Computer investigation into the anatomical location of the axes of rotation in the normal knee

Abstract

The purpose of this paper was to investigate the anatomical location of the main axes of rotation of the knee. The study was performed as follows: joint motion registration by an electrogoniometer; joint digitization by the same electrogoniometer; computer reconstruction of motion and bone geometry; comparison of 4 hypotheses on correlation between the axis of flexion–extension and the femoral anatomy and between the axis of longitudinal rotation and the tibial anatomy in 6 human knees using an original geometrical interpolation. Our results suggest that: (a) the axis of flexion-extension lies in a cone spanned by the transepicondylar line and the so called FFc line [1]; (b) the axis of longitudinal rotation can be represented by a line parallel to the tibial anatomical axis intersecting the flexion axis in the medial compartment. Such a simplified frame for the representation of knee rotations may be useful and easily computed in computer-assisted knee reconstruction.