How does a shoulder become unstable when a shoulder joint is dislocated by external force a traumatic dislocation the structures that normally provide stability stretch tear or detach from the glenoid or the humeral head or both box 1 these structures either heal in a non anatomical position or fail to heal. The unstable shoulder amazonde warren russell f craig edward v altchek david w fremdsprachige bucher wahlen sie ihre cookie einstellungen wir verwenden cookies und ahnliche tools um ihr einkaufserlebnis zu verbessern um unsere dienste anzubieten um zu verstehen wie die kunden unsere dienste nutzen damit wir verbesserungen vornehmen konnen und um werbung anzuzeigen. An unstable shoulder can present either from a traumatic event or atraumatic atraumatic instability is due to repetitive joint stresses over time particularly with throwing sports or those with overhead activities such as water polo cricket or swimming the majority of shoulder instabilities are secondary to an acute traumatic incident in which excessive stress to the shoulder joint . This is the second lesson in the unstable shoulder module traumatic and atraumatic instability differ in the structural and neuromuscular mechanisms an accurate diagnosis is required to ensure appropriate treatment is provided in this lesson we cover pathological basis for clinical presentations of shoulder instability