What is the initial management for a patient with unilateral ankle swelling?

Initial Management of Unilateral Ankle Swelling

The first priority is to determine if trauma occurred and apply the Ottawa Ankle Rules to decide if imaging is needed, followed by ruling out deep vein thrombosis (DVT) if no trauma is present, as these are the two most critical diagnoses affecting morbidity and mortality. 1

Step 1: Determine if Trauma is Present

If Trauma Occurred (or within 3 weeks of injury):

Apply the Ottawa Ankle Rules immediately to determine if radiographs are necessary 1, 2:

• Order ankle radiographs if ANY of the following are present 1, 2:

  • Inability to bear weight immediately after injury OR inability to take 4 steps in the emergency department 1
  • Point tenderness over the posterior edge or inferior tip of the medial malleolus 1
  • Point tenderness over the posterior edge or inferior tip of the lateral malleolus 1
  • Point tenderness over the talus or calcaneus 1

• Do NOT apply Ottawa Ankle Rules if 2:

  • Patient has peripheral neuropathy 2
  • Patient has diabetes with neuropathy 3, 2
  • Suspected foreign body 2
  • High-energy trauma 2

The Ottawa Ankle Rules have 92-100% sensitivity for detecting fractures, making them highly reliable for excluding fractures when negative 1, 2.

If Radiographs are Negative or Ottawa Rules are Negative:

Begin immediate functional treatment rather than immobilization 4, 2:

• Apply a lace-up or semi-rigid ankle brace within 48 hours and continue for 4-6 weeks, which is superior to immobilization and leads to return to sports 4.6 days sooner 4, 2
• Start supervised exercise therapy within 48-72 hours, including proprioception training, strengthening exercises, coordination drills, and functional exercises 1, 4, 2
• Consider NSAIDs for pain control (ibuprofen, naproxen, diclofenac, or celecoxib) for short-term use (<14 days) 1, 4
• Avoid prolonged immobilization beyond initial pain control, as this delays recovery without improving outcomes 1, 4

Common pitfall: The traditional RICE protocol alone has no evidence for effectiveness in ankle sprains 1, 4. While individual components like ice may provide comfort, they should not be the sole treatment 1.

If Pain Persists Beyond 1 Week with Negative Radiographs:

Order MRI without IV contrast as the next study, as it is most sensitive for detecting occult fractures, ligamentous injuries, osteochondral injuries, and soft-tissue abnormalities 1, 2.

Step 2: If No Trauma is Present

Rule Out Deep Vein Thrombosis (DVT):

Unilateral swelling without trauma raises immediate concern for DVT, which is a life-threatening condition requiring urgent diagnosis 1, 5:

• Obtain venous duplex ultrasound of the lower extremity as the initial imaging study 1, 6, 5
• Ultrasound has >80% sensitivity and specificity for detecting DVT 1
• Look for risk factors: recent immobilization, surgery, malignancy, indwelling catheters, hypercoagulability, heart failure, or advanced age 1

Critical point: DVT can present with unilateral edema, pain, and functional impairment, and must be excluded before attributing swelling to benign causes 1.

If DVT is Excluded, Consider Other Causes:

Evaluate for the following based on clinical presentation 1, 6, 5:

• Chronic venous insufficiency: Most common cause of unilateral leg swelling in the absence of acute DVT 5
• Lymphedema: Due to lymphatic obstruction from malignancy or previous surgery 1
• Infection/cellulitis: Look for erythema, warmth, and systemic signs 1
• Lipedema: Rare but characterized by subcutaneous adipose tissue deposition, typically bilateral but can appear asymmetric 6
• Musculoskeletal causes: Achilles tendinopathy, bursitis, or muscle injury 1, 7

Step 3: Special Considerations

For Patients with Diabetes:

• Do NOT use Ottawa Ankle Rules if peripheral neuropathy is present 3, 2
• Perform vascular assessment including pedal pulse palpation and consider ankle-brachial index (ABI) if pulses are diminished (normal ABI 0.90-1.30) 3
• Screen for neuropathy using 10-g monofilament to test for loss of protective sensation 3

Red Flags Requiring Immediate Attention:

• Signs of compartment syndrome (severe pain, paresthesias, pallor) 1
• Neurovascular compromise 1
• Signs of DVT (warmth, tenderness, positive Homan's sign) 1, 5
• Critical skin injury 1

Avoid manipulation of the ankle prior to radiographs in the absence of neurovascular deficit or critical skin injury to prevent complications 1.