Definition
Failure of a scaphoid fracture to unite by 6 months. Untreated nonunion progresses to scaphoid nonunion advanced collapse (SNAC) arthritis.
Aetiology
- Retrograde blood supply entering distally, see Blood Supply of the Wrist and Scaphoid
- Proximal pole fractures, with the highest nonunion and avascular necrosis risk
- Displacement over 1 mm, delayed diagnosis and smoking
- Missed or untreated Scaphoid Fractures
Pathology
- Humpback deformity from flexion of the distal fragment
- DISI pattern as the lunate extends with the proximal fragment
- Radiolunate joint spared by its spherical congruence
Classification
- SNAC Stage I. Arthritis between the radial styloid and distal scaphoid
- SNAC Stage II. Scaphocapitate arthritis
- SNAC Stage III. Capitolunate arthritis
- Radius and proximal scaphoid articulation spared at every stage
Clinical Features
- Snuffbox and scaphoid tubercle tenderness
- Painful, reduced wrist extension and grip
- May present years after a forgotten injury
Investigations
- Scaphoid series radiographs
- CT for union, humpback deformity and an intrascaphoid angle above 35 degrees
- MRI for proximal pole vascularity
Differential Diagnosis
- Preiser disease
- Bipartite scaphoid
- Scapholunate instability, see Carpal Instability
- Kienbock’s Disease
Management
- Bone graft and fixation. Matti-Russe inlay or Fisk-Fernandez wedge graft, see Scaphoid ± Bone Graft
- Vascularised bone graft. Proximal pole avascular necrosis, using 1,2 ICSRA or medial femoral condyle graft
- Radial styloidectomy. Added to grafting in Stage I SNAC
- Proximal row carpectomy. Stage II with preserved capitate head and lunate fossa cartilage
- Scaphoid excision and four-corner fusion. Stage II and III, see Four-corner Fusion vs Proximal Row Carpectomy
- Total wrist fusion. Pancarpal arthritis or failed salvage
Prognosis
- Few displaced nonunions are free of arthritis after 10 years
- Radioscaphoid arthritis in 75% of nonunions at 4 years
- Displacement and carpal instability predict earlier arthritis
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 19 October 2026.