Fig. 9a. SLAC / SNAC wrist. Both scaphoid fractures and scapholunate ligament tears allow independent motion of two mechanical sections which are ordinarily linked. If not corrected, this changes joint tracking, introduces incongruity and in time results in degenerative changes at the radioscaphoid, capitolunate and then remaining joints, referred to either as ScaphoLunate Advanced Collapse (SLAC wrist) or Scaphoid Nonunion Advanced Collapse (SNAC wrist).