Peripheral quantitative Computed Tomography (PQCT) in the evaluation of bone geometry, biomechanics and mineral density in postmenopausal women

AIM: Non-invasive assessment of bone geometry, biomechanics, and mineral content in postmenopausal women by peripheral quantitative Computed Tomography (pQCT). MATERIAL AND METHODS: Total, trabecular and cortical mineral density (totBMD, cortBMD, trabBMD), and the geometrical (total area, trabecular area, cortical area) and biomechanical properties of bone (strength-strain index, cortical thickness) were assessed in 93 consecutive post-menopausal women (mean age: 63+/-7 yrs; age at menopause: 49+/-6 yrs; years since menopause: 14+/-9 yrs) by pQCT at the ultradistal radius of non-dominant forearm. RESULTS: Compared with 50 healthy women at peak of bone mass, volumetric total, trabecular and cortical bone densities were significantly reduced in postmenopausal subjects (TotBMD: 318+/-106 mg/cm3 vs ctr 442+/-100, -28%, p<0.001; TrabBMD: 117+/-59 mg/cm3 vs ctr: 203+/-47, -42%, p<0.001; CorBMD: 764+/-159 mg/cm3 vs 921+/-111, -17%, p<0.001). The bone loss was greater in trabecular bone. Cortical area (0.7+/-0,1 cm2 vs ctr: 0.8+/-0.1, -12.5%, p<0.001), cortical thickness (0.151+/-0.02 cm vs ctr: 0.169+/-0.03, -11%, p<0.001), and strength-strain index (686+/-207 mm3 vs ctr: 883+/-165, -22%, p<0.001) were significantly lower in post-menopausal women in comparison with the controls. Years since menopause and age showed a significant negative correlation with bone mineral densities and biomechanical parameters. CONCLUSIONS: In post-menopausal women pQCT showed: 1) osteopoenia in all bone compartments, greater at the trabecular level, related to age and years since menopause; 2) reduced cortical density and cortical thickness, consistent with a reduced ability of bone to absorb loading forces; 3) reduced strength-strain index, indicative of inability to adapt to mechanical use and augmented risk for fracture. We conclude that pQCT is a valuable tool for measuring the true volumetric mineral density and the geometrical and biomechanical indexes of bone, which could be proposed in current clinical practice for the assessment of osteoporosis