Abstract: ObjectiveTo investigate the expression of aquaporin 4 (AQP4) and aquaporin 9 (AQP9) in the knee articular cartilage of rabbits with knee osteoarthritis (OA), so as to discuss the roles of AQP4 and AOP9 in the pathogenesis of knee osteoarthritis. MethodsThe right hind limbs of rabbits were immobilized with a plaster cast in the extension position to establish an OA model. The rabbits were sacrificed after 2, 4, 6, 8 and 10 weeks and their femoral condyle cartilage were taken to prepare histopathology sections for optical microscopic observation. ResultsThe damages in rabbit cartilages were worsen as the modeling process extended. According to immunohistochemistry, the expression of AQP4 and AQP9 were higher in the knee cartilage of the experimental groups than that of the control group, with statistical difference (P<0.01). ConclusionsAQP4 and AQP9 are highly expressed in the knee cartilage of OA, which indicates that AQP4 and AQP9 may be associated with the pathogenesis of OA.