Sinusoidal alternating electromagnetic field accelerates fracture healing in rats.

Objectives: To investigate the effect of sinusoidal alternating electromagnetic field (SEMF) on fracture healing and its mechanism.

Methods: Femoral fracture model was established using specific pathogen free male Wistar rats. Thirty rats were randomly divided into the control and SEMF groups with 15 rats in each group. The SEMF group was given 50 Hz 1.8 mT for 90 min every day, while the control group was not treated. X-ray examinations were performed every two weeks to determine the formation of bone scabs. Three rats from both groups were sacrificed after 2 and 4 weeks of treatment. Protein was extracted from the fractured femurs, and the expression of type Ⅰ collagen (COL-1), osterix (OSX), Runt-related transcription factor 2 (RUNX2), and vascular endothelial growth factor (VEGF) was detected by Western blotting. After 8 weeks, the femur on the operated side was taken for micro-CT scanning to observe fracture healing, angiography to observe blood vessel growth, and organs such as hearts, livers, spleens, lungs, and kidneys were taken for safety evaluation by hematoxylin-eosin staining (HE staining).

Results: The bone scab scores of the SEMF group were significantly higher than those of the control group after 2, 4, 6, and 8 weeks of treatment (all P<0.01). The fracture healing of the SEMF group was better than that of the control group after 8 weeks, and the bone volume scores of the two groups were 0.243±0.012 and 0.186±0.008, respectively (P<0.01); the number of blood vessels in the SEMF group was also more than that of the control group after 8 weeks. Western blotting results showed that the expressions of COL-1, OSX, RUNX2, and VEGF were higher in the SEMF group than those in the control group after 2 and 4 weeks of treatment (all P<0.05). HE staining showed that histopathological results of the examined organs were normal in both groups.

Conclusions: SEMF can accelerate fracture healing by promoting the expression of osteogenic factors and vascular proliferation without significant adverse effects.