To observe the effects of close-to-bone needing combined with electroacupuncture (EA) on cartilage collagen type Ⅱ/discoidin domain receptor/matrix metalloproteinase 13 (collagen type Ⅱ/DDR2/MMP 13) signaling pathway in rabbits with knee osteoarthritis (KOA), and to explore the possible action mechanism of this method on repair of extracellular matrix of knee cartilage.
Forty New Zealand white rabbits were randomly assigned into a normal group (10 rabbits) and a model establishing group (30 rabbits). The Hulth-Telhag technique was applied to establish the model of KOA, and X-ray was used for outcome assessment. The rabbits with successful modeling were randomly assigned into a model group, a close-to-bone needing group, a regular acupuncture group, 10 rabbits in each one. The rabbits in the close-to-bone needing group were treated with close-to-bone needing and EA; the rabbits in the regular acupuncture group were treated with regular acupuncture and EA. "Neixiyan" (EX-LE 4), "Dubi" (ST 35), "Yinlingquan" (SP 9), "Zusanli" (ST 36) and "Liangqiu" (ST 34) were selected in the two groups. The intervention was given for 20 min, once a day; the intervention of 5 days made 1 session, 2 days as the interval and totally 4 sessions were given. Rabbits in normal and model group were immobilized without any treatment. After the treatment, western blotting method was applied to evaluate the expression of DDR2 and collagen type Ⅱ; the activity of collagen type Ⅱ, DDR2 and MMP 13 was assessed by immunohistochemistry method; the mRNA expression of DDR2 and MMP 13 was determined by reverse transcription-polymerase chain reaction (RT-PCR).
Compared with the normal group, the activity expression of collagen type Ⅱ were significantly reduced in the other groups (all 
The close-to-bone needing combined with EA and regular EA could both promote the repair of knee cartilage, where closing-to-bone needing combined with EA shows a superior efficacy. The mechanism may be associated with the blocking effect of collagen type Ⅱ/DDR2/MMP13 signaling pathway and the inhibiting effect of degradation in extracellular matrix of cartilage.