This trial will compare the effectiveness of electrothermal arthroscopic capsulorrhaphy (ETAC) to the current reference standard procedure, open inferior capsular shift (ICS), for the treatment of shoulder instability caused by ligamentous capsular redundancy. Multi-directional instability (MDI) and multi-directional laxity with anteroinferior instability (MDL-AII) are the two types of shoulder instabilities included in this trial.