Cytogenetic analysis of the pathology of frozen shoulder

BACKGROUND: Frozen shoulder (FS) is a debilitating musculoskeletal condition with an uncertain etiology and pathogenic mechanism. The aim of this study was to investigate the hypothesis that an alteration in the level of cytokines may disrupt the normal inflammatory and tissue healing process in the shoulder, leading to the development of FS. MATERIALS AND METHODS: A prospective case–control study was undertaken, analyzing patients undergoing arthroscopic treatment of FS and control patients being treated for subacromial bursitis. Synovial biopsies were taken from all subjects. Synovial RNA levels were analyzed using quantitative polymerase chain reaction (qPCR) RESULTS: Thirteen patients with FS were recruited, four of whom were diagnosed with diabetes mellitus, along with 10 control patients. Cytogenetic analysis using qPCR revealed both fibrogenic cytokine matrix metalloproteinase 3 (MMP 3) (1.98×10 (5) vs. 755.0, P=0.068) and inflammatory cytokine interleukin 6 (IL 6) (1679.2 vs. 372.8, P=0.062) to be elevated in FS cases as compared to controls. Comparison between diabetic and non-diabetic patients revealed a decrease in the level of expression of inflammatory cytokine, monocyte colony stimulating factor (M-CSF) (12,496 vs. 305.1, P=0.04) in diabetic FS patients. CONCLUSIONS: The results demonstrate that levels of inflammatory and fibrogenic cytokines are elevated in the synovium of patients with FS compared with controls. This indicates that altered levels of inflammatory cytokines may be associated with the pathogenesis of inflammation evolving into fibrosis, which is the characteristic feature of FS. We have also shown the opposite to be the case in patients with diabetic FS.