Fig. 2.

a US is measured with the perpendicular line drawn from the distal end of the ulna to the linear axis of the forearm; b RAA is the angle between a line drawn along the articular surface of the radius and the other perpendicular to a line that bisects the head of the radius and passes through the radial edge of the distal radial epiphysis; c CS is measured as the percentage of contact of the lunate with the radius. This percentage is determined by drawing an axial line from the center of the olecranon through the ulnar edge of the radius