Table 3

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

GroupsHC (n=96)RA+ (n=96)RA− (n=84)
Male (n=38)Female (n=58)Male (n=26)Female (n=70)Male (n=22)Female (n=62)
 Stiffness, kN/mm57.2±10.1*†37.5±11.4†48.0±13.5*32.1±11.4‡51.9±11.6*37.8±10.8
 Failure load, N2752±445*†1813±508†2331±584*1563±492‡2502±517*1803±484
Bone structure (HR-pQCT)
 Volumetric bone mineral density
  Dtotal, mg HA/cm³301±52†282±57259±50255±61‡288±56286±63
  Dtrab, mg HA/cm³185±28*†151±36†145±42124±47‡170±30*142±43
  Dmeta, mg HA/cm³240±30*†211±37†212±3191±46227±25*200±43
  Dinn, mg HA/cm³147±27*†109±38†116±4*291±43131±16*102±44
  Dcomp, mg HA/cm³767±51*799±71734±91756±108‡776±77*827±62
  Meta/Inn, %1.66±0.17*2.15±0.72.17±1.32.32±0.931.86±0.472.14±0.70
 Bone microstructure
  BV/TV, %0.15±0.02*†0.13±0.030.13±0.03*0.11±0.040.14±0.03*0.12±0.04
  Tb.N, 1/mm2.18±0.21*1.95±0.32†1.93±0.42*1.76±0.412.17±0.27*1.84±0.37
  Tb.Th, mm0.07±0.01*0.06±0.010.07±0.010.06±0.010.07±0.010.06±0.01
  Tb.Sp, mm0.39±0.04*0.47±0.13†0.49±0.180.55±0.240.40±0.06*0.52±0.23
  Tb.1/N.SD, mm0.16±0.030.20±0.08†0.27±0.220.29±0.250.18±0.060.25±0.17
  Ct.Th, mm0.70±0.170.64±0.180.61±0.210.58±0.21‡0.70±0.230.69±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.