Table 1.

Summary of mechanical characterization techniques with outcome variables based on length scale and type of specimen

Length scale	Type of specimen	Mechanical testing mode	Outcome variables
Whole bone	Long bones, vertebra	Bending, tension, compression, torsion, compression	Extrinsic mechanical properties, i.e., structural stiffness, max load, work to fracture, fracture load
Tissue	Cortical beam, dumbbell, dog bone, single-edged notched specimen (SEB), cancellous cores	Tension, compression, torsion, bending fatigue, compression (static or cyclic)	Intrinsic mechanical properties, i.e., Young’s modulus, yield, fatigue and ultimate strength, fracture toughness
Micro	Cortical bone cubes up to 5 mm thick, cortical or trabecular bone slices	Microscratch, microindentation, reference point indentation	Material level properties i.e. fracture toughness, hardness, modulus (elastic and reduced), elastic work, total work, total indentation distance, indentation distance increase
Nano	Cortical or trabecular bone specimen 2–3 mm thick, cortical or trabecular bone slices	Nanoindentation, in situ testing (tension, compression, bending)	Material level properties, i.e., hardness, modulus, fibril strain, mineral stress