MMP9 and osteonecrosis: Notably, MMP-9 and VEGF-C were significantly lower in patients with incident osteonecrosis before (p = 0.030 and p = 0.027, respectively), during (p = 001 and p = 0.004, respectively) and after (p < 0.001 and p = 0.006, respectively) the event (Figure 5g,h), suggesting their potential as predictive biomarkers of ON in subjects at risk.