What are the criteria for diagnosing a Lisfranc injury?

Diagnostic Criteria for Lisfranc Injury

Lisfranc injuries require a comprehensive imaging approach, with weight-bearing radiographs as the initial step, followed by advanced imaging such as CT or MRI when radiographic findings are inconclusive but clinical suspicion remains high. 1

Clinical Presentation

• Patients typically present with midfoot pain, swelling, and ecchymosis 2
• Even subtle injuries can result in significant morbidity if not properly diagnosed and treated 2
• Lisfranc injuries range from simple capsular ruptures to complex fracture-dislocations 3

Initial Radiographic Evaluation

• Three-view radiographic study (anteroposterior, oblique, and lateral) should be the first imaging modality 1
• Weight-bearing radiographs are essential as non-weight-bearing images are unreliable for detecting subtle injuries 1, 4
• An additional anteroposterior view with 20° craniocaudal angulation improves visualization of the Lisfranc joint 1
• Bilateral imaging with both feet on anteroposterior radiographs helps detect subtle malalignment when compared to the uninjured side 1

Key Radiographic Findings

• Diastasis between the first and second metatarsal bases 1
• Presence of the "fleck" sign (small avulsion fracture at the Lisfranc ligament attachment) 1
• Displacement of one or more metatarsals from the tarsus 5
• Conventional radiographs including weightbearing images are not sufficient for routine diagnostic workup of acute hyperflexion injuries 6

Advanced Imaging

• When radiographs are normal but clinical suspicion remains high, further imaging is warranted 1, 7
• CT is recommended as the primary imaging technique for:
  • Acute hyperflexion injuries 6
  • High-energy polytrauma 6
  • Patients unable to bear weight 6
  • Demonstrating multiple metatarsal and cuneiform fractures associated with ligamentous Lisfranc injury 6
• MRI is indicated for:
  • Evaluation of the Lisfranc ligamentous complex when radiographs are normal but clinical suspicion remains high 6, 1
  • Direct visualization of ligamentous injuries 3
  • 3-D volumetric acquisitions have proven superiority over orthogonal proton density fat-suppressed imaging 6
  • High correlation with intraoperative findings for unstable Lisfranc injuries 6, 4

Special Considerations

• In polytrauma patients, approximately 25% of midfoot fractures identified on CT are overlooked on radiographs 1
• Patients with neuropathy require special attention as they may be able to bear weight despite fractures 1
• Purely ligamentous injuries without diastasis are particularly challenging to diagnose and may require MRI 1
• Ultrasound may have a limited role in Lisfranc injury evaluation but is not considered a primary diagnostic tool 1

Common Pitfalls to Avoid

• Relying solely on non-weight-bearing radiographs can lead to missed diagnoses 1
• Delay in diagnosis has a negative impact on outcome 7
• Failure to obtain advanced imaging when radiographs are inconclusive but clinical suspicion remains high 2
• Overlooking subtle injuries that can lead to chronic pain, mobility challenges, and post-traumatic osteoarthritis 2, 8

Diagnostic Algorithm

1. Initial assessment with weight-bearing three-view radiographs when possible 1
2. If radiographs are inconclusive but clinical suspicion remains:
   • Obtain CT for detailed osseous evaluation and detection of nondisplaced fractures 1, 2
   • Consider MRI for direct visualization of ligamentous injuries 1, 3
3. Assess stability with weight-bearing radiographs when possible 7
4. Consult orthopedic surgery for all diagnosed Lisfranc injuries 2