Symptomatic internal impingement of the shoulder in overhead athletes.

The term "internal impingement" describes the normal physiological contact that occurs between the posterosuperior glenoid and the greater tuberosity in positions of hyperabduction and external rotation. This physiological contact can become symptomatic when repeated overhead motion results in partial articular-sided posterosuperior rotator cuff tears and lesions of the posterosuperior glenoid labrum. The precise pathophysiology involved with the development of symptomatic internal impingement has been debated extensively over the past few decades. However, current literature suggests that symptomatic internal impingement may result from a combination of multiple factors involving repetitive overhead activity, physiological remodeling of the throwing shoulder, posterior capsule contracture, and scapular dyskinesis, among other factors. These can all lead to scapulohumeral hyperangulation and associated pathologic findings. The purpose of this article is to review the relevant anatomy, pathophysiology, diagnosis, and management of symptomatic internal impingement through a critical review of current evidence.