Reduction in Resorption Cavity Size following Anti-Resorptive Drug Treatment

Raloxifene treatment increases bone strength more than would be expected from changes in bone mass or bone turnover A possible mechanism through which raloxifene treatment increases bone strength independent of bone mass and bone turnover is by reducing the size of resorption cavities formed during bone remodeling. A novel three-dimensional dynamic bone histomorphometry approach was used to determine the effects of raloxifene treatment on the three-dimensional size of individual bone remodeling events (both resorption cavities and subsequent bone formation events) in cancellous bone using an ovariectomized rat model. Raloxifene treated animals were found to have reduced cavity volume and maximum cavity depth compared to both ovariectomized and sham control groups. Sham control and raloxifene treated animals also have reduced formation event size compared to OVX animals. Raloxifene leads to reduced size of remodeling events compared to ovariectomized and sham controls. Differences in cavity size may influence subsequent bone biomechanical performance independent of bone turnover.