Figure 5
Coordinate system for the direction of translation of the joint contact area centroid. (A) The anatomical coordinate systems of the humerus, (B) radius, and (C) ulna. Rotation around the X-axis, Y-axis, and Z-axis is indicated as varus (+)/valgus (ā), internal rotation (+)/external rotation (ā), and flexion (+)/extension (ā), respectively. Translation along the X-axis, Y-axis, and Z-axis is indicated as the anterior (+)/posterior (ā) direction, proximal (+)/distal (ā) direction, and lateral (+)/medial (ā) direction, respectively.
