Updated: 11/5/2022

Lunate Dislocation (Perilunate dissociation)

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  • Summary
    • Lunate/perilunate dislocations are high energy injuries to the wrist associated with neurological injury and poor functional outcomes.
    • Diagnosis requires careful evaluation of plain radiographs.
    • Treatment requires urgent closed versus open reduction and stabilization.
  • Epidemiology 
    • Incidence
      • rare
        • < 1 per 100,000 injuries annually 
      • commonly missed (~25%) on initial presentation
  • Etiology
    • Mechanism of injury
      • 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
    • 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
  • Anatomy
    • 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
  • Classification
      • 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
  • Presentation
    • 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
  • Imaging
    • Radiographs
      • recommended views
        • PA
        • lateral
      • findings
        • PA
          • break in Gilula's arc
          • lunate and capitate overlap
          • "piece-of-pie sign"
            • triangular appearance of lunate
            • due to palmar rotation from dorsal force of carpus
        • lateral
          • loss of colinearity of radius, lunate, and capitate
          • SL angle >70 degrees
          • spilled teacup sign
    • MRI
      • usually not required for diagnosis
  • Treatment
    • 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
  • Techniques
    • 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
  • Complications
    • Transient ischemia of the lunate  
      • radiodense appearance of the lunate on radiograph reported in up to 12.5% of cases
      • usually identified 1-4 months post-injury
      • treatment
        • observation (benign and self-limiting)

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Questions (11)
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(SBQ17SE.47) A 24-year-old stagehand fell 12 feet off of a ladder while preparing a set. As he tried to brace his fall, he landed directly on his extended and ulnarly deviated left hand. He was taken to the local teaching hospital where radiographs were taken, shown in Figures A and B. What additional data is most necessary to obtain before a reduction is attempted?

QID: 211622

Distal vascular exam



Neurological exam



Wrist MRI



Doppler Allen test



DRUJ stability assessment



L 2 A

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(SBQ17SE.67) A lumberjack in rural Michigan falls 10 feet from an Evergreen branch onto an outstretched arm and develops immediate wrist pain. He is not able to see a physician for 4 months. When he finally does, he is diagnosed with a perilunate dislocation and indicated for a Proximal Row Carpectomy (PRC). Figure A is an intraoperative photo. The black dot in the photo is the capitate. The instrument touches a structure that prevents ulnar translocation of the carpus after a PRC. What is this structure?

QID: 211842

Short Radiolunate ligament (SRL)



Lunotriquetral ligament (LTL)



Radioscapholunate ligament (RSL)



Scapholunate ligament (SL)



Radioscaphocapitate ligament (RSC)



L 1 A

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(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?

QID: 3040

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



L 1 C

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Evidence (33)
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