Scapholunate Instability

Other Names

• Scapholunate Ligament Injury
• Scapholunate Injury
• Dynamic scapholunate instability
• Rotatory subluxation of the scaphoid
• Scapholunate dissociation
• Dorsal intercalated segment instability (DISI)
• Scapholunate advanced collapse (SLAC)

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Background

• Refers to widening of the scapholunate space on radiographs involving injury to the Scapholunate Ligament
• Most common and significant ligamentous injury of the wrist
• Describes a spectrum of conditions, listed in order of increasing severity
  • Dynamic scapholunate instability
  • Rotatory subluxation of the scaphoid
  • Scapholunate dissociation
  • Dorsal intercalated segment instability (DISI)
  • Scapholunate advanced collapse

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Pathophysiology

• Direct trauma with wrist in extension and ulnar deviation
• Associated injuries
  • Scaphoid Fracture
  • Radial Styloid Fracture

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Risk Factors

• Ulna minus configuation
• Slope of radial articular surface
• Lunotriquetral coalition

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Differential Diagnosis

• Fractures
  • Distal Radius Fracture
    • Barton's Fracture
    • Chauffer's Fracture
    • Colles' Fracture
    • Die-Punch Fracture
    • Radial Styloid Fracture
    • Smith's Fracture
  • Distal Ulna Fracture
  • Carpal Fractures
    • Scaphoid Fracture
    • Lunate Fracture
    • Triquetrum Fracture
    • Pisiform Fracture
    • Trapezium Fracture
    • Trapezoid Fracture
    • Capitate Fracture
    • Hamate Fracture
  • Essex Lopresti Fracture
• Dislocations
  • Carpometacarpal Joint Dislocation
  • Distal Radioulnar Joint Dislocation
  • Lunate Dislocation
  • Perilunate Dislocation
• Instability & Degenerative
  • Scapholunate Instability
  • Lunotriquetral Instability
  • Scaphoid Nonunion Advanced Collapse
  • Distal Radial Ulnar Joint Instability
  • Kienbocks Disease
  • Dorsal Wrist Impingement
• Tendinopathies & Ligaments
  • De Quervain's Tenosynovitis
  • Intersection Syndrome
  • TFCC Injury
  • Wrist Tendinopathies
  • Extensor Carpi Ulnaris Instability
• Neuropathies
  • Carpal Tunnel Syndrome
  • Pronator Teres Syndrome
  • Anterior Interosseus Nerve Syndrome
  • Posterior Interosseus Nerve Syndrome
  • Guyon Canal Syndrome
• Pediatric Considerations
  • Distal Radial Epiphysitis (Gymnast's Wrist)
  • Torus Fracture
• Arthropathies
  • Wrist Osteoarthritis
  • Rheumatoid Arthritis
  • Gout
• Cartilage
  • Osteochondral Defect
• Vascular
  • Hypothenar Hammer Syndrome
• Other
  • Ganglion Cyst of Wrist
  • Ulnar Impingement Syndrome
  • Infectious Tenosynovitis

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Clinical Features

• General: Physical Exam Wrist
• Pain and tenderness along carpal bones
• Scaphoid Shift Test: Pain with manipulation of scaphoid

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Evaluation

MRI in coronal plane showing scapholunate dissociation

Radiographs

• Standard Radiographs Wrist
• 3 views initially
• Frequently missed due to normal appearance of initial radiographs
• Scapholunate gap view
• Clenched fist view: evaluate for dynamic wrist instability

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Classification

• N/a

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Management

Nonoperative

• Strongly encouraged to consult hand surgery with management decisions
• Nonoperative/ conservative management is limited to dynamic scapholunate instability only
  • Includes
  • Activity modification
  • Physical Therapy
  • NSAIDS
  • Wrist Splinting

Operative

• Indicated in most cases including:
  • Rotatory subluxation of the scaphoid
  • Scapholunate dissociation
  • Dorsal intercalated segment instability (DISI)
  • Scapholunate advanced collapse

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Return to Play

• At the discretion of the surgeon

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Complications

• Disease progression
  • Dynamic scapholunate instability
  • Rotatory subluxation of the scaphoid
  • Scapholunate dissociation
  • Dorsal intercalated segment instability (DISI)
  • Scapholunate advanced collapse

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See Also

• Internal
  • Forearm Pain (Main)
  • Wrist Pain (Main)
  • Hand and Wrist Anatomy (Main)
  • Physical Exam Wrist
• External
  • Sports Medicine Review Wrist Pain: https://www.sportsmedreview.com/by-joint/wrist/

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