Perilunate and lunate dislocations: Difference between revisions
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**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 | ||
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[[File:Perilunate Dislocation.jpg|thumb|Perilunate Dislocation]] | [[File:Perilunate Dislocation.jpg|thumb|Perilunate Dislocation]] | ||
[[File:Lunate_Dislocation.jpg|thumb|Lunate Dislocation]] | [[File:Lunate_Dislocation.jpg|thumb|Lunate Dislocation]] | ||
{| class="wikitable" | |||
|- | |||
! 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=== | ===Perilunate Dislocation=== | ||
*Lateral view | *Lateral view | ||
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{{Carpal fractures}} | {{Carpal fractures}} | ||
== | ==Management== | ||
*Closed reduction and long-arm splint | *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== | ==See Also== | ||
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
| 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
- Scaphoid fracture
- Lunate fracture
- Triquetrum fracture
- Pisiform fracture
- Trapezium fracture
- Trapezoid fracture
- Capitate fracture
- Hamate fracture
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