http://upload.orthobullets.com/topic/6045/images/lunate dislocation.jpg
http://upload.orthobullets.com/topic/6045/images/greater and lesser.jpg
  • High energy injury with poor functional outcomes
  • Commonly missed (~25%) on initial presentation
  • Categories
    • perilunate dislocation 
      • lunate stays in position while carpus dislocates
      • 4 types
        • transcaphoid-perilunate
        • perilunate
        • transradial-styloid
        • transcaphoid-trans-capitate-perilunar
    • lunate dislocation   
      • lunate forced volar or dorsal while carpus remains aligned
  • Mechanism
    • traumatic, high energy
    • occurs when wrist extended and ulnarly deviated
      • leads to intercarpal supination
  • Pathoanatomy
    • sequence of events
      • scapholunate ligament disrupted -->
      • disruption of capitolunate articulation --> 
      • disruption of lunotriquetral articulation --> 
      • failure of dorsal radiocarpal ligament --> 
      • lunate rotates and dislocates, usually into carpal tunnel
    • dislocation can course through
      • greater arc
        • ligamentous disruptions with associated fractures of the radius, ulnar, or carpal bones
      • lesser arc
        • purely ligamentous
  • Normal wrist anatomy
  • Osseous
    • proximal row
      • scaphoid
      • lunate
      • triquetrum
      • pisiform
    • distal row
      • trapezium
      • trapezoid
      • capitate
      • hamate
  • Ligaments
    • interosseous ligaments
      • run between the carpal bones
        • scapholunate interosseous ligament
        • lunotriquetral interosseous ligament
      • major stabilizers of the proximal carpal row
    • intrinsic ligaments
      • ligaments the both originate and insert among the carpal bones
        • dorsal intrinsic ligaments 
        • volar intrinsic ligaments
    • extrinsic ligaments
      • connect the forearm bones to the carpus
        • volar extrinsic carpal ligaments 
        • dorsal extrinsic carpal ligaments
 Mayfield Classification
Stage I  • scapholunate dissociation
Stage II  • + lunocapitate disruption
Stage III  • + lunotriquetral disruption, "perilunate"
Stage IV  • lunate dislocated from lunate fossa (usually volar)
 • associated with median nerve compression
  • Symptoms
    • acute wrist swelling and pain
    • median nerve symptoms may occur in ~25% of patients
      • most common in Mayfield stage IV where the lunate dislocates into the carpal tunnel
  • Radiographs
    • required views
      • PA/lateral wrist radiographs
    • findings
      • AP 
        • break in Gilula's arc
        • lunate and capitate overlap
        • lunate appears triangular "piece-of-pie sign"
      • lateral
        • loss of colinearity of radius, lunate, and capitate
        • SL angle >70 degrees
  • MRI
    • usually not required for diagnosis
  • Nonoperative
    • closed reduction and casting
      • indications
        • no indications when used as definitive management
      • outcomes
        • universally poor functional outcomes with non-operative management
        • recurrent dislocation is common
  • Operative
    • emergent closed reduction/splinting followed by open reduction, ligament repair, fixation, possible carpal tunnel release
      • indications
        • all acute injuries <8 weeks old
      • outcomes
        • emergent closed reduction leads to 
          • decreased risk of median nerve damage
          • decreased risk of cartilage damage
        • return to full function unlikely
        • decreased grip strength and stiffness are common
    • proximal row carpectomy
      • indications
        • chronic injury  (defined as >8 weeks after initial injury)
          • not uncommon, as initial diagnosis frequently missed
    • total wrist arthrodesis
      • indications
        • chronic injuries with degenerative changes
  • Closed Reduction 
    • technique
      • finger traps, elbow at 90 degrees of flexion
      • hand 5-10 lbs traction for 15 minutes
      • dorsal dislocations are reduced through wrist extension, traction, and flexion of wrist
      • apply sugar tong splint
      • follow with surgery
  • Open reduction, ligament repair and fixation +/- carpal tunnel release
    • approach (controversial)
      • dorsal approach
        • longitudinal incision centered at Lister's tubercle
        • excellent exposure of proximal carpal row and midcarpal joints
        • does not allow for carpal tunnel release
      • volar approach
        • extended carpal tunnel incision just proximal to volar wrist crease
      • combined dorsal/volar
        • pros
          • added exposure
          • easier reduction
          • access to distal scaphoid fractures
          • ability to repair volar ligaments
          • carpal tunnel decompression
        • cons
          • some believe volar ligament repair not necessary
          • increased swelling
          • potential carpal devascularization
          • difficulty regaining digital flexion and grip
    • technique
      • fix associated fractures
      • repair scapholunate ligament
        • suture anchor fixation
      • protect scapholunate ligament repair
        • controversy of k-wire versus intraosseous cerclage wiring
      • repair of lunotriquetral interosseous ligament
        • decision to repair based on surgeon preference as no studies have shown improved results
    • post-op
      • short arm thumb spica splint converted to short arm cast at first post-op visit
      • duration of casting varies, but at least 6 weeks
  • Proximal row carpectomy
    • technique
      • perform via dorsal and volar incisions if median nerve compression is present
      • volar approach allows median nerve decompression with excision of lunate
      • dorsal approach facilitates excision of the scaphoid and triquetrum

Please rate topic.

Average 3.8 of 41 Ratings

Questions (1)

(OBQ09.227) A 35-year-old professional football player complains of severe wrist pain after making a tackle. He reports paresthesias in his thumb and index finger. AP and lateral radiographs of the wrist are shown in figures A and B respectively. What is the most appropriate next step in management? Review Topic


short arm thumb spica cast




long arm thumb spica cast




urgent closed reduction and splinting




MR arthrogram of the wrist to assess ligamentous injuries




bone scan to assess vascularity



Select Answer to see Preferred Response


This patient is presenting with a perilunate dislocation with carpal tunnel symptoms. The most important next step in treatment is reduction of the dislocation. This is generally performed in the emergency room, and if unsuccessful, immediate reduction and stabilization in the operating room is indicated.

Kozin et al note that these injuries can be overlooked and have variable propagation patterns through the carpus/carpal ligaments. This patient has a radial styloid fracture due to avulsion of the radiocarpal ligaments.

Melone et al note that these injuries were historically treated with closed reduction and pinning, but more recently the trend is for open reduction and fixation, for optimal anatomic restoration.

Figure A is an AP radiograph that shows obvious scapholunate diastasis due to a perilunate dislocation. Figure B shows the 'empty teacup' sign due to the empty articulation of the distal lunate.

Please rate question.

Average 4.0 of 28 Ratings

Question COMMENTS (7)
Sorry, this question is available to Virtual Curriculum members only.

Click HERE to learn more and purchase the Virtual Curriculum today!

Topic COMMENTS (12)
Private Note