Position of probe: Place the probe in short axis orientation on the dorsal aspect of the proximal wrist. The ulnar side of the probe should lay on the dorsal ulnar head. The radial side of the probe should lay on the distal dorsal radius. The probe should span the radioulnar joint. The convex surface of the ulnar dome should be visible on the left side of the screen. Lister’s tubercle may be visible on the right side of the screen. The radioulnar articulation should be visible near the center of the screen, slightly to the left side. Ideally, a thin layer of gel should be seen between the probe and skin surface (to confirm that no pressure is being applied to the joint).