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Tarsal Tunnel Syndrome (TTS) occurs when the tibial nerve is compressed or irritated as it passes through the tarsal tunnel, a narrow space on the inside of the ankle. This can lead to pain, tingling, or numbness in the foot and ankle. Treatment depends on the underlying cause and the severity of the symptoms, ranging from non-surgical approaches to surgery.

Anatomy: Understanding the Tarsal Tunnel

The tarsal tunnel is a small, enclosed space on the inner side of the ankle, just behind the bony bump known as the medial malleolus. It is formed by bones and covered by a thick ligament called the flexor retinaculum. Inside this space are:

  • Tendons: These include the tibialis posterior, flexor digitorum longus, and flexor hallucis longus tendons, which help stabilise and move the foot and toes.
  • Blood vessels: The posterior tibial artery and vein supply blood to the foot.
  • Tibial nerve: This nerve splits into smaller branches that control sensations and some movements in the foot.

Compression or irritation of the tibial nerve within this confined space causes the symptoms of TTS.

Signs and Symptoms

  • Pain: Burning, aching, or shooting pain in the foot or ankle, often radiating to the sole.
  • Tingling or numbness: A “pins and needles” sensation or a feeling that part of the foot is asleep.
  • Weakness: Difficulty or reduced strength in moving the toes, especially in advanced cases.
  • Tenderness: Soreness around the inside of the ankle.
  • Worsening with activity: Symptoms often get worse with walking, running, or prolonged standing.
  • Night pain: Pain or strange sensations may disrupt sleep.

Risk Factors

Several factors can increase the risk of developing TTS:

Accessory and Extra Muscles

  • Variants in ankle anatomy, such as accessory muscles, can reduce space in the tarsal tunnel and compress the tibial nerve.
    • The flexor digitorum accessorius longus (FDAL) is the most common accessory muscle associated with TTS.
    • Other accessory muscles, like the tibiocalcaneus internus or accessory soleus muscle, can mimic mass lesions and lead to nerve compression.
    • Case studies show successful outcomes with surgical removal of accessory muscles, such as FDAL and accessory soleus muscles, resolving TTS symptoms.

Chronic Medial Ankle Instability

  • Repeated ankle sprains or injuries can weaken the ligaments stabilising the medial ankle, increasing the risk of chronic instability and TTS.

Surgical Procedures

  • Procedures to correct foot deformities, such as pes cavovarus (high arch), can narrow the tarsal tunnel and increase pressure on the nerve.

Trauma and Heterotopic Ossification (HO)

  • Severe trauma can lead to the formation of HO, where bone develops in soft tissues, compressing the tibial nerve.

Systemic Conditions

  • Gout: Uric acid crystals may cause inflammation or masses, such as tophi, which can compress the tibial nerve.
  • Diabetes Mellitus: Increased nerve vulnerability and swelling in the tunnel may lead to TTS.

Recurrent Ganglion Cysts

  • Ganglion cysts, which are fluid-filled sacs, can form inside or near the tarsal tunnel and compress the nerve. Rare cases report recurrence over many years with different types of cysts affecting the same individual.

Diagnosis and Imaging

Diagnosing TTS involves a combination of clinical examination and imaging studies:

  • Physical examination: This includes:
    • Checking for tenderness along the tarsal tunnel.
    • Performing the Tinel’s test (tapping the nerve to reproduce symptoms).
    • Assessing foot and ankle movement and strength.
  • Diagnostic imaging:
    • Ultrasound: Useful for identifying swelling or structural issues such as cysts or thickened ligaments. It’s cost-effective and allows comparison with the unaffected side.
    • Magnetic Resonance Imaging (MRI): Often considered the gold standard for identifying pathologies in the tarsal tunnel. MRI can detect space-occupying lesions like tumours, cysts, or varicose veins and may show signs of muscle atrophy related to nerve compression. Studies have found that MRI identifies relevant pathology in up to 88% of symptomatic cases.

Treatment

Non-Surgical Treatment

Conservative management is often successful, especially in cases where symptoms are mild or caused by reversible factors. The goal is to relieve pain, reduce inflammation, and address biomechanical stressors.

  • Activity modification: Avoiding activities that worsen symptoms, such as prolonged standing or high-impact sports.
  • Medications:
    • Pain relievers: Non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen can reduce inflammation and pain.
    • Neuropathic pain medications: Gabapentin, pregabalin, or tricyclic antidepressants can help manage nerve pain.
    • Topical treatments: Creams with lidocaine or NSAIDs can provide localised relief.
  • Corticosteroid injections: These may reduce swelling and inflammation in the tarsal tunnel.
  • Physiotherapy: (See detailed section below)
  • Supportive devices:
    • Orthotic shoes or insoles to correct foot alignment and relieve pressure on the nerve.
    • Night splints, or temporary walking boots to immobilise and offload the affected foot.

For space-occupying lesions like ganglion cysts, aspiration under ultrasound guidance can alleviate symptoms.

Physiotherapy

Physiotherapy is an essential component of managing TTS. A physiotherapist tailors treatment to the individual’s symptoms and underlying cause, focusing on pain relief, improving function, and preventing recurrence.

  1. Pain Relief and Inflammation Management:
    • Modalities like ultrasound therapy, cryotherapy (ice), and iontophoresis (delivering medication through the skin) can reduce inflammation and discomfort.
  2. Strengthening and Stabilisation:
    • Strengthening the tibialis posterior muscle and other foot stabilisers helps support the arch and reduces strain on the tarsal tunnel.
  3. Stretching Exercises:
    • Stretching tight calf muscles and the plantar fascia can ease tension in the foot and ankle.
  4. Nerve Mobilisation:
    • Gentle nerve gliding exercises improve the mobility of the tibial nerve, helping to reduce irritation.
  5. Biomechanical Support:
    • Custom orthotics or kinesiology tape can support the arch, correct foot alignment, and reduce biomechanical stress.
  6. Education and Activity Modification:
    • Patients are guided on how to modify their daily activities to avoid aggravating the condition and allow the nerve to heal.

Surgical Treatment

Surgery may be considered if conservative treatments fail or if there is a clear, correctable cause of nerve compression (e.g., a tumour or cyst).

  • Procedure: The flexor retinaculum (the ligament covering the tarsal tunnel) is released to create more space for the nerve. If needed, additional structures compressing the nerve are also released.
  • Success rates: Surgical outcomes vary, with success rates ranging from 44% to 96%. Better results are observed in:
    • Younger patients.
    • Those with early diagnosis and a clear cause.
    • Cases with a positive Tinel’s sign before surgery.
  • Risks: Like any surgery, risks include infection, scarring, and the possibility of symptoms not fully resolving.

Information is provided for education purposes only. Always consult your physiotherapist or other health professional.