Table 4.

Relative correlation coefficients (R values) for QUS, μCT and mechanical testing. SCAN determined ultrasound parameters are able to predict structural and strength properties of trabecular bone. Combined BUA and UV indexes improve the correlation coefficients consistently above 0.75 with regard to the elastic modulus, bulk modulus, yield or ultimate strength. Strong correlations were also found between combined BUA & UV from single direction, i.e., ML, and structural and strength parameters, suggesting QUS signals extracted from particular direction (e.g., under in vivo condition) are able to predict overall trabecular bone density and stiffness.

	ATT	UV	BUA	Combo BUA & UV in ML	Combo BUA & UV in AP	Combo BUA & UV
AP Modulus	−0.71	0.79	−0.31	0.74	0.74	0.80
	p<0.001	p<0.001	p=0.033	p<0.001	p<0.001	p<0.001
LG Modulus	−0.75	0.79	−0.221	0.63	0.67	0.81
	p<0.001	p<0.001	p=0.131	p<0.001	p<0.001	p<0.001
ML Modulus	−0.673	0.89	−0.483	0.79	0.74	0.78
	p<0.001	p<0.001	p=0.001	p<0.001	p<0.001	p<0.001
Bulk Modulus	−0.75	0.82	−0.358	0.76	0.75	0.84
	p<0.001	p<0.001	p=0.012	p<0.001	p<0.001	p<0.001
Yield Strength	−0.72	0.90	−0.85	0.87	0.89	0.93
	p<0.001	p<0.001	p<0.001	p<0.001	p<0.001	p<0.001
Ulti. Strength	−0.75	0.90	−0.85	0.87	0.88	0.94
	p<0.001	P<0.001	P<0.001	P<0.001	P<0.001	p<0.001
BV/TV	−0.37	0.93	−0.73	0.93	0.93	0.93
	p=0.018	p<0.001	p<0.001	p<0.001	p<0.001	p<0.001
BMD	0.74	0.85	−0.75	0.86	0.85	0.87
SMI	0.3	0.9	0.66	0.91	0.92	0.93
	p=0.034	p<0.001	p<0.001	p<0.001	p<0.001	p<0.001
Conn.D.	−0.12	−0.33	0.07	0.32	0.39	0.42
	p=0.5	p=0.006	p=0.5	p=0.025	p=0.006	p=0.003
Tr.Th.	−0.17	0.69	−0.34	0.83	0.64	0.67
	p=0.368	p<0.001	p=0.01	p<0.001	p<0.001	p<0.001
DA	−0.278	0.5	−0.32	0.34	0.44	0.50
	p=0.056	p<0.001	p=0.26	p=0.17	p=0.002	p<0.001