What is the Lisfranc Joint of the Foot?
The Lisfranc joint, also known as the tarsometatarsal (TMT) joint, is a critical joint located in the midfoot region of the foot. It is named after the French surgeon Jacques Lisfranc de St. Martin, who described this anatomical region in the early 19th century.
The Lisfranc joint is where the metatarsal bones (the long bones of the foot that connect to the toes) articulate with the tarsal bones (the smaller bones in the midfoot). This joint plays a crucial role in maintaining the arch of the foot and in weight-bearing activities. It also allows for a limited amount of motion, which is essential for walking, running, and other activities that require flexibility and stability in the foot.
How Is the Lisfranc Joint Injured?
Direct Trauma: The most common cause of Lisfranc injuries is direct trauma to the midfoot. This can occur in various ways, such as a heavy object falling on the foot, a car accident where the foot is trapped, or a sports-related injury where the foot is twisted or crushed.
Falls: Falling from a height or slipping and landing on the midfoot can result in Lisfranc injuries. The impact of the fall can cause fractures or dislocations in the bones of the midfoot.
Twisting Injuries: Sudden twisting or rotational forces applied to the foot can also lead to Lisfranc injuries. This can occur during sports activities like soccer, football, or basketball, where the foot gets caught or twisted while in motion.
Motor Vehicle Accidents: High-velocity car accidents can exert significant forces on the foot, leading to Lisfranc injuries. The dashboard or other parts of the vehicle can impact the foot, causing fractures or dislocations.
What is a Subtle Lisfranc Injury?
A subtle Lisfranc injury, sometimes referred to as a “subtle Lisfranc sprain” or “low-grade Lisfranc injury,” is a type of Lisfranc injury that is less severe and may not involve obvious fractures or dislocations of the bones in the midfoot. Instead, it typically involves sprains or minor ligament damage in the Lisfranc joint complex. These injuries are often more challenging to diagnose compared to more severe Lisfranc fractures or dislocations because the signs and symptoms may be subtle.
Here are some characteristics of subtle Lisfranc injuries:
Mild to Moderate Pain: Patients with subtle Lisfranc injuries often experience mild to moderate pain in the midfoot region. The pain may be aggravated by weight-bearing activities or walking.
Swelling: Some swelling may be present around the midfoot area, but it might not be as pronounced as in more severe injuries.
Difficulty Walking: Patients may have difficulty walking or may experience pain with each step, particularly when trying to push off with the affected foot.
Bruising: There may be some bruising on the top or bottom of the foot, but it is generally not as extensive as what might be seen in severe Lisfranc injuries.
Limited Range of Motion: There could be limited range of motion in the affected foot, especially in dorsiflexion (lifting the foot upwards) and plantarflexion (pointing the foot downwards).
Normal X-rays: Initial X-rays may appear normal or show only subtle abnormalities, making it challenging to diagnose the injury definitively based solely on imaging.
Subtle Lisfranc injuries can result from traumatic events or repetitive stress, but they are considered less severe than complete fractures or dislocations of the Lisfranc joint. While these injuries may not be immediately obvious, they still require prompt medical evaluation and appropriate treatment to prevent further damage and long-term complications.
Diagnosis often involves a combination of clinical examination, imaging studies (such as X-rays or possibly MRI), and consideration of the patient’s history and symptoms. Treatment options may include immobilisation in a cast or walking boot, physical therapy, and sometimes surgical intervention, depending on the severity of the injury. Early intervention is essential to achieve the best possible outcome for subtle Lisfranc injuries.
What Happens If a Subtle Lisfranc Injury is Missed?
Missing or failing to properly diagnose and treat a subtle Lisfranc injury can have several potential consequences, including both short-term and long-term complications. It’s crucial to recognise and address these injuries promptly to prevent these issues:
Chronic Pain: One of the most common consequences of an untreated subtle Lisfranc injury is persistent foot pain. The pain may become chronic and impact the individual’s daily activities and quality of life.
Instability: Ligament injuries in the Lisfranc joint can lead to instability in the midfoot. This can affect the overall stability of the foot, leading to an increased risk of additional injuries or falls.
Arthritis: Untreated injuries can result in the development of post-traumatic arthritis in the affected joint. Over time, this can lead to pain, swelling, and reduced joint function.
Gait Abnormalities: Subtle Lisfranc injuries can alter the way a person walks (gait abnormalities). This can lead to compensatory movements in other parts of the body, potentially causing pain and discomfort in the ankles, knees, hips, and lower back.
Progression to Severe Injury: In some cases, a subtle Lisfranc injury that goes untreated or is not properly managed may worsen over time, potentially leading to more severe fractures or dislocations that require more extensive surgical intervention.
Functional Limitations: The long-term consequences of a missed subtle Lisfranc injury can result in functional limitations, such as reduced mobility and difficulty participating in physical activities and sports.
Delayed Recovery: If the injury is eventually diagnosed and treated after a significant delay, the recovery process may be more prolonged and challenging.
Given these potential consequences, it is essential to seek medical attention if you suspect a foot injury, especially if it involves the midfoot region. Even subtle injuries require proper evaluation by a healthcare professional, which may include imaging studies (X-rays, MRI), to accurately diagnose the extent of the injury. Early intervention and appropriate treatment, which may involve immobilisation, physical therapy, or surgery, can help minimise the risk of long-term complications associated with subtle Lisfranc injuries.
Case Example
A 34 year old man was playing football when his right foot accidentally twisted when it stepped onto an uneven ground on the football field. He felt a loud crunch sound in his right foot and had pain in his right foot. He was not able to play on. He had difficulty walking on his right foot due to pain.
He went to the Emergency Department of a hospital and x-rays of his right foot were taken. He was told that there was no fracture seen.
He consulted me 4 days later for his right foot injury as he was still in considerable pain and could not walk properly.
Examination of his right foot showed tenderness at the Lisfranc joint. There was no obvious bruising at the sole of his right foot.
The x-rays done 4 days ago did not show any obvious fracture or Lisfranc injury. However, I confirmed with the patient that the x-rays were non-weight bearing x-rays.
I explained to the patient that he could have a subtle Lisfranc injury to his right foot. A weight bearing x-ray of both feet will be useful to make a radiological diagnosis. He would have to stand on his painful right foot during this x-ray.
The weight bearing x-rays of both feet showed obvious widening of the right foot Lisfranc joint and also the joint space between the medial and intermediate cuneiform bones.
The patient was counselled for and underwent open reduction and internal fixation of his right foot Lisfranc joint injury.
This was done to restore stability to this vital keystone joint of the right midfoot and to prevent future post-traumatic osteoarthritis.
Learning Points
Subtle Lisfranc joint injury is easy to be missed and undiagnosed.
Non-weight bearing x-rays may not tell the full story of this injury.
A high index of suspicion on the mechanism of the injury, presentation, clinical findings and appropriate weight bearing x-rays of the affected foot will be useful to come to a proper diagnosis.
Some cases such as this patient will require prompt surgical treatment for the best outcome.
