Imaging Studies
Routine radiography of the foot should include 3 views: AP, lateral, and 45º internal oblique.
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The hindfoot is assessed via the lateral projection, and the midfoot and the forefoot via anteroposterior and oblique projections.
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Any identified hindfoot injury should prompt standard imaging of the ankle.
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Additional views, such as the Harris (axial) view to evaluate the subtalar joint and calcaneus, can be obtained to enhance imaging of certain areas of the foot.
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Weightbearing views may reveal subtle Lisfranc abnormalities.
Increasingly, CT scanning is being used to help evaluate fractures and dislocations in the foot, in particular calcaneal and talar fractures.
MRI is often used to diagnose stress fractures and to evaluate the various tendons and ligaments of the foot.
Lisfranc injuries range from sprain to fracture dislocation. Radiologists must have a thorough understanding of anatomy, mechanisms, and patterns of these injuries to diagnose and help clinicians assess treatment options and prognosis. The initial imaging evaluation of patients with a suspected Lisfranc injury consists of non-weight-bearing radiographs. With high-energy injuries, the diagnosis is straightforward, and patients usually undergo CT for surgical planning. For patients with low-energy injuries, when findings on initial radiographs are equivocal, further evaluation is performed with weight-bearing radiographs, CT, or MRI. Stable injuries are treated conservatively, whereas all other injuries require surgical intervention. [1]
Up to 20% of Lisfranc fracture dislocations are misdiagnosed or missed during initial evaluation. [16] Individuals with Lisfranc injuries typically present to the ED with pain, particularly on weight-bearing, with swelling and a characteristic description of the mechanism of injury. The injury is diagnosed via clinical examination and radiologic investigation, typically with plain radiographs and CT scans. [17] Sensitivity and specificity of MRI identification of Lisfranc injuries have been reported to be as high as 94% and 75%, respectively. [18] Ultrasound is now also being used to evaluate Lisfranc injuries. [19]
Injuries to the ankle and foot are common in the young athlete, especially with increasing participation and high levels of competitiveness in youth sports programs. Knowledge of normal development of the foot and ankle is crucial if one is to understand age-specific injury patterns, because acute or chronic/repetitive stress to the developing skeleton results in injuries that differ from those seen in adults. Congenital abnormalities may also predispose children to increased risk of injury and pain. Radiologists must be aware of these distinctions to diagnose and classify injuries correctly for optimal treatment. [20]
