http://upload.orthobullets.com/topic/6041/images/DISI - AP - Terry Thomas sign and cortical ring_moved.jpg
http://upload.orthobullets.com/topic/6041/images/reivew clenched fist.jpg
http://upload.orthobullets.com/topic/6041/images/gw300h551..jpg
http://upload.orthobullets.com/topic/6041/images/DISI - lateral_moved.jpg
http://upload.orthobullets.com/topic/6041/images/gw275h550..jpg
Introduction
  • Scapholunate ligament is important for carpal stability
    • chronic scapholunate deficiency leads to DISI (see below)
  • Epidemiology
    • incidence
      • acute injury
        • occurs in approximately 10-30% of intra-articular distal radius fractures or carpal fractures
      • degenerative injury
        • degenerative tears in >50% of people over the age of 80 years old
    • location
      • ligament has 3 components that span between the scaphoid and lunate bones
      • dorsal, proximal and volar components
      • incomplete tears > complete tears
  • Pathophysiology
    • mechanism of injury
      • sudden impact force applied to the hand and wrist causing SLIL injury and scapholunate dissociation
      • injury occurs most commonly with wrist positioned in extension, ulnar deviation and carpal supination
    • pathoanatomy
      • osseous 
        • SLIL tearing will position the scaphoid in flexion and lunate extension
      • ligamentous
        • diastasis of the scapholunate complex occurs with complete SLIL tears and capsule disruption.
  • Associated injuries
    • DISI (dorsal intercalated segmental instability)
      • scapholunate dissociation causes the scaphoid to flex palmar and the lunate to dorsiflex
      • if left untreated the DISI deformity can progress into a SLAC wrist topic
      • DISI is a form of carpal instability dissociative  
Anatomy
  • Scapholunate interosseous ligament
    • location
      • c-shaped structure connecting the dorsal, proximal and volar surfaces of the scaphoid and lunate bones
      • dorsal fiber thickened (2-3mm) compared to volar fibers
    • biomechanics
      • dorsal component provides the greatest constraint to translation between the scaphoid and lunate bones
      • proximal fibers have minimal mechanical strength
  • Overview of wrist ligaments and biomechanics 
Presentation
  • History
    • acute FOOSH injury vs. degenerative rupture 
      • age, nature of injury, duration since injury, degree of underlying arthritis, level of activity
  • Symptoms
    • usually dorsal and radial-sided wrist pain
    • pain increased with loading across the wrist (e.g. push up position)
    • clicking or catching in the wrist
    • may be associated with wrist instability or weakness
  • Physical exam
    • inspection
      • may see swelling over the dorsal aspect of the wrist 
    • palpation
      • tenderness in the anatomical snuffbox or over the dorsal scapholunate interval (just distal to Lister's tubercle)
    • motion
      • pain increased with extreme wrist extension and radial deviation
    • provocative tests
      • Watson test post
        • when deviating from ulnar to radial, pressure over volar aspect of scaphoid produces a clunk secondary to dorsal subluxation of the scaphoid over the dorsal rim of the radius
          • dorsal wrist pain or a clunk during this maneuver may indicate instability of scapholunate ligament
Imaging
  • Radiographs
    • recommended views
      • AP and lateral views of the wrist
    • additional views
      • radial and ulnar deviation views
      • flexion and extension views 
      • clenched fist  (can attenuate the diastasis)
    • findings
      • AP radiographs
        • SL gap > 3mm with clenched fist view (Terry Thomas sign)  
        • cortical ring sign (caused by scaphoid malalignment)  
        • humpback deformity with DISI associated with an unstable scaphoid fracture
        • scaphoid shortening
      • Lateral radiographs
        • dorsal tilt of lunate leads to SL angle > 70° on neutral rotation lateral 
        • capitolunate angle > 20°
      • DISI
        • normal carpal alignment  
        • increased SL angle  
  • Arthrography
    • indications
      • may be used as screening tool for arthroscopy
    • views
      • radiocarpal and midcarpal views
      • always assess the contralateral wrist for comparison
    • findings
      • may demonstrate the presence of a tear but cannot determine the size of the tear
      • positive finding of a tear may indicate the need for wrist arthroscopy
  • MRI
    • indications
      • often overused as a screening modality for SLIL tears
    • findings
      • requires careful inspection of the SLIL by a dedicated radiologist to confirm diagnosis
      • low sensitivity for tears
  • Arthroscopy
    • indications
      • considered the gold standard for diagnosis
Treatment
  • Nonoperative
    • NSAIDS, rest +/- immobilization 
      • indications
        • acute, undisplaced SLIL injuries
        • chronic, asymptomatic tears
      • technique
        • splinting and close follow-up with repeat imaging and clinical response with acute injuries
      • outcomes
        • most people feel casting alone is insufficient
        • may be effective with incomplete tears
  • Operative
    • scapholunate ligament repair
      • indications
        • acute scapholunate ligament injury without carpal malalignment 
        • chronic but reducible scapholunate ligament injuries (can peform if 18 months from the time of injury)
        • ligament pathoanatomy is ammenable to repair
    • scapholunate reconstruction
      • indications
        • acute scapholunate ligament injury without carpal malalignment where pathoanatomy is not ammenable to repair
        • reducible scapholunate ligament injuries > 18 months from the time of injury
    • scaphoid ORIF vs. CRPP (+/- arthroscopic assistance)
      • indications
        • f pathoanatomy of SL ligament injury is a scaphoid fx than repair with ORIF vs. CRPP (+/- arthroscopic assistance)
    • stabilization with wrist fusion (STT or SLC)
      • indications
        • rigid and unreducible DISI deformity
        • DISI with severe DJD
      • technique
        • scaphotrapezialtrapezoidal (STT) fusion
        • scapholunocapitate (SLC) fusion
        • scapholunate fusion alone has highest nonunion rate 
Technique
  • Scapholunate ligament direct repair SLIL with k-wires
    • approach
      • small incision is made just distal to the radial styloid
      • care to avoid cutting the radial sensory nerve branches
    • methods
      • SL joint pinning with k-wires
      • suture anchors with k-wires
      • Blatt dorsal capsulodesis 
        • often added to a ligament repair and remains a viable alternative for a chronic instability when ligament repair is not feasible
    • repair technique
      • place two k-wires in parallel into the scaphoid bone
      • reduce the SL joint by levering the scaphoid into extension, supination and ulnar deviation and lunate into flexion and radial deviation
      • pass the k wires into the lunate
      • confirm reduction of the SL joint under fluoroscopy
      • place patient in short arm cast
    • post-operative care
      • remove k-wires in 8-10 weeks
      • no heavy labor for 4-6 months
  • Scapholunate ligament reconstruction
    • approach
      • same as for repair
    • reconstruction
      • FCR tendon transfer (direct SL joint reduction)
      • ECRB tendonosis (indirect SL joint reduction)
      • weave not recommended due to high incidence of late failure
Complications
  • Disease progression (e.g. SLAC wrist)
  • Arthritis
  • Post-operative pain, stiffness, fatigue
  • Reduced grip strength
 

