Micro-CT analysis. (a) Representative micro-computed tomography (CT) image of the distal tibia for each rat group. (b) Histomorphometric analysis of the distal tibia for the various treatment groups, showing a significant increase in bone volume (BV)/tissue volume (TV) ratio, cortical thickness, trabecular and cortical bone volume and trabecular thickness in rats treated with zoledronic acid (ZA). Methotrexate (MTX) had no effect on histomorphometric parameters. Values are the mean ± standard deviation. **P < 0.005 versus CT group; ++P < 0.005 versus MTX group.