Table 1.

Micro-architectural indices measured for each volume of interest (VOI)

Micro-architectural index	Abbrev.	Unit	Description
Percentage bone volume	BV/TV	%	Measure of the ratio of solid to space within a given volume surrogate parameter for bone strength (Legrand et al. 2000)
Trabecular thickness	Tb. Th	mm	The width of the trabecular—important for determining structural integrity (Tanck et al. 2009)
Structural model index	SMI	None	Indicates relative presence of rods, plates, or cylinders in a 3D model (Hildebrand and Ruegsegger 1997). Plate 0, rod 3, sphere 4 (Skyscan 2010)
Degree of anisotropy	DA	None	Measure of how well orientated a microstructure is within a given volume (Cotter et al. 2009)
Connectivity density	Conn.D	mm-3	Number of connections between trabecular structures in a given volume—a good measure of bone structure (Fajardo and Muller 2001)