Fig. 4From: Three-dimensional preoperative planning in the weight-bearing state: validation and clinical evaluationCalculation of the mechanical axis in 3D. a The HJC is defined as the center of a sphere fitted to the femoral head. b The KJC is located in between the intercondylar eminences on the tibial plateau. c The AJC is defined as the center of all points of the distal tibial and fibular articular surfacesBack to article page