Introduction

Anatomy of the foot

The foot is a structure consisting of bones, ligaments, muscles, tendons, and joints, and can be divided into three separate sections:

1. Forefoot consists of the toes, called phalanges, and metatarsal bones
2. Mid-foot consists of tarsal bones
3. Hind foot consisting of the lower ankle (the talus) and calcaneus (which is the heel of the foot)

The Lisfranc joint is a complex connection between the forefoot and the midfoot, where the tarsal and the five metatarsal joints meet. This joint is also called the tarsometatarsal joint (TMT). 

The Lisfranc joint consists of both the tarsal and metatarsal bones, as well as the collection of Lisfranc ligaments, which stretch between the tarsals and metatarsal bones, below and across the foot, and help hold the joint together. This joint is important for the stabilisation of the arch of the foot and for performing functions such as walking.¹

What is a lisfranc injury?

A Lisfranc injury is a fracture or dislocation injury occurring in the Lisfranc area, resulting in displacement of one or more of the metatarsals from the tarsal bone. The extent of injury is broad, ranging from low-impact to high-impact sports injuries, and can affect anything from purely the Lisfranc ligaments or result in dislocation, fractures, or crush injuries of the tarsal or metatarsal bones.²

These injuries account for 0.2% of fracture injuries; however, almost one-fifth of cases are missed or diagnosed late. Early, accurate diagnosis is essential for people to receive proper treatment and prevent long-term complications, which could impact the function of the foot.  

Causes of lisfranc injuries

Lisfranc joint injuries can result from direct or indirect, high-impact or low-impact incidents. 

High-impact injuries are usually easier to diagnose, as they often result in deformities of the foot as a result of trauma, most commonly traffic incidents, and are associated with severe damage to the tissue, nerves, and blood vessels of the foot.

Low-impact injuries, often resulting from sports injuries, can be difficult and more often missed, as people often are still able to walk and will complain of swelling or pain in the foot, without any clear deformity.³ 

Evaluation and management

If a Lisfranc injury is suspected, early and efficient clinical evaluation is necessary to determine the best treatment option for a person. If injuries are not diagnosed or don’t receive appropriate treatment, short and long-term complications can occur. 

These include sudden disruption to the blood supply of the foot, which could require urgent surgery, or more long-term complications, including osteoarthritis, permanent foot deformities, and loss of function or instability of the foot.^4,5

On presentation, radiographic x-ray scans of the feet are obtained. These images will assess the nature of damage, looking at which and how many bones are involved, the direction of their dislocation, and if there is any fracture to the bones themselves.

Sometimes, a computed tomography (CT) scan will be performed for a more thorough assessment of the joint, as it can look at smaller fractures or dislocations which can be missed by X-ray scans. CT scans are more commonly used in severe fractures if surgery is considered for treatment.

Magnetic resonance imaging (MRI) scans are sometimes used and are more useful in detecting damage to the soft tissue and ligaments, rather than the bones themselves. These are therefore more commonly used in low-impact injuries.^{6, 7}

Classification of lisfranc injuries

Multiple classification systems for Lisfranc injuries exist, typically classifying them based on the pattern of injury, dislocation, or fracture, which occurs once clinical assessment and scans have been performed.

The first classification of Lisfranc injuries was established by Quenu and Kuss in 1909, which divided the injury into three different types: homolateral, isolated, and divergent.⁸ 

This classification system was simple and did not assess the severity of the injury; therefore, it could not be used to assess the best treatment and outcomes.

Classifying Lisfranc injuries is important in understanding the severity of injury, which will guide the treatment choice and impact the long-term outcome.⁹

Will will look at the following classifications: 

• The Hardcastle Classification System 
• Myerson Modification System 
• Nunley and Vertullo Classifications

The hardcastle classification system (1982)

Hardcastle modified the original Quenu and Kuss classification, expanding on it by classifying the injury based on the direction of dislocation of the joints and the number of joints involved. 

This classification system is limited by the fact that it does not help guide treatment strategies or predict long-term outcomes.⁶

This classified the Lisfranc injuries into:

• Type A
• Type B 
• Type C

Type A

In a type A Lisfranc injury, all metatarsal bones are dislocated in the same direction, and there is a total disconnect between the metatarsal and tarsal bones.

