Wrist Instability

2 carpal rows:

1. Distal

• Trapezium, trapezoid, capitate, hamate bound together by strong interosseous (intrinsic) ligaments to form distal row, which moves together as a single unit

  2. Proximal

  • Scaphoid, lunate and triquetrum form the proximal row. It has no muscle attachments and is inherently unstable in compression without its ligamentous attachments. Acts as a link between the relatively rigid distal row and the radioulnar articulations.
• Scaphoid, lunate and triquetrum form the proximal row. It has no muscle attachments and is inherently unstable in compression without its ligamentous attachments. Acts as a link between the relatively rigid distal row and the radioulnar articulations.

  Intrinsic ligaments

  • These have their origin and insertion within the same carpal row
  • Distal row
    • To bind all the distal carpal bones together
  • Proximal row
    • Scapholunate ligament
    • Lunotriquetral ligament
  • Distal row
    • To bind all the distal carpal bones together
  • Proximal row
    • Scapholunate ligament
    • Lunotriquetral ligament
  • Proximal row
    • Scapholunate ligament
    • Lunotriquetral ligament

  Extrinsic ligaments

  Volar

  • Stronger, and arranged in 2 distinct "V" shapes centred on the lunate and the capitate
  • The radioscapholunate ligament is now known to be a vascular pedicle rather than a true ligament
• Stronger, and arranged in 2 distinct "V" shapes centred on the lunate and the capitate
• The radioscapholunate ligament is now known to be a vascular pedicle rather than a true ligament