Several functional outcome scores have been proposed for the evaluation of shoulder instability. Most of these are multiple-item questionnaires which can be time consuming and difficult for patients to understand and well as lead to lack of compliance. The Single Assessment Numeric Evaluation (SANE) score is a single question which has recently gained widespread based on its simplicity and correlation with more complex scoring systems. The purpose of this study was to assess the correlation of a new modified version of the SANE score, the SANE-instability score, with the Rowe score post-treatment for shoulder instability.