Effect of flexion and rotation on measures of coronal alignment after TKA.

Attainment of a neutral mechanical axis is one of the primary goals in total knee arthroplasty (TKA). The accuracy of the procedure is evaluated by measuring the hip-knee-ankle angle (HKAA) on long leg radiographs. Rotation of the lower limb and knee flexion could possibly affect the HKAA measured on plain radiographs.