Table 4.
DXA Z-Scores and HRpQCT Data from the Radius and Tibia in Amenorrheic Athletes according to Fracture History [no fracture versus ≥1 fracture (stress and non-stress), and <2 stress fractures versus ≥ 2 stress fractures]
| No Fractures | ≥1 Fractures | P | < 2 Stress Fractures | ≥2 Stress Fractures | P | |
|---|---|---|---|---|---|---|
| DXA (BMD Z-scores) | n=53 | n = 47 | n=84 | n=16 | ||
| Femoral Neck | −0.01±1.06 | −0.33±1.05 | 0.14 | −0.09±1.07 | −0.55±0.96 | 0.11 |
| Total Hip | 0.16±1.03 | −0.09±0.97 | 0.21 | 0.12±1.02 | −0.33±0.86 | 0.10 |
| Lumbar Spine | −0.54±1.28 | −1.02±1.08 | 0.045 | −0.61±1.20 | −1.58±0.87 | 0.003 |
| Whole Body | −0.40±1.10 | −0.90±0.87 | 0.01 | −0.55±1.02 | −1.09±0.94 | 0.05 |
|
| ||||||
| HRpQCT Radius | n =45 | n =42 | n=71 | n=13 | ||
| Total area (mm2) | 263.3±45.7 | 264.1±44.8 | 0.94 | 267.9±45.8 | 240.7±32.9 | 0.045 |
| % Ct. area | 18.5±6.8 | 18.2±4.7 | 0.77 | 18.4±6.2 | 18.4±3.9 | 0.99 |
| Ct. thickness (mm) | 0.71±0.23 | 0.70±0.15 | 0.76 | 0.71±0.21 | 0.68±0.12 | 0.61 |
| Ct. porosity (%) | 1.3±0.9 | 1.1±0.7 | 0.29 | 1.2±0.9 | 0.8±0.5 | 0.07 |
| Ct. vBMD (mg HA/cm3) | 813.8±79.0 | 819.1±52.2 | 0.72 | 814.9±71.5 | 823.8±41.0 | 0.67 |
| Tb. thickness (mm) | 0.073±0.011 | 0.067±0.009 | 0.03 | 0.071±0.011 | 0.067±0.009 | 0.25 |
| Tb. vBMD (mg HA/cm3) | 170.8±4.7 | 159.1±27.9 | 0.09 | 168.5±32.2 | 148.1±21.2 | 0.03 |
| Outer Tb. vBMD (mg HA/cm3) | 230.0±31.9 | 215.7±27.8 | 0.03 | 226.8±31.1 | 204.5±21.0 | 0.02 |
| Inner Tb. vBMD (mg HA/cm3) | 129.8±35.8 | 120.0±28.8 | 0.18 | 128.3±33.8 | 109.0±21.9 | 0.05 |
| Total vBMD (mg HA/cm3) | 305.9±64.9 | 292.5±44.6 | 0.28 | 302.2±59.1 | 285.9±38.4 | 0.34 |
| Stiffness (kN/m) | 74.4±14.2 | 70.4±13.5 | 0.19 | 74.3±13.7 | 63.0±12.1 | 0.007 |
| Failure load (kN) | 3.79±0.70 | 3.58±0.69 | 0.17 | 3.78±0.68 | 3.18±0.60 | 0.004* |
| (Tb.F/TF) distal (%)* | 54.3±7.2 | 52.3±8.9 | 0.26 | 54.0±8.1 | 49.6±7.2 | 0.07 |
| (Tb.F/TF) proximal (%)* | 21.4±7.1 | 20.1±7.6 | 0.44 | 21.3±7.6 | 18.0±5.0 | 0.13 |
| TbVM (N/mm2)** | 52.9±6.9 | 49.8±7.3 | 0.049 | 51.9±7.1 | 49.0±7.6 | 0.19 |
|
| ||||||
| HRpQCT Tibia | n =45 | n = 42 | n=73 | n=14 | ||
| Total area (mm2) | 668.3±108.0 | 671.4±98.3 | 0.89 | 674.3±104.0 | 646.5±96.6 | 0.36 |
| % Ct. area | 19.2±5.2 | 18.2±4.3 | 0.32 | 18.9±4.9 | 17.8±3.9 | 0.46 |
| Ct. thickness (mm) | 1.25±0.28 | 1.19±0.22 | 0.27 | 1.24±0.26 | 1.15±0.19 | 0.23 |
| Ct. porosity (%) | 2.0±1.2 | 1.8±0.9 | 0.45 | 1.9±1.1 | 2.0±1.0 | 0.79 |
| Ct. vBMD (mg HA/cm3) | 865.8±43.8 | 869.1±28.6 | 0.68 | 867.4±4.4 | 867.3±28.1 | 1.00 |
| Tb. vBMD (mg HA/cm3) | 208.4±33.3 | 197.5±20.7 | 0.07 | 204.6±30.0 | 195.1±15.8 | 0.25 |
| Outer Tb. vBMD (mg HA/cm3) | 273.9±35.2 | 258.9±24.1 | 0.02 | 268.6±33.0 | 256.6±15.7 | 0.19 |
| Inner Tb. vBMD (mg HA/cm3) | 163.9±33.7 | 155.7±20.6 | 0.18 | 161.2±29.7 | 153.3±18.9 | 0.34 |
| Total vBMD (mg HA/cm3) | 335.1±53.6 | 320.5±37.7 | 0.15 | 330.5±49.0 | 315.4±32.4 | 0.27 |
| Stiffness (kN/m) | 230.9±31.3 | 224.7±29.6 | 0.35 | 230.7±30.3 | 213.8±28.0 | 0.05* |
| Failure load (kN) | 11.5±1.5 | 11.2±1.5 | 0.35 | 11.5±1.5 | 10.7±1.4 | 0.048* |
| (Tb.F/TF) distal (%)** | 59.6±7.3 | 59.5±6.7 | 0.96 | 59.5±7.1 | 60.1±6.2 | 0.75 |
| (Tb.F/TF) proximal (%)** | 38.6±7.3 | 38.8±6.7 | 0.89 | 38.6±7.1 | 39.9±6.5 | 0.88 |
| TbVM (N/mm2)*** | 63.94±5.01 | 63.40±4.25 | 0.60 | 63.68±4.72 | 63.66±4.37 | 0.99 |
Data presented as means ± standard deviations.
The Student t-test was used for normally distributed 2 group comparisons. The Wilcoxon Rank Sum test was used for data not normally distributed (*).
Ct.: cortical; Tb: trabecular
**
(Tb.F/TF) distal or proximal: percent load carried by trabecular bone at most distal (or proximal) slice.
***
Tb VM: Trabecular von Mises stress (amount of stress the trabecular compartment can withstand before permanently deforming)