The effects of phytoestrogens on fracture healing: experimental research in New Zealand white rabbits.

BACKGROUND Phytoestrogens are plant-derived natural molecules having some bone forming and bone substituting effects. In the present study, the role of phytoestrogens on bone healing was investigated in a rabbit fracture model. METHODS Twenty-two New Zealand white rabbits with right tibia fracture were divided into two groups randomly. The plant derived extract of Vitex agnus-castus L. (Verbenaceae) prepared before the study was administered intramuscularly in group 1 and group 2 was chosen as control. Fracture healing was monitored in weekly basis with blood alkaline phosphatase level, radiographs of extremities and 99m-Tc MDP bone scintigraphy. The study was finished at the end of the 3rd week. The extremities including tibial fractures were collected for histological examination. RESULTS Radiographic evidence of fracture healing obtained on postoperative day seven was superior in group 1 than control group (p<0.01). The 99m-Tc MDP bone scintigraphy uptake ratios on postoperative seventh day showed higher uptake in group 1 than in group 2 (p<0.05). The differences of scintigraphic uptakes in fractured tibias calculated on postoperative seventh day and postoperative 14th in group 1 were higher than group 2 (p=0.04). The histopathologic evaluation performed after sacrification of all rabbits on postoperative 25th day showed no significant difference between both groups. No statistical difference was determined related to the other variables. CONCLUSION Flavonoids affected positively the early periods of fracture healing mechanism in New Zealand white rabbits. We suggest further studies with phytoestrogens to determine the effects of various dosages and administration ways.