Low-level laser therapy prevents degenerative morphological changes in an experimental model of anterior cruciate ligament transection in rats.

The aim of this study was to analyze the effects of low-level laser therapy (LLLT) on the prevention of cartilage damage after the anterior cruciate ligament transection (ACLT) in knees of rats. Thirty male rats (Wistar) were distributed into three groups (n = 10 each): injured control group (CG); injured laser-treated group at 10 J/cm(2) (L10), and injured laser-treated group at 50 J/cm(2) (L50). Laser treatment started immediately after the surgery and it was performed for 15 sessions. An 808 nm laser, at 10 and 50 J/cm(2), was used. To evaluate the effects of LLLT, the qualitative and semi-quantitative histological, morphometric, and immunohistochemistry analysis were performed. Initial signs of tissue degradation were observed in CG. Interestingly, laser-treated animals presented a better tissue organization, especially at the fluence of 10 J/cm(2). Furthermore, laser phototherapy was able of modulating some of the aspects related to the degenerative process, such as the prevention of proteoglycans loss and the increase in cartilage area. However, LLLT was not able of modulating chondrocytes proliferation and the immunoexpression of markers related to inflammatory process (IL-1 and MMP-13). This study showed that 808 nm laser, at both fluences, prevented features related to the articular degenerative process in the knees of rats after ACLT.