What is the appropriate management for persistent ankle pain after tripping over a dog?

Management of Persistent Ankle Pain After Trauma

For persistent ankle pain over a month after an ankle injury, MRI without IV contrast is the most appropriate next imaging study to evaluate for occult fractures, ligamentous injuries, or soft tissue damage. 1

Initial Assessment and Imaging Decision Algorithm

1. First-line imaging: Radiographs (X-rays)

   • Should have been performed initially if Ottawa Ankle Rules were positive 2:
     • Inability to bear weight immediately after injury
     • Point tenderness over malleoli, talus, or calcaneus
     • Inability to ambulate for 4 steps

2. When to proceed to advanced imaging:

   • Pain persisting >1 week but <3 weeks after injury with negative initial X-rays 1
   • Pain persisting >3 weeks (chronic ankle pain) with negative X-rays 1

3. Advanced imaging options:

   • MRI without IV contrast (preferred):

     • Most sensitive for occult fractures with bone marrow edema patterns
     • Reference standard for ligamentous injury assessment
     • Best for comprehensive evaluation of all anatomic structures 1

   • CT without IV contrast (alternative):

     • Better for detailed bony assessment
     • Useful for suspected occult fractures, especially talar or calcaneal fractures 1

Common Causes of Persistent Ankle Pain

• Ligamentous injuries: Anterior talofibular ligament tears are most common (lateral ankle sprains) 1
• Occult fractures: Talar fractures (lateral process or talar dome) often missed on radiographs 1
• Osteochondral lesions: May require MRI for detection 1
• Tendon abnormalities: Peroneal tendinopathy or tears 3
• Ankle impingement syndromes: Anterolateral impingement common after lateral ankle sprains 1
• Syndesmotic injuries: "High ankle sprains" may cause prolonged symptoms 1

Treatment Approach Based on Imaging Findings

1. If occult fracture identified:

   • Orthopedic referral for appropriate management
   • May require immobilization or surgical intervention depending on location and displacement 1

2. If ligamentous injury identified:

   • Grade 1-2 sprains: Functional rehabilitation with physical therapy
   • Grade 3 complete tears: Possible orthopedic referral, especially for athletes 4

3. If tendon abnormality identified:

   • Physical therapy for tendinopathy
   • Surgical referral for complete tears or subluxation 3

4. If osteochondral lesion identified:

   • Orthopedic referral for potential arthroscopic intervention 5

5. If normal imaging but persistent pain:

   • Consider physical therapy for ankle strengthening and proprioception
   • Evaluate for chronic ankle instability
   • Consider ankle bracing for activities 4

Important Caveats

• MRI is superior to CT for soft tissue evaluation but CT better detects subtle fractures 1
• Ultrasound can be useful for focused tendon or ligament evaluation but is not recommended for comprehensive assessment 1
• Persistent pain despite negative imaging may still benefit from physical therapy focused on proprioception and strengthening 3
• Consider semirigid ankle orthosis for moderate to severe sprains for at least 6 months following injury to prevent recurrence 4

In this case of persistent ankle pain over a month after tripping over a dog, MRI without contrast is the most appropriate next step to comprehensively evaluate all potential causes of ongoing symptoms and guide appropriate treatment.