Thursday, October 6, 2011

Scapholunate ligament tear - MRI

Radiograph of wrist in 45 Year old male patient with pain in the wrist joint showing widened scapholunate joint space with focal periosteal elevation in the lunate (arrow).

Coronal PD FS image showing complete tear in the scapholunate ligament with mild marrow edema in the scaphoid and lunate bones.

Coronal GRE image well depicts the ligament tear (arrow).
Discussion:

  • Most common and most significant ligament injury of wrist causing carpal instability.
  • Risk factors: ulna minus configuation, slope of radial articular surface, and lunotriquetral coalition.
Spectrum of injury include: (increasing severity)
1. Dynamic scapholunate instability
  • No radiographic evidence of malalignment is present (ie dynamic deformity); 
  • Diagnosis is established by dorsal S-L tenderness and positive shift test; 
2. Rotatory subluxation of scaphoid:
3. Scapholunate dissociation (SLD):

  • SL ligament tear may lead to rotational dislocation of scaphoid allowing proximal pole to displace posteriorly & distal pole to displace anteriorly.
  • Scaphoid inherently tends to palmar flex because of its oblique position and the loading applied through (STT) joint.
  • Because scaphoid lacks proximal of ligament, it will rotate around radiocaptitate ligament leading to dorsal rotary subluxation of the proximal pole.
4. Dorsal intercalated segment instability: (DISI) 
5. Scapholunate advanced collapse:

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