Scaphoid fractures have one of the highest rates non-union of all fractures at ~10% (range 5-15%) .
Scaphoid non-union occurs most commonly through the middle or proximal thirds .
Six grades of non-union have been described by Slade and Dodds :
- grade 1: delayed presentation - 4-8 weeks
- grade 2: fibrous non-union - minimal fracture line; no cyst or sclerosis
- grade 3: minimal sclerosis - <1 mm bone resorption with minimal sclerosis
- grade 4: cyst formation and sclerosis - <5 mm bone resorption with cyst formation; normal scaphoid alignment
- grade 5: cyst formation and sclerosis - 5-10 mm bone resorption with cyst formation; normal scaphoid alignment
- grade 6: separate bone fragments with profound bone resorption; fragment motion and scaphoid deformity common
The following subtypes can also be applied:
- a: proximal pole non-union
- b: avascular necrosis (AVN)
- c: ligamentous injury
- d: deformity