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Questions (1)

(SBQ07.38) A 32-year-old professional baseball player presents with wrist pain after a fall on his outstretched wrist 10 days ago. He initially thought it was a sprain, but presents due to continued pain worsened by push-ups. His physical exam shows dorsal wrist tenderness and is positive for the provocative test shown in Figure V. Standard PA radiograph of the wrist is normal. Which of the following radiographic views shown in Figures A to E would be most helpful in establishing the diagnosis? Review Topic

QID:1423
FIGURES:
1

A

75%

(1025/1373)

2

B

9%

(121/1373)

3

C

9%

(121/1373)

4

D

4%

(61/1373)

5

E

3%

(36/1373)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The clinical description and video of the patient's physical exam are consistent with an acute scapho-lunate ligament tear. The video shown in the question stem demonstrates the Watson test. When positive, the patient will feel dorsal wrist pain and/or a "clunk" when the wrist is brought from extension/ulnar deviation to radial deviation. If plain radiographs are normal, a PA clenched fist radiograph as seen in Figure A should be performed.

In patients with a acute scapho-lunate ligament tear, initial radiographs may not show the characteristic "Terry Thomas" sign, or widening of the SL gap > 3mm. When making a clenched fist, the capitate is drawn proximally, stressing the SL ligament. This is an easy view to obtain during the initial patient visit and should strongly be considered if this diagnosis is suspected.

Walsh et al review the various aspects of scapholunate ligament injuries. While they agree imaging is helpful in establishing the diagnosis, they emphasize that wrist arthroscopy is the gold standard in the diagnosis of SL injuries.

Illustration A shows demonstrates a clenched fist view with obvious widening of the scapho-lunate gap.

Incorrect Answers
Answer 2: Shows a lateral radiograph in 30 degrees of supination. It is excellent for assessment of pisotriquetral arthrosis.
Answer 3: Shows a PA of the wrist in radial deviation. This view will actually close the SL gap.
Answer 4: Shows a a carpal tunnel view, used for assessment of hook of hamate fractures.
Answer 5: Shows a a stardard PA wrist in neutral aligment.

ILLUSTRATIONS:

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