The effect of low-intensity pulsed ultrasound on bone healing in SR-PLLA rod fixed experimental distal femur osteotomy in rat

摘要

The effects of low-intensity pulsed ultrasound (30 mW/cm~2) were investigated in experimental cancellous bone fracture healing in bioabsorbable self-reinforced poly-l-lactide (SR-PLLA) rod fixed distal femur osteotomy in rats. A transverse transcondylar osteotomy was fixed with one SR-PLLA rod in 32 male Wistar rats of the age of 20 weeks. Half of the rats had a daily 20-min ultrasound exposure for three weeks. The follow-up times were three, six, and 12 weeks. Radiographical, histological, microradiographical, oxy-tetracycline labeling, and histomorphometrical analyses were performed. No foreign-body reactions were noted. The biocompatibility of SR-PLLA and ultrasound was found to be good. In the radiological and histological assessments there was a slight tendency for enhanced healing in the ultrasound group at three weeks, but at six and 12 weeks no differences were observed. The histomorphometrical and oxytetracy-cline labeling analyses showed that ultrasound exposure had no significant effects on bone healing.rnThe present study shows that there were no obvious findings to support the hypothesis that low-intensity pulsed ultrasound enhances bone healing inrnself-reinforced poly-L-lactide (SR-PLLA) rod fixed experimental metaphyseal distal femur osteotomy in rats. The observed good biocompatibility provides a safe starting-point for clinical trials on bioabsorbable fixation combined with low-intensity ultrasound.