What are the diagnostic features and treatment options for a scapholunate injury visible on an image?

Diagnostic Features and Treatment Options for Scapholunate Injury

CT arthrography is the gold standard for diagnosing scapholunate ligament tears with nearly 100% sensitivity, specificity, and accuracy, and should be the preferred advanced imaging modality when conventional radiographs do not show carpal malalignment. 1

Diagnostic Features

Initial Radiographic Evaluation

• Conventional radiographs with careful attention to positioning are the first-line imaging for suspected scapholunate injuries 1, 2
• Key radiographic findings include:
  • Scapholunate diastasis >4 mm (widening of the gap between scaphoid and lunate) 1, 2
  • Dorsal tilt of the lunate >10° suggesting dorsal intercalated segmental instability (DISI) 1, 2
• In low-grade injuries, radiographs are often normal 1, 2

Advanced Imaging Options

CT Arthrography (Highest Accuracy)

• Provides the highest sensitivity (nearly 100%), specificity, and accuracy for detecting scapholunate ligament tears 1, 2
• Superior for detecting partial ligament tears compared to MRI 1
• More accurate for detecting tears of the biomechanically important dorsal ligament fibers 2

MRI

• Commonly used with reported sensitivities of 65-89% for scapholunate ligament tears 2
• 3T MRI offers better sensitivity than 1.5T for interosseous ligament tears 1
• Shows concomitant ligament injuries that may affect surgical treatment 1
• Particularly useful for evaluating soft-tissue injuries including collateral ligaments, volar plates, tendons, and pulleys 1

MR Arthrography

• More accurate than non-contrast MRI for determining which specific segments of the ligament are torn 2
• Both CT arthrography and MR arthrography have very high accuracy for diagnosing tears 1

Ultrasound

• Limited utility for scapholunate injuries 1
• Dynamic "clenched fist" maneuvers can improve diagnostic yield 2

Treatment Options

Based on Injury Stage

Acute Injuries

• Anatomic repair of the torn ligament usually leads to satisfactory results 3
• Many surgeons augment the repair with a capsulodesis technique 3
• Provisional fixation with K-wires to maintain reduction during healing 4

Chronic Injuries with Reducible Malalignment

• Ligament reconstruction using free or pedicled tendon graft 3, 5
• All-dorsal scapholunate reconstruction technique when the carpus is reducible and no arthrosis is present 4
• Outcomes include:
  • Wrist range of motion typically 55-75% of the contralateral side 4
  • Grip strength approximately 65% of the contralateral side 4
  • 50-60% of patients with physical labor jobs able to return to same level of work 4

Chronic Injuries with Static Malalignment

• More complex reconstructive procedures with generally inferior outcomes 3
• Scapho-trapezio-trapezoid arthrodesis may be considered to restore the stabilizing function of the scaphoid 5

Advanced Disease with Cartilage Loss (SLAC Wrist)

• Salvage procedures tailored to the degree of arthritis 3
• Options include proximal row carpectomy or partial/complete wrist arthrodesis 6, 3

Post-operative Management

• Immobilization until K-wires are removed (typically 8-12 weeks) 4
• Rehabilitation to restore strength and range of motion 4

Pitfalls and Caveats

• Delayed diagnosis and treatment lead to inferior outcomes 4
• Poor carpal alignment following reduction increases risk of treatment failure 4
• Even with technically successful repair, patients may experience permanent wrist stiffness and possible recurrent scapholunate diastasis 4
• MRI performed immediately at the time of injury has little added value for determining which patients require surgery 1
• Natural history is poorly understood; it remains unknown which and how many scapholunate injuries progress to wrist arthritis (SLAC wrist) 3