 Impingement of the shoulder was previously thought to be precipitated by shoulder abduction and surgical intervention focused on lateral or total acromionectomy.In 1972, Charles Neer proposed that impingement was due to the anterior third of the acromion and the coracoacromial ligament and suggested surgery should be focused on these areas.The role of anteriorinferior aspect of the acromion in impingement syndrome and excision of parts of the anteriorinferior acromion has become a pivotal part of the surgical treatment of the syndrome.