Response of cortical bone to antiresorptive treatment

A total of 113 postmenopausal women (69 controls, 33 using hormone replacem ent therapy (HRT), and 11 using bisphosphonate) were evaluated twice over 2 years with a new noninvasive, radiogrammetry-based technique called digita l X-ray radiogrammetry (DXR) and conventional bone densitometry of the spin e, hip, and forearm. Longitudinal changes in bone densitometry were compare d with changes captured by DXR: BMD evaluated by DXR (BMDDXR), cortical thi ckness of the second metacarpal (CTMC2), and porosity of cortical bone. The expected annual postmenopausal reduction in BMD in the control group was d etected by BMDspine (-0.8%, P < 0.01), BMDhip (-1.6%, P < 0.001), BMDforear m, (-1.5%, P < 0.001); DXR-BMD (-0.8% P < 0.001), and CTMC2 (-1.1%, P < 0.0 01). In the HRT group, smaller reductions were seen in BMDDXA, but only sig nificant at the hip (-1.0%, P < 0.01) and distal forearm (-1.0%, P < 0.02). In the bisphosphonate group, cortical porosity was significantly reduced ( P < 0.025). Comparing longitudinal changes in age-matched subsamples of con trols and bisphosphonate treated, BMDDXR, CTMC2, and porosity of cortical b one all differed significantly (P < 0.01, P < 0.05, P < 0.05, respectively) , whereas the BMDDXA measurements did not. In conclusion, DXR provides a de nsitometry equivalent measurement of the distal forearm and hand and seems to offer new information on the porosity of cortical bone, This may prove u seful in the evaluation of bone loss and offer new insight into the effects of different antiresorptive treatment regimens used in the prevention of o steoporosis.