Ultrasound enhanced bone formation during mandibular osteodistraction in rabbits

Abstract

Distraction osteogenesis is used in orthopedics to lengthen bones, by cutting or breaking the bone and gradually separating the two pieces as new bone fills the intervening space. This study evaluated whether pulsed ultrasound can be used to shorten the long post-distraction period associated with mandibular osteodistraction. Twenty-one rabbits were divided into three groups of seven. The distraction started 72 h after surgically severing both sides of the mandible at a rate of 3 mm/day. Group 1 received ultrasound for 20 min on both sides of the mandible every other day (alternating sides). Group 2 received ultrasound on one side of the mandible every day for 20 min. Group 3 did not receive any ultrasound. Bone formation at the distraction site was assessed by in vivo photodensitometry on head radiographs, an in vivo (nondestructive) vibratory coherence test across the distraction site, a post-mortem, ex vivo (destructive) three-point bending mechanical test, and by post-mortem, ex vivo (destructive) histological examination. Statistical analyses performed using analysis of variance (ANVOVA) tests revealed that ultrasound enhanced bone formation at the distraction site as evidenced by the increase in new bone photodensity, mechanical properties, and histological maturation, especially when ultrasound was applied daily.