Approach Considerations
Although there are no specific laboratory studies for Lisfranc injuries, the clinician should be acutely aware of those patients who may be at high risk for subtle injuries, such as individuals with undiagnosed diabetes who have decreased sensation in their feet.
Lisfranc injuries, especially subtle injuries, can often be missed. [18] As many as 20% of Lisfranc injuries are missed on initial presentation to the emergency department (ED). [19] Often, the initial radiograph is normal, particularly in athletes with only a first- or second-degree sprain. In a study by Sherief et al, eight of the nine clinicians who participated in the study missed a subtle Lisfranc injury in a diabetic neuropathic foot, and only 61% of the Lisfranc injuries in the study were accurately diagnosed by all nine. [20]
Plain Radiography
Obtain initial radiographs of the injured foot in all patients, as follows:
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Anteroposterior (AP) view of the foot in a standing position, if possible - In the normal image, the medial border of the base of the second metatarsal (MT) and the middle cuneiform should line up; any gross diastasis greater than 2 mm between the bases of the first and second MTs suggests a Lisfranc injury (see the first and second images below)
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Lateral view of the foot in a standing position, if possible - In this view, the superior border of the first MT base should align with the superior border of the medial cuneiform (see the third image below)
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Medial 30º oblique view of the foot - In this view, the medial border of the cuboid should align with the medial border of the fourth MT (see the fourth and fifth images below)
In this anteroposterior radiograph of a Lisfranc dislocation, note the disruption of the normal second tarsometatarsal alignment.
Standard anteroposterior radiograph demonstrates a Lisfranc fracture dislocation. Determining the extent of fracture involving the joint is difficult with plain radiographs.
In this lateral radiograph of a typical Lisfranc injury, note the malalignment of the metatarsal bases with the midfoot.
In this medial oblique radiograph of a normal foot, note the medial borders of the cuboid and fourth metatarsal base. They should be even, as depicted by the black lines.
In this medial oblique radiograph of a Lisfranc injury, note the loss of alignment between the cuboid and fourth metatarsal base (black lines). This is diagnostic of a Lisfranc injury and is as important as recognition of the second tarsometatarsal instability.
If a subtle injury is suspected, it is advisable to obtain a weightbearing AP view of both feet on the same cassette for direct comparison. Additionally, a stress-view radiograph can be performed in which the hindfoot position is maintained while the midfoot and forefoot are forced into pronation and abduction; this will demonstrate lateral subluxation of the first and second tarsometatarsal (TMT) joints with instability (see below).
A “fleck sign” seen on the AP radiograph is pathognomonic for a Lisfranc injury. This sign is reportedly present in 90% of Lisfranc ligament injuries. It represents an avulsion fracture from either the second MT base or the medial cuneiform, resulting from forceful abduction of the forefoot that avulses the strong Lisfranc ligament between the base of the second MT and the medial cuneiform.
The literature offers many approaches to classifying Lisfranc injuries on the basis of radiographic appearance. The value of these classifications is for reporting only. For the purposes of treatment, the major determinant is whether the joint complex is stable or unstable. This is determined by the radiographic stress views (see Procedures).
Computed Tomography
A routine computed tomography (CT) scan through the midfoot is suggested to visualize any bony injury to the plantar bony structures. CT also allows a three-dimensional (3D) assessment of surrounding joint stability. Midfoot stability is vital to adequate Lisfranc injury recovery. (See the image below.)
CT scan in the coronal plane can demonstrate the extent of injury at the joint. Compare with the plain radiograph of this injury in the related image. Note the plantar avulsion, suggesting severe disruption of the plantar ligamentous structures.
Magnetic Resonance Imaging
When compared with CT and weightbearing radiography, magnetic resonance imaging (MRI) has an advantage in identifying partial ligament injuries and subtle ligament injuries.
With this technology, one can identify isolated tears of the Lisfranc ligament, as well as associated injuries to the interosseous ligaments. Raikin et al showed that MRI is accurate for detecting traumatic injury of the Lisfranc ligament and for predicting Lisfranc joint complex instability when the plantar Lisfranc ligament bundle is used as a predictor. [21] Rupture or grade 2 sprain of the plantar ligament between the first cuneiform and the bases of the second and third MTs is highly suggestive of an unstable midfoot, which will require stabilization.
Other Imaging Studies
Bone scanning
Bone scanning is best used for suspected acute and chronic injuries of the TMT joints. A bone scan can demonstrate Lisfranc injuries that occurred 3 months before presentation and are continuing with painful weightbearing. Increased uptake on bone scans indicates degenerative changes that are not yet visible on plain films.
Ultrasonography
Nonvisualization of the of the dorsal C1-M2 ligament and a C1-C2 distance greater than 2.5 mm on ultrasonography (US) are indirect signs of a Lisfranc ligament tear. This technique also lends itself to being used in a dynamic fashion that might help make the diagnosis in patients with subtle injuries. [22]
Procedures
In the acute setting, a stress view of the foot can help identify an unstable complex; however, this procedure can cause the patient severe discomfort. Using an ankle block or intravenous sedation, stress the foot under fluoroscopic examination or with standard x-rays. The hindfoot should be maintained while the midfoot and forefoot are pronated and abducted. An AP view of the TMT joints will reveal any significant instability (see the images below).
