What are the complications and treatment options for a lunate bone collapse after a crush injury?

Complications of Lunate Bone Collapse After Crush Injury

Lunate bone collapse following crush injury can lead to significant morbidity including compartment syndrome, avascular necrosis, carpal instability, and progressive wrist arthritis if not properly managed. Early recognition and appropriate intervention are essential to prevent long-term functional impairment.

Major Complications

Immediate Complications

• Compartment Syndrome

  • Presents with the "6 Ps": pain, paresthesia, paresis, pain with passive stretch, pink color, and pulselessness 1
  • Requires immediate fasciotomy when intracompartmental pressures reach ≥30 mmHg in normotensive patients or ≥20 mmHg in hypotensive patients 1
  • Delayed recognition can lead to irreversible tissue damage and functional impairment 1

• Rhabdomyolysis

  • Indicated by CPK levels >5 times normal (approximately 1000 IU/L) 2
  • CPK levels >75,000 IU/L associated with >80% risk of acute kidney injury 2
  • Requires aggressive fluid resuscitation with 0.9% saline (avoid potassium-containing fluids) 1

Intermediate Complications

• Avascular Necrosis (Kienböck's Disease)

  • Results from disruption of blood supply to the lunate 3
  • Precarious vascularization dependent on capsular arterioles 3
  • Can lead to lunate collapse and progressive wrist degeneration 3, 4

• Carpal Instability

  • May present as scapholunate diastasis (>4 mm) or dorsal intercalated segmental instability 2
  • Can result in abnormal wrist mechanics and accelerated arthritis 5

Late Complications

• Wrist Arthritis

  • Progressive degeneration of radiocarpal and midcarpal joints 4
  • Results in chronic pain, decreased grip strength, and limited range of motion 3
  • May eventually require salvage procedures like proximal row carpectomy or wrist fusion 4

• Carpal Tunnel Syndrome

  • Compression of median nerve due to edema or altered carpal mechanics 5
  • Presents with numbness, tingling, and weakness in median nerve distribution

Diagnostic Approach

Initial Assessment

• Radiography
  • First-line imaging but may be normal in early stages 4
  • Look for lunate sclerosis, fracture, or collapse 4

Advanced Imaging

• CT/CT Arthrography

  • Superior for detecting fractures and evaluating carpal alignment 2
  • CT arthrography has nearly 100% sensitivity and specificity for scapholunate ligament tears 2

• MRI

  • Essential for early diagnosis when radiographs appear normal 4
  • Can detect avascular necrosis before radiographic changes 4
  • Useful for evaluating ligamentous injuries and bone viability 2

Treatment Algorithm

Stage I (Normal Radiographs, MRI Shows Edema)

• Immobilization with wrist splint
• Anti-inflammatory medications
• Activity modification
• Monitor for progression

Stage II (Sclerosis and Early Collapse)

• Surgical Options:
  • Lunate decompression procedures
  • Revascularization with vascularized bone grafting 3, 4
  • Radial shortening osteotomy (for negative ulnar variance) 4
  • Capitate shortening or radial-wedge osteotomy (for neutral/positive ulnar variance) 4

Stage III (Severe Collapse with Carpal Malalignment)

• Surgical Options:
  • Scaphotrapeziotrapezoid or scaphocapitate arthrodesis 4
  • Open reduction with internal fixation for acute dislocations 5, 6
  • Percutaneous screw repair under arthroscopy for fracture fragments 7

Stage IV (Degenerative Changes)

• Salvage Procedures:
  • Proximal row carpectomy
  • Partial or total wrist arthrodesis 4
  • Wrist arthroplasty in select cases

Prevention of Complications

• Early recognition and treatment of compartment syndrome (assess every 30-60 minutes in first 24 hours) 2
• Aggressive fluid resuscitation for rhabdomyolysis (3-6L/day for moderate cases, >6L for severe cases) 2
• Avoid premature closure of wounds in crush injuries 1
• Regular neurovascular assessment during the acute phase 1
• Early mobilization after appropriate stabilization to prevent stiffness 7

Pitfalls to Avoid

• Relying solely on radiographs for early diagnosis
• Delaying fasciotomy when compartment syndrome is suspected
• Inadequate fluid resuscitation in rhabdomyolysis
• Overlooking associated ligamentous injuries
• Failing to recognize progressive carpal collapse requiring intervention

The prognosis depends on the severity of initial injury, timing of intervention, and presence of complications, with early appropriate management offering the best chance for preserving wrist function and preventing long-term disability.