Three years ago was created the Upper Limb Committee of ESSKA. The goal of this committee is to promote the knowledge of Upper Limb Surgery. Among the activities carried out are Arthroscopic Shoulder Courses, Multicentric studies, meeting sessions. This book is the first publication released by our committee. We focused our attention on the "state of the art" of gleno-humeral instability. The understanding of pathomechanic, clinical evaluation and the different treatment options are changing rapidly, therefore we were happy to present the most updated concept regarding this topic. We intend this book as the first step for future European collective publications, in order to help the surgeons in their clinical practice. We would like to thank the ESSKA Board who gave us the opportunity to publish this book and all the contributors for their precious help and the time dedicated to this project. We are also thankful to Smith & Nephew that supported this publication. ttore Taverna, Pascal Gleyze and Pietro Randelli