MMP13 and osteoarthritis, knee: Moreover, our findings are the first data on the expression level of MMP13 mRNA in relation to the progression of OA in human articular cartilage with subchondral bone, which provides a basis for the conclusion that MMP13 mRNA may be a biomarker of the progression of knee osteoarthritis (OA) and may serve in future to develop a potential therapeutic strategy for the prevention and treatment of this disease.