Distal radius fractures: which combination of imaging and radiographic finding best indicates intra-articular involvement?

• A. CT scan is the first-line imaging for this injury.
• B. Plain X-rays (AP, lateral, and oblique as needed); articular step-off or joint surface incongruity indicates intra-articular involvement.
• C. MRI as initial imaging.
• D. Ultrasound as initial imaging.

Answer: (B)

Disruption of the joint surface is what defines intra-articular involvement. On the initial plain radiographs of the distal radius—taken in the standard views—look for a step-off of the articular surface or a mismatch (incongruity) of the joint surface. Seeing this joint surface disruption on X-rays directly indicates that the fracture extends into the joint.

While CT can give a more detailed map of the fracture for surgical planning, the best indicator of intra-articular involvement on the first imaging is articular step-off on plain X-rays. MRI and ultrasound aren’t the typical initial methods for this purpose; they may provide other information but aren’t as practical or definitive for identifying intra-articular involvement in the acute setting.