What are the differential diagnoses and treatment options for foot pain?

Differential Diagnoses for Foot Pain

Start with plain radiographs of the foot as your initial imaging study for any chronic foot pain of unknown etiology, as this is the most cost-effective approach that identifies the majority of structural causes. 1

Anatomic Location-Based Differential Diagnosis

Plantar Heel Pain

• Plantar fasciitis is the most common cause, presenting with pain on weight-bearing and when transitioning from sitting to standing 2
• Plantar fascia tear should be considered with acute onset of severe pain 1
• Baxter's neuropathy (inferior calcaneal nerve entrapment) manifests as denervation changes of the abductor digiti minimi muscle and causes burning heel pain 1
• Heel pad syndrome presents with diffuse heel pain 3

Posterior Heel Pain

• Achilles tendinopathy produces pain 2-6 cm proximal to the heel insertion 4
• Insertional Achilles tendonitis causes pain directly at the tendon insertion site 3
• Haglund's deformity with retrocalcaneal bursitis presents with posterior and lateral heel pain, associated with a prominent posterior superior calcaneus 3, 2
• Calcaneal stress fracture presents with progressively worsening pain following increased activity, with positive calcaneal squeeze test (medial-to-lateral compression) 3

Lateral Heel Pain

• Calcaneofibular ligament sprain occurs with inversion trauma and pain with dorsiflexion 3
• Lateral process fracture of the talus ("snowboarder's fracture") causes lateral and posterior ankle pain following inversion trauma 3
• Sinus tarsi syndrome may present with lateral heel pain 3

Midfoot Pain

• Tarsal coalitions (calcaneonavicular or talocalcaneal) can be detected on radiographs with 80-100% sensitivity for calcaneonavicular and 100% sensitivity for talocalcaneal coalitions 1
• Occult stress fractures of the navicular, cuboid, or cuneiform bones require high clinical suspicion 1
• Painful accessory ossicles may cause chronic midfoot pain 1

Forefoot Pain

• Morton's neuroma presents with burning pain in the ball of the foot and numbness radiating to the third and fourth toes, with approximately 30% not responding to conservative treatment 4
• Sesamoid pathology including sesamoiditis, dislocation, or fracture 1
• Metatarsal stress fractures have radiographic sensitivities of only 12-56% initially 1
• Freiberg's infraction (avascular necrosis of metatarsal head) 1

Fifth Toe Pain

• Fractures are detected with 80-100% sensitivity on standard three-view radiographs 5
• Osteoarthritis and other bony abnormalities are visible on plain films 5

Special Populations and Systemic Causes

Diabetic Foot Pain

• Diabetic foot infection requires evaluation for at least 2 classic signs of inflammation (erythema, warmth, tenderness, pain, induration) or purulent secretions 1
• Osteomyelitis is often difficult to diagnose and requires high clinical suspicion 1
• Charcot arthropathy requires specialized evaluation 1

Pediatric Foot Pain

• Sever disease (calcaneal apophysitis) is the most common cause of heel pain in adolescents and children 3

Systemic Disease Manifestations

• Inflammatory arthropathies (rheumatoid arthritis, spondyloarthropathies) frequently affect the foot as a first presentation 6
• Gout commonly presents in the foot 6
• Vascular compromise can result in heel pain and requires proper diagnostic evaluation 3
• Infections (soft tissue and bone osteomyelitis) rarely cause heel pain but require consultation when suspected 3

Diagnostic Algorithm

Initial Evaluation

• Obtain standard three-view radiographs (anteroposterior, oblique, lateral) as the first imaging study for any chronic foot pain 1, 5
• Radiographs have 80-100% sensitivity for tarsal coalitions, 80-100% sensitivity for toe fractures, but only 12-56% sensitivity for stress fractures 1, 5

When Radiographs Are Negative or Equivocal

For suspected stress fractures or CRPS:

• Order MRI foot without IV contrast or 3-phase bone scan as equivalent next-step options 1
• Technetium bone scanning detects stress fractures before radiographic changes appear 3

For plantar fasciitis or plantar fascia tear:

• Order MRI foot without IV contrast or ultrasound foot as equivalent options 1

For entrapment syndromes (Baxter's neuropathy):

• Order MRI foot without IV contrast to demonstrate denervation changes in the abductor digiti minimi muscle, or ultrasound foot to visualize the nerve 1

For Morton's neuroma or intermetatarsal bursitis:

• Order ultrasound or MRI to detect soft tissue pathology 5

For occult fractures or painful accessory ossicles:

• Order MRI foot without IV contrast or CT foot without IV contrast as equivalent options 1

Key Physical Examination Findings

• Point tenderness location is critical: palpate the Achilles insertion, lateral malleolus, posterior superior calcaneus, lateral calcaneal wall, and calcaneofibular ligament course 3
• Calcaneal squeeze test (medial-to-lateral compression) suggests stress fracture 3
• Rapid onset of swelling suggests acute ligamentous injury or fracture 3
• Pain relieved when walking barefoot but worsened by shoes suggests Haglund's deformity or bursitis 3, 2
• Burning or tingling suggests neurologic causes 3

Common Pitfalls to Avoid

• Overlooking small avulsion fractures on radiographs requires careful systematic review 5
• Failing to obtain weight-bearing views when indicated can miss subtle deformities 5
• Reexamining too early: always reexamine 3-5 days post-injury, as excessive swelling and pain can limit the initial examination within 48 hours 3
• Missing stress fractures: patients often report increased walking activity before symptom onset, and radiographs may initially be negative 3
• Underestimating proper footwear impact on symptom management 5
• Missing foreign bodies in cases of penetrating trauma 5
• Misdiagnosing peripheral neuropathic pain (such as saphenous nerve involvement) as plantar fasciitis 7