|
http://upload.orthobullets.com/topic/6042/images/SL angle latera_moved.jpg
http://upload.orthobullets.com/topic/6042/images/SL angle lateral new_moved.jpg
http://upload.orthobullets.com/topic/6042/images/slide1.jpg
Introduction
  • Instability of the lunotriquetral joint caused by rupture of the
    • lunotriquetral ligament and
    • dorsal radiocarpal ligament (aka radiotriquetral ligament)
  • Epidemiology
    • LT ligament injury is less common than SL ligament injury
  • Mechanism
    • LT ligament injury occurs with 
      • wrist hyperextension or 
      • extension and radial deviation
    • scaphoid induces the lunate into further flexion while triquetrum extends
  • VISI Deformity
    • stands for volar intercalated segment instability
      • a type of Carpal Instability Dissociative (CID)
    • caused by advanced injury with injury to 
      • lunotriquetral ligament
      • dorsal radiotriquetral ligament 
      • volar radiolunate ligament
    • VISI may occasionally be seen in uninjured wrists in patients with ligamentous laxity
      • this is in contrast to DISI deformity, which is always a pathologic condition
Anatomy
  • Lunotriquetral ligament
    • C-shaped intrinsic ligament spanning the dorsal, proximal and palmar edges of the joint
    • comprised of thick dorsal and volar regions and weak membranous portion
      • dorsal LT ligament
        • most important as a rotational constraint
      • volar LT ligament 
        • thickest and strongest portion of the LT ligament
        • transmits extension moment of the triquetrum
  • Dorsal radiocarpal ligament (aka dorsal radiotriquetral ligament) 
    • extrinsic ligament that serves as a secondary restraint to VISI deformity, and loss of integrity allows lunate to flex more easily
  • Volar long and short radiolunate ligaments 
    • extrinsic ligament that may be torn in advanced injury
Presentation
  • Symptoms
    • ulnar sides pain that is worse with pronation and ulnar deviation (power grip)
  • Physical exam
    • LT shuck test (aka ballottement testpost
      • grasp the lunate between the thumb and index finger of one hand while applying alternative dorsal and palmar loads across the triquetrum with the thumb and index of the other hand
      • positive test elicits pain, crepitus or increased laxity, suggesting LT interosseous injury
    • Kleinman's shear test 
      • stabilize the radiolunate joint with the forearm in neutral rotation and with the contralateral hand load the triquetrum in the AP plane, producing shear across the LT joint
      • positive test produces pain or a clunk
    • Lunotriquetral compression test
      • displacement of triquetrum ulnarly during radioulnar deviation which is associated with pain
Imaging
  • Radiographs
    • lateral
      • volar flexion of lunate leads to SL angle < 30° (normal is 47°) and VISI deformity 
      • capitolunate zigzag deformity seen with capitolunate angle increase to > 15° (lunate and capitate normally co-linear)
    • AP
      • unlike scapholunate dissociation, may not be widening of LT interval
      • break in Gilula's arc
      • may see proximal translation of triquetrum and/or LT overlap
  • Arthroscopy 
    • helpful in making diagnosis, as radiographs may be normal 
Treatment
  • Nonoperative
    • observation 
      • indications
        • may be attempted initially
  • Operative
    • CRPP (multiple K-wire fixation) with acute ligament repair +/- dorsal capsulodesis
      • indications
        • acute instability
      • technique
        • ligament reconstructions with bone-ligament-bone autograft and LT fusion have fallen out of favor in acute setting
    • LT fusion
      • indications
        • chronic instability
      • complications
        • nonunion is a known complication
    • arthroscopic debridement of LT ligament with ulnar shortening 
      • indications
        • chronic instability secondary to ulnar positive variance
          • long ulna chronically impacts the triquetrum, resulting in LT tear with instability
        • often associated with degenerative tear of triangular fibrocartilage complex (TFCC)
 

Please rate topic.

Average 3.8 of 25 Ratings

POSTS (1)
GROUPS (1)
EVIDENCE & REFERENCES (1)
Topic COMMENTS (9)
Private Note