Which carpal bone articulation forms an uppercase T on the DLPMO oblique radiograph when evaluating the dorsomedial aspect of the carpus?

Which carpal bone articulation forms an uppercase T on the DLPMO oblique radiograph when evaluating the dorsomedial aspect of the carpus?

• A. First carpal bone with radius
• B. Third carpal bone articulation
• C. Fourth carpal bone with cannon bone and lateral splint bone
• D. Second carpal bone articulation

Answer: (C)

On the DLPMO oblique view, you’re looking for a distal carpal bone that interacts with both the cannon bone (metacarpal III) and a lateral splint bone to create a recognizable T silhouette on the dorsomedial aspect. The fourth distal carpal bone does exactly this: it articulates with the cannon bone on one side and with the lateral splint bone on the other. When viewed obliquely from the dorsomedial aspect, these two articulations line up to form the vertical stem (the cannon bone) with a horizontal crossbar, producing an uppercase T on the radiograph. The other articulations involve different carpal bones or different interfaces and do not produce that T pattern on this projection, so they’re not responsible for the shape seen here.

On the DLPMO oblique view, you’re looking for a distal carpal bone that interacts with both the cannon bone (metacarpal III) and a lateral splint bone to create a recognizable T silhouette on the dorsomedial aspect. The fourth distal carpal bone does exactly this: it articulates with the cannon bone on one side and with the lateral splint bone on the other. When viewed obliquely from the dorsomedial aspect, these two articulations line up to form the vertical stem (the cannon bone) with a horizontal crossbar, producing an uppercase T on the radiograph.

The other articulations involve different carpal bones or different interfaces and do not produce that T pattern on this projection, so they’re not responsible for the shape seen here.