Evaluation of the effects of LLLT on biomechanical properties of tibial diaphysis in two rat models of experimental osteoporosis by a three point bending test.

Osteoporosis (OP) is a disease which causes bone loss and fractures, leading to severe pain and deformity. This study has aimed to assess the effects of pulsed wave low-level laser therapy (PW LLLT) on cortical bone in two experimental models of OP in rats. There were four ovariectomized (OVX-d) groups and four dexamethasone-treated groups. The healthy group were considered for baseline evaluations. At 14 weeks following ovariectomy, the OVX-d rats were further subdivided into the following: control rats with OP, OVX-d rats that received alendronate (1 mg/kg), OVX-d rats treated with LLLT, and OVX-d rats treated with alendronate and LLLT. The remaining rats received dexamethasone for 5 weeks and were divided into four groups: control, alendronate-treated rats (1 mg/kg), laser-treated rats, and laser-treated rats with concomitant administration of alendronate. The rats received alendronate for 30 days. LLLT (890 nm, 80 Hz, 0.972 J/cm(2)) was performed on the tibias three times per week for 8 weeks. After 8 weeks, tibias were extracted and submitted to a three-point bending test. PW LLLT did not increase the biomechanical parameters of osteoporotic bones compared to controls and healthy rats. PW LLLT associated with alendronate treatment significantly increased stress high load in OVX-d rats compared to the healthy group. PW LLLT at the current study parameters failed to cause beneficial biomechanical effects in the examined osteoporotic cortical bones. PW LLLT associated with alendronate treatment produced a more remarkable effect on bone strength in the ovariectomized induced OP rat model.