SCAPHOID NONUNION ADVANCED COLLAPSE (SNAC)

Question 1

Good and poor prognostic indicators for scaphoid nonunion

Answer 1

Good = punctate bleeding during surgery
Poor
1. Scaphoid nonunion of > 5yrs duration
2. Proximal pole necrosis

Question 2

Blood supply of the scaphoid

Answer 2

Major = dorsal carpal branch of radial artery
- enters dorsal surface of scaphoid via nonarticular ridge
- supplies proximal 80% of scaphoid via retrograde flow
Minor = superficial palmar branch of radial artery
- enters scaphoid tubercle
- supplies distal 20% of scaphoid

Question 3

Classification of SNAC wrist

Answer 3

Modified Watson classification = radiographic classification with 4 stages
Stage I = radial styloid arthritis
- initially between radial styloid and distal fragment
- radial styloid beaking on x-ray
Stage II = radioscaphoid arthritis
Stage III = capitolunate arthritis
- also scaphocapitate per Orthobullets
Stage IV = pancarpal including radiolunate arthritis
- periscaphoid arthritis per Orthobullets
- controversial stage = if radiolunate, suspect other cause

Question 4

Surgical options for SNAC wrist based on stage

Answer 4

Stage I = radial styloidectomy and scaphoid ORIF with bone graft
Stage II = PRC/ scaphoid excision + 4CF
Stage III = scaphoid excision + 4CF/ wrist fusion (not PRC)
Stage IV = wrist fusion