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Lunate Dislocation
Aka: Lunate Dislocation, Transnavicular Perilunate Dislocation, Perilunate Dislocation, Isolated Lunate Dislocation, Pure Volar Lunate Dislocation
- See Also
- Scapholunate Dissociation
- Mechanism
- High energy injury (e.g. fall from height, Motor Vehicle Accident)
- Precautions
- Lunate Dislocations are initially missed in up to 25% of cases
- Deformities may be subtle
- Types: Lunate Dislocation
- Transnavicular Perilunate Dislocation
- Mid-Navicular Fracture
- Posterior displacement of distal Navicular Fracture pole and associated Carpal Bones (including Lunate)
- Perilunate Dislocation
- Intact navicular bone and wrist dorsally dislocates in relation to Lunate Bone
- Isolated Lunate Dislocation (Pure Volar Lunate Dislocation)
- Lunate dislocates from Capitate
- Lunate rotates anteriorly (towards volar wrist)
- Wrist XRay lateral demonstrates anterior displacement, while on AP View, Lunate appears more triangular
- Symptoms
- Pain, swelling, tenderness and decreased range of motion of the affected wrist
- Median NerveParesthesias may be present
- Exam
- Trauma Exam
- High mechanism injury (esp. with Intoxication) is often associated with other injuries
- Multiple other injuries in 26% of Lunate Dislocation cases
- Ipsilateral upper extremity with additional injuries in 10% of cases
- Complete extremity exam (neurovascular, joint above and below, skin and compartments)
- Wrist Exam
- Hand Neurovascular Exam (esp. Median Nerve)
- Careful skin exam overlying dislocation
- Open dislocation occurs in 10% of cases
- XRay
- Wrist XRay
- Diagnostic in most cases
- Procedure: Closed Reduction of Isolated Lunate Dislocation
- Background
- All Isolated Lunate Dislocations will ultimately require ORIF (due to carpal instability)
- However, attempt closed reduction and Splinting in Emergency Department
- Anesthesia
- Procedural Sedation or
- Median Nerve Block at Wrist (Regional Anesthesia of the Median Nerve)
- Short acting agent (e.g. Lidocaine) allows for re-assessment of Median Nerve post-reduction
- Technique
- Finger traps with 10-15 pound traction for 10-15 minutes
- Performed after Median Nerve Block or systemic Analgesics
- Maintain inline traction while finger traps are removed
- Reduction (under Procedural Sedation or Median Nerve Block)
- Patient's wrist positioned in slight flexion
- Place one thumb over dorsal Lunate, providing posterior counter support
- Place other thumb over the volar Lunate and apply anterior pressure toward dorsal wrist
- Closed reduction will fail if interposed joint capsule in dislocation (requires urgent ORIF)
- Splinting
- Return wrist to slightly extended or neutral position
- Apply Sugar-Tong splint
- Disposition
- Obtain post-reduction films
- Refer to orthopedics for definitive management (i.e. ORIF)
- Surgery at 3-5 days after stable closed reduction and Splinting, without Median Neuropathy
- Urgent orthopedic evaluation for persistent or recurrent dislocation, Median Neuropathy
- Complications
- Median Nerve Injury
- Open Dislocation
- Delayed diagnosis (longterm Disability risk)
- References
- Kiel, Kumetz and Shannon (2019) Crit Dec Emerg Med 33(5): 14-5
- Mercier (1995) Practical Orthopedics, Mosby, St. Louis, p. 360-2