Lisfranc Fracture: Definition and Clinical Overview
A Lisfranc fracture is a midfoot injury involving the tarsometatarsal (TMT) joint complex where one or more metatarsals are displaced from the tarsus, encompassing a spectrum from purely ligamentous injuries in low-energy trauma to fracture-dislocations in high-energy mechanisms. 1, 2
Anatomical Definition and Injury Patterns
- The injury centers on the second tarsometatarsal joint and involves disruption of the Lisfranc ligamentous complex, which connects the medial cuneiform to the base of the second metatarsal 1, 3
- The injury spectrum ranges from subtle ligamentous sprains without diastasis to complete fracture-dislocations with multiple metatarsal and cuneiform fractures 4, 2
- Purely ligamentous injuries occur more commonly in low-energy trauma, while bone fracture-dislocations result from high-energy mechanisms like motor vehicle accidents or falls from height 2, 5
Mechanism of Injury
- Low-energy trauma typically occurs during sports activities with indirect force applied to a plantarflexed foot, often mistaken for simple midfoot sprains 2, 6
- High-energy trauma results from direct crushing forces or axial loading of the foot in plantarflexion, commonly seen in polytrauma patients 4, 2
- Acute hyperflexion injuries represent a specific mechanism requiring heightened diagnostic vigilance 4, 1
Clinical Presentation
- Patients present with evident midfoot swelling and pain, often with palpable joint instability 2
- Plantar ecchymosis is highly characteristic and should raise immediate suspicion for Lisfranc injury 2
- The injury is more frequent in men and typically occurs in the third decade of life 2
Diagnostic Challenges and Pitfalls
- Up to 20% of Lisfranc fractures are initially missed or diagnosed late, particularly low-energy injuries that are mistaken for simple sprains 2, 6
- Radiographs demonstrate moderate to poor sensitivity (25%-33%) for detecting midfoot fractures in Level 1 trauma patients 4
- In polytrauma patients, approximately 25% of midfoot fractures identified on CT are overlooked on plain radiographs 1
- Non-weight-bearing radiographs are unreliable for detecting subtle injuries and should not be relied upon exclusively 1, 7
Key Radiographic Signs
- Look for diastasis (widening) between the first and second metatarsal bases on weight-bearing anteroposterior views 1
- The "fleck" sign—a small avulsion fracture fragment between the first and second metatarsal bases—indicates ligamentous disruption 1
- Subtle malalignment is best detected by comparing bilateral feet on the same anteroposterior radiograph 1, 7
Consequences of Missed Diagnosis
- Delayed or missed diagnosis leads to devastating complications including progressive midfoot instability, arch collapse, forefoot abduction, and post-traumatic osteoarthritis 2, 5
- These complications result in chronic pain, stiffness, foot deformities, and significant long-term disability 8, 2
- Post-traumatic arthritis occurs in approximately 25% of cases despite anatomic reduction, but rates are much higher with missed injuries 8