[Subacromial impingement syndrome: pathogenesis, clinical features, and examination methods].

Although subacromial impingement syndrome is the most common cause of shoulder pain with a specific diagnosis, it is not the only cause of pain in the anterosuperior aspect of the shoulder. Appreciation of the pathophysiology plays a key role in the diagnosis and management of this syndrome. The purpose of this paper is to review some essential aspects of pathogenesis, physical examination, and diagnosis in the light of the current literature.