Carpal instability is a complex array of maladaptive and posttraumatic conditions that lead to the inability of the wrist to maintain anatomic relationships under normal loads. Many different classification schemes have evolved to explain the mechanistic evolution and pathophysiology of carpal instability, including 2 of the most common malalignment patterns: volar intercalated segment instability and the more common dorsal intercalated segment instability. Recent classifications emphasize the relationships within and between the rows of carpal bones. Future research is likely to unify the disparate paradigms used to describe wrist instability.

Definition: abnormal alignment, during motion under normal/ physiologic loads

Causes: trauma (acute/ cumulative); others

PPI:

• SLD vs scaphoid fracture (radial deviation) ← wrist extension
• Herzberg: Stage I vs II (Mayfield 4)
• Greater vs lesser arc injuries

VISI vs DISI

CID, CIND, CIC, CIA

• dorsal strongest, volar for rotation
• hyperextended wrist in ulnar deviation
• secondary stabilizers: RSC, SC, STT

• FOOSH: wrist extension and radial deviation –> hypothenar & pisiform –> shears Tq
• LTD more stable pattern compared to SLD
• LT: palmar stronger
• Secondary: dorsal RTq, scaphoTq ligament

• humpback deformity –> DISI

• CIND-VISI or palmar CIND - 'volar sag', 'catch up clunk'
• CIND-DISI or dorsal CIND - young hypermobile, dorsal capitate displacement test
• Combined CIND
• dorsal capitate displacement test
  • traction
  • flexion
  • ulnar deviation
  • dorsal pressure on scaphoid

• perilunate dislocations
• axial dislocations
  • AP crush: associated with soft tissue, neurovascular problems
  • flexor retinaculum torn, flattening of the arch
  • axial ulnar, axial radial

Lee, D. J., & Elfar, J. C. (2015). Carpal Ligament Injuries, Pathomechanics, and Classification. Hand Clinics, 31(3), 389–398. https://doi.org/10.1016/j.hcl.2015.04.011

• created 2021-03-21
• transcribed to dokuwiki 2021-05-10