The effect of low frequency magnetic fields on the healing of the osteotomized rabbit radius.

The object of this experimental work was to evaluate the effect of a noninvasive method of electrical stimulation on the healing of freshly-created osteotomies of the rabbit radius. The apparatus consisted of a solid core electromagnet energized by a square wave unidirectional current. The magnetic field was pulsed transversely across the osteotomy site of the radius while the animal was confined to a restraining device 6 hours daily for 5 days per week. In one group of animals the influence of different pulse frequencies, using 0.1 Hz, 1 Hz, and 4 Hz, was evaluated, while the period of stimulation was kept constant at 2 weeks. In another group of animals, exposure was continued for 3 and 4 weeks while the pulse frequency was kept constant at 1 Hz. Histologic and radiologic comparison with control animals revealed that the initiation of the healing process can be accelerated in magnetic fields pulsed at 1 Hz, but that this effect is not maintained, and that the total period of time required for union is not significantly shortened. In view of these findings, this form of treatment is not recommended for clinical use in the treatment of recent fractures of long bones.