| Wrist Planes of Motion |
- Joints involves
- Normal and function motion
- flexion (65 normal, 10 functional)
- 60% radiocarpal, 40% midcarpal
- extension (55 normal, 35 functional)
- 66% radiocarpal, 33% midcarpal
- radial deviation (15 normal, 10 functional)
- ulnar deviation (35 normal, 15 functional)
- 50% radiocarpal, 50% midcarpal
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| Wrist Biomechanics |
- Three biomechanic concepts have been proposed:
- Link concept
- three links: 1) radius 2) lunate 3) capitate
- links
- head of capitate acts as center of rotation
- proximal row (lunate) acts as a unit and is an intercalated segment with no direct tendon attachments
- distal row functions as unit
- function
- allows efficient motion with compromise of stability
- strong volar ligament and the scaphoid which crosses links compromise in instability
- resting forces/radial deviation push scaphoid into flexion (triquetrum into extension)
- ulnar deviation push scaphoid into extension
- Column concept
- lateral column
- scaphoid is center of motion and function is mobile
- central column
- luno-capitate articulation is center of motion and motion is flexion/extension
- medial column
- triquetrum and distal carpal row and motion is rotation
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| Volar Ligaments |
 Radioscaphoid
- functions primarily as a neurovascular conduit.
- Radioscaphocapitate
- at risk for injury with excessively large radial styloid
- Radioscapholunate
- Radiolunate (short and long)
|
| Dorsal ligaments |
 Radiotriquetral
- must also be disrupted for VISI deformity to form (in combination with rupture of lunotriquetral interosseous ligament rupture)
- Radiolunate
- Radioscaphoid
- Dorsal intercarpal
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| Interosseous ligaments |
- Proximal row
- lunotriquetral interosseous ligament
- must also be disrupted for VISI deformity to form (in combination with rupture of dorsal radiotriquetral rupture)
- scapholunate interosseous ligament
- Distal row
- trapeziotrapezoid interosseous ligament
- trapeziocapitate interosseous ligament
- capitohamate interosseous ligament
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| Midcarpal ligaments |
- Palmar midcarpal
- scaphotrapezial trapezoid
- scaphocapitate
- triquetralcapitate
- triquetralhamate
|
| Ulnocarpal ligaments |
- Ulnocapitate
- Ulnolunate
- Ulnotriquetral
|