Scapho Lunate Advanced Collapse ( SLAC) is the end result of an unstable scapholunate joint where there is significant degenerative change in the radiocarpal and mid carpal joints.

Scapho Lunate Advanced Collapse ( SNAC) is the term given for a SLAC type appearance to the wrist secondary to non union of a scaphoid fracture.

Both chronic non union (particularly of the proximal pole) and SLL tear can result in instability at the scapho-lunate joint the end result is a SLAC type wrist .

Here is the MRI appearance of SLAC and SNAC. If you haven’t reviewed the past two posts on SLL tears and DISI please see those first.

Image Above: Scapho lunate disassociation ( red arrow) with secondary advanced degenerative changes at radio scaphoid ( blue arrow) and in mid carpal row ( capito lunate yellow arrow).

 

Image Above: Scapho lunate non union  ( blue arrow) with secondary degenerative changes at radio scaphoid ( red arrow) and scapho lunate joint ( yellow arrow).