Repairing large bone fractures with low frequency electromagnetic fields.

The healing effects of low frequency pulse electromagnetic field (EMF) on bone fractures larger than 1 cm are unsatisfactory. Three- dimensional chitosan scaffolds are designed to fill in larger bone fractures and have been shown to be osteogenic. We hypothesized that EMF could accelerate the repair process of larger bone fractures with the use of chitosan scaffolds. Chitosan (96% deacetylation) films and lyophilized scaffolds, with and without osteoblast cells, were exposed to EMF (18-30 Gauss, 75 Hz) for 2 h a day for 3 weeks. Each week, the growth and phenotype expressions of osteoblasts and properties of chitosan were examined. The hydrophilicity, Young's modulus, and biodegradability of chitosan were not altered by EMF exposure. EMF osteoblasts showed 37% higher cell proliferation, 15% lower alkaline phosphatase activity, and 74% more calcium deposition than the controls. Based on SEM photomicrographs, EMF- treated cells appeared to produce more collagen fibrils, matrix vesicles, and calcium in the extracellular matrix than the controls. In conclusion, EMF was capable of enhancing the proliferation and mineralization of osteoblasts cultured on chitosan scaffolds. (c) 2009 Orthopaedic Research Society.