What is the next step after a left ankle X-ray (x-ray) is ordered for a patient?

What to Do After Ordering a Left Ankle X-Ray

After ordering an ankle X-ray, obtain three standard views (anteroposterior, lateral, and mortise) that include the base of the fifth metatarsal, then interpret the results to determine if further imaging or treatment is needed. 1

Standard Radiographic Protocol

• Three views are required: anteroposterior, lateral, and mortise views must include visualization of the base of the fifth metatarsal bone distal to the tuberosity 1
• Weight-bearing films are preferred when possible, as they provide critical information about fracture stability, particularly for malleolar fractures where a medial clear space <4 mm confirms stability 1
• Avoid ankle manipulation before obtaining radiographs unless there is neurovascular deficit or critical skin injury, as premature manipulation increases the risk of requiring re-manipulation (44% vs 18%) and may complicate the injury 2

Next Steps Based on X-Ray Results

If X-Rays Show a Fracture

CT without IV contrast is the first-line next imaging study to determine extent, displacement, comminution, intra-articular extension, and associated injuries 1

• CT is particularly critical for:

  • Subtalar, calcaneal, and talar fractures due to complex anatomy 1
  • High-impact polytrauma or complex comminuted injuries 1
  • Radiographs have only 87% sensitivity for calcaneal fractures and 78% for talar fractures compared to CT 1, 3

• MRI without contrast may be added for fractures at high risk for osteonecrosis (especially talus) or when assessing associated soft-tissue injuries, tendon entrapment, or ligamentous injuries 1

If X-Rays Are Negative But Pain Persists (>1 Week, <3 Weeks)

MRI without IV contrast is the most sensitive next study for detecting occult fractures with bone marrow edema, stress injuries, and soft-tissue injuries 1

• MRI is the reference standard for ligamentous injury assessment and cartilage abnormalities 1
• CT without contrast is an alternative if MRI is unavailable, as it can detect radiographically occult fractures in one-third of cases with large joint effusion but no visible fracture 1
• Repeat radiographs may identify early callus formation at occult fracture lines but are not typically the next best study 1

If X-Rays Show Potential Osteochondral Injury

MRI without IV contrast is the study of choice for assessing cartilage abnormalities and bone contusions, particularly with symptoms of persistent pain, stiffness, locking, clicking, or swelling 1

• 70% of ankle fractures and 50% of ankle sprains result in some cartilage injury 1
• CT can be used as an adjunct to identify, locate, and quantify cortical involvement and intra-articular ossific bodies 1

Common Pitfalls to Avoid

• Don't skip the base of the fifth metatarsal: Standard ankle views must include this area to avoid missing fractures 1
• Don't order foot or knee radiographs routinely: In the presence of inversion injury or ankle fracture, these have low yield 1
• Don't rely on radiographs alone for calcaneal or talar fractures: These are frequently missed (13-22% false negative rate) and require CT for proper evaluation 1, 3
• Don't manipulate before imaging unless there is neurovascular compromise or critical skin injury, as this significantly increases re-manipulation rates 2

Special Considerations

• For diabetic neuropathy or neurological compromise: Radiographs remain the initial study even without pain or point tenderness, as these patients may walk without discomfort despite fracture 1
• For suspected lateral talar process fractures ("snowboarder's fracture"): These are missed 40-50% of the time on routine radiographs; consider Broden view or proceed directly to CT/MRI if clinical suspicion is high 1
• Ultrasound is not routinely indicated as a next step but may be useful for focused evaluation of soft-tissue injuries, foreign bodies, or superficial occult fractures 1