Age-related decline in trabecular and cortical density: a 5-year peripheral quantitative computed tomography...

This 5-year prospective study assessed changes in trabecular and cortical volumetric bone density at the non-weight-bearing radius and weight-bearing tibia among clinically healthy pre- and postmenopausal women. Altogether 79 premenopausal (mean age +/- SD at baseline 33 +/- 2 years) and 108 postmenopausal (68 +/- 2 years) women participated in the baseline and follow-up measurements. Trabecular density (TrD) of the distal radius and tibia and cortical density (CoD) of the radial and tibial shafts were assessed by peripheral quantitative computed tomography (pQCT). Repeated measures analysis of variance was used to analyze differences of means and mean changes between the age groups. As expected, TrD and CoD values were greater among premenopausal than postmenopausal women. Changes in radial TrD were similar in both age groups: mean (95% confidence interval) TrD of the distal radius declined by 3.0 mg/cm(3) (-0.9 to 7.0) and 5.1 mg/cm(3) (1.8-8.5) in the younger and older age groups, respectively. The respective declines in TrD of the distal tibia were 4.1 mg/cm(3) (2.1-6.0) and 2.8 mg/cm(3) (1.2-4.3). Decline in CoD was greater in the older than younger age group at both the radial and tibial shafts (P < 0.001). The mean absolute declines in radial CoD were 33.3 mg/cm(3) (27.9-38.7) and 49.4 mg/cm(3) (44.9-53.9) in younger and older women, and the declines in tibial CoD were 16.5 mg/cm(3) (12.6-20.2) and 28.1 mg/cm(3) (25.0-31.2), respectively. In conclusion, volumetric TrD in the weight-bearing tibia and non-weight-bearing radius showed similar age-related declines among pre- and postmenopausal women, while the decline in CoD was greater among postmenopausal women.