肩周炎, also known as frozen shoulder, is a condition characterized by stiffness and pain in the shoulder joint. It occurs when the connective tissue surrounding the shoulder becomes inflamed and thickened, limiting movement. This condition can develop gradually and is often associated with injury, overuse, or certain medical conditions. Symptoms of 肩周炎 include difficulty in raising the arm, pain during daily activities, and discomfort at night. Treatment options typically involve physical therapy, pain management, and in some cases, corticosteroid injections. Early intervention can help improve mobility and reduce pain.