Objective: To investigate the healing effects of diagnostic ultrasound in a standardized rat femur fracture model.
Methods: Thirty-two male rats aged 14 weeks were used, and each rat's right femur was osteotomized and stabilized under anesthesia. The rats were then divided into 4 groups. Five days after surgery, ultrasound was applied every fifth day with diagnostic sonographic equipment and a probe with a 7.5-MHz frequency and 11.8-mW/cm2 total output intensity for 10 minutes in each session. Ultrasound was applied 8 times in group A, 3 times in group B, and only once in group C. Ultrasound was not applied to sham-operated group D. Healing and callus formation of the rats' femur fractures were evaluated by radiography and dual-energy x-ray absorptiometry.
Results: Dual-energy x-ray absorptiometric and radiographic results showed that the ultrasound therapy accelerated the fracture healing. Radiographically, groups A and B showed better fracture healing than groups C and D. Ultrasound exposure increased both the whole-bone mineral density and the density at the fracture region, increasing in parallel with the exposure period.
Conclusions: This study confirms the previously shown efficacy of low-intensity ultrasonic stimulation in acceleration of the normal fracture repair process even when performed with a diagnostic sonographic device.