Lateral Foot Pain: Causes and Treatment
Most Common Causes
Lateral foot pain most commonly results from lateral ankle ligament injury (particularly calcaneofibular ligament sprain), peroneal tendinopathy, cuboid syndrome, calcaneal stress fracture, or painful os peroneum syndrome. 1
Primary Differential Diagnoses
Lateral ankle ligament injury (especially calcaneofibular ligament sprain) is the most common cause, particularly following inversion trauma with pain worsening on dorsiflexion 1
Peroneal tendinopathy presents with lateral ankle and foot pain, commonly mistaken for or occurring alongside lateral ankle sprains, with varus hindfoot being a known risk factor 2
Cuboid syndrome arises from disruption of calcaneocuboid joint arthrokinematics and presents with lateral midfoot pain that resembles ligament sprain symptoms 3
Calcaneal stress fracture causes progressively worsening lateral heel pain following increased walking activity or change to harder surfaces, with tenderness localizing to the lateral calcaneal wall slightly posterior to the subtalar joint 1
Painful os peroneum syndrome should be considered when pain localizes to the plantar lateral foot, resulting from os peroneum fracture, multipartite os peroneum diastasis, peroneus longus tendon pathology, or peroneal tubercle entrapment 4, 5
Haglund's deformity with retrocalcaneal bursitis causes posterior and lateral heel pain when the prominent posterior superior calcaneus inflames the overlying bursa 1
Lateral process fracture of the talus ("snowboarder's fracture") causes lateral and posterior ankle pain with antalgic gait following inversion trauma 1
Diagnostic Approach
Key Physical Examination Findings
Palpate specific anatomical landmarks including the lateral malleolus, posterior superior calcaneus, lateral calcaneal wall, calcaneofibular ligament course, cuboid, and peroneus longus tendon 1
Perform calcaneal compression test by squeezing the calcaneus from medial to lateral—pain suggests stress fracture 1
Assess for rapid onset swelling which indicates acute ligamentous injury or fracture, with lateral gutter swelling specifically indicating lateral ligament involvement 1
Single stance heel rise and varus inversion stress test with resisted plantarflexion of the first ray localizes tenderness along the peroneus longus tendon for painful os peroneum syndrome 5
Reexamine 3-5 days post-injury if initial examination is limited, as excessive swelling within 48 hours can obscure findings 1
Imaging Strategy
Obtain initial radiographs if Ottawa Ankle Rules criteria are met: inability to bear weight immediately after injury, point tenderness over malleoli/talus/calcaneus, or inability to ambulate 4 steps 1
If radiographs are negative but pain persists >1 week, MRI without contrast or CT without contrast are equivalent alternatives for further evaluation 1
For suspected stress fracture with negative initial radiographs, obtain technetium bone scanning, as symptoms often precede radiographic findings 1
Musculoskeletal ultrasonography is useful for initial diagnosis of painful os peroneum syndrome and peroneal tendinopathy 4, 2
Treatment Algorithm
Conservative Management (First-Line)
For peroneal tendinopathy: immobilization initially, followed by laterally posted orthotics and physical therapy focusing on progressive eccentric tendon loading 2
For cuboid syndrome: manipulation of the cuboid should be considered as initial treatment unless contraindicated, along with external support 3
For calcaneal stress fracture: protect and immobilize the foot 1
For Haglund's deformity with bursitis: open-backed shoes, orthoses with accommodative padding, NSAIDs, corticosteroid injections (avoiding the Achilles tendon), and physical therapy 1
For lateral ankle ligament injury: rest, activity modification, NSAIDs, and progressive rehabilitation 1
When Conservative Treatment Fails
Refer if no improvement after 6-8 weeks of appropriate conservative treatment 1
Surgical intervention for peroneal tendinopathy is considered after 3-6 months of failed nonoperative treatment 2
Surgical treatment for painful os peroneum syndrome may be necessary for chronic fractures, tendon ruptures, or peroneal tubercle entrapment 4, 5
Critical Pitfalls to Avoid
Do not overlook stress fractures—patients often report increased walking activity before symptom onset, and radiographs may initially be negative requiring bone scan or MRI 1
Avoid corticosteroid injections near the Achilles tendon due to risk of tendon rupture 1
Do not rely solely on initial radiographs as sensitivity for stress fractures is poor (12-56%) 1
Consider painful os peroneum syndrome in the differential for lateral plantar foot pain, as it is commonly missed 4, 5
Recognize that peroneal tendinopathy is frequently mistaken for lateral ankle sprains or occurs concomitantly with them 2