Alendronate reduces periosteal microperfusion in vivo

OBJECTIVES: Bisphosphonates are known to induce a severe adverse effect known as medication-related osteonecrosis of the jaw (MRONJ). Previous studies have proven the impact of bisphosphonates on microperfusion; therefore, this study aimed to investigate alendronate-induced microcirculatory reactions in the calvarial periosteum of rats. STUDY DESIGN: Bone chambers were implanted into 48 Lewis rats. Microhemodynamics, inflammatory parameters, functional capillary density and defect healing were examined after alendronate treatment for two and six weeks using repetitive intravital fluorescence microscopy for two weeks. RESULTS: Microhemodynamics remained unchanged. In alendronate-treated rats, inflammation was slightly increased, functional capillary density was significantly reduced (day 10: controls 100.45 ± 5.38 cm/cm(2), two weeks alendronate treatment 44.77 ± 3.55 cm/cm(2), six weeks alendronate treatment 27.54 ± 2.23 cm/cm(2)) and defect healing was decelerated. The changes in functional capillary density and defect healing were dose-dependent. CONCLUSION: The bisphosphonate alendronate has a significant negative impact on periosteal microperfusion in vivo. This could be a promising target for the treatment of MRONJ.