Posterior Shoulder Instability

Posterior shoulder instability (PSI) has become an increasingly common condition, occurring in around 20% of surgically treated shoulder instability cases and most commonly in young, male athletes participating in contact or overhead sports. Patients commonly present with multiple nonspecific symptomologies and frequently do not describe specific instability, making it difficult for clinicians to make an accurate differential diagnosis. Nonoperative management is successful in some cases. However, advancements in arthroscopic and open surgical techniques have provided good outcomes in patients who fail conservative treatment when indicated. A comprehensive understanding of the pathophysiology, the relevant clinical and diagnostic modalities, and the concomitant conditions associated with PSI is vital to provide optimal results to patients. This chapter will aim to provide current concepts on the diagnosis and management of PSI, reviewing surgical indications as well as describing modern techniques and associated complications.