Table 3

Comparison of bone strength and structure in male and female healthy controls and patients with rheumatoid arthritis

Groups	HC (n=96)		RA+ (n=96)		RA− (n=84)
Groups	Male (n=38)	Female (n=58)	Male (n=26)	Female (n=70)	Male (n=22)	Female (n=62)
µFEA
Stiffness, kN/mm	57.2±10.1*†	37.5±11.4†	48.0±13.5*	32.1±11.4‡	51.9±11.6*	37.8±10.8
Failure load, N	2752±445*†	1813±508†	2331±584*	1563±492‡	2502±517*	1803±484
Bone structure (HR-pQCT)
Volumetric bone mineral density
Dtotal, mg HA/cm³	301±52†	282±57	259±50	255±61‡	288±56	286±63
Dtrab, mg HA/cm³	185±28*†	151±36†	145±42	124±47‡	170±30*	142±43
Dmeta, mg HA/cm³	240±30*†	211±37†	212±3	191±46	227±25*	200±43
Dinn, mg HA/cm³	147±27*†	109±38†	116±4*	291±43	131±16*	102±44
Dcomp, mg HA/cm³	767±51*	799±71	734±91	756±108‡	776±77*	827±62
Meta/Inn, %	1.66±0.17*	2.15±0.7	2.17±1.3	2.32±0.93	1.86±0.47	2.14±0.70
Bone microstructure
BV/TV, %	0.15±0.02*†	0.13±0.03	0.13±0.03*	0.11±0.04	0.14±0.03*	0.12±0.04
Tb.N, 1/mm	2.18±0.21*	1.95±0.32†	1.93±0.42*	1.76±0.41	2.17±0.27*	1.84±0.37
Tb.Th, mm	0.07±0.01*	0.06±0.01	0.07±0.01	0.06±0.01	0.07±0.01	0.06±0.01
Tb.Sp, mm	0.39±0.04*	0.47±0.13†	0.49±0.18	0.55±0.24	0.40±0.06*	0.52±0.23
Tb.1/N.SD, mm	0.16±0.03	0.20±0.08†	0.27±0.22	0.29±0.25	0.18±0.06	0.25±0.17
Ct.Th, mm	0.70±0.17	0.64±0.18	0.61±0.21	0.58±0.21‡	0.70±0.23	0.69±0.18

Bonferroni-Holm adjustment: critical P values indicating significant results for all investigated parameters were as follows: P1=0.0056, P2=0.0063, P3=0.0071, P4=0.0083, P5=0.01, P6=0.0125, P7=0.0167, P8=0.025, P9=0.05.
*Significance between men vs women in the same group.
†Significance between HC vs RA+ of same sex.
‡Significance between RA+ vs RA− of same sex.
§Significance between HC vs RA− of same sex.
BV/TV, trabecular bone volume per tissue volume; Ct.Th, cortical thickness; Dcomp, compact (cortical) volumetric bone mineral density (vBMD); Dinn, inner trabecular vBMD; Dmeta, meta-trabecular vBMD; Dtotal, total vBMD; Dtrab, trabecular vBMD; HC, healthy controls; HR-pQCT, high-resolution peripheral CT; Meta/Inn, ratio of meta-to-inner density; RA+, anti-citrullinated protein autoantibody-positive rheumatoid arthritis (RA); RA−, anti-citrullinated protein autoantibody-negative RA; Tb.1/N.SD, inhomogeneity of network; Tb.N, trabecular number; Tb.Sp, trabecular separation; Tb.Th, trabecular thickness; µFEA, micro-finite element analysis.