Pulsed Nd:YAG laser therapy accelerates fracture healing in a rat femoral osteotomy model

This study aimed to evaluate the effects of Nd:YAG laser treatment on fracture healing in a rat model. We hypothesized that laser therapy would accelerate healing by stimulating early neovascularization and osteoblast recruitment.

A total of 54 male Sprague-Dawley rats received intramedullary Kirschner wire (K-wire) osteosynthesis following femoral osteotomy, and were randomly divided into two groups (n = 27 each): the control group, and the laser group that received daily pulsed Nd:YAG laser for ten days immediately after osteotomy. Fracture sites were assessed using micro-CT (μCT; n = 8 at each timepoint), histology (n = 4), and three-point bending tests (n = 4) at week 2, week 4, and week 6, respectively. At week 2, an additional three rats per group were selected for the western blot tests.

Compared to controls, the laser group showed higher vascular endothelial growth factor (VEGF), CD31, and Runx2 protein expression, and significantly higher neovascular area density and osteoblast density (p = 0.025 and p = 0.008, respectively) at week 2. At week 4, the laser treatment led to higher histological fracture healing scale and flexural modulus, and less strain (p = 0.001, p = 0.020, and p = 0.004, respectively). Macroscopically, the laser group showed higher mature bone volume fraction and radiological union score at weeks 4 and 6 (volume fraction: p = 0.017 and p = 0.001; union score: p = 0.001 and p = 0.024, respectively).

Pulsed Nd:YAG laser therapy accelerates multiple quantitative indicators of fracture healing within six weeks in a rat femoral osteotomy model, which was associated with enhanced angiogenesis and osteogenesis during the early healing phase.