Stress view. This patient, with a suspected Lisfranc injury, presents with a normal appearing anteroposterior radiograph of the foot. Plantar ecchymosis and clinical presentation of pain warrant further investigation. In this radiograph, alignment of the medial border of the second metatarsal and the medial cuneiform is near normal. Patient is unable to bear weight due to a femur fracture sustained in the same accident.
In this stressed view, with adequate anesthesia to the patient, the foot is stressed in a medial/lateral plane. The forefoot is forced laterally with the hindfoot brought medially. Note that the second tarsometatarsal joint opens up, and the normal alignment between the medial border of the second metatarsal base and the middle cuneiform is distorted. This injury requires surgical stabilization.
Histologic Findings
Intraoperative findings that suggest a possible pathologic process should be sent to pathology for accurate diagnosis.
Staging
In athletic injuries, Nunley and Vertullo suggested a three-stage diagnostic classification, as follows [23] :
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Stage I - Tear of dorsal ligaments with sparing of the Lisfranc ligament
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Stage II - Direct injury to the Lisfranc ligament with elongation or rupture
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Stage III - Progression of the above, with damage to the plantar TMT ligaments and joints, along with potential fracture and loss of arch
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Radiograph illustrating diabetic patient with first ray instability of the right foot. The articular surfaces of the second and first metatarsal are level in the transverse plane, indicating proximal migration of the first ray. The left foot shows the advanced stage of an untreated Lisfranc injury with similar first ray instability.
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Clinical identification of typical plantar ecchymosis pattern observed in Lisfranc injuries.
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In this anteroposterior radiograph of a Lisfranc dislocation, note the disruption of the normal second tarsometatarsal alignment.
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In this lateral radiograph of a typical Lisfranc injury, note the malalignment of the metatarsal bases with the midfoot.
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In this medial oblique radiograph of a normal foot, note the medial borders of the cuboid and fourth metatarsal base. They should be even, as depicted by the black lines.
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In this medial oblique radiograph of a Lisfranc injury, note the loss of alignment between the cuboid and fourth metatarsal base (black lines). This is diagnostic of a Lisfranc injury and is as important as recognition of the second tarsometatarsal instability.
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Stress view. This patient, with a suspected Lisfranc injury, presents with a normal appearing anteroposterior radiograph of the foot. Plantar ecchymosis and clinical presentation of pain warrant further investigation. In this radiograph, alignment of the medial border of the second metatarsal and the medial cuneiform is near normal. Patient is unable to bear weight due to a femur fracture sustained in the same accident.
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In this stressed view, with adequate anesthesia to the patient, the foot is stressed in a medial/lateral plane. The forefoot is forced laterally with the hindfoot brought medially. Note that the second tarsometatarsal joint opens up, and the normal alignment between the medial border of the second metatarsal base and the middle cuneiform is distorted. This injury requires surgical stabilization.
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Standard anteroposterior radiograph demonstrates a Lisfranc fracture dislocation. Determining the extent of fracture involving the joint is difficult with plain radiographs.
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CT scan in the coronal plane can demonstrate the extent of injury at the joint. Compare with the plain radiograph of this injury in the related image. Note the plantar avulsion, suggesting severe disruption of the plantar ligamentous structures.
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This diagram depicts the suggested fixation order of placement and alignment of screws for surgical fixation of unstable Lisfranc injuries.
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Preoperative anteroposterior radiograph demonstrates a Lisfranc dislocation.
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Preoperative lateral radiograph demonstrates a Lisfranc dislocation.
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Postoperative anteroposterior radiograph demonstrates reduction and fixation of Lisfranc dislocation.
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Postoperative lateral radiograph illustrates placement of fixation screws for stabilization of Lisfranc joint.
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Preoperative anteroposterior radiograph demonstrates a Lisfranc injury with proximal tarsal instability. The medial cuneiform is displaced medially, bringing the joint line level with the second. The proximal anatomy must be restored and stabilized before addressing the tarsometatarsal joint.
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Postoperative anteroposterior radiograph demonstrates restoration of normal midfoot alignment. Screw fixation was used to stabilize the cuneiform prior to realigning the Lisfranc joint. Due to comminution of the second and third metatarsal shafts, Kirschner wires were used to hold their position. In this case, due to continued instability, a wire through the fourth tarsometatarsal joint was also used.
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Preoperative anteroposterior radiograph demonstrates a Lisfranc injury with associated distal fracture. Note the displacement of the base of the first metatarsal.
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Postoperative anteroposterior radiograph demonstrates fixation of the metatarsal, as well as stabilization of the Lisfranc joint.
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Preoperative anteroposterior radiograph demonstrates a missed old Lisfranc injury with subsequent valgus foot deformity and painful weight bearing throughout the midfoot.
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Preoperative lateral radiograph demonstrates loss of plantar integrity through Lisfranc joint area. The normal linear alignment of the bones from the metatarsal to the talus is lost, with a sag at the tarsometatarsal joint.
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In this postoperative anteroposterior radiograph demonstrating reduction of Lisfranc alignment and screw configuration for tarsometatarsal fusion, note that only the medial 3 joints are fused. The lateral 2 joints remain mobile and actually open up when compared with the previous pictures.
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Postoperative lateral radiograph demonstrates restoration of alignment with tarsometatarsal fusion.
