Distal femoral medial closing wedge osteotomy is useful for mechanical axis realignment to unload the lateral compartment of the valgus knee. The primary indication for unloading the lateral compartment is lateral unicompartmental osteoarthritis. Alternative treatment options include lateral unicompartment or total knee arthroplasty (TKA). Prerequisites for the osteotomy include a 90° arc of motion, age younger than 60 years, and an active patient capable of an extensive period of rehabilitation. Surgery is carried out through a midline skin incision and uses a subvastus approach. The medial femoral closing wedge osteotomy is fixed with a 90° dynamic compression blade plate. A critical technical point is the need to insert the blade plate parallel to the joint line. The right angle plate corrects the tibialfemoral angle to 0°. A benefit of the closing wedge over an opening wedge osteotomy is reduced risk of nonunion. Survivorship and functional outcome of 41 patients with 45 distal femoral varus osteotomies at a mean follow-up of 13.3 years were retrospectively analyzed. Survivorship at 10, 15, and 20 years was 90%, 79%, and 21.5% respectively. Mean Modified Knee Society Score was 36.1 preoperatively, 74.4 at 1-year postoperatively, and 60.5 at last follow-up. Distal femoral varus osteotomy is effective at unloading the lateral compartment in unicompartmental arthritis in the valgus knee. It may be indicated in the young, high activity demand, and overweight patient. By 20 years after the osteotomy most patients require conversion to TKA.