MMP13 and arthritic joint disease: Specifically, Brophy et al. have recently reported an elevation in the gene expression of arthritis-related markers, including a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), MMP-1 and MMP-13 in patients with meniscal injuries under the age of 40 years (Brophy et al. 2012).