What are the criteria for diagnosing a Lisfranc (Lisfranc joint injury) fracture of the foot?

Diagnostic Criteria for Lisfranc Fracture of the Foot

Radiographic evaluation with weight-bearing views is the cornerstone of diagnosing Lisfranc injuries, with specific attention to diastasis between the first and second metatarsal bases and the presence of the "fleck" sign. 1

Clinical Presentation and Initial Assessment

• Pain, swelling, and inability to bear weight are typical presenting symptoms of Lisfranc injuries 2
• Plantar ecchymosis in the midfoot region is highly characteristic of Lisfranc injuries 3
• Up to 20% of Lisfranc injuries are initially missed or diagnosed late, particularly in low-energy trauma cases 3, 4
• Palpation along the tarsometatarsal articulations elicits pain, and applied force may cause medial or lateral pain 2

Radiographic Criteria for Diagnosis

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

Key Diagnostic Findings

• Diastasis (widening) between the bases of the first and second metatarsals is a classic radiographic sign 5
• The "fleck sign" - a small bone fragment in the space between the base of the first and second metatarsals - represents an avulsion fracture of the Lisfranc ligament 5
• Loss of alignment between the medial border of the second metatarsal and the medial border of the middle cuneiform on anteroposterior views 3, 6
• Displacement of the metatarsal bases from their respective cuneiforms 3, 4

Advanced Imaging

• When radiographs are normal but clinical suspicion remains high, further imaging is warranted 1
• CT is recommended for evaluating the true extent of osseous injury and detecting nondisplaced fractures 1
• 3D CT and multiplanar reconstructions provide detailed anatomic information for surgical planning 5
• MRI is the gold standard for evaluating ligamentous injuries, especially the Lisfranc ligament complex 3, 6
• MRI shows high correlation with intraoperative findings for unstable Lisfranc injuries 1

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
• Failing to obtain additional imaging when clinical suspicion remains high despite normal initial radiographs 3, 6
• Not considering Lisfranc injury in patients with midfoot pain following seemingly minor trauma 2
• Overlooking subtle alignment abnormalities that may indicate significant ligamentous injury 3, 4