​Emergency And Acute Medicine – Lunate Dislocation
​Basics description
Lunate dislocation is a disruption of the lunate relative to the distal radius and the remaining carpal bones. Most dislocations are volar, though dorsal displacement can occur. The injury typically results from high-energy wrist hyperextension combined with ulnar deviation and represents a severe carpal instability pattern.
Etiology
Lunate dislocation implies complete disruption of all four perilunate ligaments as well as the radiocarpal ligament, corresponding to stage IV of the Mayfield classification. Volar dislocations are commonly associated with median nerve compression within the carpal tunnel. Concomitant fractures of the radial styloid, scaphoid, capitate, or triquetrum are frequent and should heighten suspicion for occult perilunate ligamentous injury.
Diagnosis signs and symptoms
This injury is frequently missed. Patients usually report wrist pain following a fall or motor vehicle collision. Examination may reveal swelling or a palpable mass on the volar or dorsal wrist depending on the direction of dislocation. Gross deformity can be obscured by edema. Symptoms or signs of median nerve dysfunction, including numbness or paresthesia in the radial digits, may be present.
Essential workup
Clinical examination alone is often insufficient for diagnosis. Skin integrity and full neurovascular status should be assessed, including two-point discrimination. Radiographic evaluation is essential.
Diagnosis tests and interpretation
Standard wrist radiographs should include posteroanterior, lateral, and oblique views. The lateral view is most diagnostic, demonstrating disruption of the normal colinear alignment of the radius, lunate, and capitate. In volar dislocations, the lunate is tilted with its concavity facing the palm, producing the classic “spilled teacup” sign. On the posteroanterior view, the lunate often appears triangular rather than quadrangular, and disruption of Gilula’s arcs suggests carpal instability. Pediatric interpretation may be difficult due to incomplete ossification, while older adults commonly have associated fractures.
Differential diagnosis
Consider lunate fracture, perilunate dislocation, scapholunate dissociation, and scaphoid fracture.
Treatment pre hospital
Open wounds should be dressed and the wrist immobilized in a neutral position.
Initial stabilization therapy
Immobilize the wrist in a position of comfort using a volar splint or sugar-tong splint and provide adequate analgesia.
Ed treatment procedures
Evaluate for associated traumatic injuries. Early consultation with a hand or orthopedic surgeon is essential, as closed reduction is often unstable or unsuccessful. Definitive management frequently requires open reduction and internal fixation.
Medication
Pain control may be achieved with opioids or NSAIDs depending on severity. Morphine or combination acetaminophen–opioid preparations may be used for severe pain, while NSAIDs such as ibuprofen or naproxen are appropriate for moderate pain when not contraindicated. Caution is required with codeine in children due to variable metabolism.
Follow up disposition
Admission is commonly required for definitive surgical management, particularly in open injuries or polytrauma. Patients with closed dislocations that are successfully reduced and immobilized may be discharged with close orthopedic follow-up.
Follow up recommendations
Prompt outpatient follow-up with orthopedics or hand surgery is mandatory. Return to sports or heavy activity should be avoided until complete healing is confirmed.
Key points
Lunate dislocation is a commonly missed but serious wrist injury. Always assess for median nerve compromise. Early recognition and surgical consultation are critical to prevent complications such as avascular necrosis of the lunate and degenerative arthritis.