Table 5.
Mean (SD) parameters within each cluster analysis group among women
| Cluster 1 (n = 23) | Cluster 2 (n = 39) | Cluster 3 (n = 47) | Cluster 4 (n = 62) | |
|---|---|---|---|---|
| Bone microarchitectural (standardised) | ||||
| Total area | 0.65 (0.89) | −0.43 (0.95) | 0.60 (0.88) | −0.42 (0.78) |
| Cortical area | −1.05 (0.76) | 0.10 (0.88) | −0.44 (0.80) | 0.66 (0.77) |
| Cortical thickness | −1.32 (0.59) | 0.26 (0.72) | −0.61 (0.58) | 0.79 (0.68) |
| Cortical density | −1.23 (0.87) | 0.53 (0.73) | −0.54 (0.66) | 0.53 (0.77) |
| Cortical porosity | −0.11 (1.08) | −0.63 (0.91) | 0.24 (0.87) | 0.25 (0.96) |
| Trabecular area | 0.84 (0.95) | −0.41 (0.80) | 0.67 (0.86) | −0.55 (0.68) |
| Trabecular density | −1.02 (0.59) | −0.93 (0.70) | 0.09 (0.50) | 0.89 (0.65) |
| Trabecular number | −0.60 (0.80) | −0.88 (0.75) | 0.19 (0.82) | 0.63 (0.81) |
| Trabecular thickness | −1.19 (0.72) | −0.58 (0.88) | 0.04 (0.68) | 0.78 (0.64) |
| Trabecular separation | 0.67 (0.72) | 0.91 (0.75) | −0.15 (0.73) | −0.71 (0.79) |
| FEA (standardised) | ||||
| Bone stiffness | −1.42 (0.37) | −0.52 (0.57) | −0.09 (0.63) | 0.92 (0.66) |
| Bone failure load | −1.37 (0.40) | −0.59 (0.57) | −0.01 (0.65) | 0.89 (0.68) |
| % load trabecular (distal) | 1.13 (0.42) | −0.94 (0.74) | 0.78 (0.52) | −0.42 (0.69) |
| % load trabecular (proximal) | 0.89 (0.88) | −1.16 (0.73) | 0.66 (0.75) | −0.10 (0.48) |
| Young modulus | −1.59 (0.37) | −0.18 (0.64) | −0.40 (0.42) | 1.00 (0.48) |
| Von Mises stresses (trabecular) | −0.76 (0.55) | −0.89 (0.79) | 0.17 (0.80) | 0.72 (0.73) |
| Von Mises stresses (cortical) | −1.10 (1.20) | 0.45 (0.68) | −0.34 (0.90) | 0.38 (0.74) |
| Trabecular strain | −0.86 (0.49) | −0.84 (0.85) | 0.14 (0.75) | 0.74 (0.72) |
| Cortical strain | −0.59 (1.71) | 0.11 (0.64) | 0.08 (1.15) | 0.09 (0.57) |
| DXA | ||||
| Femoral neck aBMD (g/cm2) | 0.75 (0.09) | 0.79 (0.11) | 0.80 (0.10) | 0.90 (0.12) |
| Pvalue | < 0.001 | < 0.001 | < 0.001 | Reference |
| Normal* | 3 (13.0%) | 10 (27.0%) | 10 (21.7%) | 39 (66.1%) |
| Osteopenic* | 16 (69.6%) | 20 (54.1%) | 32 (69.6%) | 18 (30.5%) |
| Osteoporosis* | 4 (17.4%) | 7 (18.9%) | 4 (8.7%) | 2 (3.4%) |
| Fracture | ||||
| Prevalent fracture* | 10 (50.0%) | 14 (37.8%) | 15 (33.3%) | 11 (19.6%) |
| Relative risk of fracture | 2.55 (1.28,5.07) | 1.93 (0.98,3.78) | 1.70 (0.86,3.33) | Reference |
| Pvalue | 0.008 | 0.057 | 0.124 | Reference |
| Vertebral fracture* | 3 (13.6%) | 4 (10.8%) | 3 (6.4%) | 4 (6.5%) |
Cluster analysis was performed on the combined set of bone microarchitectural and FEA parameters
Bold if mean > 1 standard deviation from sample mean
P values for relative risk of prevalent fracture were calculated using Poisson regression with robust variance estimation. P values for differences in femoral neck aBMD were calculated using linear regression. P values are for differences compared to Cluster 4 (lowest risk)
*N (%)