Hyaline cartilage fibrosis is one of the important reasons for the poor prognosis of advanced osteoarthritis (OA), and is the main factor leading to joint stiffness and deformity. However, the mechanism of hyaline cartilage fibrosis remains largely unclear. Here we found that DDX5, one of the founding members of the DEAD-box RNA helicase family, was dramatically downregulated in the degenerated articular cartilage of aged mice, destabilization of the medial meniscus murine model as well as patients with OA. Our data suggest that strategies aimed at upregulation of DDX5 will be of great value for the treatment of cartilage fibrosis and damage in OA.