The incidence of patellar dislocation is highest in physically active adolescents and reaches up to 30/100,000 per year. While the first episode of traumatic patellar dislocation might be appropriately treated conservatively, recurrent dislocations can necessitate surgical therapy to restore anatomic patellar tracking, correct limb alignment and rotation. There are over 100 operations described in the literature for the treatment of patellar instability and most present good results. The Elmslie-Trillat procedure is a procedure for correction of patello-femoral malalignment in acute and recurrent dislocations or subluxation of the patella. Originally described by Cesar Roux, the procedure was modified by Elmslie diffused in literature by Trillat. The operation involves a lateral retinacular release, medial capsular reefing, and medial displacement of the anterior tibial tuberosity hinged on a distal osteoperiosteal flap. The patients affected by recurrent patellar instability treated from June 2005 to February 2013 that underwent the Elmslie-Trillat procedure were clinically and radiografically evaluated at a minimum follow up of 25 months. Our study confirms that the Elmslie-Trillat procedure is safe and effective in the treatment of patellar instability with an high rate success.