of pain. As the pain worsens, the shoulder loses motion. Stage two: The "frozen" or adhesive stage is marked by a slow improvement in pain but the stiffness remains. This stage generally lasts from four to twelve months. Stage three: The "thawing" or recovery, when shoulder motion slowly returns toward normal. This generally lasts from 5 to 26 months. Physical exam findings include restricted range of motion in all planes of movement in both active and passive range of motion. This contrasts with conditions such as shoulder impingement syndrome or rotator cuff tendinitis in which the active range of motion is restricted but passive range of motion is normal. Some exam maneuvers of the shoulder may be impossible due to pain. Causes The causes of adhesive capsulitis are incompletely understood; however, there are several factors associated with higher risk. Risk factors for secondary adhesive capsulitis include injury or surgery leading to prolonged immobility. Risk factors for primary, or idiopathic adhesive capsulitis include many systemic diseases, such as COVID-19, diabetes mellitus, stroke, lung disease, connective tissue diseases, thyroid disease, heart disease, autoimmune disease, and Dupuytren's contracture. Both type 1 diabetes and type 2 diabetes are risk factors for the condition. Primary Primary adhesive capsulitis, also known as idiopathic adhesive capsulitis, occurs with no known trigger. It is more likely to develop in the non-dominant arm. Secondary Adhesive capsulitis is called secondary when it develops after an injury or surgery to the shoulder. Pathophysiology The underlying pathophysiology is incompletely understood, but is generally accepted to have both inflammatory and fibrotic components. The hardening of the shoulder joint capsule is central to the disease process. This is the result of scar tissue (adhesions) around the joint capsule. There also may be a reduction in synovial fluid, which normally helps the shoulder joint, a ball and socket joint, move by lubricating the gap between the humerus and the socket in the shoulder blade. In the painful stage (stage I), there is evidence of inflammatory cytokines in the joint fluid. Later stages are characterized by dense collagenous tissue in the joint capsule. Under the microscope, the appearance of the affected shoulder joint capsule tissue is similar to the appearance of the tissue that restricts finger movement in Dupuytren's contracture. Diagnosis Adhesive capsulitis can be diagnosed by history and physical exam. It is often a diagnosis of exclusion, as other causes of shoulder pain and stiffness