Perilunate Perilunate dislocationsdislocations

Dr. P Kruger

General pointsGeneral 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 injuryMechanism 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

DiagnosisDiagnosis• 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

ManagementManagement

• ABC

• Splint immobilization or backslab

• Analgesia

• Elevation

• IV antibiotics if open fracture

• Refer to hand surgeon

- Closed reduction or ORIF

StagesStages

• 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 1Stage 1 – Scapholunate dissociation

Widening of scapholunate joint > 2mm on PA viewTerry Thomas sign

Stage II Stage II - Capitate - Capitate dislocationdislocation

• 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 Stage III – Triquetrum – Triquetrum dislocationdislocation

• Perilunate dislocation

• Triquetral and scaphoid malrotation

• Lunate remains normal position, other carpal bones dislocated posteriorly

• May be associated with triquetrial fracture

Stage IVStage IV - Lunate - Lunate dislocationdislocation

• 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

Triangular shaped lunate

                                       

Volar lunate dislocation

X-ray ExamplesX-ray Examples

Normal X-raysNormal X-rays

Stage I

Volar perilunate dislocation

Dorsal perilunate dislocation

Lunate dislocation

Perilunate dislocation