ObjectiveTo explore the mechanism of Cangxi Tongbi capsules （CXTB） in regulating the p38 mitogen-activated protein kinase （p38 MAPK）/NOD-like receptor protein 3 （NLRP3）/cysteine protease-1 （Caspase-1） signaling pathway to inhibit pyroptosis of cartilage cells in knee osteoarthritis （KOA）. MethodSixty male SD rats were randomly divided into a sham operation group， a model group， low， medium， and high dose CXTB groups， and a positive control group， with 10 rats per group. The modified Hulth method was employed to establish a rat model of KOA. According to their respective assignments， rats were administered CXTB （0.25， 0.5， 1.0 g·kg^-1） and Celecoxib （24 mg·kg^-1） by gavage. The sham operation and model groups were given an equivalent volume of physiological saline. Treatment was performed once daily for 28 days. Micro-computed tomography （Micro-CT） was used to assess bone volume/total volume （BV/TV） and trabecular separation （Tb.Sp）. Joint degeneration was evaluated through hematoxylin-eosin （HE） staining， safranin-fast green （SO） staining， and Osteoarthritis Research Society International （OARSI） scoring. Western blot analysis was conducted to measure the expression levels of p38 MAPK， phosphorylated p38 MAPK （p-p38 MAPK）， NLRP3， Caspase-1， and gasdermin D （GSDMD） proteins. Real-time PCR was used to assess mRNA expression levels of p38 MAPK， NLRP3， Caspase-1， and GSDMD genes. Enzyme-linked immunosorbent assay （ELISA） was used to measure serum concentrations of inflammatory cytokines including tumor necrosis factor-alpha （TNF-α）， interleukin-1 beta （IL-1β）， and interleukin-18 （IL-18）. After knee replacement surgery， cartilage tissue was analyzed using Western blot to assess the protein expression levels of p38 MAPK， p-p38 MAPK， NLRP3， Caspase-1， and GSDMD， and Real-time PCR was used to evaluate gene expression levels of p38 MAPK， NLRP3， Caspase-1， and GSDMD. ResultMicro-CT analysis revealed significant narrowing of the joint space and increased bone spur formation in KOA rats compared with the sham operation group， with a decrease in BV/TV ratio and an increase in Tb.Sp value （P<0.01）. Serum levels of TNF-α， IL-1β， and IL-18 were elevated （P<0.01）. The protein expression levels of p-p38 MAPK， NLRP3， Caspase-1， and GSDMD in cartilage were significantly increased （P<0.01）， and the mRNA expression levels of p38 MAPK， NLRP3， Caspase-1， and GSDMD were also enhanced （P<0.01）. Significant differences in protein expression of p-p38 MAPK， NLRP3， Caspase-1， and GSDMD were observed between normal and diseased cartilage tissues after knee replacement surgery （P<0.05）， and the gene expression of p38 MAPK， NLRP3， Caspase-1， and GSDMD were also significantly different （P<0.01）. HE and SO staining showed roughened joint surfaces， reduced cartilage thickness， and disordered cellular arrangement in KOA rats. OARSI scores were significantly higher （P<0.01）. Compared with the model group， treatment with low， medium， and high concentrations of CXTB resulted in increased BV/TV ratios and decreased Tb.Sp values in the knee joints of rats （P<0.01）. HE and SO staining indicated a trend towards smoother joint surfaces and reduced OARSI scores （P<0.01）. The protein expression levels of p-p38 MAPK， NLRP3， Caspase-1， and GSDMD were notably decreased （P<0.05）， as were the mRNA expression levels of p38 MAPK， NLRP3， Caspase-1， and GSDMD （P<0.01）. Additionally， serum concentrations of TNF-α， IL-1β， and IL-18 were significantly reduced （P<0.01）. ConclusionCXTB intervention may alleviate knee joint degeneration in KOA rats and inhibit the expression of inflammatory factors and pyroptosis of cartilage cells， thereby protecting cartilage. The underlying mechanism may involve modulation of the p38 MAPK/NLRP3/Caspase-1 signaling pathway.