Computer-assisted osteotomies for genu varum deformity: which osteotomy for which varus?

High tibial osteotomy (HTO) is commonly used for genu varum deformity in young and active patients. Corrective valgus osteotomy may however lead to an oblique joint line in cases of associated femur varum or absence of tibia vara. The over-correction, needed to obtain good long-term clinical results, may increase the obliquity even more. To avoid this drawback, the authors suggest use of an accurate and reproducible radiological protocol including at least a standing AP long-leg X-ray to measure not only the hip-knee-ankle (HKA) angle but also the medial distal femoral mechanical angle (MDFMA) and the medial proximal tibial mechanical angle (MPTMA). These measures will guide the surgeon to choose the best indication, including HTO, double level osteotomy (DLO) and distal femoral osteotomy (DFO). Computer-navigation of the osteotomies is the best choice to achieve the preoperative goal. This paper will present the pre- and perioperative protocols of HTO and DLO and the rationale behind this way of thinking.