Imaging Diagnosis of SLAP Tears and Microinstability

The glenohumeral joint is the most mobile joint in the body. Static and dynamic stabilizers play a vital role in maintaining the stability of the shoulder, negotiating the fine balance between physiologic mobility and pathologic laxity. The glenoid labrum is an important static stabilizer of the glenohumeral joint, consisting of a ring of fibrous and fibrocartilaginous tissue along the glenoid rim. In this chapter, we review the imaging of common pathologies affecting the superior labrum, in particular superior labrum anterior-posterior (SLAP) tears and microinstability. Microinstability is generally understood to consist of poorly localized shoulder pain related to pathologic laxity without frank dislocation. Microinstability is discussed both in the context of the overhead-throwing athlete, with an emphasis on internal impingement and posterior capsular contracture/glenohumeral internal rotation deficit, and in those not engaged in overhead motions, with microinstability generally related to injuries of the supporting ligamentous structures of the shoulder. We review the imaging appearance of the different types of SLAP lesions and discuss how to optimize the imaging protocol for the diagnosis of SLAP lesions. Finally, we discuss how to differentiate SLAP lesions from normal variants of the superior and anterosuperior labrum.