What is the initial imaging modality and management for a patient with a possible fracture of the foot?

Initial Imaging for Suspected Foot Fracture

Standard three-view radiographs (anteroposterior, lateral, and oblique) are the first-line imaging modality for evaluating suspected foot fractures, with 99% sensitivity when Ottawa rules are positive. 1

Standard Radiographic Approach

• Obtain AP, lateral, and oblique radiographs as the initial imaging study for any suspected foot fracture 1, 2
• Weightbearing views should be obtained when clinically feasible, as they improve diagnostic accuracy particularly for Lisfranc injuries and midfoot pathology 1, 2
• Radiographs remain superior to ultrasound for initial evaluation, as ultrasound has only 90.9% sensitivity compared to radiography's 99% 3

Location-Specific Imaging Modifications

Calcaneal fractures:

• Add an axial calcaneal view to the standard three-view study to increase specificity and better distinguish intra-articular involvement 1

Lisfranc injuries (midfoot):

• Obtain standard three views plus an AP view with 20° craniocaudal angulation 1
• Weightbearing radiographs are strongly recommended when possible, as these injuries are frequently overlooked on non-weightbearing films 1
• Include both feet on AP radiographs to detect subtle malalignment by comparison with the uninjured side 1

Toe fractures:

• Radiographs are necessary to document or rule out fracture, as Ottawa rules do not address toe injuries 3
• Obtain radiographs when there is point tenderness or pain with gentle axial loading of the digit 3

When Ottawa Rules Do NOT Apply

Do not use Ottawa rules in these situations (obtain radiographs regardless): 4, 1

• Penetrating trauma
• Pregnancy
• Any skin wound
• Patient transferred with radiographs already taken
• More than 10 days after trauma
• Return visit for continued traumatic foot pain
• Polytrauma setting
• Altered sensorium
• Neurologic abnormality affecting the foot (including diabetic neuropathy)
• Underlying bone disease

In these scenarios, radiograph the foot even without positive Ottawa criteria, as pain perception may be diminished and patients may ambulate despite fractures 4

When to Consider CT as Initial Imaging

CT should be the primary imaging modality in: 4, 1

• High-energy polytrauma patients (approximately 25% of midfoot fractures are missed on radiographs in this population) 4
• Complex midfoot injuries where radiographic sensitivity is only 25-33% 4, 5
• When evaluating true extent of osseous injury in complex fractures for surgical planning 4

Modalities NOT Recommended as Initial Imaging

• MRI is not routinely used as first-line imaging for acute foot trauma 4
• Ultrasound is not routinely used as first-line imaging for acute foot trauma, though it may be useful for radiolucent foreign bodies (wood, plastic) in penetrating trauma 4, 1
• CT, MRI, and ultrasound should be reserved for problem-solving after initial radiographic evaluation 1

Critical Pitfalls to Avoid

• Failing to obtain weightbearing views when Lisfranc injuries are suspected leads to missed diagnoses, as joint widening may only be apparent with weight-bearing 1
• Applying Ottawa rules to toe injuries will result in missed fractures, as these rules specifically exclude the toes 3
• Relying on radiographs alone in polytrauma patients risks missing up to 25% of midfoot fractures 4
• Using ultrasound as first-line imaging has lower sensitivity than standard radiography 1