The primary indications for performing a medial closing wedge distal femoral osteotomy are valgus knee malalignment, lateral knee compartment overload, lateral meniscus insufficiency, and/or lateral compartment osteoarthritis or cartilage damage. Without correction of this malalignment, there is an increased risk for chondral damage in the lateral and patellofemoral compartment of the knee. The optimal candidates for this procedure are young, active individuals with moderate to severe arthritis in the lateral compartment. Recently, preoperative planning for high tibial and distal femoral osteotomies (HTOs and DFOs) using 3-dimensional (3D) patient-specific instrumentation (PSI) has increased in popularity. Successful patient outcomes have been reported using this technique. This Technical Note illustrates our preferred technique that uses 3D PSI in addition to a patellar OCA transplant when treating a symptomatic cartilage lesion associated with genu valgum.