Anterior-superior internal impingement of the shoulder: an evidence-based review

Internal impingement syndrome is a painful shoulder condition related to the impingement of the soft tissue, including the rotator cuff, joint capsule and the long head of the biceps tendon and glenoid labrum. Two types of internal impingement syndrome can be differentiated: posterior-superior impingement and anterior-superior impingement (ASI). The aetiology of ASI in particular is not clear. The purpose of this paper is to discuss the different aetiological theories relating to ASI, try to clarify the clinical, radiological and arthroscopic findings and, finally, suggesting treatment for this complex shoulder syndrome.The article is based on own research and clinical experience, as well as a non-systematic search in the PubMed database.The aetiology of ASI appears to be related to the pulley lesion and instability of the long head of the biceps tendon. It can be caused by trauma or degenerative factors, which produces anterior shoulder pain in middle-aged patients, particularly when performing overhead activities.The ASI is probably more frequent than previously reported. There is no evidence to prove the efficacy of a specific rehabilitative protocol, and the gold standard of surgical management has to be ascertained. However, in patients with a pulley lesion, there is some evidence that early surgical management, when minor soft injury lesions are present, produces better clinical outcomes.