The Effect Of Low-intensity Pulsed Ultrasound On Distraction Osteogenesis In A Rabbit Tibia Lengthening Model Assessed By High-resolution Micro-computer Tomography

【Objective】This study was designed to evaluate the effect of low-intensity pulsed ultrasound stimulations (LIPUS) on the bone microstructure during distraction osteogenesis using a rabbit tibia lengthening model.【Method】38 skeletally mature female New Zealand White rabbits were randomly divided into the LIPUS treatment group and the control group. All animals were undergone mid-diaphyseal tibial osteotomy and were immobilized in an Orthofix M103 Mini lengther. Gradual distraction of 0.5 millimeters every twelve hours for a ten-day period were performed following a seven-day latency period. A four-week course of LIPUS stimulation was applied to the distraction site for a period of twenty minutes daily immediately after distraction. Control samples were prepared in the same manner without exposing to LIPUS. The lengthening bone was harvested at week 4, 8, and 12 after LIPUS treatment for evaluating the bone microstructure by micro-CT analysis. The samples were taken X-ray photography for radiographic analysis at 7 days, 17 days, 45 days after operation.【Results】1.The micro-CT results showed that cortical bone mineral content (cBMC), cortical bone mineral density (cBMD), volumetric bone mineral content (vBMC), volumetric bone mineral density (vBMD), bone volume fraction (BVF), trabecular number (Tb. N) and trabecular thickness (Tb. Th) of whole distraction region in LIPUS treatment group were higher than those of control group (P＜0.05 for all) at week 4, 8 and 12.2. X-ray examination showed more mature bone callus were found in LIPUS group when compared with the control group (P＜0.05).【Conclusion】LIPUS as a biophysical stimulation might promote distraction osteogenesis in a rabbit tibia lengthening model.