A Moderate-Intensity Static Magnetic Field Enhances Repair of Cartilage Damage in Rabbits

Background and Aims. Electromagnetic fields have been proposed to enhance healing of cartilage defects by stimulation of chondrocyte proliferation, proteoglycan synthesis as well as decreasing pain and improving motion in osteoarthritic patients. However, the effects of a moderate-intensity static magnetic field on cartilage repair have not been investigated. This study tries to determine the effects of a moderate-intensity permanent magnetic field of 40 mT on cartilage repair. Methods. Defects of 3 mm in diameter and 6 mm in depth were made on the weight bearing surface of the right medial femoral condyle of 30 rabbits. The animals were divided randomly into three equal groups (magnet, sham and control). In the magnet group, cylindrical permanent magnets were implanted subcutaneously medial to the medial femoral condyle, while in the sham group the cylindrical ceramic were not magnetized, and nothing was implanted in controls. After 12 weeks of observation, Mankin's microscopic scoring was done on all specimens, and irregularity of surface characteristics, cell colonization, hypocellularity, cartilage matrix formation, and presence of empty lacunae were investigated. Results. Each of these characteristics showed significant differences in magnet group relative to control and sham groups (p < 0.05). Mankin's score was 1.6 +/- 0.6 in magnet group, 7.2 +/- 1.6 in sham group and 7.7 +/- 1 in control group (p < 0.001). Conlusions. In this animal study, microscopic Mankin's scoring depicted histological improvement in cartilage of magnet group. (C) 2011 IMSS. Published by Elsevier Inc.