What are the differentials and management options for ankle pain?

Differential Diagnoses for Ankle Pain

The most common cause of ankle pain is lateral ankle ligament sprain from inversion injury, but a systematic approach must evaluate traumatic, degenerative, inflammatory, and soft tissue pathologies to avoid missing critical diagnoses. 1

Traumatic Causes

Ligamentous Injuries

• Lateral ankle sprain (anterior talofibular, calcaneofibular, posterior talofibular ligaments) is the most frequent acute ankle injury, accounting for approximately 2 million injuries annually in the United States 1
• High ankle (syndesmotic) sprain occurs from dorsiflexion and eversion with internal rotation of the tibia, injuring the posterior and anterior tibiofibular ligaments 1
• The crossed-leg test (pressure on medial knee producing syndesmosis pain) identifies high ankle sprains 1

Fractures

• Lateral process fracture of the talus ("snowboarder's fracture") causes lateral and posterior ankle pain with antalgic gait following inversion trauma 2
• Calcaneal stress fracture presents with progressively worsening pain after increased activity, with tenderness on the lateral calcaneal wall and positive calcaneal squeeze test (medial-to-lateral compression) 2
• Acute calcaneal fracture from fall onto heel causes diffuse rearfoot pain, poorly localized with intra-articular involvement 2
• Apply Ottawa Ankle Rules to determine radiograph necessity: inability to bear weight immediately after injury, point tenderness over malleoli/base of 5th metatarsal/navicular bone, or inability to walk 4 steps 1, 3

Degenerative and Overuse Causes

Tendon Pathology

• Insertional Achilles tendonitis produces pain at the tendon insertion site on the posterior calcaneus 2
• Peroneal tendon tears (partial or complete) cause lateral ankle pain and may persist after initial sprain 4, 5

Bursitis and Deformity

• Haglund's deformity with retrocalcaneal bursitis presents with posterior and lateral heel pain from prominent posterior superior calcaneus causing bursal inflammation 2
• Pain relieved when walking barefoot but worsened by shoes strongly suggests this diagnosis 2

Osteoarthritis

• Degenerative joint disease of the ankle or hindfoot can be identified on initial radiographs 1

Intra-articular Pathology

Osteochondral Lesions

• Osteochondral defects of the talus cause persistent pain and may not be visible on plain radiographs 1
• MRI without contrast has 93-96% sensitivity and 100% specificity for detecting these lesions 1

Impingement Syndromes

• Anterolateral impingement from soft tissue scarring or synovitis causes anterior ankle pain with dorsiflexion 1, 6
• Anterior impingement from osseous spurs limits dorsiflexion 6
• Posterior impingement causes pain with plantarflexion 6

Loose Bodies

• Intra-articular loose bodies or synovial osteochondromatosis can be identified on radiographs 1

Inflammatory and Infectious Causes

• Arthritides (rheumatoid, psoriatic, reactive) should be considered with bilateral symptoms, pain in other joints, or known inflammatory conditions 2
• Soft tissue infections and osteomyelitis rarely cause heel pain but require diagnostic testing and consultation when suspected 2

Neurologic Causes

• Peripheral nerve entrapment (tarsal tunnel syndrome, sural nerve) causes burning or tingling sensations 2
• Ultrasound has higher resolution than MRI for peripheral nerve evaluation 1

Pediatric-Specific Causes

• Sever disease (calcaneal apophysitis) is the most common cause of heel pain in adolescents and children 2

Diagnostic Algorithm

Initial Assessment

1. History: Mechanism of injury, timing, previous sprains, location of pain, aggravating factors 1
2. Physical examination findings:
   • Point tenderness location (malleoli, lateral calcaneal wall, Achilles insertion, calcaneofibular ligament course) 2
   • Anterior drawer test for lateral ligament integrity (84% sensitivity, 96% specificity when delayed 4-5 days post-injury) 1
   • Calcaneal squeeze test for stress fracture 2
   • Crossed-leg test for syndesmotic injury 1

Imaging Strategy

1. Plain radiographs (AP, lateral, mortise views) are the most appropriate initial study for all ankle pain 1
2. Reexamine at 3-5 days if initial exam limited by swelling—excessive swelling and pain can obscure findings within 48 hours 1
3. Advanced imaging when radiographs normal:
   • MRI without contrast for suspected osteochondral lesions, impingement syndromes, occult fractures, or pain of uncertain etiology 1
   • MRI or ultrasound for suspected tendon abnormalities 1
   • MRI or MR arthrography for suspected ankle instability 1
   • CT without contrast for suspected occult fractures when MRI unavailable 1
   • Technetium bone scan for stress fractures with negative radiographs, as symptoms precede radiographic findings 2

Critical Pitfalls to Avoid

• Do not rely on initial examination alone—always reexamine 3-5 days post-injury when swelling subsides for accurate assessment of ligament rupture versus partial tear 1
• Stress radiographs are obsolete—they have limited diagnostic value and cause pain; use delayed physical examination instead 1
• Ultrasonography for ligament assessment has good sensitivity (92%) but poor specificity (64%) compared to delayed physical examination 1
• Symptoms precede radiographic findings in stress fractures—order bone scan or MRI if clinical suspicion high despite negative radiographs 2
• Avoid corticosteroid injections near the Achilles tendon—this increases rupture risk 2