Effects of low energy laser therapy and herbal medication on ligament healing in rats

Low level laser therapy (LLLT) and Chinese herbal medications are commonly used to treat musculoskeletal injuries in Eastern and Western communities. However, there is a lack of evidence supporting the use of these treatments during the sub-acute and chronic stages of recovery. Therefore, the present study investigated the biomechanical and ultrastructural effects of gallium aluminum arsenide (GaAlAs) LLLT and external herbal application on injured rat medial collateral ligaments (MCLs).; One hundred and twelve mature male rats were randomly allocated into 7 groups of equal number. Having the right MCL surgically transected, the experimental rats were treated with either one dose of LLLT (31.6 Jcm −2 or 63.2 Jcm−2), or alternate day of cutaneous herbal application. All animals were tested at 3 weeks (n = 56) or 6 weeks (n = 56) after operation. The analyses included tissue biomechanical properties and ultrastructural collagen morphology. The results were compared with the respective controls (untreated injured ligaments) and shams (intact ligaments). Two-way analysis of variance and Kruskal-Wallis test were used to compare the data with alpha set at 0.05.; Biomechanically, both LLLT and herb groups showed significantly higher ultimate tensile strength (UTS) and stiffness compared to the controls (p < 0.05). There was no significance difference between the UTS of the LLLT groups and the stiffness of the herb group compared with the respective sham groups. The herb group had significantly larger stiffness compared to both LLLT groups (p < 0.05).; Morphologically, out of 770,526 fibrils, the mean collagen fibril diameters in both the LLLT and herb groups were larger than the untreated controls (p < 0.001). Although the core mean collagen fibril diameters of the LLLT and herb groups were smaller than the sham groups (p < 0.001), the peripheral fibril sizes were comparable. From 3 to 6 weeks post-injury, the core fibril sizes of the LLLT and herb groups approached the values of the sham groups.; The present study showed that both GaAlAs LLLT and externally applied Chinese herbal medicine can improve biomechanical and morphological properties of repairing MCL in rats. These results are so promising that some findings of the treatment groups are comparable to the intact ligaments.