›Widening > 4 mm indicates medial structural injury
›Tibiofibular clear space
›Normal < 6 mm on AP view
›Widening indicates syndesmotic disruption
›Tibiofibular overlap
›Normal > 6 mm on AP view
›Normal > 1 mm on mortise view
›MRI indications for Maisonneuve fracture
›Deltoid ligament integrity assessment
›When medial clear space widening present without visible medial malleolus fracture
›Differentiates deltoid ligament tear from bony avulsion
›Interosseous membrane disruption extent
›Correlates with injury severity and instability
›Extent of interosseous membrane tear affects prognosis
›Osteochondral lesion assessment
›Talar dome injury associated with ankle trauma
›Important for long-term outcome planning
›MRI protocol considerations
›Sequences
›Short tau inversion recovery (STIR) for ligament edema
›Proton density fat-suppressed for cartilage
›T1 weighted for bony anatomy
›Limitations
›Not routine for acute ED evaluation
›Used as adjunct when CT findings are insufficient
›Useful in subacute and pre-operative planning context
›CT indications
›Preoperative assessment of posterior malleolus fracture
›Posterior malleolus fracture present in approximately 80% of Maisonneuve cases
›CT defines fragment size, displacement, and articular involvement
›Fragment size guides fixation decision
›Fibula position in fibular notch assessment
›Determines if fibula is reduced or displaced in fibular notch
›Critical for surgical planning
›Medial malleolus fracture characterization
›Present in approximately 37% of cases
›Fragment anatomy and displacement
›Associated injury identification
›Additional osteochondral or bony injuries not seen on plain film
›CT protocol
›CT of ankle without contrast
›Thin slice reconstruction (1 mm) for ankle joint detail
›Multiplanar reconstruction in coronal and sagittal planes
›Postoperative CT role
›Confirms reduction accuracy after syndesmotic fixation
›Recommended to verify fibula position in notch
›Closed reduction has up to 50% malposition rate (open reduction preferred)
›CT findings in Maisonneuve fracture
›Proximal fibula spiral fracture above the level of the syndesmosis
›Widening of the tibiofibular clear space
›Posterior malleolus involvement
›Ultrasound role in Maisonneuve fracture
›Soft tissue and ligament assessment
›Deltoid ligament integrity in medial ankle
›Anterior tibiofibular ligament visualization
›Real-time dynamic stress assessment possible
›DVT assessment during immobilization period
›Compressibility of popliteal, femoral veins
›Non-weight-bearing status increases DVT risk
›Point-of-care ultrasound
›Limited role in primary diagnosis
›Plain radiograph and CT are primary imaging modalities
›Ultrasound not recommended as first-line for fracture diagnosis
›Soft tissue swelling characterization
›Hematoma versus fluid collection
›Can guide aspiration if needed
Plain Radiography (Primary Imaging)
›Ankle radiograph series (first-line)
›AP, lateral, and mortise views of the ankle
›May show widened medial clear space > 4 mm
›May show widened tibiofibular clear space
›May show medial malleolus fracture
›Distal fibula may appear normal
›Medial clear space widening without distal fibula fracture
›Must suspect Maisonneuve until proven otherwise
›Mandates full-length tibia/fibula radiographs
›Full-length tibia/fibula radiographs
›AP and lateral views of entire tibia and fibula
›Critical step when syndesmotic injury suspected
›Mandatory when proximal fibula tenderness is present
›Reveals the proximal fibula spiral fracture
›Imaging pearl
›In 24% of cases, proximal fibula fracture is visible only on the lateral view of the lower leg