Hand Conditions

Scapho-lunate Advanced Collapse (SLAC)

Definition:

Advanced arthritis of the radiocarpal and midcarpal joints due to progressive instability/dissociation between the scaphoid and lunate (carpal) bones.

Symptoms:

  • Dorsal (top side) wrist joint pain localized over the region of the scapholunate interval.
  • Progressive wrist stiffness and weakness.
  • Increased pain with weight bearing across the wrist (push-up activity).

Pathology:

  • Chronic ligament instability between the scaphoid and lunate creates a DISI (dorsal intercalated segment instability) deformity.
    • Scaphoid flexed and lunate extended
    • Can progress to capitolunate joint (capitate and lunate carpal bones).
  • X-rays
    • PA views demonstrate scapholunate widening (separation > 3mm), joint space narrowing between the scaphoid and radial styloid and sclerosis (increased bone density/hardening).
    • Lateral views demonstrate DISI deformity (flexed scaphoid and extended lunate).
  • Radiolunate joint is spared

Treatment:

Non-surgical

  • Rest, activity modifications, bracing, ice and NSAIDs (ibuprofen)
  • Corticosteroid injection

Surgical

  • Reconstructive surgery involves excising the scaphoid and arthrodesis and is indicated when non-operative treatment fails.