How does this injury occur?
High energy injury when wrist EXTENDED and ULNARLY deviated -> intercarpal supination
Does this injury have good functional outcomes
No they are poor
What are the type of disslocation?
Perilunate dislocation- lunate stays in position while carpus dislocates
Lunate dislocation-( see pic) lunate forced volar/dorsal whilst carpus remains alligned
What is the pathoanatomy?
- 1) Scapholunate ligament disrupted
- 2) Capitolunate articulation disrupted
- 3) Lunotriqetral articulation disrupted
- 4) Failure of dorsal radiocarpal ligament
- then lunate rotates and dislocates
Where can the dislocation occur?
- Thru greater arc- ligamentous and fracture
- Lesser arc- just ligamentous
what bones are in the proximal row?
what bones are in the distal row?
What are the major stabilisers of the proximal row?
- scapholunate ligament
- lunotriquetral ligament
What are the intrinsics ligaments?
- Dorsal and volar intrinsic ligaments
What are the extrinsics ligaments in the hand?
- volar extrinsic
- dorsal extrinsic
Name the classification system for perilunate dislocation ?
Can you describe the MAYFIELD classification?
- stage 1- scapholunate dissociation
- stage 2- + capitolunate dissociation
- Stage 3 - + lunotriquetral disruption, perilunate(seepic)
- Stage 4- + lunate DISLOCATED from lunate fossa usually volar-
What is stage 4 associated with ?
MEDIAN N compression
What do you see on X-rays?
- Break in GILULA's arc ( see pic)
- lunate and capitate overlap
- lunate appears triangular piece of pie sign
- loss of colinearity of radius, lunate and capitate
- Scapholunate angle >70 degrees
How do you tx perilunate dislocation?
Closed reduction and casting but lead to poor functional outcomes so reduce the 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
What are the indications for closed/open reduction , fracture fixation, ligament repair and splinting?
A injury <8 weeks old
What other tx are available?
- Proximal row carpectomy- for chronic injury >8 weeks, not uncommon as injury often initally missed
- Total wrist arthrodesis- chronic injury with degenerative changes
What surgical approach would you use to open and reduce the lunate?
- 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
What is the principles of surgical tx?
- Fix fractures
- Repair SL lig- suture anchor protect SL lig repair- K wire vs circulage wire
- Repair Lunotriquetral ligament
What would you do post op?
- Short arm thumb spica cast
- convert to short arm cast at first post op visits
- cast at least 6 weeks
What is the principles of prix row carpectomy tx?
- 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
Describe how you would preform a close reduction of the lunate?
- 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
How are the unusual dorsal dislocations reduced?