Comparative study of how low-level laser therapy and low-intensity pulsed ultrasound affect bone repair in rats.

OBJECTIVE

This study aimed to compare the consequences of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on bone repair.

BACKGROUND DATA

Many studies have assessed the effects of LLLT and LIPUS on bone repair, but a comparison of them is rare.

METHODS

Male Wistar rats (n = 48) with tibial bone osteotomy were used. One group had the osteotomized limb treated with LLLT (GaAlAs laser, 780 nm, 30 mW, 112.5 J/cm(2)) and the second group with LIPUS (1.5 MHz, 30 mW/cm(2)), both for 12 sessions (five times per week); a third group was the control. After 20 days, rats were sacrificed and had their tibias submitted to a bending test or histomorphometric analysis.

RESULTS

In the bending test, maximum load at failure of LLLT group was significantly higher (p < 0.05). Bone histomorphometry revealed a significant increase in osteoblast number and surface, and osteoid volume in the LLLT group, and a significant increase in eroded and osteoclast surfaces in the LIPUS group.

CONCLUSION

LIPUS enhanced bone repair by promoting bone resorption in the osteotomy area, while LLLT accelerated this process through bone formation.