Objective To investigate the changes of lumbar bone histomorphometry after exposure to low frequency pulsed electromagnetic fields (PEMFs), and to further understand the effect of PEMFs on osteoporosis (OP) in ovariectomizedOP rats. Methods Sixty-six 3-month-old Sprague Dawley rats were randomly divided into 4 groups: group A(n=12), groupB (n=12), group C (n=12), and group D (n=30). In group A, the ovaries were not resected as sham-ovariectomy; in groupsB, C, and D, the ovaries were resected. At 12 weeks after ovariectomy, the rats were exposed to PEMFs at 8 Hz, 3.8 mT, and 40 minutes/ day for 30 days in group B; the rats were administered with premarin [0.065 mg/(kg·d) by gavage for 30 days] in group C; in group D, the rats were housed as ovariectomy control. The hair and activity of rats were observed; the levels of serum estradiol were determined. At 30 days after intervention, all rats were sacrificed to harvest the L4 vertebrae for bone histomorphometry. Results General observation showed hair loss and decreased activity in group D, and no abnormal appearances in groups A, B, and C. The level of serum estradiol in group A was significantly higher than that in group D [(54.93 ± 23.52) pg/mL vs. (31.99 ± 23.45) pg/mL] (t=2.345, P=0.029). Histological observation showed thinness of sclerotin, bigger medullary cavity, and sparse and thinner bone trabecula in group D; uniform bone trabecula with no breakage in groups A, B, and C at 30 days after intervention. The ratio of trabecular bone area in group B was significantly higher than that in group D (P lt; 0.05); it was higher than that in groups A and C, showing no significant difference (P gt; 0.05). The trabecular thickness in group B was significantly higher than that in group D (P lt; 0.05), but it was lower than that in groups A and C, showing no significant difference (P gt; 0.05). The trabecular number in group B was significantly lower than that in group D (P lt; 0.05), but it was higher than that in groups A and C, showing no significant difference (P gt; 0.05). The trabecular separation in group B was higher than that in group D and lower than that in groups A and C, showing no significant difference (P gt; 0.05). Conclusion PEMFs at 8 Hz and 3.8 mT can significantly improve the character of bone microstructure in ovariectomized OP rats, increase the ratio of bone trabecular area and trabecular thickness, and decrease the trabecular number.
We investigated the effects and optimal treatment frequency of pulsed electromagnetic fields (PEMFs) on postmenopausal osteoporosis (PMO). A comparison was performed with the cyclical alendronate and a course of PEMFs in the treatment for postmenopausal osteoporosis on bone mineral density (BMD), pain intensity and balance function. There was no significant difference between the two groups on mean percentage changes from baseline of BMD within 24 weeks after random treatments (P≥0.05). However, at the ends of 48 weeks and 72 weeks, the BMD of the PEMFs group were significantly lower than that of the alendronate group (P<0.05). No significant difference was detected between the two groups with regard to treatment effects on Visual Analogue Scale score, the Timed Up & Go Test and Berg Balance Scale score. Compared with cyclical alendronate, a course of PEMFs was as effective as alendronate in treating PMO for at least 24weeks. So its optimal treatment frequency for PMO may be one course per six months.