NHx
Convincing association with development of osteoarthritis
- arthritic changes beginning at radial styloid
- progress to scaphocapitate & capitolunate
End point representing scaphoid nonunion advanced collapse wrist (SNAC)
Issues
AVN
Humpback deformity (must correct to improve kinematics)
SNAC (contraindication to surgery to achieve union)
Xray
Sclerotic margins / no sign of healing
Humpback deformity
Look for signs of AVN
MRI
Advantage
- exclude AVN
- AVN has low signal on T1 and T2
- if AVN use vascularised bone graft
CT
Identify humpback deformity / plan size and shape of bone graft
Options
1. Russe-type inlay corticocancellous bone graft
- volar approach
- 2 corticocancellous struts
- cancellous surfaces facing each other
- placed longitudinally inside scaphoid
- 85% to 95% union
2. Fisk wedge graft
- trapezoidal / triangular iliac crest graft
- designed to restore the scaphoid alignment
- correct humpback deformity
- union rates of 95 - 100% with fixation
Waist Non union
Technique
Volar approach
- clean fracture site of fibrous tissue
- osteotomes to reduce deformity
- do not disrupt dorsal cortex
- burrs if needed to remove fibrotic tissue
Assess for AVN
- look for evidence of punctate bleeding from distal fragment
Place bone graft
- reduce deformity if necessary
- fix with K wire
- place cannulated screw
Results
90% union
- some loss of ROM and strength
Proximal pole non union
Dorsal approach
Lower union rates
- 67%
- ? role for vacularised bone graft