What is the diagnosis and treatment for a Lisfranc (midfoot) fracture?

Diagnosis and Treatment of Lisfranc (Midfoot) Fractures

Lisfranc injuries require standard radiographs as first-line imaging, followed by CT and/or MRI for definitive diagnosis, with treatment determined by stability - stable injuries can be managed conservatively while unstable injuries require surgical fixation to prevent long-term disability. 1

Diagnosis

Clinical Assessment

• Look for midfoot swelling, pain, and plantar ecchymosis (highly characteristic sign) 2
• Specific clinical tests:
  • Apply dorsomedial to plantar-lateral force across the 1st metatarsal base (positive test indicates hypermobility) 1
  • Evaluate sagittal plane motion (>4 degrees indicates hypermobility) 1
  • Assess transverse plane motion (>8 degrees indicates hypermobility) 1

Imaging Protocol

1. Initial Imaging: Three-view radiographic study (anteroposterior, oblique, lateral) 3, 1

   • Add AP view with 20° craniocaudal angulation for suspected Lisfranc injury 3
   • Weight-bearing radiographs are crucial as they increase visibility of abnormal alignment 3, 1
   • Include both feet on AP radiographs to compare with uninjured side 3

2. Advanced Imaging:

   • CT scan: Essential for detecting non-displaced fractures (25% of midfoot fractures are missed on radiographs) 1

     • Weightbearing CT provides functional assessment of instability under physiologic load 1
     • Particularly important for preoperative planning and polytrauma cases 3, 1

   • MRI: Gold standard for ligamentous injuries 1, 2

     • Most sensitive for occult fractures and bone stress changes 1
     • Indicated when radiographs are normal but clinical suspicion remains high 1

Caution: Up to 20% of Lisfranc injuries are initially missed or diagnosed late, especially low-energy trauma that may be mistaken for simple midfoot sprains 2, 4

Treatment

Classification-Based Management

Treatment depends on stability and displacement:

1. Stable, Undisplaced Injuries (Stage I):

   • Conservative management 2, 5
   • Non-weightbearing immobilization for 6 weeks 1, 2
   • Immobilization options (in order of preference):
     • Non-removable knee-high total contact cast (first-line) 1
     • Pre-fabricated knee-high walker (second-line) 1
     • Removable knee-high device (third-line) 1

2. Unstable or Displaced Injuries (Stage II/III):

   • Surgical intervention required 1, 2, 4
   • Surgical options:
     • Open reduction and internal fixation (ORIF) with transarticular screws 1, 4
     • Dorsal plate fixation (preferred for comminuted fractures) 4
     • Primary arthrodesis in certain cases 4
     • Percutaneous screw fixation (minimally invasive option) 1

Post-Treatment Protocol

• Non-weightbearing for 6 weeks post-treatment 1
• Partial progressive weightbearing with arch support from weeks 6-12 1
• Full weightbearing and return to activity at 12-16 weeks 1
• Long-term use of appropriate footwear and orthoses 1

Potential Complications

• Post-traumatic osteoarthritis (occurs in up to 45% of cases despite appropriate treatment) 1, 2
• Chronic pain and foot deformities 2, 4
• Hardware failure and loss of reduction 1

Key to Success: Anatomical reduction is the major determinant of good long-term outcomes 1, 4. Early detection and appropriate management are essential to prevent progression to arthritis and long-term disability 1.

Follow-up

• Regular clinical and radiographic follow-up to ensure proper alignment and healing 1
• Long-term monitoring for development of post-traumatic arthritis 1
• Functional rehabilitation once healing permits 1