In measuring Wrist Ulnar Deviation, what is the distal landmark?

• A. Third metacarpal
• B. Distal radius
• C. Proximal phalanx
• D. Lunate

Answer: (D)

Wrist ulnar deviation is measured by tracking movement at the radiocarpal joint, so you want a landmark that reflects the wrist’s rotation rather than finger or forearm motion. The lunate sits centrally in the proximal carpal row and articulates with the radius, anchoring the wrist’s axis of rotation. Using the lunate as the distal landmark gives a stable reference that isolates the wrist’s motion from finger or forearm movement, producing a more accurate measurement of ulnar deviation. The other options either move with the fingers (third metacarpal), lie in the forearm (distal radius), or are too distal in the finger (proximal phalanx) to reflect true radiocarpal motion.