Effect of external pulsing electromagnetic fields on the healing of soft tissue

Since fibroblast behavior in bone healing can be altered electrically, it is plausible to hypothesize that fibroblast proliferation and function in soft tissue healing also would respond to an electromagnetically induced pulse. Reports of clinical impressions of accelerated closure of chronic skin wounds overlying areas being treated for nonunion have produced support for this hypothesis, but experimental data have been lacking. This study was designed to evaluate the effect of pulsed electromagnetic fields (PEMFs) with clinically employed wave-form parameters on the rate of closure of excisional wounds in normal animals and those with steroid retarded wound healing. Four groups, each containing 12 PEMF-treated rats and 12 control rats, were given different field exposures and two groups were treated with methylprednisolone. The wound areas were measured and tissue was harvested for histological examination at intervals for 28 days after wounding. There was no difference in the gross or microscopical appearance of wounds in each active group and its respective control group. Differences in the number of counted fibroblasts were not significant (p less than 0.5), and wound contraction and epithelialization proceeded at the same rate (t-test for equality of means, power = 90%). Electrical PEMF stimulation with the driving pulse used clinically for nonunion bony repair did not affect soft tissue healing in this model. No experimental support is provided for the reports of accelerated skin healing within therapeutic fields. It is possible that different wave-form characteristics are needed to provoke a response in soft tissue.