What are the steps to diagnose plantar fasciitis?

Diagnosing Plantar Fasciitis

Plantar fasciitis is predominantly a clinical diagnosis based on characteristic history and physical examination findings, with imaging reserved for atypical presentations or symptoms persisting beyond 3 months despite treatment. 1, 2

Clinical Diagnosis

Key Historical Features

• Stabbing, nonradiating heel pain that is worst with first steps in the morning or after prolonged sitting/rest 3, 2
• Pain located on the plantar medial heel at the proximal plantar fascia 1, 4
• Pain that worsens at the end of the day with prolonged standing 2
• Symptoms are typically not inflammatory in nature (plantar fasciopathy is more accurate) 2

Physical Examination Findings

• Point tenderness at the medial tubercle of the calcaneus where the plantar fascia originates—this is the key diagnostic finding 3, 1
• Pain can be elicited by passive dorsiflexion of the ankle and first toe, which stresses the proximal plantar fascia 1
• Palpation along the medial plantar calcaneal region reproduces the painful symptoms 4

Risk Factors to Identify

• Limited ankle dorsiflexion, increased body mass index, prolonged standing 2
• Excessive foot pronation, excessive running in athletes 1
• Gastrocnemius tightness is commonly associated 3

When to Order Imaging

Imaging is not necessary for initial diagnosis but should be obtained in specific circumstances: 1, 2

Indications for Weightbearing Radiographs

• If diagnosis is unclear or symptoms persist beyond 3 months despite conservative treatment 5, 6
• The American College of Radiology recommends weightbearing radiographs as the initial imaging study for painful heel with 85% sensitivity and 95% specificity 5, 6
• Radiographs help exclude other pathologies such as calcaneal stress fractures, tarsal tunnel syndrome, or plantar fascia rupture 5
• Presence of a heel spur indicates the condition has been present for at least 6-12 months but is not causative 4

Advanced Imaging Options

MRI is the most sensitive imaging modality for definitive diagnosis when uncertainty persists after initial evaluation 5, 6

• MRI allows accurate characterization of the plantar fascia and adjacent soft tissues/bones 6
• MRI findings must be correlated with clinical symptoms to avoid overcalling plantar fasciitis, as some findings appear in asymptomatic patients 6

Ultrasound provides good diagnostic accuracy as a less expensive alternative 5, 6

• Conventional ultrasound has 80% sensitivity and 88% specificity compared to MRI 5, 6
• Diagnostic findings include abnormal focal echogenicity within plantar fascia, perifascial edema, and plantar fascia thickness >4mm (abnormal) 5
• US elastography demonstrates superior accuracy with 95% sensitivity and 100% specificity versus conventional ultrasound (66% sensitivity, 75% specificity) 6

Diagnostic Algorithm

1. Start with focused history and physical examination looking for characteristic morning heel pain and point tenderness at the medial calcaneal tubercle 3, 1

2. If clinical presentation is typical, no imaging is needed—begin conservative treatment 1, 2

3. If diagnosis is uncertain or atypical, obtain weightbearing radiographs to exclude other pathologies 5, 6

4. If symptoms persist beyond 3 months despite treatment, obtain weightbearing radiographs if not already done 5, 6

5. If diagnosis remains uncertain after radiographs, consider MRI for definitive evaluation or ultrasound for cost-effective confirmation 5, 6, 2

Common Pitfalls

• Do not routinely order imaging for typical presentations—this delays treatment and increases costs without changing management 1, 2
• Do not assume heel spurs are causative—they indicate chronicity but are not the source of pain 4
• Do not rely solely on imaging findings without clinical correlation—asymptomatic patients can have abnormal imaging 6
• Do not miss differential diagnoses including calcaneal stress fracture, tarsal tunnel syndrome, or plantar fascia rupture, which require different management 5