2015 ISAKOS Biennial Congress ePoster #2431
Increased Synovial-Based Inflammation in Glenohumeral Rotator Cuff Tears and Osteoarthritis
Geoffrey D. Abrams, MD, Stanford, CA UNITED STATES
Ayala Luria, PhD, Palo Alto, CA UNITED STATES
Rebecca A. Carr, BA, Palo Alto, CA UNITED STATES
Christopher Rhodes, BS, Palo Alto, CA UNITED STATES
William H. Robinson, MD, PhD, Palo Alto, CA UNITED STATES
Jeremy Sokolove, MD, Palo Alto, CA UNITED STATES
Veterans Administration Palo Alto/Stanford University, Palo Alto, CA, USA
FDA Status Not Applicable
Summary: Rotator cuff tears and glenohumeral osteoarthritis have increased synovial-based inflammation
Osteoarthritis (OA) and degenerative rotator cuff tears have traditionally been thought of as a non-inflammatory condition. We hypothesize that both conditions have a significant synovial-based inflammatory component.
A total of 38 patients undergoing shoulder arthroscopy or shoulder arthroplasty consented to have synovial biopsies taken from the rotator interval during their surgical procedure. No patients had a history of inflammatory arthritis or acute injury to the shoulder within the six months prior to surgery. There were 20 patients having arthroscopically confirmed normal cartilage status with full thickness rotator cuff tears (Group A), seven having severe glenohumeral OA undergoing total shoulder arthroplasty (Group B), and 11 patients with normal cartilage status and no full thickness rotator cuff tears (Group C). Synovial biopsies were embedded in optimum cutting temperature (OCT) compound and cryosections were stained with hematoxylin and eosin (H&E). Serial sections were also stained and assessed by semi-quantitative confocal immunofluorescent microscopy to evaluate for CD45 (pan-leukocyte), CD31 (endothelial cell), and CD68 (macrophage) cell surface markers. A previously published “synovitis score” grading system was utilized to determine the amount of synovitis seen under light microscopy. Quantitative analysis for cell surface marker staining presence and intensity using confocal laser scanning microscopy was carried out using digital image analysis (ImageJ, National Institutes of Health, Bethesda, MD). Scoring was assessed twice by two independent blinded reviewers for the synovitis score and mean values were calculated. Student’s t-tests were used to examine statistical differences between groups and a kappa-statistic was calculated for inter- and intra-observer correlation coefficients (ICC). An alpha value of 0.05 was set as significant.
Those in Group A and Group B demonstrated a significantly higher synovitis score versus Group C (p < 0.002). There was no significant difference in the synovitis score between groups A and B. Scores for both inter-observer (k = 0.816) and intra-observer (k = 0.767) correlation coefficients demonstrated substantial agreement. Cell surface marker staining intensity for CD31, CD45, and CD68 were all significantly higher in groups A and B versus group C (p < 0.01). No difference was seen in immunofluorescence staining between groups A and B.
Patients with full thickness rotator cuff tears and those with OA undergoing shoulder arthroplasty demonstrated significantly increased synovial inflammation as well as inflammatory cell infiltrate staining compared to those with normal cartilage status and intact rotator cuffs. This data suggests that chronic rotator cuff tears and glenohumeral osteoarthritis have an inflammatory component which may contribute to and perpetuate ongoing pain and tissue damage. The identification of increased endothelial cell staining in rotator cuff tears suggests that chronic inflammation in this disease processes may be characterized by neovascularization. This increased vascularity may facilitate leukocyte presence in the synovium and eventual infiltration into the joint, further perpetuating the inflammatory process.