Fig. 1From: Prevalence of extra-articular tibia valga morphology in valgus knees and its implications for primary total knee arthroplastyHip–knee–ankle (HKA) angle. A pre-operative weightbearing lower-limb anteroposterior EOS digital radiograph is shown. The HKA is the angle between the femoral and tibial mechanical axes. Varus, negative; valgus, positiveBack to article page