Effects of laser irradiation on arthritic histopathology and heat shock protein 70 expression in C57 black mice with osteoarthritis

OBJECTIVE To study the effects of three different laser treatments (650 nm alone, 10.6 μm alone and combined laser of 650 nm and 10.6 μm) on experimental osteoarthritis of the knees in C57 black mice. METHODS Sixty C57 black mice were divided randomly into 6 groups. Ten mice were assigned to a normal control group (no intervention) and the other 5 groups were subjected to a forced running regimen to induce osteoarthritis. One group was set as the model control group. The other 4 groups were given 90 s of a 650 nm laser, 90 s of a 10.6 μm laser, 90 s of a combined laser, or a sham treatment on acupoint Dubi (ST35) of the rear left leg 3 times per week for 4 weeks. The modified Mankin score was used to evaluate the degree of cartilage degradation. Immunohistochemical staining for heat shock protein (HSP) 70 was conducted. RESULTS Mankin scores of the model control group and the sham control group were significantly higher than that of the normal control group (P