Introduction

‘This is an AP/lateral/oblique radiograph of the right/left wrist, or scaphoid series.’

Views

1. • AP and lateral.

Anatomy

Bones

1. • Distal radius and ulna.

2. • Carpal bones: scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, hamate.

3. • If the lunate is anteriorly displaced this is termed a lunate dislocation.

4. • If the lunate (which is moon-shaped – with the concave side holding the rest of the carpus) – or cup of the lunate are empty then this is termed a perilunate dislocation – the capitate is displaced dorsally.

5. • Space > 2 mm between scaphoid and lunate is abnormal (scapholunate dissociation) (Terry Thomas sign).

Lines

1. • Normal radius has palmar/volar tilt (2–20°). If lost, suspect a fracture of the radius.

2. • Radial wrist normally more distal than ulna. If lost, this may suggest that the radius has impacted and is shortened.

3. • Dorsal angulation fracture of radius = Colles’ fracture.

4. • Volar angulation fracture of radius = Smith's fracture.

5. • If there is an intra-articular fracture involving either the posterior cortex or more commonly the anterior cortex of the radius, the vertical fracture pattern causes subluxation of the carpal bones= Barton's fracture (unstable).

Pathology

Radius fractures

1. • Fractures involving the growth plate. Salter–Harris classification:

2. I S – Straight through

3. II A – Above/metaphyseal

4. III L – Lower/epiphyseal

5. IV T – Through both metaphyisis and epiphysis

6. V S – Squashed

7. • Colles’ and Smith's fractures: distal radial fracture with no joint involved.

8. • Barton-type fracture: distal radial fracture that is longitudinal and involves the joint space; it can have a volar or dorsal angulation and is associated with carpal displacement (unlike Colles’ or Smith's).

Scaphoid

1. • Tenderness in anatomical snuffbox: ask for four-view scaphoid series.

2. • Normal radiographs but clinical suspicion: treat as fracture and repeat radiographs in 10–14 days.

3. • 80% waist: most common fracture (avascular necrosis likely).

4. • 10% proximal pole (avascular necrosis very likely).

5. • 10% distal pole (avascular necrosis unlikely).

6. • Scaphoid fractures may be associated with perilunate dislocation.