Fig. (1) Antero-posterior knee radiographs illustrating severe bilateral knee osteoarthritis and windswept deformity before (1a) and 18 months after (1b) implantation of a left mechanically aligned TKA. The Femoro-Tibial Angle (FTA) was 158°, suggesting extreme valgus limb deformity (1b). A 5 mm bone loss was suspected from both the lateral femoral condyle and tibial plateau (1b). The medial compartment opening also suggested the medial collateral ligament may have been slightly stretched (1b).