What could be causing pain and swelling in my ankles and the top of my feet?

Differential Diagnosis of Ankle and Foot Pain with Swelling

Pain and swelling in the ankles and top of the feet can result from multiple causes including ligamentous injury, tendinopathy, inflammatory arthritis, infection, or stress fracture—and initial plain radiographs are essential to guide further evaluation. 1, 2

Initial Diagnostic Approach

Start with Plain Radiographs

• Radiography is the mandatory first imaging study for ankle and foot pain with swelling 1
• Obtain anteroposterior, lateral, and mortise views (mortise requires 15-20 degree internal rotation) 1
• Radiographs can identify fractures, osteoarthritis, joint effusions (53-74% accuracy), osteochondral abnormalities, stress fractures, ossific fragments suggesting ligament injury, and periostitis adjacent to tenosynovitis 1
• Apply the Ottawa Ankle Rules to determine if radiographs are needed: obtain imaging if the patient has inability to bear weight immediately after injury, point tenderness over malleoli/talus/calcaneus, or inability to walk 4 steps 2

Key History Elements to Elicit

• Mechanism of injury: Inversion trauma suggests lateral ligament sprain; dorsiflexion with eversion and internal tibial rotation suggests high ankle (syndesmotic) sprain 1
• Timing: Rapid onset of swelling indicates acute ligamentous injury or fracture 1, 2
• Activity changes: Increased walking activity before symptom onset suggests stress fracture 1, 2
• Location specificity: Posterior heel pain indicates Achilles tendonitis or bursitis; lateral heel pain suggests Haglund's deformity or sinus tarsi syndrome; diffuse heel pain suggests stress fracture 2, 3
• Bilateral symptoms or other joint involvement: Consider inflammatory arthritis, particularly spondyloarthritis (more likely than rheumatoid arthritis for ankle involvement) 4

Critical Physical Examination Findings

• Palpate specific anatomic structures: Achilles insertion, lateral malleolus, posterior superior calcaneus, lateral calcaneal wall, and calcaneofibular ligament course 2
• Calcaneal compression test (medial-to-lateral squeeze): Highly suspicious for stress fracture if positive 1, 2
• Anterior drawer test: Detects excessive anterior displacement of talus, indicating anterior talofibular ligament tear 1
• Grade III sprain indicators: Swelling, hematoma, pain on palpation, and positive anterior drawer test together have 96% likelihood of lateral ligament rupture 1
• Reexamine at 3-5 days post-injury: Excessive swelling and pain limit examination accuracy within the first 48 hours 1, 2

Most Common Causes by Presentation Pattern

Acute Traumatic Swelling

• Lateral ligament injury (anterior talofibular, calcaneofibular ligaments): Most common ankle sprain, occurs with inversion in plantar-flexed position 1, 2
• High ankle (syndesmotic) sprain: Dorsiflexion/eversion mechanism, test with crossed-leg test (pressure on medial knee produces syndesmosis pain) 1
• Lateral process fracture of talus ("snowboarder's fracture"): Inversion trauma causing lateral and posterior ankle pain with antalgic gait 2
• Acute calcaneal fracture: Fall from height causing diffuse rearfoot pain, confirmed by radiographs 1, 2

Gradual Onset with Activity-Related Pain

• Stress fracture of calcaneus: Progressive pain with increased activity, tenderness at lateral calcaneal wall posterior to subtalar facet, positive calcaneal squeeze test 1, 2
• Tendinopathies: Posterior tibial (medial ankle pain with flat-footed deformity and "too many toes sign"), peroneal (lateral ankle pain and instability), Achilles (pain 4-6 cm above calcaneal insertion), or flexor hallucis longus (posteromedial ankle pain in dancers) 5, 6
• Plantar fasciitis: Pain on weight bearing, especially transitioning from sitting to standing, affecting plantar heel 3, 6

Inflammatory Pattern (Bilateral or Systemic Symptoms)

• Spondyloarthritis or undifferentiated arthritis: More likely than rheumatoid arthritis for new ankle involvement 4
• Gout: More common than CPPD for ankle arthritis 4
• Septic arthritis: Consider bacterial, chikungunya, or HIV-related infection; ankle is commonly involved 4

Red Flags Requiring Urgent Evaluation

• High pain level, rapid swelling, coldness/numbness, inability to bear weight, or complicating conditions (diabetes) warrant urgent assessment 1
• Suspected infection: Obtain radiographs first, then consider image-guided aspiration for culture if joint effusion or fluid collection present 1

Next Steps When Initial Radiographs Are Normal or Nondiagnostic

If Pain Persists >1 Week After Negative Radiographs

• MRI without contrast or CT without contrast are equivalent alternatives for further evaluation 2
• MRI globally evaluates ligaments, tendons, cartilage, bone marrow, synovitis, and impingement lesions with high accuracy 1, 7

If Stress Fracture Suspected with Negative Radiographs

• Technetium bone scanning can detect stress fractures before they become radiographically visible 1, 2
• Symptoms often precede radiographic findings by weeks 1

If Septic Arthritis or Soft Tissue Infection Suspected

• Image-guided aspiration (fluoroscopy, ultrasound, or CT) for culture is essential when imaging cannot distinguish infected from noninfected fluid 1
• Aspiration allows organism identification and directly affects treatment 1

Common Pitfalls to Avoid

• Don't dismiss negative initial radiographs in stress fracture: Bone changes lag behind symptoms; use bone scan or MRI if clinical suspicion remains high 1, 2
• Don't examine only once acutely: Always reexamine 3-5 days post-injury when swelling has decreased 1, 2
• Don't overlook primary ankle osteoarthritis: This is rare and should prompt investigation for underlying causes, especially hemochromatosis 4
• Don't confuse periarticular swelling with true ankle arthritis: Conditions like Lofgren's syndrome cause subcutaneous edema without joint involvement 4
• Don't assume unilateral ankle arthritis is osteoarthritis: Consider spondyloarthritis, gout, or infection first 4