Matrix metalloproteinase levels as a marker for rotator cuff tears

Although many studies report the role of matrix metalloproteinases (MMPs) in rotator cuff tears, a paucity of data exists correlating the clinical severity of the disease with the implicated MMP levels. The purpose of this study was to investigate and compare the levels of expression of MMP-1, -3, -9 and -13 in patients with rotator cuff tears. We hypothesized that patients with clinically worse symptoms as measured by a standardized pain and function scale would have a higher expression of MMPs.Rotator cuff specimens were obtained from 16 consecutive patients undergoing rotator cuff repair. Total protein was extracted from these specimens and quantified. Equalized total protein extracts were used for performing enzyme-linked immunosorbent assay for quantitative determination of MMP-1, -3, -9 and -13. Preoperatively, the University of California, Los Angeles (UCLA) Shoulder Rating Scale was administered to each patient. Statistical comparisons were performed using analysis of variance. The expression of MMP-13 was notably increased in the rotator cuff extracts of all patients (P=.02). In addition, MMP-13 levels showed a significant proportional correlation with the patient pain score as per their UCLA ratings (r=-0.5). Although higher MMP-9 levels were assayed, this was not statistically significant. Expression of MMP-1 and-3 was insignificant.Our data suggest a critical role for MMP-13 in rotator cuff tears; elevated levels are a possible indicator for an impending tear. Further studies with increased sample size are warranted to prove the possible use of MMP-13 as therapeutic targets that may be inhibited by anti-inflammatory agents to limit disease progression.