Review Question - QID 217353

This patient has stage II scaphoid nonunion advanced collapse (SNAC) wrist. Distal scaphoid excision is contraindicated in stage II and III SNAC wrist (Answer 2)

SNAC describes the predictable pattern of progressive arthritis of the wrist which occurs secondary to chronic scaphoid nonunion. Degenerative changes progress from the radioscaphoid articulation through to pancarpal/midcarpal involvement. Owing to a tenuous, retrograde blood supply, the scaphoid is at particular risk for avascular insult with subsequent avascular necrosis and collapse. SNAC wrist is classified radiographically, with treatment dependent on radiographic stage. Stage I is localized radioscaphoid arthrosis (Illustration A), Stage II is scaphocapitate arthrosis in addition to Stage I changes (Illustration B), and Stage III (Illustration C) represents periscaphoid arthrosis with possible sparing of the proximal lunate and capitate.

Malerich et al. reported on 19 patients with SNAC wrist secondary to scaphoid nonunion who underwent distal scaphoid excision. They note that overall both range-of-motion and grip strength improved, and 13 patients experienced complete pain relief. They do caution, however, that distal pole excision should be avoided in patients with capitolunate arthritis: 2/4 (50%) of patients with capitolunate arthritis had persistent symptoms and three had radiographic progression of their arthritis.

Shah and Stern provide a comprehensive review on the treatment of SNAC and scapholunate advanced collapse (SLAC) wrist. They state that if the capitolunate joint is well-preserved, distal scaphoid excision is an attractive surgical option that can preserve range of motion while providing marked pain relief, while still allowing for future salvage procedures to be performed, if needed. They do note, however, that capitolunate arthritis serves as a contraindication to distal scaphoid excision.

Dunn and coauthors report on capitolunate arthrodesis (CLA) for stage II and III SNAC wrist. They report that CLA can provide improvements in pain and restoration of grip strength which surpass that provided by four-corner fusion while maintaining a comparable complication rate. The authors conclude that CLA is an attractive surgical option for patients with type II or III SLAC wrist in whom preservation of motion is of paramount concern.

Figure A demonstrates a scaphoid fracture, while Figure B demonstrates Stage II SNAC wrist with radioscaphoid and scaphocapitate arthrosis with preservation of the capitate head. Illustration A demonstrates a graphical representation of Stage I SNAC wrist, with radioscaphoid arthrosis. Illustration B demonstrates Stage II SNAC wrist, with scaaphocapitate involvement in addition to Stage I changes. Illustration C demonstrates periscaphoid arthrosis consistent with Stage III SNAC wrist.

Incorrect Answers:
Answers 1,2,4,5: all of these are possible appropriate treatment options for Stage II SNAC wrist.