Bone healing stimulated by low-intensity pulsed ultrasound (LIPUS) in critical-sized bone defects in rats.

Objectives: The potential for clinicians to accelerate bone healing through low-intensity pulsed ultrasound (LIPUS) has a wide range of opportunities in the medical health field and has been shown to accelerate osteogenesis at the molecular, cellular and clinical level. However, further studies, including the effects of the ultrasound setting, treatment times, and overall effects in an appropriate animal model are still required for optimizing clinical use. Given the osteogenic properties stimulated by LIPUS, we tested the hypothesis that minimal, daily LIPUS treatment can promote bone regeneration in critical-size defects in an animal model.
Methods: Full-thickness calvarial defects with 7 and 5-mm sizes were produced bilaterally in the parietal bones of 12 female Sprague-Dawley rats. The rats were equally divided into a control or LIPUS treatment group. Daily LIPUS was applied to the calvaria of treatment rats for 5 minutes for 8 weeks. Rats were sacrificed at 8 weeks post-operatively and their calvarium removed for bone-healing analysis by histology and micro-CT.
Results: Tissues surrounding the calvarium healed over the defects and there were no animal deaths or evidence of distress throughout the study. Calvarial bone defects did not heal in either control or LIPUS rats after the 8-week period and no significant difference in healing between the control and LIPUS group was noted by the micro-CT and histology.
Conclusions: Daily, short-duration, LIPUS did not enhance bone healing of critical-sized rat calvarial defects as examined radiographically and histologically. Our current results, in conjunction with previous research, suggest that longer treatment times may be needed to accelerate osteogenesis by LIPUS.