Subacromial impingement syndrome (SAIS) is a commonly diagnosed disorder of the shoulder. Though this disorder has been known for a long time, it remains a poorly understood entity.
Since decompression with surgery does not provide any additional benefits as compared to conservative treatment for patients with SAIS, the impingement theory has become antiquated and surgical treatment should have no role in the treatment of such patients. There are calls by some practitioners to abandon the term impingement syndrome and rename it as anterolateral shoulder pain syndrome. It appears that SAIS is a medical myth. There are others who called SAIS as a clinical illusion.