Low-intensity pulsed ultrasound accelerates bone maturation in distractionosteogenesis in rabbits

We investigated the effects of low-intensity pulsed VV ultrasound on distra ction osteogenesis in a rabbit model, Callotasis of the right tibia was performed in 70 male Japanese white rabbi ts using mini-external fixators, In the first part of the study in 64 anima ls using normal distraction (waiting period seven days; distraction rate 0. 5 mm/12 hours; distraction period ten days), we evaluated the distraction s ite by radiography, measurement of the bone mineral density (BMD), mechanic al testing, and histology, In the second part in six rabbits using fast dis traction (waiting period 0 days; distraction rate 1.5 mm/12 hours; distract ion period seven days) the site was evaluated radiologically, Half of the a nimals (35) had received ultrasound to their right leg (30mW/cm(2)) for 20 minutes daily after ceasing distraction (ultrasound group), while rigid fix ation only was maintained in the other half (control group), With normal di straction, the hard callus area, as shown by radiography, the BMD, and the findings on mechanical testing, were significantly greater in those receivi ng ultrasound than in the control group. Histological analysis showed no ti ssue damage attributable to exposure to ultrasound. With fast distraction, immature bone regeneration was observed radiologically in the control group , while bone maturation was achieved in the ultrasound group. We conclude that ultrasound can accelerate bone maturation in distraction o steogenesis in rabbits, even in states of poor callotasis.