What is the recommended treatment for scapholunate ligament disruption and dissociation with a scapholunate distance of 6.42 mm?

Treatment of Scapholunate Ligament Disruption with 6.42 mm Diastasis

Surgical reconstruction is indicated for this scapholunate ligament disruption, as the scapholunate distance of 6.42 mm exceeds the 4 mm threshold for static instability and requires operative intervention to prevent progressive carpal collapse and arthritis. 1

Severity Assessment and Surgical Indication

Your imaging findings demonstrate static scapholunate dissociation requiring surgical treatment:

• Scapholunate diastasis >4 mm indicates static instability with complete ligament disruption, which mandates operative intervention rather than conservative management 1
• The 6.42 mm gap represents significant carpal malalignment that will not heal with immobilization alone 2
• Untreated chronic scapholunate dissociation leads to scapholunate advanced collapse (SLAC) and progressive painful wrist arthritis 3, 2

Recommended Surgical Approach

The optimal treatment is open reduction with scapholunate ligament reconstruction using either dorsal capsulodesis or tenodesis techniques, provided the carpus remains reducible and no secondary osteoarthritis has developed 4, 3, 5:

Primary Reconstruction Options

• All-dorsal scapholunate reconstruction using suture tape or bone-ligament-bone repair to stabilize the scaphoid and lunate in their anatomic position 4
• Dorsal intercarpal ligament (DICL) capsulodesis that transfers the DICL proximally to reinforce the dorsal scapholunate interosseous ligament 5
• Extensor carpi radialis longus (ECRL) tenodesis combined with dorsal capsulodesis for chronic cases where native ligament tissue is insufficient 3

Surgical Technique Components

The procedure requires several critical steps 4, 5:

• Dorsal approach with ligament-sparing capsulotomy to visualize the carpus
• Joystick pin reduction of the scaphoid and lunate to correct carpal malalignment
• Temporary K-wire fixation across scapholunate, lunotriquetral, and midcarpal joints using 0.062-inch wires 4
• Ligament reconstruction using available dorsal ligament remnant reinforced with capsulodesis or tenodesis 5
• Extended carpal tunnel release volarly to aid reduction and decompress the median nerve 4

Postoperative Protocol

• Immobilization for 8-12 weeks until K-wire removal 4
• Wrist brace for 3-6 months depending on occupation and activity level 5
• Gradual return to dart-throwing motion after temporary fixation removal 5

Role of Arthroscopy in Associated Injuries

Arthroscopic evaluation during surgical fixation is an option to identify and treat concomitant ligament injuries 6:

• The American Academy of Orthopaedic Surgeons recommends considering arthroscopy to improve diagnostic accuracy for associated wrist ligament injuries (lunotriquetral or TFCC tears) during surgical treatment 6
• However, this represents a weak recommendation based on limited evidence showing only short-term functional benefit at 3 months but no difference at 1-2 years 6

Expected Outcomes and Counseling Points

Patients must understand that permanent functional limitations are expected even with successful reconstruction 4:

• Wrist range of motion typically recovers to only 55-75% of the contralateral side 4
• Grip strength averages approximately 65% of the uninjured wrist 4
• DASH scores average 24-30, indicating moderate residual disability 4
• Only 50-60% of manual laborers return to full-time work at their previous level 4

Risk Factors for Poor Outcomes

Specific factors predict inferior results 4:

• Delayed surgical treatment beyond the acute/subacute period
• Poor carpal alignment following reduction
• Open injuries with soft tissue compromise

Critical Pitfall to Avoid

Do not attempt conservative management with immobilization alone for this degree of scapholunate dissociation 2:

• While judicious use of wrist splinting may be considered for dynamic instability in elite athletes during competition season, static instability with >4 mm diastasis requires aggressive surgical treatment to prevent inevitable progression to SLAC wrist 2
• Acute repair remains the gold standard and produces superior outcomes compared to any reconstructive procedure performed for chronic injuries 2

Alternative if Reconstruction Fails

If the carpus is not reducible or if secondary osteoarthritis is already present, wrist-salvage procedures (arthrodesis or arthroplasty) become the primary treatment rather than ligament reconstruction 4, 3.