Understanding Lisfranc Complex Injuries: A Comprehensive Guide
Lisfranc injuries refer to a spectrum of trauma affecting the midfoot and tarsometatarsal (TMT) joints, ranging from ligamentous sprains to more severe fractures and dislocations. These injuries are often overlooked or misdiagnosed, particularly in cases with low-energy trauma. If left untreated or improperly managed, Lisfranc injuries can lead to chronic pain, post-traumatic osteoarthritis (OA), and permanent disability. This article provides an in-depth look at Lisfranc injuries, covering their anatomy, mechanisms of injury, diagnosis, treatment options, and potential outcomes.
Anatomy of the Lisfranc Joint
The Lisfranc joint complex consists of the three cuneiform bones (C1-C3) and the cuboid bone (Cu) proximally, along with the five metatarsal bases (M1-M5) distally. These bones are connected by a ligamentous capsule, forming a complex structure that provides stability to the midfoot. The joint is divided into three longitudinal columns:
- Medial column – Comprised of the first cuneiform (C1) and the first metatarsal (M1).
- Central column – Involving the second and third cuneiforms (C2, C3) along with the second and third metatarsals (M2, M3).
- Lateral column – Composed of the cuboid (Cu) and the fourth and fifth metatarsals (M4, M5).
The stability of the Lisfranc joint is largely attributed to the trapezoidal shape of the metatarsal bases, which form a stable “transverse arch” (or Roman arch) with the second TMT joint acting as the keystone. The ligaments surrounding the joint include dorsal, plantar, and interosseous ligaments, with the Lisfranc ligament (interosseous ligament) being the most critical for maintaining stability.
Causes and Mechanisms of Injury
Lisfranc injuries can be caused by both direct and indirect trauma.
- Direct trauma often results from crush injuries or falls from height, leading to severe soft tissue damage and potential neurovascular compromise.
- Indirect trauma is more common in athletes and occurs when the foot is subjected to excessive bending, twisting, or rotation forces. This typically results in sprains or fractures of the tarsometatarsal joints.
These injuries are commonly seen in sports activities such as football, gymnastics, and running, as well as in falls or high-impact accidents.
Clinical Presentation
Patients with Lisfranc injuries usually present with midfoot swelling and pain, particularly during weight-bearing activities. A hallmark sign of Lisfranc injury is plantar ecchymosis (bruising) in the foot’s bottom, which is highly suggestive of the condition. Severe cases may present with visible deformity, and the patient may be unable to bear weight on the affected foot.
In less severe cases, symptoms can be subtler, making diagnosis challenging. The “piano key” test and “gap sign” are useful clinical maneuvers for diagnosing Lisfranc injuries, with the gap sign indicating separation between the first and second metatarsals.
Diagnosis
Imaging is crucial for diagnosing Lisfranc injuries:
- X-rays: The first-line imaging tool, typically performed in three projections (anteroposterior, oblique, and lateral). X-rays help identify misalignment between the cuneiforms and metatarsals, displacement, or fractures.
- CT scans: Useful for detecting subtle fractures or joint misalignments not visible on X-ray, especially in high-energy injuries.
- MRI: The gold standard for diagnosing ligamentous injuries, such as damage to the Lisfranc ligament.
Classification of Lisfranc Injuries
Lisfranc injuries are classified based on their severity and the structures involved. The Hardcastle classification (A, B, C) is the most commonly used:
- Type A: Complete displacement of all metatarsals in one direction.
- Type B: Partial dislocation with one or more metatarsals displaced.
- Type C: A divergent pattern of injury affecting multiple TMT joints.
More recently, Myerson and other authors have further refined these classifications to better account for the complexity of these injuries, especially with respect to ligament and bone involvement.
Management of Lisfranc Injuries
The treatment of Lisfranc injuries depends on the severity and type of injury.
Non-Surgical Treatment
Stable, non-displaced injuries can often be treated conservatively with immobilization in a non-weight-bearing cast for 6 weeks. If the pain persists, further immobilization with a weight-bearing orthotic may be required. Early mobilization and physical therapy are essential to ensure a full recovery and prevent long-term disability.
Surgical Treatment
Surgical intervention is necessary for displaced or unstable injuries to achieve anatomical reduction and restore joint stability. There are various surgical options, including:
- Open Reduction and Internal Fixation (ORIF): A common surgical approach where screws or plates are used to stabilize the bones.
- Primary Arthrodesis (PA): In severe cases, particularly when there is significant joint damage, primary fusion of the joint may be performed to prevent long-term arthritis and deformity.
The choice between ORIF and PA depends on the nature of the injury, with PA offering better outcomes in patients with severe joint damage.
Complications
Missed or inadequately treated Lisfranc injuries can lead to serious complications, including:
- Post-traumatic arthritis: A common outcome, especially in cases treated with ORIF, where up to 94% of patients may develop arthritis.
- Joint instability: If anatomical reduction is not achieved, the foot may remain unstable, leading to long-term disability.
Conclusion
Lisfranc injuries are complex and can vary greatly in severity. Early diagnosis and prompt treatment are crucial for minimizing long-term disability and optimizing functional outcomes. While non-surgical treatment is effective for stable, non-displaced injuries, surgical intervention is necessary for more severe cases to restore foot function and prevent complications. Understanding the anatomy, classification, and treatment options for Lisfranc injuries is essential for orthopedic professionals in managing these challenging cases effectively.
