Scaphoid Nonunion Advanced Collapse (SNAC) - Hand

Summary
- Scaphoid Nonunion Advanced Collapse (SNAC) describes the specific pattern of progressive arthritis of the wrist that results from a chronic scaphoid nonunion.
- Diagnosis is made clinically with progressive wrist pain and wrist instability with radiographs showing scaphoid fracture nonunion with advanced arthritis of the radioscaphoid joint.
- Treatment involves observation in early stages of disease. A variety of operative procedures may be indicated depending on severity of disease and patient's symptoms.

Etiology
- Pathophysiology
  - pathoanatomy
    
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Classification

Radiographic Classification
Stage I	Arthrosis localized to the radial side of the scaphoid and radial styloid
Stage II	Scaphocapitate arthrosis in addition to Stage 1
Stage III	Periscaphoid arthrosis (proximal lunate and capitate may be maintained)

Prognosis
- Patients with scaphoid nonunions of > 5 years duration or proximal pole necrosis have less favorable outcomes
- Punctate bleeding of bone during surgery is a good prognostic indicator of union
  - 92% union with obvious bleeding, 71% with questionable bleeding, 0% with no bleeding
  - results show decreased rate of arthritis (down to 40-50%)

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