The aetiology of subacromial impingement syndrome

Subacromial impingement syndrome has been described as the most common form of shoulder pathology (Jobe and Jobe, 1983; Kessel and Watson, 1977). Neer (1972, 1983) argued that 100% of impingement lesions and 95% of rotator cuff pathology are caused by friction between the acromion and surrounding tissues within the subacromial space. This concept has been challenged and the literature suggests that the aetiology of subacromial impingement is multifactorial. These causes include anatomical and mechanical factors, rotator cuff pathology, glenohumeral instability, restrictive processes of the glenohumeral joint, imbalance of the muscles controlling the scapula, and postural considerations. The purpose of this paper is to explore the potential factors contributing to pathology.