The effect of pulsed electromagnetic fields on the osteointegration of hydroxyapatite implants in cancellous bone:: a morphologic and microstructural in vivo study

Effects of pulsed electromagnetic fields (PEMFs. 75 Hz. L6 mT) were investigated in 12 rabbits after placing hydroxyapatite (HA) implants in their femoral condyles. Six animals were stimulated with PEMFs, for three consecutive weeks, 6 h/day, while the remaining animals were sham-treated (Control Group). Rabbits were sacrificed at 3 and 6 weeks (after a 3-week non-stimulation period) For histomorphometric analysis and microhardness testing (at 200, 500, 1000, 2000 mum from the implant) around the implants. Histomorphometric analysis did not highlight any significant changes. On the contrary, there were statistically significant differences between the effects produced by PEMFs and Control Groups (r = 149.70, p = 0.0005) on the Affinity Index results as well as by the experimental time of 6 and 3 weeks (F = 17.12, p = 0.001) on the same results. In PEMF-stimulated animals the microhardness (HV) values measured in trabecular bone at a distance of 200 and 500 mum from the implants, were significantly higher with respect to controls. At 6 weeks HV values at the bone implant interface in PEMF-stimulated animals were not significantly different with respect to normal bone, while they remained significantly loader in control animals, Both morphological and structural results demonstrated a positive therapeutic effect of PEMFs in accelerating HA osteointegration in trabecular bone. (C) 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.