Wrist and hand X-rays: distal radius and scaphoid

What it is

After a fall on the outstretched hand the wrist X-ray (posteroanterior and lateral, with dedicated scaphoid views when the scaphoid is tender) answers two questions. First, is the distal radius broken, and how is the distal fragment displaced? The Colles fracture is an extra-articular distal radius fracture with dorsal tilt and displacement (the «dinner fork» deformity), typical of older adults with osteoporosis; the Smith fracture is the reverse, with volar displacement; the Barton fracture is an intra-articular fracture of the dorsal or volar rim with the carpus moving with it. Second, is the scaphoid broken? Scaphoid fractures, most often at the waist, can be invisible on the first X-rays. Because the blood supply enters distally and runs backward, a missed fracture can lead to non-union and avascular necrosis of the proximal pole. The lateral view also checks the alignment of the radius, lunate and capitate to catch carpal dislocations.

What to check

• Normal PA: the distal radius slopes toward the ulna (radial inclination about 20–25°) and stands above the ulna; the carpal bones form three smooth arcs (Gilula lines).
• Normal lateral: the distal radial joint surface tilts volarly (about 10°); the radius, the lunate «cup» and the capitate line up.
• Colles: distal radius, extra-articular, distal fragment tilted and shifted dorsally; often with an ulnar styloid fracture.
• Smith: distal fragment tilted volarly. Barton: intra-articular rim fracture with the carpus subluxed with the fragment.
• Scaphoid: look for a thin lucent line across the waist on the scaphoid (ulnar-deviated PA) view; the scaphoid fat stripe may be blurred.
• Boxer's fracture: neck of the fifth metacarpal with the head angled toward the palm.

Reading it step by step (and why)

1. Confirm a true PA and a true lateral (radius and ulna superimposed) — a rotated lateral hides tilt and dislocation.
2. Trace the cortex of the distal radius and ulna on both views — buckles and thin lines hide at the metaphysis.
3. On the PA, check radial inclination and length against the ulna — loss of height means impaction or shortening.
4. On the lateral, check the tilt of the radial joint surface — dorsal tilt is Colles-type, volar tilt Smith-type.
5. Look for a step in the joint surface — an intra-articular step changes treatment and often needs CT.
6. Follow the three carpal arcs on the PA — a broken arc suggests a carpal fracture or dislocation.
7. On the lateral, line up radius, lunate and capitate — a tipped lunate («spilled teacup») is a lunate dislocation.
8. Examine the scaphoid on its own view, waist and poles — the most often missed wrist fracture.
9. Scan the metacarpals and phalanges at the film edges — a second fracture is easy to miss.

Common mistakes

• Sending home a tender anatomical snuffbox because the X-ray was «normal»: an occult scaphoid fracture can follow.
• Accepting a rotated lateral view, which can hide dorsal tilt and perilunate dislocation.
• Missing the distal radioulnar joint and ulnar styloid when the radius fracture draws all the attention.
• Calling a child's buckle fracture normal because no line crosses the bone.
• Forgetting median nerve symptoms after a displaced distal radius fracture.

Next step

• Snuffbox or scaphoid tenderness with normal X-rays: thumb spica immobilization and repeat X-ray in about 10–14 days, or early MRI (most sensitive) or CT if available.
• Displaced, angulated or intra-articular distal radius fracture: reduction and orthopaedic referral; repeat two views after reduction.
• Joint-surface step or comminution: CT to plan fixation.
• Lunate or perilunate dislocation, or numbness in the median nerve territory: urgent orthopaedic call.
• Low-energy distal radius fracture in an older adult: think of osteoporosis assessment.

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Elsewhere in DurgiPedia

• Joint examination: inspection, palpation and range of motion
• Hand deformities: Heberden, Bouchard, swan neck, boutonnière

Connections

← All of radiology

Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.

Sources: Distal Radius Fractures (StatPearls (NCBI Bookshelf), 2023); Scaphoid Wrist Fracture (StatPearls (NCBI Bookshelf), 2023).

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