Among the many different procedures available in the treatment of shoulder instability, the Trillat procedure remains indicated in case of recurrent shoulder instability in elderly patient with an irreparable cuff tear or in case of hyperlaxity. Despite the constantly increasing number of arthroscopic assisted techniques, the open procedure remains a simple, reliable and fast surgical procedure with a shorter learning curve than the arthroscopic techniques. It consists in a partial osteotomy of the anterior cortical of the coracoid process which is then tilted and fixed with a screw into the anterior part of the scapula downwards and medially to obtain a re-centering effect due to the conjoint tendon on the humeral head when rotational movement are applied. This article aims to present a stepwise approach for the open surgical technique.