Electrical stimulation with a pulsing electromagnetic fields (PEMFs) is used to promote osteogenesis. In this study, the effect of PEMFs on bone ingrowth into porous coated implants was studied in a rabbit model. Twenty mature rabbits had an implant of Titanium alloy inserted via their greater tubercle. An electromagnetic field pulse generator then stimulated this implant. The intensity of the magnetic field generated was 2 gauss, frequency was 10 Hz and pulse duration was 25μsec. Each rabbit was settled in a wooden immobilizer for 5 or 10 hours a day for 2 weeks. After 2 weeks of stimulation, the humerus was isolated. Nondecalcified specimens were cut into sections 100μm thick, and stained with fuchsine methylene blue. To quantify the biological response, a method of surface measurement using a digitizer was used. New bone formation was found to be present in the margins between the humeral cortical bone and implant in the stimulation group. In comparison, only a small amount of new bone formation was observed in the control group.
In this study, bone ingrowth was promoted by PEMFs. These results suggest that PEMFs is useful clinically to protect loosening and shorten the period of non-weight bearing after artificial joint replacement.
