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Hands FRCS > Lunate Dislocations ( perilunate dissocation)- wrist instability > Flashcards

Lunate Dislocations ( perilunate dissocation)- wrist instability Flashcards

1
Q

How does this injury occur?

A
  • High energy injury when wrist EXTENDED and ULNARLY deviated -> intercarpal supination
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2
Q

Does this injury have good functional outcomes

A

No they are poor

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3
Q

What are the type of disslocation?

A
  • Perilunate dislocation- lunate stays in position while carpus dislocates
    • Transcaphoid-perilunate
    • Perilunate
    • Transradial-styloid
    • Transscaphoid-trans-capitate-perilunar
  • Lunate dislocation-( see pic) lunate forced volar/dorsal whilst carpus remains alligned
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4
Q

What is the pathoanatomy?

A
  • 1) Scapholunate ligament disrupted
  • 2) Capitolunate articulation disrupted
  • 3) Lunotriqetral articulation disrupted
  • 4) Failure of dorsal radiocarpal ligament
  • then lunate rotates and dislocates
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5
Q

Where can the dislocation occur?

A
  • Thru greater arc- ligamentous and fracture
  • Lesser arc- just ligamentous
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6
Q

what bones are in the proximal row?

A
  • scaphoid
  • lunate
  • triquetrum
  • pisiform
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7
Q

what bones are in the distal row?

A
  • trapezium
  • trapezoid
  • capitate
  • hamate
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8
Q

What are the major stabilisers of the proximal row?

A
  • scapholunate ligament
  • lunotriquetral ligament
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9
Q

What are the intrinsics ligaments?

A
  • Dorsal and volar intrinsic ligaments
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10
Q

What are the extrinsics ligaments in the hand?

A
  • volar extrinsic
  • dorsal extrinsic
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11
Q

Name the classification system for perilunate dislocation ?

A
  • MAYFIELD
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12
Q

Can you describe the MAYFIELD classification?

A
  • stage 1- scapholunate dissociation
  • stage 2- + capitolunate dissociation
  • Stage 3 - + lunotriquetral disruption, perilunate(seepic)
  • Stage 4- + lunate DISLOCATED from lunate fossa usually volar-
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13
Q

What is stage 4 associated with ?

A

MEDIAN N compression

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14
Q

What do you see on X-rays?

A

AP-

  • Break in GILULA’s arc ( see pic)
  • lunate and capitate overlap
  • lunate appears triangular piece of pie sign

LAT

  • loss of colinearity of radius, lunate and capitate
  • Scapholunate angle >70 degrees
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15
Q

How do you tx perilunate dislocation?

A

NON OP

Closed reduction and casting but lead to poor functional outcomes so reduce the surgery!!

SURGERY

  • EMERGENCY CLOSED REDUCTION /SPLINTING + **open reduction, ligament repair fixation and possible carpal tunnel release= **all acute injuries <8 wks
  • oc- reduced median nerve damage/ cartilage damage
  • Return to full function unlikely, reduced grip strength and stiffness common
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16
Q

What are the indications for closed/open reduction , fracture fixation, ligament repair and splinting?

A

A injury <8 weeks old

17
Q

What other tx are available?

A
  • Proximal row carpectomy- for chronic injury >8 weeks, not uncommon as injury often initally missed
  • Total wrist arthrodesis- chronic injury with degenerative changes
18
Q

What surgical approach would you use to open and reduce the lunate?

A

Contraversial!!

  • Dorsal - longitudinal centred over listers tubercle
  • excellent exposure of prox row and mid carpal joints but can’t do carpal tunnel thru this
  • Volar- extended carpal tunnel incision just prox to volar wrist crease
  • Both dorsal and volar approach- adv: added exposure, easier reduction, access distal scaphoid fracture, ability to repair volar ligaments and carpal tunnel decompression
  • dis= some believe volar lig no need for repair, increase swelling, potential carpal devascularisation, difficult regaining digital flexion grip
19
Q

What is the principles of surgical tx?

A
  • Fix fractures
  • Repair SL lig- suture anchor protect SL lig repair- K wire vs circulage wire
  • Repair Lunotriquetral ligament
20
Q

What would you do post op?

A
  • Short arm thumb spica cast
  • convert to short arm cast at first post op visits
  • cast at least 6 weeks
21
Q

What is the principles of prix row carpectomy tx?

A
  • Preform volar and dorsal incisions
  • if median n compression is present volar approach allows median N decompression and excision of lunate
  • dorsal approach facilities excision of scaphoid and triquetrum
22
Q

Describe how you would preform a close reduction of the lunate?

A
  • Finger traps, elbow at 90 degrees
  • hand 5-10 ILbs for 15 mins
  • dorsal disolocations reduced thru wrist Extension, traction and flexion of the wrist
  • Apply split
  • Follow with surgery
23
Q

How are the unusual dorsal dislocations reduced?

A
  • Wrist extension, traction and flexion apply a long splint and follow up with surgery

Hands FRCS (28 decks)

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