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 login to view 1 more bullet lesser arc login to view 1 more bullet Categories perilunate dislocation lunate stays in position while carpus dislocates 4 types login to view 4 more bullets 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 login to view 2 more bullets major stabilizers of the proximal carpal row intrinsic ligaments ligaments the both originate and insert among the carpal bones login to view 2 more bullets extrinsic ligaments connect the forearm bones to the carpus login to view 2 more bullets 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 Imaging Radiographs recommended views PA lateral findings PA login to view 5 more bullets lateral login to view 3 more bullets MRI usually not required for diagnosis Treatment Nonoperative closed reduction and casting indications login to view 1 more bullet outcomes login to view 2 more bullets Operative emergent closed reduction/splinting followed by open reduction, ligament repair, fixation, possible carpal tunnel release indications login to view 1 more bullet outcomes login to view 5 more bullets proximal row carpectomy indications login to view 2 more bullets total wrist arthrodesis indications login to view 1 more bullet 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 login to view 3 more bullets volar approach login to view 1 more bullet combined dorsal/volar login to view 11 more bullets technique fix associated fractures repair scapholunate ligament login to view 1 more bullet protect scapholunate ligament repair login to view 1 more bullet repair of lunotriquetral interosseous ligament login to view 1 more bullet 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)