Bone Abstracts

Minodronate has been reported to increase bone mineral density (BMD) and reduce fracture risk. The purpose of this study was to clarify the effect of minodronate on the three-dimensional vertebral microarchitecture in vivo.

Minodronate-treated osteoporosis female patients (n=9) and non-treated age-matched historical control (n=5) were retrospectively evaluated. After areal BMD (aBMD) evaluation by DXA, 3rd lumbar spine was scanned by quantitative computed tomography (qCT) at a spatial resolution of 351×351×500 μm, and were re-evaluated after 1-year. Through the compilation of consecutive 2D data set of the whole bone, a 3D reconstructed data providing an isotropic voxel was obtained after appropriate interpolation. Bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tn.N), and connectivity density (CD) were calculated by custom-made software. In addition, bone changes in each of the patients were visualized by subtraction method, which superimpose and subtract longitudinal 3D-reconstructed data sets.

After 1 year, non-treated control lost −2.1% of aBMD, and the minodronate group gained 5.4%, while BV/TV changed −7.1 and +17.2%, respectively. Tb.Th and Tb.N in non-treated control were severely decreased over 1-year period (−6.3%, −0.3% respectively), whereas minodronate treatment could reverse changes in those parameters (+6.3%, +10.0% respectively). CD, however, could not be improved by the treatment (−2.3 vs −3.6%). Subtraction method revealed severe bone loss in the non-treated control and bone formation achieved in the minodronate group.

Our results indicate that evaluation of aBMD by DXA would underestimate both volumetric bone loss and gain of the vertebra. Despite the apparent increase in bone volume by minodronate treatment, it might be difficult to reestablish trabecular connectivity. In order to prevent connectivity loss, earlier therapeutic intervention would be necessary before the connectivity has been lost.