Introduction

Midfoot injuries are often misdiagnosed, with approximately 20% of Lisfranc injuries initially being missed or mistaken for a simple sprain.  These injuries must be identified early to help prevent injury-induced midfoot arthritis, chronic pain, and chronic foot instability.³

The Lisfranc fracture is named after 19th-century French surgeon Jacques Lisfranc.  He discovered this fracture when soldiers were knocked off their horses while their feet were trapped in the stirrups. This led to a significant disruption of the foot's metatarsal bones, which was also often associated with fractures.¹

Midfoot injuries can oftentimes be more complicated than initially thought. Diagnosing these injuries is essential to ensure the patient receives the correct care. When comparing a midfoot sprain to a Lisfranc fracture, the injuries are quite different, and the consequences for not catching and diagnosing a Lisfranc fracture can be high. A midfoot sprain is often treated nonsurgically; however, a Lisfranc fracture typically requires surgery and a prolonged recovery.⁵ Many Lisfranc injuries can be misdiagnosed as a midfoot sprain initially, which can delay healing.²

Anatomy of the midfoot and Lisfranc joint

The Lisfranc joint is a complex structure comprising many small bones in the foot that form the arch.² It connects the metatarsal and tarsal bones, including the cuneiform and cuboid.³ This joint is essential to maintaining foot stability, the arch of the foot, and helping distribute force when doing weight-bearing activities such as walking and running.²  Lisfranc injuries can significantly impact the functional ability of the foot.

Mechanism of injury

Lisfranc fractures/dislocations

Lisfranc injuries commonly result from high-velocity trauma or when the foot is forced upward, outward, and twisted under significant pressure, such as body weight. Some everyday activities that can lead to this injury include playing football or other sports where the toes are pointed into the ground and the weight is placed on the heel. Injuries also commonly occur when the foot is twisted off a curb, the foot impacts a brake pedal, or the foot is braced during a motor vehicle accident.²

Midfoot sprains

While a Lisfranc injury is typically caused by high-velocity trauma, a simple midfoot sprain more commonly occurs in low-velocity traumas, such as awkward landings, missteps, or rolling or twisting the foot. While these incidents commonly occur in athletic settings, they can also happen during mundane daily activities. These injuries, although painful, are typically much less severe than a Lisfranc injury.³

Clinical presentation

Shared symptoms

A sprain and a Lisfranc injury present with pain in the middle of the foot, swelling, and pain while walking. Here, we will explore the key differences between these two diagnoses. 

Lisfranc-specific clues

Lisfranc injuries typically present with significant swelling and pain in the middle of the foot; however, they are most notable with bruising on the bottom of the foot. They also tend to have a lot of resistance to weight-bearing.⁴ Occasionally, some foot widening or flattening may be present, or an appreciable gap between the 1st and 2nd metatarsals/toes. The patient typically experiences difficulty with walking or rotating the foot.³

Midfoot sprains

A simple midfoot sprain typically results in less swelling or bruising, and a patient can often walk, although it may be uncomfortable. The absence of plantar ecchymosis or x-ray findings is also a great indicator that this is a simpler injury than a Lisfranc injury.³

Physical exam findings

When you present for a physical exam, your health care provider will likely start by taking X-rays and asking questions about your injury.  They may want to assess your ability to walk and will likely palpate around your foot to determine where you're tender. If the injury is located in the midfoot, it may lead to a diagnosis of a midfoot sprain or a Lisfranc injury. They will perform special tests, such as rotating and turning your foot.  They may even ask you to perform specific movements like a single-leg heel raise or test your strength with different movements.³

Imaging and diagnosis

Lisfranc fracture/dislocation

Weight-bearing X-rays are useful in assessing the stability of a foot injury. The key finding of widening between the 1st and 2nd metatarsals can suggest a Lisfranc fracture.^3,4 Oftentimes, it is helpful to get an X-ray of the other foot as a comparison to help determine if further imaging is necessary in more subtle cases.  Additional imaging may involve a CT or an MRI scan.²
Other signs on X-ray can suggest a Lisfranc injury, such as the “fleck sign”.  This finding occurs when a bone chip is present between the first and second metatarsal on X-ray.  The health care provider reading the X-ray will also look at the lateral view to see if the metatarsal bones are displaced relative to the rest of the foot.^3,6

X-rays are only beneficial for identifying 84% of Lisfranc injuries; thus, a CT scan or MRI may be needed in more complex or subtle injuries. Your health care provider may order one of these tests to obtain a more accurate diagnosis.³

Midfoot sprains

When imaging doesn't show any signs of a Lisfranc injury and physical exam doesn't reveal any telltale signs, such as plantar ecchymosis, the suspicion for a midfoot sprain increases. However, the same idea applies: if an injury seems either a bit more subtle or complex, your healthcare provider may order more advanced imaging, such as an MRI, which can help identify a ligament sprain and thus diagnose a midfoot sprain.³ 

Treatment and prognosis

Lisfranc injuries

Stable Lisfranc injuries can frequently be treated without surgery; however, they often require casting and six weeks of limited or non-weight-bearing movement. However, surgery is usually necessary to restore joint alignment if the injury is unstable or displaced. In surgical cases, recovery times can extend up to a year.^4,6
One of the reasons it is essential to diagnose and treat a Lisfranc fracture properly is that a misdiagnosis can lead to long-term complications, such as chronic pain, disruption of the foot arch integrity leading to collapse, or arthritis.^3,6

Midfoot sprains

Midfoot sprains, on the other hand, are typically easier to treat, often requiring only conservative treatment, including a walking boot, rest, ice, compression, and elevation.  After the initial symptoms have resolved, the patient can gradually wean out of the boot and return to physical activity. Some patients may enrol in physical therapy to help regain strength, mobility, and foot stability if symptoms persist.^3,7

Summary

Lisfranc injuries can often be missed or mistaken for midfoot sprains; however, proper education can help prevent these types of misdiagnoses.  With good imaging and a thorough physical examination, we can avoid some long-term complications that can occur when a misdiagnosis is made. If there is any concern or doubt about the accuracy of the diagnosis, it is vital to utilise advanced imaging such as CT or MRI to confirm the diagnosis.  Timely and accurate treatment helps preserve the foot's function, prevent instability, chronic pain, or post-traumatic arthritis. It also enables patients to return to their favourite activities as soon as possible, with minimal delays and no long-term consequences.