Table 4 Comparison of HRpQCT and BMD among patients with AS based on sex, mSASSS, and HLA-B27

 Trabecular vBMD (mg/cm³)

165.3 ± 45.7

186.1 ± 39.6*

140.0 ± 40.0

168.8 ± 54.4

161.3 ± 34.2

175.7 ± 39.9

142.8 ± 52.3^†

 Cortical vBMD (mg/cm³)

854.7 ± 66.2

826.8 ± 51.8*

864.0 ± 55.2

821.6 ± 57.8**

868.4 ± 43.1

845.3 ± 59.2

834.0 ± 90.9

 Total vBMD (mg/cm³)

315.4 ± 64.4

322.5 ± 62.8

306.8 ± 66.7

303.42 ± 74.28

328.88 ± 49.49

324.0 ± 57.5

300.3 ± 77.4

 Trabecular number (/mm³)

2.02 ± 0.34

2.13 ± 0.24*

1.86 ± 0.43

1.99 ± 0.44

2.04 ± 0.25

2.07 ± 0.29

1.89 ± 0.48

 Trabecular thickness (mm)

0.068 ± 0.012

0.073 ± 0.012*

0.062 ± 0.010

0.069 ± 0.013

0.066 ± 0.011

0.071 ± 0.01

0.061 ± 0.01^†

 Trabecular separation (mm)

0.457 ± 0.185

0.402 ± 0.061*

0.523 ± 0.254

0.479 ± 0.246

0.432 ± 0.068

0.423 ± 0.08

0.535 ± 0.31^†

 BV/TV (%)

0.138 ± 0.038

0.155 ± 0.033*

0.117 ± 0.033

0.141 ± 0.045

0.134 ± 0.029

0.147 ± 0.03

0.119 ± 0.40^†

 Cortical thickness (mm)

0.765 ± 0.153

0.748 ± 0.148

0.786 ± 0.159

0.715 ± 0.159**

0.821 ± 0.126

0.770 ± 0.165

0.760 ± 0.160

 Cortical porosity (%)

0.020 (0.010–0.025)

0.022 (0.018–0.026)*

0.010 (0.008–0.020)*

0.021 (0.019–0.027) **

0.012 (0.009–0.018)

0.020 (0.016–0.024)

0.016 (0.009–0.023)

 Stiffness (N/mm)

1.4 ± 0.4

1.4 ± 0.4

1.3 ± 0.4

1.3 ± 0.04

1.5 ± 0.4

1.4 ± 0.4

1.3 ± 0.5

 Stress (MPa)

27.7 ± 9.4

28.72 ± 9.35

26.38 ± 9.57

26.0 ± 9.9

29.5 ± 8.7

28.8 ± 8.9

25.8 ± 10.7

 Trabecular vBMD (mg/cm³)

159.9 ± 43.7

176.6 ± 38.5*

139.8 ± 41.9

162.8 ± 44.8

157.4 ± 43.5

170.9 ± 40.7

136.9 ± 43.4^†

 Total vBMD (mg/cm³)

296.4 ± 55.5

302.9 ± 46.0

288.5 ± 65.1

285.1 ± 57.2

308.2 ± 52.1

309.4 ± 39.3

272.5 ± 74.8^†

 Cortical vBMD (mg/cm³)

843.7 ± 56.1

848.4 ± 43.4

862.2 ± 86.7

835.2 ± 79.3**

876.9 ± 39.1

865.4 ± 50.8

834.0 ± 91.0

 Trabecular number (per mm³)

1.89 ± 0.45

2.05 ± 0.29*

1.70 ± 0.533

1.95 ± 0.42

1.84 ± 0.47

1.96 ± 0.42

1.71 ± 0.49

 Trabecular thickness (mm)

0.07 ± 0.01

0.070 ± 0.014

0.071 ± 0.015

0.070 ± 0.013

0.073 ± 0.015

0.073 ± 0.014

0.070 ± 0.011

 Trabecular separation (mm)

0.50 ± 0.23

0.43 ± 0.07*

0.60 ± 0.31

0.47 ± 0.13

0.53 ± 0.29

0.46 ± 0.13

0.60 ± 0.35^†

 BV/TV (%)

0.133 ± 0.036

0.147 ± 0.032*

0.117 ± 0.035

0.131 ± 0.037

0.136 ± 0.036

0.143 ± 0.034

0.114 ± 0.036^†

 Cortical thickness (mm)

0.744 ± 0.180

0.695 ± 0.137*

0.804 ± 0.208

0.691 ± 0.182**

0.804 ± 0.161

0.766 ± 0.185

0.705 ± 0.169

 Cortical porosity (%)

0.049 (0.035–0.067)

0.061 (.044–0.075)**

0.039 (0.029–0.056)**

0.062 (0.045–0.091)**

0.040 (0.033–0.056)

0.047 (0.032–0.070)

0.056 (0.035–0.071)

 Stiffness (N/mm)

1.51 ± 0.42

1. 6 ± 0.3

1.5 ± 0.4

1.6 ± 0.3

1.5 ± 0.4

1.6 ± 0.3

1.4 ± 0.4^†

 Stress (MPa)

31.6 ± 9.1

32.7 ± 8.0

31.1 ± 9.5

30.6 ± 8.7

33.5 ± 8.5

33.8 ± 7.2

28.8 ± 10.4^†

 L1–L4 BMD

0.994 ± 0.179

1.018 ± 0.163

0.964 ± 0.198

1.001 ± 0.214

0.986 ± 0.138

1.024 ± 0.182

0.944 ± 0.161

 Total hip BMD

0.904 ± 0.149

0.943 ± 0.125*

0.858 ± 0.165

0.887 ± 0.158

0.921 ± 0.140

0.925 ± 0.123

0.857 ± 0.197

 Femoral neck BMD

0.767 ± 0.142

0.795 ± 0.153

0.733 ± 0.124

0.735 ± 0.125

0.798 ± 0.153

0.786 ± 0.130

0.727 ± 0.169

 Distal 1/3 radius BMD

0.740 ± 0.127

0.802 ± 0.067*

0.659 ± 0.142

0.771 ± 0.080

0.708 ± 0.156

0.764 ± 0.088

0.679 ± 0.185^†

 Ultradistal radius BMD

0.477 ± 0.078

0.505 ± 0.079*

0.441 ± 0.061

0.481 ± 0.086

0.472 ± 0.069

0.488 ± 0.084

0.453 ± 0.059