[Total ankle arthroplasty in valgus ankle osteoarthritis]

Ankle osteoarthritis (OA) is often associated with deformities. Valgus OA is less frequent than varus OA and causes of valgus OA include medial ligament instability, flat foot and posttraumatic situations, e.g. fractures of the fibula or lateral tibial plafond. The importance of the mechanical axis is generally accepted in orthopedic surgery. In cases of implantation of total ankle replacements the normal biomechanics need to be restored in order to have a correct and pain-free functioning total ankle replacement both in the short and long-term. The two most important criteria are (1) an anterior tibio-talar angle of about 90° and (2) a neutral hindfoot position. The hindfoot position is measured with the hindfoot alignment view according to Saltzman. In this view, healthy feet are in neutral or minimal varus position of 1-2° and not in a valgus position as generally assumed. The following operative steps are performed depending on the degree and localization of the valgus deformity: (1) total ankle replacement, (2) supramalleolar or (3) inframalleolar osteotomy/arthrodesis, (4) medial ligament repair, (5) fibula osteotomy and (6) syndesmotic reconstruction.