Perilunate and lunate dislocations: Difference between revisions

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== Background ==
==Background==
*Occur via high-energy FOOSH injury (fall from height, MVC)
*Occur via high-energy FOOSH injury (fall from height, MVC)
**Perilunate Dislocation = Lunate stays in place, capitate is displaced
**Perilunate Dislocation = Lunate stays in place, capitate is displaced
**Lunate Dislocation = Capitate stays in place, lunate is displaced
**Lunate Dislocation = Capitate stays in place, lunate is displaced
*Commonly missed (~25%) on initial presentation
*Must rule-out median nerve injury
*Must rule-out median nerve injury
*Must rule out carpal bone fractures
*Must rule out carpal bone fractures


== Clinical Features ==
==Clinical Features==
*Perilunate dislocation: dorsal swelling with palpable mass
*Perilunate dislocation: dorsal swelling with palpable mass
*Lunate dislocation: volar swelling with palpable mass
*Lunate dislocation: volar swelling with palpable mass


== Diagnosis ==
==Evaluation==
*Perilunate Dislocation
[[File:Perilunate Dislocation.jpg|thumb|Perilunate Dislocation]]
**Lateral view
[[File:Lunate_Dislocation.jpg|thumb|Lunate Dislocation]]
***Capitate displaced dorsal to lunate
{| class="wikitable"
***Lunate retains its normal contact w/ radius
|-
**PA view
! Mayfield Classification !! Level of carpal instability
***Capitolunate joint space is obliterated as the bones overlap one another
|-
*Lunate Dislocation
| Stage I: scapholunate dissociation || Disruption of scapholunate ligament with +Terry Thomas sign; exacerbated in clenched fist view
**PA view
|-
***Lunate has triangular shape ("piece-of-pie sign")
| Stage II: perilunate dislocation || +Disruption of capitolunate joint; high association with scaphoid fractures
**Lateral view
|-
***Lunate is pushed off the radius into the palm ("spilled teacup" sign)
| Stage III:  midcarpal dislocation || +Disruption of triquetrolunate joint; neither capitate or lunate is aligned with distal radius
|-
| Stage IV: lunate dislocation || +Disruption of radiolunate joint
|}


==DDX ==
===Perilunate Dislocation===
#Fractures of distal radius, carpal bones (esp scaphoid)
*Lateral view
#[[Scapholunate Dissociation]]
**Capitate displaced dorsal to lunate
**Lunate retains its normal contact with radius
*PA view
**Capitolunate joint space is obliterated as the bones overlap one another


== Treatment ==
===Lunate Dislocation===
#Both dislocations require emergent ortho consultation (very difficult to reduce)
*Lateral view
#Closed reduction and long-arm splint
**Lunate is pushed off the radius into the palm ("spilled teacup" sign)
*PA view
**Lunate has triangular shape ("piece-of-pie sign")


== Source ==
==Differential Diagnosis==
{{Carpal dislocation DDX}}
 
{{Carpal fractures}}
 
==Management==
*Closed reduction and long-arm splint
**Requires emergent ortho consultation (very difficult to reduce with high incidence of median nerve compression), and usually emergent operative management
 
==See Also==
*[[Carpal dislocations]]
 
==References==
<references/>
*Emergency Orthopedics, The Extremeties
*Emergency Orthopedics, The Extremeties
*Radiopaedia.org
*Radiopaedia.org
*Tintinalli
[[Image:PL 1.jpg|thumb|left|200x264px|PL 1.jpg|Perilunate lateral]]<br>
[[Image:PL 2.jpg|thumb|center|279x293px|PL 2.jpg|Perilunate AP]]


[[Image:Lun 1.jpg|thumb|left|201x299px|Lun 1.jpg|Lunate]]


[[Category:Ortho]]
[[Category:Orthopedics]]

Latest revision as of 16:12, 23 March 2020

Background

  • Occur via high-energy FOOSH injury (fall from height, MVC)
    • Perilunate Dislocation = Lunate stays in place, capitate is displaced
    • Lunate Dislocation = Capitate stays in place, lunate is displaced
  • Commonly missed (~25%) on initial presentation
  • Must rule-out median nerve injury
  • Must rule out carpal bone fractures

Clinical Features

  • Perilunate dislocation: dorsal swelling with palpable mass
  • Lunate dislocation: volar swelling with palpable mass

Evaluation

Perilunate Dislocation
Lunate Dislocation
Mayfield Classification Level of carpal instability
Stage I: scapholunate dissociation Disruption of scapholunate ligament with +Terry Thomas sign; exacerbated in clenched fist view
Stage II: perilunate dislocation +Disruption of capitolunate joint; high association with scaphoid fractures
Stage III: midcarpal dislocation +Disruption of triquetrolunate joint; neither capitate or lunate is aligned with distal radius
Stage IV: lunate dislocation +Disruption of radiolunate joint

Perilunate Dislocation

  • Lateral view
    • Capitate displaced dorsal to lunate
    • Lunate retains its normal contact with radius
  • PA view
    • Capitolunate joint space is obliterated as the bones overlap one another

Lunate Dislocation

  • Lateral view
    • Lunate is pushed off the radius into the palm ("spilled teacup" sign)
  • PA view
    • Lunate has triangular shape ("piece-of-pie sign")

Differential Diagnosis

Carpal Dislocations

Carpal fractures

AP view

Management

  • Closed reduction and long-arm splint
    • Requires emergent ortho consultation (very difficult to reduce with high incidence of median nerve compression), and usually emergent operative management

See Also

References

  • Emergency Orthopedics, The Extremeties
  • Radiopaedia.org
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