What is the diagnostic workup for non-traumatic foot pain that starts medially and radiates distally?

From the Guidelines

The diagnostic workup for nontraumatic foot pain that starts medially and radiates down the foot should begin with weight-bearing foot radiographs to evaluate for structural abnormalities, arthritis, or stress fractures, as recommended by the American College of Radiology Appropriateness Criteria 1. This presentation is highly suggestive of tarsal tunnel syndrome or medial plantar nerve entrapment, though posterior tibial tendonitis and plantar fasciitis should also be considered. Initial evaluation should include a thorough history and physical examination, focusing on the timing, quality, and exacerbating factors of the pain. If the radiographs are unremarkable, an ultrasound can assess for soft tissue pathology such as tendinopathy or plantar fasciitis, as it may be performed when there is a high clinical suspicion of pathologic conditions of the Achilles tendon, plantar fascia, and other conditions such as tarsal tunnel syndrome, Morton’s neuroma, plantar plate tears, and intermetatarsal bursitis 1. For persistent symptoms, MRI provides detailed evaluation of soft tissues, nerves, and bone marrow edema, and is usually appropriate as the next imaging study after negative or equivocal radiographs in patients with chronic foot pain, especially when clinical concern includes entrapment syndromes or Baxter’s neuropathy 1. Electrodiagnostic studies (EMG/NCS) are particularly valuable when nerve entrapment is suspected, as they can confirm tarsal tunnel syndrome by demonstrating delayed nerve conduction. Laboratory tests including ESR, CRP, uric acid, and rheumatoid factor may be appropriate if inflammatory conditions are suspected. Conservative management can be initiated concurrently with diagnostics and typically includes rest, NSAIDs (such as ibuprofen 400-800mg three times daily with food), appropriate footwear with arch support, and physical therapy. Key considerations in the diagnostic workup include:

• Initial weight-bearing foot radiographs to evaluate for structural abnormalities, arthritis, or stress fractures
• Ultrasound for soft tissue pathology if radiographs are unremarkable
• MRI for detailed evaluation of soft tissues, nerves, and bone marrow edema in persistent symptoms
• Electrodiagnostic studies for suspected nerve entrapment
• Laboratory tests for suspected inflammatory conditions
• Conservative management with rest, NSAIDs, appropriate footwear, and physical therapy.

From the Research

Diagnostic Approach

To diagnose nontraumatic foot pain that starts medial and radiates down the foot, several conditions should be considered:

• Medial plantar nerve compression, which is often seen in running athletes and typically presents with pain radiating to the medial arch 2
• Posterior tarsal tunnel syndrome, resulting from compression of the posterior tibial nerve 2
• Distal tarsal tunnel syndrome, which is often misdiagnosed as plantar fasciitis and results from entrapment of the first branch of the lateral plantar nerve 2

Diagnostic Tools

The following diagnostic tools can be used to evaluate foot pain:

• Electrodiagnostic (EDX) studies, which can help guide treatment options and provide a comprehensive assessment of foot pain 3
• Imaging studies, such as MRI or ultrasound, which can help define the exact site of nerve entrapment and detect any masses present 4

Differential Diagnosis

A broad differential diagnosis should be considered, including:

• Neuropathic conditions, such as nerve entrapment or compression 2, 4
• Nonneuropathic conditions, such as proximal plantar fasciitis or metatarsalgia 5
• Systemic causes of foot pain, which can be evaluated using EDX studies and imaging 3