Study of the Effects of Low-Intensity Pulsed Ultrasound on Fracture Healing ?of Tibia in Rabbits (A Histomorphometrical and Immunohistochemical ?Evaluation) ?
Trauma Monthly: 12 (3); 229-237 Article Type: Research Article
January 1, 2007
January 1, 2007
A, et al. Study of the Effects of Low-Intensity Pulsed Ultrasound on Fracture Healing ?of Tibia in Rabbits (A Histomorphometrical and Immunohistochemical ?Evaluation) ?,
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Introduction. The aim of this study was to examine whether the stimulatory effect of low-intensity pulsed ultrasound results in increased bone trabeculae and/or cell proliferation. Material and Methods. Twenty adult male Dutch rabbits were divided into one control (sham) and two ultrasound stimulation groups. Under anesthesia, a standardized mid-tibial osteotomy was created in the right tibial bone. Bilateral external fixator was applied to both aspects of the leg. Three days after the surgery, the rabbits in the ultrasound groups received ultrasound pulses with the intensity of 50 and 100 mw/cm2 for 15 min/day. Ultrasound was also utilized in the control group but the intensity was zero mw/cm2. The rabbits were killed at week 7 post surgery by inhalation of chlorophorm. For histological evaluation, the callus fracture tissues were processed. The samples were fixed in 10% formaldehyde, decalcified in 5% nitric acid, processed in the tissue processor and embedded in parafin wax. The paraffin blocks were sectioned longitudinally at 5 microns and were then stained with hematoxylin - eosin (H&E) and massons trichrome. Results. The slides were studied for histomorphometric evaluation of trabecula and connective vascular tissue in the callus area. Slides were used for cell counting of osteoblast in the callus region in all groups. In addition, some slides were used for immunohistochemical study using ki67 marker to study the cell proliferation of osteoblasts in the callus region in all groups. Data was then compared in all groups. Histomorphometric evaluation demonstrated that the mean of trabeculae in the fracture area was 64.44.06 in the control group while it was 56/57 3/81 in 50 mw/cm2 ultrasound group and 84.04 5.74 in 100 mw/cm2 ultrasound group. There were no significant differences between ultrasound and control groups (p<0.05). The mean osteoblast number in the fracture area was 23.26 1.08 in the control group while it was 17.58 0.95 in the first ultrasound group (50 mw/cm2) and 26.80 1.65 in the second ultrasound group (100 mw/cm2). There were no significant differences between ultrasound and control groups (p<0.05). Conclusion. These results showed that fractured callus tissue is not sensitive to this level of ultrasound application and it had no effect on fracture repair and callus formation in rabbits' tibiae.
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