Effects of a therapeutic laser on the ultrastructural morphology of repairing medial collateral ligament in a rat model

Background and Objectives Low energy laser therapy has been shown to enhance mechanical strength of healing medial collateral ligament (MCL) in rats. The present study investigated its effects on the ultrastructural morphology and collagen fibril profile of healing MCL in rats. Study Design/Materials and Methods Thirty‐two mature male Sprague–Dawley (SD) rats were used. Twenty‐four underwent surgical transection to their right MCLs and eight received only skin wound. Immediately after surgery, eight of the MCL transected rats were treated with a single dose of laser therapy at 63.2 J cm−2, eight were treated with a single dose of laser therapy at 31.6 J cm−2, the rest had no treatment and served as control. At 3 and 6 weeks after surgery, the MCLs were harvested and examined with electron microscopy for collagen fibril size, distribution, and alignment. Results Significant differences (P