Effects of Low Intensity Pulsed Ultrasound on Healing of Denervated Tibial Fracture in the Rabbit

Background: Low intensity pulsed ultrasound (LIPUS) has been shown in healing of fractures. This study investigates the effect of LIPUS as a fracture-healing adjunct on the denervated tibial fractures in rabbit model. Methods: Twenty four male Dutch rabbits were randomly divided into four groups including two control and two ultrasound-treated (US-treated) groups. A standardized mid-tibial osteotomy was performed in the right tibia. Ipsilateral sciatic nerve was cut two centimeter above the right knee. After three days, the rabbits of US-treated groups received the therapeutic dose (100 mW/cm²) of ultrasound for 15 minutes per day until the 6th and 8th week and the control groups did not receive any treatment. The rabbits were sacrificed at weeks 6th and 8th post surgery and the external fixator and tibia were carefully removed. Radiographs were taken by lateral and anteroposterior views. Mechanical testing of rabbit’s tibiae was used. The specimens were taken from callus of fracture for histomorphometric study of trabecula in the fractured area. Immunohistochemical staining for ki67 was used to evaluate cellular proliferation. Results: Radiographs showed the callus was visible indicating the ossification of the callus tissue without any significant difference between US- treated and control groups. Biomechanical, histomorphic and immunohistochemical evaluations had no significant difference between control and US-treated groups after 6 and 8 weeks postoperation. Conclusion: These finding suggest that ultrasound therapy with features which applied in this study had no significant effect on denervated tibial fracture repair in rabbits.