Frontal plane varus or valgus deformity causes overload in the ipsilateral compartment and may induce and accelerate cartilage damage. Osteotomy around the knee should be considered in symptomatic constitutional and posttraumatic metaphyseal deformities of more than 3-degree deviation. Age, grade of osteoarthritis, obesity, and nicotine consumption are no exclusion criteria for osteotomy. For correction of varus deformity, biplanar open wedge osteotomy of the tibia with fixation by a plate fixator has proven to be a safe and stable construct allowing for early weight-bearing. Valgus deformities of the tibia can be treated by biplanar closed wedge osteotomy of the proximal tibia. For femur deformities closed wedge biplanar osteotomy and fixation with a specific plate fixator is an attractive solution reducing implant-related morbidity. Osteotomy around the knee may also be used to protect cartilage reconstruction and meniscus transplantation. Corrections in the sagittal plane may improve the anteroposterior stability of the knee significantly and can be combined with frontal plane corrections.