an increasing trendP < 0.05
We also observed an increasing trend of ferritin and Fe 2+ levels in the synovium with the progression of K–L grade (Fig. 8 C, * P < 0.05, ** P < 0.01, *** P < 0.001 versus K–L Grade 2; # P < 0.05, ### P < 0.001 versus K–L Grade 3).