Definition and Classification of Different Forms of Impingement

Abstract

Since Neer’s report of impingement syndrome, various forms of impingement have been reported in the literature. They are categorized into three groups: (1) subacromial impingement, (2) posterosuperior impingement, and (3) anterior impingement. The subacromial impingement is the classic type of impingement. The word “subacromial impingement syndrome” covers wide spectrum of rotator cuff pathologies and sometimes used synonymously with shoulder pain. Due to this vague definition, various pathologies are included under the diagnostic label of impingement syndrome. As a result, outcome of surgical treatment such as acromioplasty is controversial. We need further long-term studies to clarify the efficacy of acromioplasty, especially paying more attention to the pathology of the acromion and the rotator cuff tendon. The posterosuperior impingement is found specifically in throwing athletes. This pathology and treatment are described in detail in other chapters. The anterior impingement includes various types of impingement that occur around the anterior shoulder. The most common type is the subcoracoid impingement. However, the pathoanatomy and pathophysiology of this impingement is not clearly understood such as why an articular side tear of the subscapularis occurs as a result of subcoracoid impingement. More recently, anterosuperior impingement has been reported which seems to better explain the mechanism of articular side tear of the subscapularis. We need more evidence on this specific group of anterior impingement.