Table 3.

Heatmap of correlations indicating degree of association among femur variables (rows) and spine variables (columns).

		Vitamin D Status			Spine Micro CT Data			Spine Biomechanical Data
		Dietary D	Serum D at surg	Serum D at sac	BMD	BV	BV/TV	Stiffness	Fusion MP
Vitamin D Status	Dietary D	1.0000	0.9683	0.9818	0.4963	0.4106	0.5089	0.3328	0.1997
	Serum D (surg)	0.9683	1.0000	0.9648	0.4721	0.3801	0.5055	0.3386	0.1233
	Serum D (sac)	0.9818	0.9648	1.0000	0.4985	0.3528	0.5187	0.3369	0.1841
Femur Micro CT Data	Cortical Thickness	0.2703	0.3391	0.2505	0.1885	0.4239	0.3397	0.2963	−0.1319
	X-sectional Area	0.3831	0.4102	0.3524	0.0447	0.5533	0.1818	0.4160	−0.0265
	Moment of Inertia	0.3590	0.3590	0.3334	−0.0032	0.5093	0.1019	0.4020	0.0081
	BMD	0.0855	0.1454	0.0602	0.2226	0.2399	0.3165	0.0086	−0.0620
	BV	0.3661	0.3895	0.3343	0.0468	0.5622	0.1941	0.3902	−0.0123
	BV/TV	0.0845	0.1510	0.0611	0.1956	0.2525	0.3166	−0.0345	−0.0614
Femur Biomechanical Data	Stiffness	0.4468	0.4496	0.4606	0.1633	0.5451	0.1954	0.2690	−0.1075
	Max Load	0.4927	0.4958	0.4828	0.1181	0.6061	0.2183	0.4942	−0.0626
	Young’s Modulus	−0.0373	−0.0382	0.0049	0.1322	−0.2006	0.0075	−0.3014	−0.1439
Femur Ashing Data	Dry Weight	0.2425	0.2018	0.2458	−0.0737	0.4378	−0.0025	0.4452	0.0394
	Ash Weight	0.3591	0.3248	0.3586	0.0316	0.5120	0.1092	0.4811	0.0781
	Ash Fraction	0.5687	0.5865	0.5528	0.4252	0.4230	0.4661	0.2328	0.1867
	Ash Density	0.5312	0.5886	0.5317	0.3738	0.2582	0.3878	−0.0524	−0.0792

Cells correspond to correlation coefficients, r-values (range from −1 to +1), indicating degree of association. The more extreme the value, the more associated the variables. Corresponding p-values for these data are regarded as: r ≥ 0.6 | r ≤ −0.6, p<0.0001, ‘strong association’; r ≥ 0.48 | r ≤ −0.48, p<0.001, ‘moderate’; r ≥ 0.33 | r ≤ −0.33, p<0.01, ‘weak’; r ≥ 0.29 | r ≤ −0.29, p<0.05, ‘very weak’.