Effect of electrical stimulation on callus maturation during callus distraction in rabbits

Callus distraction is currently the most widely used technique for limb lengthening. Prolonged treatment time is its main shortcoming. In this study, we tested the effectiveness of electrical stimulation during various stages of lengthening in order to decrease the treatment time. Seventy-five New Zealand white rabbits, about 2 kg in body weight, were divided into five groups. All groups received single level tibial lengthening of 1 cm by callotasis using a mini-lengthener. Group 1 rabbits did not receive electrical stimulation and could move freely in their cages. Group 2 rabbits (sham control), with electrodes on their left legs, were restrained on a wooden frame for 8 hours every day without electrical stimulation. Group 3 rabbits received capacitively coupled electrical stimulation, 60 kHz, 500 mV, on the left leg for 8 hours every day during the distraction period. Group 4 rabbits received electrical stimulation during the neutralization period. Group 5 rabbits received electrical stimulation during both the distraction and neutralization period. All rabbits were restrained during electrical stimulation. Weekly radiographs were taken to determine the time of appearance of at least three neocortices in the lengthening callus. At that time, the fixators were removed. The healing indexes (total time in fixator divided by length gained, days/cm) in the five groups of rabbits were compared. The range of motion of the ipsilateral knees and ankles and complications of treatment were recorded. The results showed that electrical stimulation applied during leg lengthening by callus distraction can significantly reduce the treatment time and the healing indexes, but the electrical stimulation may contribute to decreased motion in the ipsilateral knee and ankle joints.