Evaluation the Effect of Low Power Laser Irradiation on Healing of Induced Tendon Injuries in Rabbits

This study aimed to evaluate the efficacy of diode laser in accelerating the healing process of ‎injured tendons and to determine the best ‎irradiation doses for impulse and continuous laser ‎irradiation. The semimembranosus muscle tendon of forty mature local breed rabbits ‎‎(Oryctolagus cuniculus) of both sexes was partially injured under ‎general anesthesia. The rabbits ‎were randomized into five groups and treated on the first day postoperatively. Group C served ‎as a control and ‎received no treatment, while groups A, B, and D were subjected to diode ‎impulse laser with a power of 2×10-3 watts and a wavelength of 904 ‎nm for 15, 25, and 35 ‎min per session, respectively. Group E received continuous diode laser for 30 min per ‎session with a power of 3×10-3 watts and a wavelength of 904 ‎nm. The treated groups received irradiation for 5, 8, ‎‎15, and 21 days postoperatively. Subsequent healing processes were ‎assessed macroscopically ‎and microscopically at each time point. In treated groups versus the control group, epitenon ‎thickness increased ‎from day 5, inflammatory and fibroblast cell responses were more evident, ‎and collagen fibers were clearer and more differentiated. On day 15, when the remodeling ‎stage began, group B healed best. The impulse diode laser was found to be more effective than ‎the ‎continuous diode laser in promoting the healing of surgical defects of the tendons at varying ‎degrees. In the continuous diode laser group, ‎there was a sustained high cellular response until ‎day 21 with the appearance of unorganized and irregular collagen fibers. This study ‎‎demonstrated that diode laser can accelerate the healing process of injured tendons and that ‎impulse diode laser is more effective than ‎continuous diode laser.