For MCP Abduction (2-5 digits), which landmark is used as the distal landmark?

• A. Dorsal midline metacarpal
• B. Proximal phalanx dorsal plane
• C. Dorsal midline proximal phalanx
• D. Dorsal midline distal phalanx

Answer: (C)

When measuring MCP abduction of digits 2–5, the moving segment is the proximal phalanx, while the fixed reference is the metacarpal. The distal landmark used for the goniometer’s moving arm should be on the dorsal midline of the proximal phalanx. This places the distal landmark on the segment that actually moves relative to the metacarpal across the MCP joint during abduction, giving a true measure of the joint’s angle.

If you used the metacarpal’s dorsal midline as the distal landmark, you’d be placing the moving arm on the wrong segment. If you referenced the distal phalanx, you’d be measuring a different joint entirely or introducing unnecessary variation. The dorsal midline of the proximal phalanx is the correct distal reference because it aligns with the moving segment across the MCP joint during abduction.