Table 2

Bone strength and structure in healthy controls and patients with rheumatoid arthritis

	HC	RA+	RA−
µFEA
Stiffness, kN/mm	45.3±14.6*	36.4±13.9*†	41.5±12.5†
Failure load, N	2184±667*	1771±619*†	1986±579†
Bone structure (HR-pQCT)
Volumetric bone mineral density
Dtotal, mg HA/cm³	289±56*	256±58*†	286±61†
Dtrab, mg HA/cm³	164±37*‡	130±47*†	150±42†‡
Dmeta, mg HA/cm³	223±37*‡	196±43*†	207±41†‡
Dinn, mg HA/cm³	124±39*	98±44*	110±44
Dcomp, mg HA/cm³	786±66*‡	750±104*†	814±69†‡
Meta/Inn, %	1.96±0.65*	2.28±1.02*	2.06±0.66
Bone microstructure
BV/TV, %	0.14±0.03*‡	0.12±0.04*†	0.12±0.03†‡
Tb.N, 1/mm	2.04±0.30*‡	1.81±0.42*†	1.93±0.37†‡
TbTh, mm	0.07±0.01*	0.06±0.01*	0.06±0.01
Tb.Sp, mm	0.44±0.11*‡	0.54±0.23*†	0.49±0.21†‡
Tb.1/N.SD, mm	0.19±0.07*‡	0.29±0.24*	0.23±0.15^b
Ct.Th, mm	0.67±0.18*	0.59±0.21*†	0.69±0.19†

Bonferroni-Holm adjustment: critical P values indicating significant results for all investigated parameters were as follows: P1=0.0167, P2=0.025, P3=0.05.
*Significance between HC vs RA+.
†Significance between RA+ vs RA−.
‡Significance between HC vs RA−.
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.