Type B

In a Type B Lisfranc injury, there is partial dislocation between the tarsal and metatarsal bones. Here, one or more of the metatarsals are dislocated, either moving inwards (medial displacement) or outwards (lateral displacement).

Type C

In Type C Lisfranc Injury, the dislocations do not occur in the same direction. Dislocation of the metatarsals can involve some or all of them, which move away (diverge) from each other in their separate directions.

The myerson modification (1986)

Myerson modified Hardcastle’s classification, expanding on it to provide more detail on the nature of injury. This system not only looks at partial injuries of the Lisfranc joint, but also includes details on fracture change to the bone, further subdividing Type B into B1 and B2 injuries, and Type C into C1 and C2 injuries.

Clinically, this is the most commonly used classification system for assessing these injuries. 

This system classifies Lisfranc injuries as:^{6, 10, 11}

• Type A
• Type B
  • Type B1 
  • Type B2 
• Type C
  • Type C1
  • Type C2 

Type A

In a Type A injury, there is total dislocation between the tarsal and metatarsal bones in the same direction.

Type B

In type B, there is partial dislocation between the tarsal and metatarsal bones, without complete dislocation of all bones. It is further subdivided into:

Type B1

This subtype specifically refers to partial dislocation of the first toe, moving inwards (medial dislocation).

Type B2

This subtype refers to the outward (lateral dislocation) of the second to fifth toe bones.

Type C

In Type C Lisfranc injuries, separate tarsal and metatarsal dislocations occur, moving away from each other in different directions (divergent dislocations).

Type C1

Type C1 refers to the partial dislocation of some of the tarsal and metatarsal bones moving in opposite directions.

Type C2

Type C2 is the complete dislocation of all tarsal and metatarsal bones, moving in opposite directions.

Nunley and vertullo classification

The Hardcastle and Myerson classification systems are both typically used for high-impact Lisfranc injuries, rather than smaller, low-impact injuries such as sprains. 

Nunley and Vertullo developed a classification for less traumatic injuries, including low-impact sprains, which typically affect athletes. Unlike the Myerson and Hardcastle classification systems, this system is also intended to help in guiding clinical treatment of injuries.

This classifies Lisfranc injuries into 3 stages:

• Stage 1
• Stage 2
• Stage 3

Stage 1

Sprain of a Lisfranc ligament, with no findings on scans such as x-rays, no loss of structure of the foot or arch of the foot, and no changes to the bone. These patients should be managed conservatively, not requiring an operation.

Stage 2

Clear injury to the Lisfranc ligaments, of one to five millimetre change, with no loss of structure to the foot or the arch of the foot. These patients will need to be managed by reducing the ligament disruption and bringing the bones together.

Stage 3

Clear injury to the Lisfranc ligament, greater than 5 millimetres in length, with additional damage to the plantar ligaments, and a possible fracture in the bones of the feet. Here, there is a loss in the structure of the foot and a reduction in the arch of the foot.

Again, for management in Stage 3, the aim is to reduce the displacement between the bones and the ligament disruption non-operatively, or if required, internal fixing of the ligaments.¹²

Summary

A Lisfranc injury refers to a dislocation or fracture of the Lisfranc, or tarsometatarsal joint, in the middle of the foot. The extent of injury can range from damage to the ligaments of the Lisfranc joint or more serious fractures in the bones of the Lisfranc joint.

Lisfranc injuries must be assessed quickly and efficiently, as delayed diagnosis and inappropriate treatment can lead to severe, long-term complications such as damage to the blood supply, osteoarthritis, instability, permanent deformity, or loss of function of the foot.

Assessment of injury clinically will involve a scan to assess the extent and nature of damage and allow for classification of the injury. Multiple classification systems exist to describe the broad range and complexity of Lisfranc injuries. 

Lisfranc injuries were first simply classified by Quenu and Kuss, but since then, the Hardcastle and Myerson classifications have evolved from their predecessors for more detailed classifications of high-impact injuries. For low-impact injuries, the Nunley and Vertullo classification is more widely used. While multiple classification systems exist, the Myerson classification is most widely used and is helpful clinically to guide treatment and predict the long-term outcomes for people with a Lisfranc injury.