Effect of low-level laser therapy on healing of medial collateral ligament injuries in rats: an ultrastructural study

Abstract

Objective: This study sought to investigate whether low-level laser therapy (LLLT) with a helium-neon (He-Ne) laser would increase fibril diameter of transected medial collateral ligament (MCL) in rats.

Background data: It has been shown that LLLT can increase ultimate tensile strength MCL healing.

Methods: Thirty rats received surgical transect to their right MCL, and five were assigned as the control group. After surgery, the rats were divided into three groups: group 1 (n = 10) received LLLT with He-Ne laser and 0.01 J/cm(2) energy fluency per day, group 2 (n = 10) received LLLT with 1.2 J/cm(2) energy fluency (density) per day and group 3 (sham-exposed group; n = 10) received daily placebo laser with shut-down laser equipment, while control group received neither surgery nor LLLT. Transmission electron microscope (TEM) examination was performed on days 12 and 21 after surgery and dimension and density of ligament fibrils were measured. The data were analyzed by Student t-test and Mann-Whitney tests, respectively.

Results: On day 12, the fibril dimension of group 2 and their density were higher than of groups 1 and 3.

Conclusion: LLLT with He-Ne laser on incised MCL in rats could not significantly increase fibril diameter and their density in comparison with sham-exposed group.