Evaluation of Low Intensity Pulsed Ultrasound Effects on the Osteogenesis Potential of Demineralized Bone Matrix in Experimental Tibial Defect in Rabbits

Abstract

Background: Many studies have assessed the effects of either low intensity pulsed ultrasound (LIPUS) or demineralized bone matrix (DBM) on bone repair; however, an evaluation of the combination of these modalities (LIPUS + DBM) has not yet been considered.Objectives: This study aimed to investigate combined effects of DBM and LIPUS on fracture healing. Methods: Bilateral 5-mm tibial defects were created in male Dutch rabbits (n = 30). Animals were divided to two groups of empty defect (A) and DBM group (B), in which commercial DBM putty was used in defects. In each animal left tibia was treated with LIPUS (intensity = 30 mW/cm 2 , I SATA, 1 MHz, 20 min/day, pulsed duty 1:4) and the contralateral limb was used as the control. Animals, after 14, 28 and 60 days, were submitted to radiographic or computerized tomography (CT) scanning analysis.Results: At two weeks, LIPUS had no substantial effect on bone formation. Slight increase of average rates in LIPUS group (A2) were seen compared to the empty defect group (A1) at day 21 and 28. In the DBM-treated group compared with the sham LIPUS, bone-healing rate was reduced at the end of the period (60 days) after surgery. The average healing rate in group B at the end of the 60-day period was less than group A after 21 days. Conclusions:The present study discusses systemic effect of LIPUS because of non-significant results between treated group and control group and is the first to demonstrate that LIPUS decreases bone formation induced by DBM.

Histological and Radiological Evaluation of Low-Intensity Pulsed Ultrasound Versus Whole Body Vibration on Healing of Mandibular Bone Defects in Rats

“…Thus, LIPUS can directly stimulate the proliferation of osteoblasts mechanically, induce the ossification of cartilage, and increase bone mineralization. Other mechanisms of action of LIPUS include change in function of cell membrane and subsequently increased the level of cellular calcium, stimulation of fibroblast activity, increased protein synthesis, enhanced permeability of vessels and angiogenesis [ 19 ]. It seems that LIPUS increases the expression of genes involved in osteogenesis by osteoblasts such as Runt-related transcription factor-2, alkaline phosphatase, osteorix, and cyclin-D1, which explains the pro-osteogenesis effects of LIPUS [ 20 ].…”

“…Their results were different from ours, which may be due to the fact that they used a hand-made LIPUS device, so make their results incomparable to our findings. The clinical protocol for the application of LIPUS includes the application of 1 MHZ sine waves with 1 KHz frequency, a mean intensity of 30 mW/cm 2 and pulse width of 200 ms for 20 min a day [ 19 ]. However, no consensus has been reached regarding the frequency of LIPUS for therapeutic purposes.…”