The aim of RSA is to lower the shoulder's center of rotation which increases tension in the deltoid muscle, thus increasing muscle fiber recruitment in its anterior and posterior heads, in order to compensate the deficient rotator cuff. Today, this procedure is commonly performed even if the rate of intra- or postoperative complication remains high. Inadequate deltoid tension is an accepted major risk factor for complication. Postoperatively, the mean humerus lengthening is approximately 2 mm and the arm approximately 24 mm. As for humerus and arm shortening, it is known to increase the risk of dislocation and to lead to poor anterior active elevation, respectively. The type of surgical approach does not play a role in postoperative function. Subclinical neurologic lesions are frequent, are not related to the glenosphere position in the vertical plane, with a drastically increasing prevalence above 40 mm of arm lengthening. A reasonable goal for arm length should thus be between 0 and 20 mm. Preoperative planning seems mandatory in revision cases. Finally, experience can lead to a dramatic decrease in complications over time.