Diagnostic Ultrasound Treatment Increases the Bone Fracture-Healing Rate in an Internally Fixed Rat Femoral Osteotomy Model

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.