An increased posterior tibial slope has been identified as an independent risk factor for anterior cruciate ligament (ACL) graft rupture, with a critical threshold of 12°. Surgical slope correction by anterior closing wedge (ACW)-high tibial osteotomy (HTO) can reduce ACL force and anterior tibial translation with good clinical outcomes when combined with revision ACL reconstruction. Performing ACW-HTO preserving the tibial tubercule can be challenging for inexperienced surgeons. Patient-specific cutting guides have been shown to be effective in facilitating the surgeon's learning curve in medial opening wedge-HTO by reducing operative time and the use of fluoroscopy as well as decreasing anxiety. The present technique describes a retro-tibial tubercule ACW-HTO using a patient-specific cutting guide.