Histologic analysis of structural damage in the articular cartilage following long term usage of Dex in experimental OA model. (A) The articular cartilage was stained with Safranin O-fast green at 4 and 12 weeks after DMM surgery following long term usage of Dex to assess the extent of articular cartilage degeneration, expansion of the region occupied by articular cartilage. (B-E) OARSI scoring system showed intraperitoneal Dex injection exacerbates the pathological severity of articular cartilage at 4 weeks after DMM surgery (n = 5). (F-I) OARSI scoring system showed intraperitoneal Dex injection exacerbates the pathological severity of articular cartilage at 12 weeks after DMM surgery (n = 5). MFC: medial femoral condyle; MTP: medial tibial plateau. Scale bar: 100 µm. Comparisons of multiple groups were evaluated using analysis of variance (ANOVA) followed by Tukey's test. Data were expressed as the mean ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.