The effect of pulsed electromagnetic fields on the biomechanical properties of the femur in ovariectomized rats

Abstract

Objective To observe the effect of pulsed electromagnetic fields （PEMFs） of different intensities on the biomechanical properties of the femur in ovariectomized rats so as to determine the intensity for the best therapeutic efficacy. Methods Fifty female Sprague-Dawley rats were randomly divided into （1） a sham-operated control group （no PEMF treatment） , （2） ovariectomized control group （no PEMF treatment） （3） ovariectomized group Ⅰ （PEMF treatment at 8 Hz and 0.77 mT intensity, 40 min daily for 30 days） （4） ovariectomized group Ⅱ （PEMF treatment at 8 Hz and 3.82 mT intensity, 40 min daily for 30 days） and （5） ovariectomized group Ⅲ（ PEMF treatment at 8 Hz and 9.87 mT intensity, 40 min daily for 30 days）. Except for the 10 rats of the sham-operated control group, all the others received a standard ovariectomy. Serum estradiol （E2） and the biomechanical properties of one femur （peak load, maximum displacement, maximum energy absorption, maximum stress, maximum strain and modulus of elasticity） were assessed after 30 days of PEMF treatment. Results In group Ⅱ the biomechanical properties of the femur were significantly better than in group Ⅰ or the ovariectomized control group. In groups Ⅰ and Ⅲ the biomechanical properties of the femur were not significantly better than in the sham-operated group. In group Ⅱ the biomechanical properties of the femur were significantly better than in groups Ⅰ or Ⅲ. Conclusion PEMFs at 3.82 mT can improve the biomechanical properties of the femur significantly. Key words: Pulsed electromagnetic fields; Magnetic field intensity; Ovariectomized rats; Biomechanical properties