An in vivo and in vitro study of the effect of low level laser therapy on bone repair in a femoral fracture model in rats

• Grant number: 09/10506-3
• Support Opportunities: Regular Research Grants
• Start date: January 01, 2010
• End date: June 30, 2011
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Helio Plapler
• Grantee: Helio Plapler
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

This study aims to determine the effect of low intensity laser therapy on the repairing of bone cells after femoral fractures. Ninety adult, male Wistar-EPM1 rats, weighing approximately 350g, will be used. The animals will be distributed into three groups (A, B and C) in accordance with the procedure to be carried through and each group will be subdivided in three sub-groups (1, 2 and 3) regarding the time of death. A model of femoral bone fracture will be created, removing a 1,6mm length segment from the middle part of the left femoral diaphise for the "in vitro" study of the cellular alterations that occur with this tissue. For this, an especial clamp was designed to withdraw this bone segment. After clamping the femur, an osteotomy will be executed using an oscillatory saw at each side of this clamp so that the segment of the bone is removed. The bone segments will be stabilized by a special plate of 4 holes and fixed with 3 1,5mm screws and one 1,7mm screw, leaving a 2mm gap between osteotomy surfaces. The excluded segment will be immediately designated to laboratory to culture procedings. Both animals and corresponding culture from group A will be irradiated by a low intensity laser (GaAlAs) , at 200 mW of power, wave length of 808 nm, dosage of 2J/cm2 in a controlled environment. Eight applications in consecutive days will be carried through (from the first until the eighth post-operative day). Group B will receive the same treatment and it will be the sham group that will not be exposed to the laser irradiation. Group C is the control group, that will suffer no intervention. The animals' death in all groups will occur respectively in the 8o, 13o and 18o postoperative day, after a functional evaluation and blood collection for laboratorial tests. Total and bone alkaline phospatase, total calcium, cortisol, osteoblasts and osteoclasts counting and calcium aggregation will be carried through. Immunohistochemical analysis using bone cell growth markers will be measure osteocalcine, osteopontine and osteonectine. The results will be analyzed statistically by Kruskal-Wallis and Fisher´s exact tests. (AU)