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Scapholunate Instability

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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)

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

Pathophysiology


Risk Factors

  • Ulna minus configuation[1]
  • Slope of radial articular surface
  • Lunotriquetral coalition

Differential Diagnosis


Clinical Features


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

Classification

Geissler's Classification[2]

  • Grade I
    • Attenuation and/or hemorrhage of the interosseous ligament as observed from RC space.
    • No incongruence of carpal alignment in MC space
    • Treatment: immobilization
  • Grade II
    • Attenuation and/or hemorrhage of the interosseous ligament as observed from RC space
    • Incongruence and/or step-off as observed from MC joint
    • A slight gap (less than the width of a probe, < 2 mm) between the carpal bones may be present
    • Treatment: reduction and pinning
  • Grade III
    • Incongruence and/or step-off of the carpal alignment are observed in both the RC, MC space
    • The probe may rotate and pass through the gap (> 2 mm) between the carpal bones
    • Treatment: arthroscopic reduction or open reduction and pinning or repair
  • Grade IV
    • Incongruence and/or step-off of the carpal alignment are observed in both the RC, MC space
    • Gross instability with manipulation is noted
    • Drive through phenomena: A 2.7-mm arthroscope may be passed through the gap between the bones
    • Treatment: open re-insertion or ligament reconstruction

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

Return to Play

  • At the discretion of the surgeon

Complications

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

See Also


References

  1. http://www.wheelessonline.com/ortho/scapholunate_instability
  2. Geissler WB, Freeland AE, Savoie FH, McIntyre LW, Whipple TL. Intracarpal soft-tissue lesions associated with an intra-articular fracture of the distal end of the radius. J Bone Joint Surg [Am] 1996;78-A:357-365.
Created by:
John Kiel on 18 June 2019 23:12:13
Authors:
Last edited:
27 December 2023 22:21:27
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