Matrix metalloproteinase-1 and matrix metalloproteinase-9 are highly expressed in the joint capsule of diabetic frozen shoulder

The pathophysiology of frozen shoulder (FS) involves abnormal expressions of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) that lead to capsular fibrosis. However, there has been little concern for why diabetic FS has more protracted fibrotic condition. The objective of this study was to compare the expression levels of MMPs and TIMPs in the joint capsule of patients with diabetic and nondiabetic FS.