A distal femoral osteotomy (knock knee surgery) is a procedure whereby a surgical fracture is created at the end of the femur and the shape of the bone is changed. In general, these are performed for patients with knock knees, which we call valgus alignment, and the goal of the surgery is to realign them such that the weightbearing axis is changed to pass either through the center of the knee or just barely into the inside compartment of the knee.