r=0.685, p=0.042) in only the premenopausal group.	132
Proteoglycan content	1365–1390 cm−1/ν2PO4 and 1365–1390 cm−1 / amide III	IA ratio	Proteoglycan content normalized to mineral was significantly higher in both idiopathic osteoporosis and idiopathic low BMD group than in control group (p<0.01). Proteoglycan content normalized to organic matrix was not significantly different among the three study groups	133

^aSee Table 3 for correlations between other Raman properties and mechanical properties of bone.