- See: Radiographic Imaging
- Discussion:
- unstable scaphoid fractures not only impact the potential for healing with non operative treatment, but they also impact on the position of
healing (and possible scaphoid non union or malunion);
- indicators of instability:
- trans-scaphoid perilunate dislocation;
- displacement: greater than 1 mm of step off;
- scapholunate dissociation:
- plastic deformation of the interosseous ligament may occur in upto 10 % of scaphoid frx;
- scapholunate angulation: greater than 60 deg of scapholunate angulation (on lateral view);
- lunocapitate angulation:
- greater than 15 deg of lunocapitate angulation as observed on CT or x-ray;
- humpback scaphoid deformity is often associated w/ DISI deformity;
- DISI deformity is produced by a significant scaphoid humpback deformity;
- distal fragment continues to follow the palmarflexion tendency (of scaphoid), while proximal fragment tends to follow the lunate into extension;
- this results in dorsal intercalated segment instability, in which lunate is dorsiflexed abnormally forany given wrist position;
- interscaphoid angulation:
- typically will have a dorsal scaphoid gap;
- w/ CT scanning: lateral interscaphoid angulation should not exceed 25 deg, and the posteranterior angulation should not exceed 35 deg;
- in the study by Amadio et al (1989), more than 45 deg of lateral intrascaphoid angulation, was
associated w/ an unsatisfactory outcome in 83% of patients