Osteoarthritis (OA) is a degenerative disease that occurs mostly in the elderly, and its specific pathogenesis is still unknown, but recent studies have found that circular RNA generally display aberrant expression in OA. Our study explored the expression characteristics and mechanism of action of circ‐NT5C2 in OA. Circ‐NT5C2, microRNA‐142‐5p (miR‐142‐5p), and nicotinamide phosphoribosyltransferase (NAMPT) mRNA levels were measured using RT‐qPCR. Western blot was employed to assess the protein level of NAMPT and extracellular matrix (ECM) production‐related markers. The viability, proliferation, apoptosis and inflammation were examined using 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide (MTT) assay, 5‐ethynyl‐2′‐deoxyuridine (EdU) assay, flow cytometry, and enzyme‐linked immunosorbent assay, respectively. Relationship between miR‐142‐5p and circ‐NT5C2 or NAMPT was demonstrated by dual‐luciferase reporter system and RNA immunoprecipitation assay. We reported that circ‐NT5C2 and NAMPT were greatly upregulated, and miR‐142‐5p level was constrained in OA tissues and in a cell model. Circ‐NT5C2 silencing alleviated IL‐1β‐induced inhibitory effects on chondrocyte proliferation and ECM generation, meanwhile the promotional role of IL‐1β on chondrocyte apoptosis and inflammation was also weakened. The targeting relationship of miR‐142‐5p with either circ‐NT5C2 or NAMPT was confirmed. Knockdown of miR‐142‐5p reversed the suppressive effects of circ‐NT5C2 silencing on the OA progression in vitro, and NAMPT overexpression also attenuated the effects of miR‐142‐5p upregulation in an OA cell model. Collectively, circ‐NT5C2 accelerated the OA process by targeting the miR‐142‐5p/NAMPT axis. This study provides valuable information to find a better treatment for OA.

To discuss the method and effect of total knee arthroplasty osteotomy and soft tissue release for serious knee joint space narrowing. Clinical data of 80 patients from October 2013 to December 2014 was selected with a retrospective method. All patients have undergone total knee arthroplasty. Then the X-rays plain film in weight loading was measured before and after operation and osteotomy was performed accurately according to the knee joint scores and the conditions of lower limb alignments. The average angle of tibial plateau osteotomy of postoperative patients was 4.3°, and the corrective angle of soft tissue balancing was 10.7°; the postoperative patients’ indicies including range of joint motion, knee joint HSS score, angle between articular surfaces, tibial angle, femoral-tibial angle and flexion contracture were distinctly better than the preoperative indicies (p<0.05) and the differences were statistically significant; the postoperative patients’ flexion contracture and range of joint motion were distinctly better than the preoperative indicies (p<0.05) and the differences were statistically significant. The effective release of the soft tissue of the posterior joint capsule under direct vision can avoid excess osteotomy and get satisfactory knee replacement space without influencing the patients’ joint recovery.