What MRI view is best to evaluate a foot injury due to internal rotation?

MRI Evaluation of Foot Internal Rotation Injury

For evaluating foot injuries from internal rotation mechanisms, obtain standard MRI sequences in all three orthogonal planes (axial, coronal, and sagittal), as no single specialized view is specifically required—the key is comprehensive multiplanar imaging to assess the Lisfranc ligamentous complex, lateral ligaments, and associated soft tissue structures. 1, 2

Imaging Protocol and Planes

Standard MRI Approach

• Acquire images in all three standard planes (axial, coronal, and sagittal) using high-resolution, small-field-of-view technique with multiple pulse sequences 3, 4
• 3-D volumetric acquisitions are superior to standard orthogonal imaging for evaluating the Lisfranc ligamentous complex, which is frequently injured in rotational mechanisms 1, 2
• Proton density fat-suppressed sequences should be included as they are essential for detecting ligamentous injuries and bone marrow edema 1

Why Multiplanar Imaging Matters

• The foot and ankle have complex three-dimensional anatomy that requires multiplanar evaluation—no single view is sufficient 3
• Internal rotation injuries commonly affect the Lisfranc joint complex (tarsometatarsal joints), lateral ligament complex (particularly the anterior talofibular ligament), and associated tendons 1, 5, 6
• MRI allows global evaluation of bones, tendons, ligaments, and other structures in a single examination that exceeds other imaging modalities 3

Clinical Context: When to Use MRI

Initial Imaging Should Be Radiographs First

• Always obtain weight-bearing radiographs as the mandatory first-line study before proceeding to MRI 2, 7
• Include an anteroposterior view with 20° craniocaudal angulation to improve visualization of the Lisfranc joint complex 2, 7
• Bilateral comparison views help identify subtle malalignment 2, 7

MRI Indications After Radiographs

• Order MRI when radiographs are negative but clinical suspicion remains high for ligamentous injury, particularly purely ligamentous Lisfranc injuries without diastasis 1, 2, 7
• MRI shows high correlation (approaching 100%) with intraoperative findings for unstable Lisfranc injuries 1, 2
• MRI is superior for detecting occult fractures, bone stress injuries, and high-grade contusions not visible on radiographs 1, 2

Specific Structures to Evaluate in Internal Rotation Injuries

Lisfranc Ligamentous Complex

• Internal rotation mechanisms frequently cause Lisfranc injuries affecting the metatarso-cuneiform and naviculo-cuneiform articulations 7
• The Lisfranc ligament itself requires careful evaluation on coronal and axial sequences 5
• Look for associated metatarsal and cuneiform fractures that accompany ligamentous injuries 1

Lateral Ligament Complex

• The anterior talofibular ligament (ATFL) is most commonly torn in inversion-internal rotation injuries 1, 5, 6
• ATFL sectioning causes threefold increase in internal talocrural rotation (from 3.67° to 9.6°) 6
• Evaluate for associated calcaneofibular ligament injury, which increases rotational laxity to 13.43° 6

Additional Soft Tissue Structures

• Assess peroneal tendons for tears, dislocations, or entrapment 1, 5
• Evaluate the spring ligament complex and plantar fascia 4, 5
• Look for tarsal tunnel syndrome or interdigital neuromas if clinically suspected 4

Critical Pitfalls to Avoid

• Never rely on non-weight-bearing radiographs alone for suspected Lisfranc injuries—they miss the majority of cases 2, 7
• Do not use MRI as first-line imaging when appropriate radiographs have not been obtained 1, 2
• In diabetic patients with neuropathy, image more liberally as they may bear weight despite significant injuries 2, 7
• Remember that CT is superior to MRI for detecting nondisplaced fractures and should be considered in high-energy mechanisms or polytrauma 2

Alternative Imaging Considerations

• CT should be the primary advanced imaging technique (not MRI) for acute hyperflexion injuries, high-energy polytrauma, or when patients cannot bear weight 1, 2
• Ultrasound has similar sensitivity to MRI for acute ligamentous and tendinous disruption but is operator-dependent 1
• Dynamic ultrasound during foot positioning can reveal peroneal nerve subluxation not apparent on static MRI 8