Tarsal Tunnel Syndrome

What is Tarsal tunnel syndrome?

Tarsal tunnel syndrome is the compression of the posterior tibial nerve within the narrow fibro-osseous space at the inner ankle known as the tarsal tunnel. This tunnel sits beneath the flexor retinaculum, located posterior to the medial malleolus (the inner ankle bone).

The condition is relatively uncommon, often underdiagnosed, and can occur at any age. Early identification is vital to prevent permanent nerve dysfunction or muscle atrophy in the foot.

What causes Tarsal tunnel syndrome?

Compression may result from intrinsic tunnel abnormalities, external or systemic factors, or biomechanical forces that increase pressure or traction on the tibial nerve. Inflammation of the tendon sheaths, known as tenosynovitis, or the presence of varicosities (enlarged veins) often crowds the nerve. Space-occupying lesions, such as ganglion cysts or small tumors, can also elevate internal compartment pressure.

Foot deformities like flatfoot (pes planus) increase mechanical traction on the nerve. Systemic conditions such as diabetes mellitus and rheumatoid arthritis further increase an individual’s susceptibility to neural injury. Following an ankle sprain, localized edema (swelling) or hemorrhage can increase pressure within the confined tunnel and irritate or compress the nerve.

What are the signs and symptoms of Tarsal tunnel syndrome?

Patients typically present with sharp, burning pain, numbness, or tingling along the plantar (sole) aspect of the foot. Tarsal tunnel syndrome symptoms frequently worsen with activity or during prolonged weight-bearing. Many individuals report nocturnal paresthesia (abnormal sensations like “pins and needles”) that disrupts sleep.

The main differential diagnoses include plantar fasciitis, lumbar radiculopathy, peripheral polyneuropathy, Morton metatarsalgia, stress fracture, tendinopathy, and other causes of heel or plantar foot pain. Clinicians must also distinguish this condition from anterior tarsal tunnel syndrome, which involves the deep peroneal nerve on the front of the ankle. While the posterior version affects the sole, the anterior variant produces numbness specifically in the first dorsal web space between the toes.

How is Tarsal tunnel syndrome diagnosed?

Diagnosis is based on the overall clinical picture. Clinicians may find a positive Tinel sign, where percussion over the tibial nerve reproduces paresthesia. The dorsiflexion-eversion test may also reproduce symptoms by stretching and compressing the tibial nerve within the tunnel.

Standard tarsal tunnel syndrome tests include nerve conduction studies and electromyography, but normal results do not rule it out. Providers may utilize ultrasound or MRI to visualize ganglion cysts or tenosynovitis. Imaging can help identify local structural causes of compression, while the clinical exam and electrodiagnostic studies help distinguish tarsal tunnel syndrome from mimics such as lumbar radiculopathy.

How is Tarsal tunnel syndrome treated?

Initial treatment focuses on unloading the nerve through activity modification and rest. Providers often recommend custom orthoses (specialized shoe inserts) to maintain the medial arch and reduce traction. Physical therapy incorporates specific tarsal tunnel syndrome exercises, such as nerve-gliding maneuvers, calf stretching, strengthening, and other measures to reduce symptoms and improve foot mechanics.

If symptoms persist, nonsteroidal anti-inflammatory drugs may help with pain and inflammation, while gabapentinoids may be considered for neuropathic discomfort. Surgery may be considered when conservative measures fail or when a clear compressive lesion is identified. This procedure involves releasing the flexor retinaculum and removing any space-occupying lesion to decompress the tibial nerve.

What are the most important facts to know about Tarsal tunnel syndrome?

• Tarsal tunnel syndrome is a compression neuropathy of the tibial nerve located behind the inner ankle bone.
• Structural factors like cysts, varicosities, and flatfoot deformity may contribute to nerve strain and compartment pressure.
• Hallmark tarsal tunnel syndrome symptoms include burning pain and numbness on the sole.
• Diagnosis is primarily clinical, supported when needed by electrodiagnostic studies and imaging to identify local causes or rule out mimics.
• Treatment begins with conservative measures such as rest, orthoses, physical therapy, and pain control, while surgery may be considered for refractory cases or identifiable compressive lesions.