Bone consolidation: effects of the ultra-sound and the low level laser therapy on bone defects

Abstract

Million of fractures occurs every year worldwide. Many of them show delayed healing and persist for more than nine months and some termed in non-unions fratures. A lot of methods for treating delayed and non-unions fractures have been investigated and promissing treatments are the use of ultra-sound (US) and low level laser therapy (LLLT). Some studies have shown that US and LLLT are able to stimulate the osteogenesis of bone tissue, increasing osteoblast proliferation and accelerating fracture consolidation. In spite of a series of radiographic and biomechanic evidences of the osteogenic effects of both treatments, the celular and molecular mechanisms by which these treatments act on bone consolidation are not fully understood. Then, aim of this study is to investigate the effects of US and LLLT on gene synthesis and bone callus formation of fractured tibias in rats, in different periods of bone regeneration. One hundred twenty male Wistar rats will be used in this study. Bone defects will be performed in both tibias. The procedures will be done under Ketamine/ Xilazine anesthesia (80/10 mg/Kg). The mid-regions of the tibial will be shaved and disinfected with povidone iodin. A dermo-periostal incision will be performed to exposed the tibia. A 1,5mm of diameter cavity defect will be made, using an espherical bur under copious irrigation with saline solution. In the treated animals, the cavities will be filled with the corresponding biomaterial. The cutaneous flap will be replaced and sutured with resorbable polyglactin. Rats will be divided into the following groups: standard control group, control bone defect group, bone defect treated with US group and bone deffect treated with LLLT group. All groups will be divided in 3 sub-groups, with 10 animails each: group A (animals that will receive 3 sessions of treatment), group B (animals that will receive 6 sessions of treatment) and groupd C (animals that will receive 12 sessions of treatment). Animals of the intact group will be sacricied at the same period of time of the treated groups. The protocol of treatment will start 24 hours after surgery and it will be performed in every 48 hours. The animals will be euthanasied 24 hours after the last session of treatment, with an intra-peritoneal injection of general anesthetic. The tibias will be defleshed and soft tissues will be removed for analysis. The Real Time- PCR will be used to evaluated the synthesis of genes related to bone formation and histologic analysis will be used to analyse bone callus formation. (AU)