Wrist
Page Index: Tips | Anatomy |Gilula carpal arcs | Scapholunate interval (SLAC)| Distal radius Fractures |
Tips:
Assess Gilula carpal arcs
Assess Scapholunate interval
Normal: Frontal
1. metacarpal bone 2. carpometacarpal joint 3. trapezoid 4. trapezium 5. scapho-trapezio-trapezoid (STT) joint 6. scaphoid 7. styloid process of radius 8. radiocarpal joint 9. lunate 10. radius 11. ulna 12. distal radioulnar joint 13. styloid process of ulna 14. triquetrum 15. pisiform 16. capitate 17. hamate
Normal: Lateral
1. metacarpal bone 2. carpometacarpal joint 3. trapezoid 4. trapezium 5. scapho-trapezio-trapezoid (STT) joint 6. scaphoid 7. styloid process of radius 8. radiocarpal joint 9. lunate 10. radius 11. ulna 12. distal radioulnar joint 13. styloid process of ulna 14. triquetrum 15. pisiform 16. capitate 17. hamate
Normal: Oblique
Gilula carpal arcs
Gilula three carpal arcs are used in the assessment of normal alignment of the carpus on PA wrist radiographs. They entail:
first arc: is a smooth curve outlining the proximal convexities of the scaphoid, lunate and triquetrum
second arc: traces the distal concave surfaces of the same bones
third arc: follows the main proximal curvatures of the capitate and hamate
Scapholunate interval
The scapholunate interval or gap is the radiographic measurement of the scapholunate joint and widening is indicative of a scapholunate ligament injury.
In adults, the normal value is usually taken as <2 mm, with an interval of >3 mm (see: Terry Thomas sign) generally considered diagnostic of scapholunate dissociation.
Scapholunate interval should be measured at the midpoint of the adjacent parallel articular contours of the two bones (the scapholunate interval normally narrows proximal to distal)
Distal Radius Fractures
Lunate dislocation
Lunate dislocation
Lunate dislocation: the normal alignment of the distal radius, carpus and metacarpals should remain normal with the exception of the lunate which will be displaced and rotated volarly.
Perilunate dislocation
Perilunate dislocation
Capitate (C, blue) is dislocated dorsal to the lunate (L, yellow). The proximal pole of the scaphoid (PP) has remained aligned with the lunate, whereas the distal pole (DP) has followed the capitate dorsally. The lunate and the distal radius (green) remain normally aligned.
Wrist radiograph (an approach)
Wrist X-ray
Mikael Häggström, CC0, via Wikimedia Commons