PTGS2 and Arthritis: To further explore the different expression levels of chondrogenesis-related genes and arthritis-related genes in cartilage with different Ficat stages, the qRT-PCR analysis was used to detect the expression levels of six chondrogenesis-related genes (MMP13, ASPN, COL1A1, OGN, COL2A1, BMP2) and four arthritis-related genes (IL1β, IL6, TNFα, PTGS2) in different Ficat stages of cartilage specimens.