BACKGROUND:Acupotomy is effective in the treatment of knee osteoarthritis,but its mechanism is not very clear. OBJECTIVE:To observe the effect of acupotomy on the apoptosis of knee chondrocytes in knee osteoarthritis rats based on osteoclast associated receptor(OSCAR)-tumor necrosis factor-associated apoptosis-inducing ligand(TRAIL)-osteoprotetin(OPG)pathway. METHODS:Twenty-seven Sprague-Dawley rats were randomly divided into normal group(n=9),model group(n=9)and acupotomy group(n=9).Rats in the normal group were routinely housed without any treatment.Animal models of knee osteoarthritis were established by knee injection of papain.Acupotomy intervention was performed 1 week after modeling,once a week for a total of three times.Relevant tests were performed at the end of the intervention. RESULTS AND CONCLUSION:The Lequesne MG behavioral scores of rats in the model group were elevated compared with the normal group(P<0.01),while the Lequesne MG behavioral scores of rats in the acupotomy group were decreased comparedwith the model group(P<0.01).Hematoxylin-eosin staining results showed that compared with the normal group,the cartilage surface of the rat's knee joints in the model group was worn and uneven and the chondrocytes were swollen,ruptured,reduced in number,and arranged disorderly;while the cartilage surface of the rat's knee joints in the acupotomy group was relatively smooth,and the chondrocytes were high in number and arranged in an orderly manner,with the structure basically clear.Immunohistochemical staining results showed that compared with the normal group,the positive expressions of OSCAR and TRAIL were increased in the model group(P<0.01),while the positive expression of OPG was decreased(P<0.01).Compared with the model group,the positive expressions of OSCAR and TRAIL in the acupotomy group were decreased(P<0.01),while the positive expression of OPG was increased(P<0.01).TUNEL staining results showed that compared with the normal group,the number of apoptotic cells in the model group were increased(P<0.01);compared with the model group,the number of apoptotic cells in the acupotomy group decreased(P<0.01).RT-qRCR and western blot results showed that compared with the normal group,the protein expressions of OSCAR,TRAIL and Bax in the model group were increased(P<0.01),and the protein expressions of OPG and Bcl-2 were decreased(P<0.01);compared with the model group,the protein expressions of OSCAR,TRAIL,and Bax in the acupotomy group were decreased(P<0.01),and the protein expressions of OPG and Bcl-2 were increased(P<0.01).To conclude,acupotomy can reduce cartilage injury of the knee joint in rats with knee osteoarthritis,which may be related to the blockage of mitochondrial pathway apoptotic signaling release by the OSCAR-TRAIL-OPG pathway.