Effects of different vardenafil doses on bone healing in a rat fracture model

OBJECTIVES: We aimed to investigate the radiological, biomechanical, histopathological, histomorphometric, and immunohistochemical effects of different doses of vardenafil on fracture healing. MATERIALS AND METHODS: Fifty-one rats were divided into three groups. Group V5 was given 5 mg/kg/day of vardenafil; Group V10 was given 10 mg/kg/day of vardenafil; and the control group was given the same volume of saline. Six rats from each group were sacrificed on Day 14 (early period) and the remaining rats were sacrificed on Day 42 (late period). Callus/femoral volume and bone mineral density were measured using micro- computed tomography. Five femurs from each group in the late period were examined by biomechanical tests. In addition to the histopathological and histomorphometric evaluations, immunohistochemical analyses were performed to examine the levels of inducible nitric oxide synthase (iNOS), transforming growth factor-3 (TGF-β3), and nuclear factor kappa B (NF-κB) proteins. RESULTS: Both doses of vardenafil increased primary bone volume and maximal bone fracture strength in late period, compared to the control group (p<0.05). Histological healing scores of vardenafil groups were significantly higher in early period (p<0.001). While cartilaginous callus/total callus ratio in early period was higher, callus diameter/femoral diameter ratio in late period was lower in vardenafil groups (p<0.01). The NF-κB immunopositivity in V10 group decreased in early period, compared to control group (p<0.001). The TGF-β3 and iNOS immunopositivity increased in both V5 and V10 groups, compared to the control group in early period, but returned to normal in late period. CONCLUSION: During the first period of fracture healing process in which vasodilation is mostly required with increasing inflammation, vardenafil has ameliorating effects on the bone union and supports fracture healing.