"The patient is approached by the examiner as if to engage in arm wrestling, face to face across a table with diagonally opposed hands raised (right to right or left to left) and elbows resting on the surface in between. With the patient's forearm slightly pronated, the examiner grasps the wrist from the radial side, placing his thumb on the scaphoid tuberosity (as if pushing a button to open a car door) and wrapping his fingers around the distal radius. The examiner's other hand grasps at the metacarpal level, controlling the wrist position. Starting in ulnar deviation and slight extension, the wrist is moved radially and slightly flexed with constant thumb pressure on the scaphoid. This radial deviation causes the scaphoid to flex. The examiners thumb pressure opposes this normal rotation, causing the scaphoid to shift in relation to the other bones of the carpus. This scaphoid shift may be subtle or dramatic. A truly positive test requires both pain on the back of the wrist (not just where you are pressing on the scaphoid tuberosity), and comparison with the opposite wrist is essential."