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Perilunate dislocations. Dr. P Kruger. General points. Can be missed easily If left untreated lead to high incidence of long term functional disability and chronic pain. Perilunate dislocations more common than lunate dislocations. Mechanism of injury. Hyperdorsiflexion of wrist
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Perilunate dislocations Dr. P Kruger
General points • Can be missed easily • If left untreated lead to high incidence of long term functional disability and chronic pain. • Perilunate dislocations more common than lunate dislocations
Mechanism of injury • Hyperdorsiflexion of wrist • Hyperextension of wrist • Usually due to high-energy trauma to the wrist e.g. - Fall on outstretched hand - Motor vehicle and motorcycle accidents
Diagnosis • Clinical history • Index of suspicion • Examination of hand • X-Ray + other views if indicated - closed fist ulnar/radial stress view - Scaphoid view - Supination oblique view - Carpal tunnel view
Management • ABC • Splint immobilization or backslab • Analgesia • Elevation • IV antibiotics if open fracture • Refer to hand surgeon - Closed reduction or ORIF
Stages • 4 stages • Originally described by Mayfield. • Each stage represent a sequential intercarpal injury. • Can be associated with specific bony fractures including the radial styloid, scaphoid, capitate and triquetrum.
Stage 1 – Scapholunate dissociation Widening of scapholunate joint > 2mm on PA view Terry Thomas sign
Stage II - Capitate dislocation • Dislocation or subluxation of capitate • Best seen on lateral view • Lunate remains in normal position in relation to distal radius, capitate is dislocated. ( usually dorsally ) • Scaphoid fracture or subluxation can also occur.
Stage III – Triquetrum dislocation • Perilunate dislocation • Triquetral and scaphoid malrotation • Lunate remains normal position, other carpal bones dislocated posteriorly • May be associated with triquetrial fracture
Stage IV - Lunate dislocation • Most severe of carpal instabilities • Most commonly associated with trans scaphoid fracture • Produces volar dislocation and forward rotation of lunate. Capitate drops into place vacated by lunate • Lunate appears triangular in shape on frontal view ( piece of pie sign ) • Spilled tea cup sign
Spilled tea cup sign
