A method for generating a reference
system for kinematic alignment is performed by acquiring a 3D model of a patient's
femur at a pre-operative stage and selecting a plurality of points on the anterior cortex (11C) of a distal end (10) of the
femur, on a distal superficial portion of each
condyle (11 A, 11 B), and on a posterior superficial portion of each
condyle (11 A, 11 B). A provisional
coronal plane (CP-CP) passing through the 3 reference points (12) and, for each
condyle (11 A, 11 B), a distal approximating surface (15) and a posterior approximating surface (16) are then generated as a function of these points. The approximating surfaces are used to generate an axial plane (A-A) perpendicular to the provisional
coronal plane (CP-CP), facing the distal superficial portions and tangent to each distal approximating surface (15) and a final
coronal plane (C-C) perpendicular to the axial plane (A-A), facing the posterior superficial portions and tangent to each posterior approximating surface (16). The reference
system is defined by the axial plane (A-A) and the final coronal plane (C-C).