54 patients, with multidirectional instability or multidirectional laxity, were randomly assigned to either one of the two groups; electrothermal arthroscopic capsulorrhaphy (ETAC) or open inferior capsular shift (ICS). This study aimed to determine the difference in clinical outcomes in patients with shoulder instability due to ligamentous or capsular redundancy who received either an open ICS or an ETAC treatment. At 2 years postoperatively, there were no significant differences in Western Ontario Shoulder Instability Index, American Shoulder and Elbow Surgeons score, Constant score ot complications between the two groups. Nevertheless, the target sample size was not achieved due to slow recruitment, and therefore comparisons may have been underpowered to reveal differences between groups.