Pulsed electromagnetic field treatments enhance the healing of fibular osteotomies

This study tested the hypothesis that pulsed electromagnetic field (PEMF) treatments augment and accelerate the healing of bone trauma. It utilized micro-computed tomography imaging of live rats that had received bilateral 0.2 mm fibular osteotomies (∼0.5% acute bone loss) as a means to assess the in vivo rate dynamics of hard callus formation and overall callus volume. Starting 5 days post-surgery, osteotomized right hind limbs were exposed 3 h daily to Physio-Stim® PEMF, 7 days a week for up to 5 weeks of treatment. The contralateral hind limbs served as sham-treated, within-animal internal controls. Although both PEMF- and sham-treatment groups exhibited similar onset of hard callus at ∼9 days after surgery, a 2-fold faster rate of hard callus formation was observed thereafter in PEMF-treated limbs, yielding a 2-fold increase in callus volume by 13-20 days after surgery. The quantity of the new woven bone tissue within the osteotomy sites was significantly better in PEMF-treated versus sham-treated fibulae as assessed via hard tissue histology. The apparent modulus of each callus was assessed via a cantilever bend test and indicated a 2-fold increase in callus stiffness in the PEMF-treated over sham-treated fibulae. PEMF-treated fibulae exhibited an apparent modulus at the end of 5-weeks that was ∼80% that of unoperated fibulae. Overall, these data indicate that Physio-Stim® PEMF treatment improved osteotomy repair. These beneficial effects on bone healing were not observed when a different PEMF waveform, Osteo-Stim®, was used. This latter observation demonstrates the specificity in the relationship between waveform characteristics and biological outcomes.