Effects of alendronate on bone formation and osteoclastic resorption after implantation of beta-tricalcium phosphate

The aim of this study was to determine the effects of alendronate (ALN) on osteoclastic resorption of beta-tricalcium phosphate (beta-TCP) and bone formation. beta-TCP blocks of 75% porosity, with or without ALN treatment, were implanted into cavities drilled in rabbit femoral condyles. New bone formation, residual amount of beta-TCP, and the number of tartrate-resistant acid phosphatase-positive cells were evaluated 2 weeks after surgery. The results show that local application of ALN at a concentration of 10(-2) to 10(-6) M reduced the number of osteoclasts on the surface of beta-TCP. New bone formation was also inhibited by ALN in a dose-dependent manner. Thus, inhibition of osteoclast formation resulted in reduced beta-TCP resorption and bone formation. These results suggest that osteoclast-mediated resorption plays an important role in bone formation and a coupling-like phenomenon could occur in beta-TCP-filled bone defects. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 93A: 469-474, 2010