Although not all investigators agree that there is significant increase in the serum MMP-3 concentrations in patients with OA, Pengas et al. reported that knee synovial MMP-3 concentrations correlated with serum MMP-3 concentrations concluding that serum MMP-3 concentrations could be used as a potential biomarker for knee osteoarthritis and possible disease predictor22. Here, MMP3 is linked to osteoarthritis, knee.