| Objective To investigate the effect of the different intensity of 50 Hz sinusoidal electromagnetic fields (SEMFs) on the biomechanical properties in rats. Methods Twenty-four 6-week-old female SD rats were fed for 1 week. They were randomly divided into 3 groups: normal control group, 0.1 mT SEMFs group, and 0.6 mT SEMFs group. Except to rats in the control group, rats in other groups were given SEMFs for 3h every day. After 8 weeks, bone mineral density (BMD) of the whole body was measured using dual-energy X-ray absorptiometry. Bilateral femurs and the tibia were collected. The biomechanical properties of the left femurs and the vertebrae were tested using an AG-X multifunctional detector. The microstructure of the right femurs was scanned and analyzed using μ-CT. The heart, the liver, the spleen, the lung, the stomach, the kidney, the adrenal gland, and the uterus were all collected and weighed. The organ index was calculated and the routine pathological detection was performed. Results The organ index of all the organs showed no significant difference, and the pathological observation also showed no abnormal changes. Comparing to those in control group, the whole body BMD, femur maximum load, elastic modulus, yield strength, the fourth lumbar maximum load, elastic modulus, and bone volume, trabecular number and thickness from micro-CT scans increased significantly in 50Hz 0.1mT SEMFs group (P<0.01). Trabecular separation in 50Hz 0.1mT SEMFs group was significantly lower than that in control group (P<0.01). No statistical difference was found between 50Hz 0.6mT SEMFs group and control group. Conclusion 50 Hz 0.1 mT SEMFs can effectively increase BMD, improve the bone microstructure organization and the biomechanical properties, and reduce the risk of osteoporotic fractures. |