Effects of Boric Acid on Fracture Healing: An Experimental Study.

Boric acid (BA) has positive effects on bone tissue. In this study, the effects of BA on fracture healing were evaluated in an animal model. Standard closed femoral shaft fractures were created in 40 male Sprague-Dawley rats under general anesthesia. The rats were allocated into five groups (n = 8 each): group 1, control with no BA; groups 2 and 3, oral BA at doses of 4 and 8 mg/kg/day, respectively; group 4, local BA (8 mg/kg); and group 5, both oral and local BA (8 mg/kg/day orally and 8 mg/kg locally). After closed fracture creation, the fracture line was opened with a mini-incision, and BA was locally administered to the fracture area in groups 4 and 5. In groups 2, 3, and 5, BA was administered by gastric gavage daily until sacrifice. The rats were evaluated by clinical, radiological, and histological examinations. The control group (group 1) significantly differed from the local BA-exposed groups (groups 4 and 5) in the clinical evaluation. Front-rear and lateral radiographs revealed significant differences between the local BA-exposed groups and the control and other groups (p < 0.05). Clinical and radiological evaluations demonstrated adequate agreement between observers. The average histological scores significantly differed across groups (p = 0.007) and were significantly higher in groups 4 and 5 which were the local BA (8 mg/kg) and both oral and local BA (8 mg/kg/day orally and 8 mg/kg locally), respectively, compared to the controls. This study suggests that BA may be useful in fracture healing. Further research is required to demonstrate the most effective local dosage and possible use of BA-coated implants.