What are the causes of ankle swelling?

Common Causes of Ankle Swelling

Ankle swelling is most commonly caused by trauma (sprains/fractures), venous disorders, or systemic conditions affecting fluid balance, with proper diagnosis requiring careful assessment of onset timing, associated symptoms, and risk factors.

Traumatic Causes

Ankle Sprains

• Most common cause of acute ankle swelling in active individuals
• Typically results from inversion injuries in plantar-flexed position 1
• Severity classification:
  • Grade I: Stretching of ligaments with minimal damage
  • Grade II: Partial tears of ligaments
  • Grade III: Complete ligament rupture with significant swelling, hematoma, and pain 1
• Lateral ligaments (anterior talofibular, calcaneofibular, posterior talofibular) most commonly affected
• High ankle (syndesmotic) sprains occur with dorsiflexion and eversion with internal rotation of tibia 1

Fractures

• Ottawa Ankle and Foot Rules help determine need for radiography:
  • Inability to bear weight immediately after injury
  • Point tenderness over malleoli, posterior edge/inferior tip of lateral malleolus, talus, or calcaneus
  • Inability to ambulate for 4 steps 1
• Radiographs can miss some fractures; consider advanced imaging if high clinical suspicion
• Ankle fractures are associated with prolonged venous dysfunction causing persistent swelling for up to 18 weeks 2

Osteochondral Lesions

• Result from trauma to articular cartilage and subchondral bone
• Present with persistent pain, stiffness, locking, clicking, and ankle swelling 1
• MRI is preferred for diagnosis as it shows both bone and cartilage injuries

Vascular Causes

Deep Vein Thrombosis (DVT)

• Upper extremity DVT principles apply similarly to lower extremity
• Presents with unilateral swelling, pain, and sometimes functional impairment 1
• Risk factors include:
  • Immobilization (e.g., after fracture/surgery)
  • Hypercoagulability
  • Advanced age
  • Heart failure
  • Cancer
  • Trauma 1

Venous Insufficiency

• Chronic condition with persistent swelling
• Often bilateral and worse at end of day
• Associated with varicose veins, skin changes, and history of DVT

Vascular Injuries

• Rare but potentially limb-threatening
• Pseudo-aneurysm can occur even after seemingly minor trauma 3
• Consider when no definitive musculoskeletal cause is found with significant pain/swelling

Inflammatory/Infectious Causes

Cellulitis

• Presents with erythema, warmth, tenderness, and swelling
• May complicate ankle sprains, especially with broken skin 4
• Can progress to antibiotic-resistant infections requiring specialized treatment

Post-traumatic Arthritis

• Develops after injury to joint surfaces
• Presents with chronic swelling, pain with activity, and decreased range of motion

Ligament Adhesions

• Forms approximately 6 weeks after injury
• Results from immobilization leading to inelastic scar tissue
• Patients complain of pain and sometimes swelling after exertion 5

Systemic Causes

Heart Failure

• Bilateral ankle swelling (often with pitting edema)
• Associated with dyspnea, fatigue, and other cardiac symptoms
• Swelling typically worse in evening and improves with elevation

Kidney Disease

• Bilateral swelling often extending beyond ankles
• Associated with hypertension, fatigue, and changes in urination

Liver Disease

• Bilateral swelling with possible ascites
• Associated with jaundice, abdominal distension, and other liver dysfunction signs

Medication Side Effects

• Calcium channel blockers, NSAIDs, steroids, and hormonal therapies
• Usually bilateral and dose-dependent

Diagnostic Approach

1. Determine acuity of onset:

   • Acute (hours to days): Trauma, DVT, infection
   • Chronic (weeks to months): Venous insufficiency, systemic disease

2. Assess for trauma history:

   • Mechanism of injury (inversion vs. eversion)
   • Ability to bear weight after injury
   • Presence of instability or mechanical symptoms

3. Evaluate for systemic symptoms:

   • Bilateral vs. unilateral swelling
   • Associated cardiopulmonary symptoms
   • Fever or other signs of infection

4. Consider appropriate imaging:

   • X-rays for suspected fractures using Ottawa rules
   • Ultrasound for suspected DVT
   • MRI for suspected ligament/tendon injuries or osteochondral lesions

Treatment Considerations

• For ankle sprains: PRICE protocol (Protection, Rest, Ice, Compression, Elevation) 1
• NSAIDs may help reduce pain and swelling but may suppress natural healing 1
• Functional rehabilitation with supervised exercise-based programs preferred over passive modalities 1
• Semirigid or lace-up ankle supports recommended for treatment and prevention of recurrence 1
• Surgery reserved for cases not responding to comprehensive exercise-based treatment 1

Common Pitfalls

1. Assuming all ankle swelling is due to simple sprains without proper evaluation
2. Missing fractures by not applying Ottawa Ankle Rules appropriately
3. Overlooking vascular causes like DVT in patients with risk factors
4. Failing to recognize systemic causes in bilateral swelling
5. Prolonged immobilization leading to ligament adhesions and chronic instability
6. Not considering rare but serious causes like vascular injuries or infections

By systematically evaluating the timing, associated symptoms, and risk factors, clinicians can accurately diagnose and appropriately manage ankle swelling to improve outcomes and prevent complications.