Effect of different low level laser protocols on rat Achilles tendon healing after partial transection

Abstract

The Achilles tendon is considered the strongest tendon in the human body but is most affected by the tendon rupture, particularly in sports. The tendon injuries can cause significant joint instabillity, leading to damage of other tissues and the development of degenerative joint disease. The healing process in tendon often results in a less organized ECM which reduces its tensile strength and make the tendon more vulnerable. Different treatments are applied in an attempt to expedite the repair. Therapy with low level laser (LLL) has been effective, but there are contradictory results about the protocols for use, meaning there is still much to be learned about its mechanisms, and a potential to be exploited. In this study, we propose to evaluate the effects of different therapies with LLL in partially tenotomized Achilles tendon. Will be used young adult male Wistar rats, divided into 7 groups: G l-tendon intact, G2- sectioned tendon, G3- injury + LLL (4J/crn2-continuous), G4 - injury + LLL (4J/crn2- 20 Hz), G5-sectioned tendon, G6 - injury + LLL (4J/crn2-contínuo) and G7- injury + LLL (4J/cm2-20 Hz until the 7th day and 2KHz from 8 to 14 days). G2, G3 and G4 were sacrificed on day 8 after injury, and G5, G6 and G7 on the 15th day. For biochemical analysis will be held for dosages of noncollagenous proteins, hydroxyproline, electrophoresis in SDS-polyacrylamide, zymography and westem blotting. The structural study will be done by the light microscopy and transrnission electron microscopy for ultrastructural study. (AU)