Hand & Wrist COPY COPY COPY Flashcards
(48 cards)
What is a radiocarpal dislocation? How does it differ from perilunate dislocations?
Dislocation of the radius from the carpal bones. Differs from perilunate dislocation because the carpal bones are still aligned
Which direction do radiocarpal dislocations commonly occur?
Dorsal > volar dislocation (of the carpus on the radius)
What is the primary soft-tissue restraint against volar translation of the carpus?
Short radiolunate ligaments
What are the origin and insertions of the short radiolunate ligaments?
O: Radius on the ulnar, volar margin of the lunate facet
I: volar surface of the lunate
What is the main restraint of ulnar translation of the carpus?
Radioscaphocapitate ligament
What is the classification system of radiocarpal dislocation?
Dumontier:
Group 1: radiocarpal fracture-dislocation that is purely ligamentous or involves only a small cortical avulsino fracture off the radius
Group 2: radiocarpal fracture-dislocation associated with a large radiostyloid fracture fragment (involving at least 1/3 of the scaphoid fossa)
Are group 1 or group 2 radiocarpal dislocations harder to treat? Why?
Group 1 are harder to treat
- These represent global ligamentous disruptions resulting in multidirectional instability
- Unlike group 2’s, they DO NOT have any bony fragments attached to ligaments that will be more easily fixed with surgery
What are the commonly avulsed fracture fragments in radiocarpal dislocation?
- Radial styloid avulsion by the radioscaphocapitate ligament
- Volar lunate facet by the short radiolunate ligament
- Ulnar styloid
What are the 3 main groups of wrist ligaments?
Palmar radiocarpal ligaments
Ulnar carpal ligaments
Dorsal ligaments
What comprises the palmar radiocarpal ligaments?
Radioscaphocapitate ligament
Long radiolunate ligament
Short radiolunate ligament
Radioscapholunate ligament
What comprises the dorsal ligaments of the wrist?
Dorsal radiocarpal ligament
Dorsal intercarpal ligament
What comprises the ulnar carpal ligaments of the wrist?
Ulnolunate ligamnet
Ulnotriquetral ligament
Ulnocapitate ligament
Describe dorsal versus volar perilunate dislocations:
Dorsal: dorsal dislocation of the capitate with respect to the lunate while the lunate stays in good position
Volar: This is the final stage of injury. The capitate has reduced and the lunate is dislocated volarly
What is the classification of perilunate dislocations?
Mayfield Classification Stage 1: Scapholunate dissociation Stage 2: + Lunocapitate dissociation Stage 3: + Lunotriquetral dissociation Stage 4: Lunate dislocation
What are the common directions of perilunate dislocations?
Volar > dorsal
What is the pathomechanical force of perilunate dislocation?
Wrist extension, ulnar deviation and intercarpal supination
Which way does a perilunate injury propogate?
Ulnarly, with the initial injury coming at the scapholunate interval
- Scapholunate interval -> Space of Poirier/capitolunate articularion -> lunotriquetral articularion -> failure of dorsal radiocarpal ligament
In the final stage of lunate dislocation, where does the lunate dislocate into?
Carpal tunnel
What are greater and lesser arc perilunate injuries?
Greater arc: Injuries that involve bone
Lesser arc: Injuries that are purely ligamentous
What is a translunate arc injury?
Rare injury involving a perilunate dislocation with a fracture of the lunate itself
What are the arcs of Gilula?
Refers to the curves produced by the anatomic alignment of the carpal row bones
Are the volar or dorsal radiocarpal ligament stronger?
Volar
This is why most radiocarpal dislocations occur dorsally
What does VISI stand for?
Volar intercalated segmental instability
What is the pathomechanism of VISI?
Disruption of the triquetrum, due to distuption in lunotriquetral ligament complex
Leads to hyperflexion of the radio-luno-capitate alignment, where the lunate and capitate have excessive flexion
