What is the differential diagnosis for a patient presenting with a warm heel and burning pain?

Differential Diagnosis for Warm Heel with Burning Pain

A warm heel with burning pain most likely indicates either diabetic foot infection (if the patient has diabetes and a wound), Charcot neuro-osteoarthropathy (if diabetic with neuropathy and intact skin), or nerve entrapment syndrome—each requiring immediate and distinct management pathways.

Critical First Step: Rule Out Infection

If the patient has diabetes and any foot wound, infection must be excluded first as this represents the highest morbidity/mortality risk 1:

• Classic inflammatory signs (redness, warmth, swelling, tenderness, pain) or purulent secretions indicate infection 1
• Warmth combined with erythema in a diabetic foot wound requires immediate antibiotic therapy and wound debridement 1
• Assess for systemic signs of infection and classify severity to determine hospitalization need 1
• Evaluate for underlying osteomyelitis with imaging if infection is present 1

If Diabetic with Intact Skin: Consider Charcot Neuro-osteoarthropathy

Active Charcot neuro-osteoarthropathy should always be suspected when a diabetic patient with neuropathy presents with a unilateral red, warm, swollen foot and intact skin 1:

• Temperature difference ≥2°C between feet supports the diagnosis, though isolated temperature elevation alone is insufficient 1
• Pain may be absent or mild due to sensory neuropathy, but some patients experience severe pain despite neuropathy 1
• Initiate knee-high immobilization/offloading immediately while pursuing confirmatory imaging (MRI or bone scan) 1
• Untreated Charcot carries high risk of fractures, dislocations, deformity, ulceration, and amputation 1

Neurologic Causes: Nerve Entrapment

Burning pain specifically suggests nerve entrapment rather than mechanical causes 2, 3:

• Burning, tingling, or numbness distinguish neurologic from mechanical heel pain 2, 4, 5
• Tarsal tunnel syndrome causes medial midfoot heel pain with burning quality, particularly with prolonged weight-bearing 4, 5
• Immediate subspecialist referral is necessary for neurologic heel pain, including electromyography, nerve conduction studies, and MRI 3

Mechanical/Inflammatory Causes with Warmth

Calcaneal Stress Fracture

• Presents with progressively worsening pain following increased activity or harder walking surface 6, 4, 5
• Calcaneal squeeze test (medial-to-lateral compression) is highly suspicious 3, 6
• Tenderness localizes to lateral calcaneal wall 3
• Symptoms often precede radiographic findings; technetium bone scan or MRI needed if X-rays negative 2, 6

Insertional Achilles Tendinopathy

• Pain at posterior heel at tendon insertion site 3, 6
• Palpate for prominence and spurring medially/laterally to insertion 2
• Never inject corticosteroids near Achilles tendon due to rupture risk 2, 3

Haglund's Deformity with Retrocalcaneal Bursitis

• Posterior and lateral heel pain with prominent posterior superior calcaneus 3, 4, 5
• Pain relieved barefoot but worsened by shoes 2, 3
• Tenderness lateral to Achilles tendon 2

Plantar Fasciitis

• Medial plantar heel pain, especially with first weight-bearing steps after rest 4, 5
• Point tenderness at medial plantar calcaneal region 2

Algorithmic Diagnostic Approach

1. Assess diabetes status and skin integrity first 1

   • Wound present → Rule out infection with clinical signs and cultures 1
   • Intact skin + diabetes + neuropathy → Measure temperature difference and immobilize for suspected Charcot 1

2. Characterize the burning quality 2, 3

   • Burning/tingling/numbness → Nerve entrapment, refer immediately 2, 3
   • No neurologic symptoms → Proceed to mechanical causes

3. Localize pain anatomically 2, 3, 4:

   • Posterior heel → Achilles tendinopathy or Haglund's deformity
   • Lateral heel → Haglund's, sinus tarsi syndrome, or lateral ligament injury
   • Plantar heel → Plantar fasciitis or calcaneal stress fracture
   • Diffuse heel → Stress fracture or heel pad syndrome

4. Perform specific physical tests 2, 3:

   • Calcaneal squeeze test for stress fracture
   • Palpate specific anatomic landmarks
   • Assess footwear relationship to pain

5. Order imaging based on Ottawa Ankle Rules 2, 3:

   • Initial radiographs if unable to bear weight or point tenderness over bone
   • MRI or bone scan if radiographs negative but pain persists >1 week 2, 6

Critical Pitfalls to Avoid

• Never delay immobilization if Charcot is suspected—consequences of missed diagnosis include limb loss 1
• Reexamine 3-5 days post-injury as initial swelling can obscure findings 3
• Do not rely on radiographs alone for stress fractures—symptoms precede radiographic changes 2, 6
• Avoid corticosteroid injections near the Achilles tendon insertion 2, 3
• Do not dismiss burning quality—this mandates neurologic workup 2, 3