A Lisfranc dislocation or injury typically describes a spectrum of injuries involving the tarsometatarsal joints of the foot. The Lisfranc joint itself is composed of the articulation between the first, second, and third metatarsals bones, and the cuneiform bones. Injuries of the joint can range from complete tarsometatarsal displacement with associated fractures and ligamentous tears to partial sprains with no displacement. Although a Lisfranc injury can involve various parts of the foot the Lisfranc ligament itself is an isolated ligament that connects the medial cuneiform to the second metatarsal. Lisfranc joint injuries are uncommon and are often misdiagnosed and mismanaged. It is important to recognize these injuries early and start treatment promptly because failure to recognize and treat these will lead to midfoot arthritis, chronic pain, and functional instability. Even when recognized and treated promptly, there is still a high risk for chronic disability and complications.
There are usually two main mechanisms that cause this type of injury: direct, and indirect. A direct mechanism of injury occurs as a crush injury to the joint region from an event such as a motor vehicle collision or industrial accident. Because of the mechanisms' high levels of force, there is usually no pattern or classic appearance. An indirect injury is more common than a direct injury and is often associated with sports participation. This mechanism of injury usually involves a longitudinal force while the foot is plantar flexed with a medial or lateral rotational force. Another frequent presentation is stepping awkwardly off a curb with the foot forcefully plantar flexed.
Lisfranc injuries are relatively uncommon. They account for 0.2% of all fractures, but the prevalence is likely higher as these frequently go undiagnosed. The reported incidence of this injury is approximately 1 per 55,000 persons per year. This injury can occur in all ages but is more common in the third decade of life and is more common in males. Lisfranc injuries occur more frequently in athletes and have become increasingly diagnosed in this group.
A Lisfranc injury occurs as a traumatic injury without underlying pathophysiology. There is a small subset of patients who may be more susceptible to this injury. This subset includes people with diabetes or individuals with nerve damage that causes decreased sensation to the feet. Decreased pain sensation can lead to repetitive injury or wear and tear causing the patient to be more susceptible to a Lisfranc injury from a minor mechanism.
Usually, the patient will complain of midfoot pain with varying amounts of pain with weight bearing, following an acute injury. The injury will often occur by one of the mechanisms described previously. The pain is classically worsened by forefoot weight bearing, and the patient may describe pain or difficulty with the push-off phases of walking and/or running. It is important to note that the severity of the injury is often underestimated at the time of initial injury and the presentation may be delayed. If there is midfoot pain beyond five days, swelling, and/or difficulty with push-off activities, then a Lisfranc injury should be highly suspected. The physical exam can be very helpful and suggestive of these injuries. Inspection of the affected foot can reveal significant swelling, ecchymosis, and although less common, obvious anatomic deformity. There is typically pain with palpation over the dorsal mid-foot, more specifically the tarsometatarsal joints. There is often pain with combined abduction and eversion of the forefoot. Pain can also commonly be reproduced with passive pronation or supination of the tarsometatarsal joint. One should also ensure the injury is closed as open fracture dislocations are a surgical emergency.
When a Lisfranc injury is suspected, anteroposterior, 30-degree oblique and lateral weight-bearing radiographs should initially be obtained. Compliance with weight-bearing films is as difficult as it is essential. Both the patient and radiography technician should be educated on the importance. While more obvious in boney injuries, in purely ligamentous injuries, an axial force during the radiograph is needed to illustrate the injury better. Radiographic findings of a Lisfranc injury or dislocation typically show misalignment of the lateral margin of the first metatarsal base with the lateral edge of the medial cuneiform, misalignment of the medial aspect of the second metatarsal base with the medial edge of the middle cuneiform, and/or small avulsion fragments a one of metatarsal or cuneiform bones. In these instances, the finding of avulsion fractures are commonly referred to as a “fleck sign” and suggest a Lisfranc injury. Displacement of more than 2 mm between the first and second metatarsal bases is considered a positive radiographic finding and is strongly suggestive of a Lisfranc injury as well. On oblique view radiographs, the medial aspect of the cuboid should line up with the medial aspect of the fourth metatarsal base. The dorsal cortex of the first metatarsal and medial cuneiform should be aligned on the lateral weight-bearing radiographs.
Whenever in doubt a CT scan is more diagnostic as they may reveal small avulsion fractures that may be otherwise missed. CT scan may also be helpful for surgical planning. MRI may be helpful in evaluating the extent of the ligamentous injury.
Lisfranc injuries can be managed operatively or non-operatively depending on the clinical presentation. Initial treatment includes reduction, splitting, and aggressive elevation. Non-operative treatment is only reserved for anatomically stable and non-displaced injuries. In this case, the patient is immediately made non-weight bearing and put in a cast or boot. Repeat evaluation and radiographs should be performed after two weeks to rule out any diastasis that might convert the patient into surgical management. After at least six weeks if the patient is completely non-tender and radiographs are again negative, then there can be a consideration to begin weight bearing and a rehabilitation program. If there is any tenderness but still no displacement then the patient should be in a boot or cast again for at least another four weeks before starting rehabilitation. Any diastasis or displacement requires surgical fixation. The patient should be non-weight bearing after surgery for six to eight weeks. At that time re-evaluation is performed and a walking boot or cast can be considered as clinical presentation indicates. This cast or boot is then usually worn for another six weeks. At that time, again as clinical presentation dictates, a progressive functional rehabilitation program can be started.
As many as 20% of Lisfranc injuries are missed on initial presentation to the emergency department. Lisfranc injuries in athletes have been classified according to the American Medical Association’s Standard Nomenclature of Athletic Injuries. First-degree and second-degree sprains have been classified as partial ligament tears with swelling, focal pain, no instability, and normal radiographs. Instability and diastasis greater than 2 mm between the first and second metatarsals, as seen on anteroposterior radiographs, is consistent with a third-degree sprain. Post-traumatic arthrosis is a very common complication of Lisfranc joint injury associated with higher injury mechanism and purely ligamentous dislocations.