Bone – How laser therapy & ultrasound promote repair

Lasers Med Sci. 2010 Jun 3. [Epub ahead of print]

Comparative study of the effects of low-intensity pulsed ultrasound and low-level laser therapy on bone defects in tibias in rats.

Fávaro-Pípi E, Feitosa SM, Ribeiro DA, Bossini P, Oliveira P, Parizotto NA, Renno AC.

Department of Physiotherapy, Federal University of São Carlos, Rodovia Washington Luís (SP-310), Km 235, São Carlos, SP, Brazil.


The aim of this study was to investigate and to compare the effects of low intensity ultra-sound (LIPUS) and low-level laser therapy (LLLT) during the process of bone healing by means of histopathological and morphometric analysis. The animals were randomly distributed into three groups of 30 animals each: the control group (bone defect without treatment); the laser-treated group: (bone defect treated with laser), and the LIPUS-treated (bone defect treated with ultrasound). Each group was further divided into three different subgroups (n = 10) and on days 7, 13, and 25 post-injury, rats were killed with an intra-peritoneal injection of general anesthetic. The rats were treated with a 30-mW/cm(2) low-intensity pulsed ultrasound and a 830-nm laser at 50 J/cm(2). The results showed intense new bone formation surrounded by highly vascularized connective tissue presenting a slight osteogenic activity, with primary bone deposition being observed in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). This was confirmed by morphometric analysis in which significant statistical differences (p < 0.05) were noticed when compared to the control. No remarkable differences were noticed in the specimens treated with ultrasound with regard to the amount of newly formed bone in comparison to the control group. Taken together, our results indicate that laser therapy improves bone repair in rats as depicted by histopathological and morphometric analysis, mainly at the late stages of recovery. Moreover, it seems that this therapy was more effective than US to accelerate bone healing.

Photomed Laser Surg. 2006 Dec;24(6):735-40.

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

Lirani-Galvao AP, Jorgetti V, Da Silva OL.

Bioengineering Department, University of Sao Paulo, Sao Paulo, Brazil.

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.