Image Diagnosis: Scapholunate Dissociation

Scapholunate (SL) dissociation is part of a spectrum of traumatic carpal bone instabilities and is defined as disruption of the ligamentous complex holding the scaphoid and lunate together.1 The SL ligament complex consists of the volar, dorsal, and intermediate components, with the dorsal component being the strongest and primary stabilizer of the SL joint.2 SL dissociation often results from rupture of the SL interosseous ligament following forceful wrist extension, allowing for widening of the SL joint.3 These injuries typically occur in the setting of a hyperextended wrist that is in ulnar deviation after a fall on an outstretched hand, but they have also been noted to occur in the setting of spastic paresis, rheumatoid arthritis, and congenital ligament laxity.1,