SNAC and SLAC of the wrist

January 10, 2021 | By : OrthoFixar | Hand Surgery
| Last updated on February 19, 2021


What is SNAC and SLAC of the wrist stands for?

1. SLAC of the wrist:

  • SLAC stands for Scaphoid Lunate Advanced Collapse.
  • It has been proposed by Watson and associates to define the progression of degenerative changes secondary to SL (Scapholunate) dissociation.
  • There were only 3 stages of SLAC of the wrist identified by Watson, then a recent investigation by Lluch identified five stages of this degenerative.
  • Watson scaphoid shift test is used to examine the patient with SLAC of the wrist.
  • Clinically:
    1. Difficulty bearing weight with the hand.
    2. Pain in region of scapholunate interval.
    3. Progressive weakness of affected hand.
    4. Wrist stiffness.

Stages of SLAC of the wrist:

StagesDegenerative Changes Location
IRadioscaphoid joint
IIScaphocapitate joint
IIILunocapitate joint
IVTriquetrohamate joint
VRadiolunate joint
SLAC Stages

Treatment:

Nonoperative:
  • In mild disease:
    1. NSAIDs.
    2. Wrist splinting.
    3. Corticosteroid injections.
Operative:
StageProcedure
Stage I– Radial styloidectomy + scaphoid stabilization.
– PIN and AIN denervation
Stage II– Proximal row corpectomy
– Scaphoid excision and Four-corner fusion
Stage III– Scaphoid excision and Four-corner fusion
– Wrist arthrodesis
Treatment of SLAC based on stages

2. SNAC of the wrist:

  • SNAC stands for Scaphoid Nonunion Advanced Collapse.
  • It’s a characteristic progression of posttraumatic osteoarthrosis that result from untreated, chronic scaphoid nonunion.

Stages of SNAC:

StagesDegenerative Changes Location
IRadioscaphoid joint arthritis
IIInvolvement of Scaphocapitate joint
IIILunocapitate joint
SNAC Stages

Treatment

Nonoperative:
  • Patients with low functioning demands.
Operative:
StageProcedure
Stage I– Radial styloidectomy + scapholunate reduction and stabilization.
Stage II– Proximal row corpectomy
– Four-corner fusion
– Wrist arthrodesis
Stage III– Proximal row corpectomy
– Four-corner fusion
– Wrist arthrodesis
Treatment of SNAC based on stages

In stage I, the earliest osteoarthritic changes will differ among SLAC and scaphoid nonunion advanced collapse (SNAC) wrists.
In SLAC of the wrists, osteoarthritis includes the proximal scaphoid and the dorsal rim of the radius.
In SNAC of the wrists, osteoarthritis develops between the distal scaphoid and the radial styloid, while the proximal fragment of the scaphoid remains free of pathology.


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