AIM:The biochemical changes associated with rotator cuff tearing are still unclear. The aim of this study is to assess whether concentrations of matrix metalloproteinase in the synovial fluid are specifically altered in shoulders with torn rotator cuff tendons.PATIENTS AND METHOD:Synovial fluid was extracted via arthroscopy in 21 patients with complete rotator cuff tears (RCTs). The control group was composed of 21 patients without complete tears. The catabolic cartilage metabolism markers MMP-1 (collagenase), MMP-3 (stromelysin1) and MMP-13 (collagenase3) were quantified by an ELISA test and these results were then statistically analysed using SAS.RESULTS:The mean concentration of the 21 samples with rotator cuff tears shows a higher concentration of MMP 3 (2601.73 ng/mL vs. 1775.67 ng/mL) and MMP 13 (2.69 ng/mL vs. 2.35 ng/mL) as well as a significantly higher concentration of MMP 1 (p=0.0047) in the control group.CONCLUSIONS:A significant variation in the concentration of catabolic cartilage enzymes in the synovial fluid in patients with and without rotator cuff tears could not be found. Nonetheless, there is a bias for the MMP-3 and MMP-13 values, which makes a conductive influence in the aetiology of osteoarthritis probable.