Capacitively coupled electrical stimulation treatment: results from patients with failed long bone fracture unions

To determine the extent to which capacitively coupled electrical stimulation (CCEST) at a long bone fracture site can promote healing of nonunited fractures.

Sixteen patients with nonunited fractures of nine to seventy-six months were treated with CCEST. Thirteen patients had previously undergone one or more surgical procedures, and the other three had been given plaster casts. A sixty-three-kilohertz, six-volt peak-to-peak sine wave signal was applied across two forty-millimeter-diameter stainless steel plates placed on the skin at opposite sides of the fracture site. The device was used for up to thirty weeks until either healing occurred or it was removed after this period and considered to have failed.

Eleven of the nonunions achieved union at an average of fifteen weeks of stimulation. The only significant factor determining the success of healing was the distance between the plates; a distance of eighty millimeters or less resulted in healing in all cases. Healing was not affected significantly by any of the following factors: whether or not the nonunion had been treated surgically prior to stimulation, whether or not it had been infected, whether or not the patient bore weight after treatment, or by the presence or absence of metal at the fracture site from previous surgery.

These findings confirm those of previous studies that CCEST promotes bone healing of fracture nonunions. The dependence of healing on the interplate distance suggests that maintaining sufficient current across the plates is necessary to allow healing, which for larger bones may be achieved by increasing the area of the plates, the applied voltage, or the excitation frequency of the stimulation signal.