Objective To investigate the therapeutic effect and mechanism of ultrashort-wave therapy combined with electroacupuncture on the experimental rabbits with knee osteoarthritis.Methods Ten of fifty-five experimental Japanese big-ear rabbits were randomized into the blank control group

and the other 45 were made knee osteoarthritis models by prolonged fixation of the right posterior knee joint in extension for 6 weeks. The 40 successfully made models were randomized into model control group

electroacupuncture group

ultrashort-wave group

and combined electroacupuncture and ultrashort-wave group

10 in each. The electroacupuncture group was treated with electroacupuncture at Xuehai （SP 10）

Liangqiu （ST 34）

Yanglingquan （GB 34）

and Zusanli （ST 36） of the right posterior leg

the ultrashort-wave group was treated with ultrashort-wave therapy

and the combined electroacupuncture and ultrashort-wave group was treated with electroacupuncture and ultrashort-wave therapy

each time 25min

once a day. After treatment for 30 days

the levels of superoxide dismutase （SOD）

malondialdehyde （MDA）

and nitric oxide （NO） in serum and the movement of affected knee joint were measured respectively in each group. Results Compared with the model control group

there was a significant increase of SOD

decrease of NO and MDA and knee movement improvement in the electroacupuncture

ultrashort-wave

and combined groups （P < 0.01）

and the effect of the combined group was better than that of ultrashort-wave and electroacupuncture groups （P < 0.01）.Conclusion The ultrashort-wave therapy combined with electroacupuncture therapy is effective for knee osteoarthritis of rabbits

and is better than that of single use of ultrashort-wave therapy and electroacupuncture. The functional mechanism is possibly related with the improvement of metabolism of free radicals.