Electrical and electromagnetic devices have been shown to be effective in the management of delayed unions and nonunions . The development of these treatment methods is based on the discovery that dry bone  and hydrated bone  have electrical properties. In brief, mechanically stimulated bone cells produce an electrical field, which mediates cell proliferation . In the past few years, some studies gave further information about the action of the electrical fields on signal transduction pathways and on GFs [2,6].
Three modalities of electrical stimulation of bone growth are presently available for nonunion treatment:
- Direct current (DC) stimulation employing percutaneously implanted electrodes (invasive method). With this method a constant current of about 20 ^A and 1 V is generated between two electrodes inserted in the nonunion site. This technique has quite a high rate of good results (78%-86%), according to some Authors [7,8] (Fig. 1).
- Electromagnetic stimulation by inductive coupling (IC) uses magnetic fields (noninvasive method). This technique, developed by Bassett et al. , is based on the action of pulsed electromagnetic fields produced by external devices that generate a current of 20 mV and about 10 ^A/cm2 in the tissues. Bassett et al.  reported a success rate of 87% in the management of nonunions.
- Capacitive coupling (CC) stimulation employs electrodes placed on the skin (noninvasive method). Disk-shaped electrodes to which transducer gel has been applied are placed on the skin and transmit a uniform electric current (3-6 V, 5-10 mA) at the nonunion site. A success rate of 82% has been reported .
Double-blind studies to test the efficacy of electrical stimulation on long bone nonunions were performed and gave statistical evidence of these good results [11,12]. In conclusion, this treatment has proven to be effective, particularly in hypertrophic nonunions.
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