Effects of pulsed electromagnetic fields on bone healing in a rabbit tibial osteotomy model

Objective: The purpose of this study was to determine the effect of pulsed electromagnetic field (PEMF) exposure on healing tibial osteotomies in New Zealand White rabbits. Design: One-millimeter Gigli saw osteotomies were stabilized by external fi xation. One day after surgery, rabbits were randomly assigned to receive ei ther no exposure (sham control) or thirty minutes or sixty minutes per day of low-frequency, low-amplitude PEMF. Radiographs were obtained weekly thro ughout the study. Rabbits were euthanized at fourteen, twenty-one, or twent y-eight days, and tibiae underwent either destructive torsional testing or histologic analysis. To determine the baseline torsional strength and stiff ness of rabbit tibiae, eleven normal intact tibiae were tested to failure. Results: Sixty-minute PEMF-treated osteotomies had significantly higher tor sional strength than did sham controls at fourteen and twenty-one days post operatively. Thirty-minute PEMF-treated osteotomies were significantly stro nger than sham controls only after twenty-one days. Normal intact torsional strength was achieved by fourteen days in the sixty-minute PEMF group, by twenty-one days in the thirty-minute PEMF group, and by twenty-eight days i n the sham controls. Maximum fracture callus area correlated with the time to reach normal torsional strength. Conclusion: In this animal model, low-frequency, low-amplitude PEMF signifi cantly accelerated callus formation and osteotomy healing in a dose-depende nt manner.