Carpal instability Flashcards
gap between the scaphoid and the lunate bones, and between the lunate and triquetral bones, should normally be no more than
3 mm (can be more, especially in adolescence)
Gilula’s arc are what, why are they important
three lines across the carpal bones. No steps
Scaholunate angle?
The lunate axis is a line (L) perpendicular to a line drawn across the distal poles of the lunate. Scaphoid axis is derived by drawing a line along the volar convexitie4s of the scaphoid. Scapholunate anbgle is normally about 60 degrees .
How does the scaphoid change during ulnar and radial deviation?
In radial deviation it is flexed and so apperas end on. Ulnar deviation it is extended, therefore more appropriate to review scaphoid fractures.
What are slac, visi and disi?
SLAC 0 scapholunate advanced collapse, Visi - volar intercalated segment instability, DISI - dorsal interclaated segment instability
If there is a fracture to the waist of the scaphoid
The proximal pole is then free to rotate dorsally with the rest of the proximal row
the scapholunate ligament is disrupted then the lunate and triquetral can
can rotate independently of the scaphoid in a volar direction
dorsal intercallated segment instability (DISI).
identified on a lateral view by rotation of the lunate in a dorsal direction with an increase of the scapholunate angle.
volar intercallated segment instability (VISI).
lunate triquetral ligament is ruptured the lunate is free to rotate in a volar direction. Decrease in the scapholunate angle.
A communication between the wrist and midcarpal compartment implies a defect in either the
scapholunate or lunotriquetral ligaments.
who should get MRI for wrist instability
only if requested by the surgeons. Large number of non pathological carpa llaxicity especially in young women.
Over imaging will lead to over diagnosis where this no clinical problem .
