Fig. 1

Study design. The right knee joint had an intra-articular injection of MIA at day 0. The left knee had PBS as a control. The pain avoidance behavior tests (Incapacitance test and von Frey Hair test) were performed as indicated. Histological evaluations (hematoxylin and eosin (HE), Masson Trichrome (MT)) and immunohistochemical assessments (anti-ED1 immuno-staining) were performed at days 0, 1, 3, 5, and 7. Steel’s test was employed to analyze the results of incapacitance test and von Frey Hair test. Asterisks (Fig. 2) indicated that the values were significantly altered with those of pre-experimental levels (0 day). Kruskal-Wallis test followed by Steel-Dwass test was performed to analyze the results of histological evaluations between 5 independent time points (Figs. 3, 4, and 5). Asterisks indicated that the values were significantly altered from those of pre-experimental levels (0 day)