Tarsal Tunnel Syndrome

**Tarsal tunnel syndrome (TTS)** occurs when the posterior tibial nerve is compressed or entrapped as it passes through the tarsal tunnel — a narrow space on the inner (medial) side of the ankle formed by the ankle bones and a thick band of ligament (the flexor retinaculum). The tibial nerve divides into the **medial plantar nerve**, **lateral plantar nerve**, and **calcaneal nerve** within the tarsal tunnel, supplying sensation and motor function to the bottom of the foot. Compression at any point along this pathway can produce symptoms. Common causes of compression include: - **Space-occupying lesions**: Ganglion cysts (most common, 20-30%), varicose veins, lipomas, accessory muscles - **Biomechanical**: Flat feet (pes planus) causing nerve stretch — present in 50-60% of TTS cases - **Inflammatory**: [Rheumatoid arthritis](/condition/rheumatoid-arthritis), tendon sheath inflammation, post-traumatic scarring - **Systemic**: [Diabetes](/condition/diabetes), hypothyroidism — contribute to nerve vulnerability - **Idiopathic**: No identifiable cause found in 20-40% of cases The condition is analogous to [carpal tunnel syndrome](/condition/carpal-tunnel-syndrome) in the wrist — both involve peripheral nerve compression in a confined fibro-osseous tunnel.

## Root Causes The posterior tibial nerve becomes compressed in the tarsal tunnel due to: **Structural/Mechanical:** - Flat feet (pes planus) — the most common biomechanical contributor (50-60% of cases); the collapsed arch stretches and irritates the tibial nerve - Space-occupying lesions — ganglion cysts (20-30%), varicose veins, lipomas, or accessory muscles within the tunnel - Bony abnormalities — tarsal coalition, post-fracture deformity, bone spurs **Inflammatory:** - Tendon inflammation (tenosynovitis) of the flexor tendons running through the tunnel - [Rheumatoid arthritis](/condition/rheumatoid-arthritis) or other inflammatory arthropathies - Post-traumatic scarring from ankle sprains or fractures **Systemic:** - [Diabetes](/condition/diabetes) — increases peripheral nerve vulnerability (double crush phenomenon) - Hypothyroidism — tissue edema compresses the nerve - Pregnancy — fluid retention increasing tunnel pressure **Activity-Related:** - Repetitive dorsiflexion/eversion (runners, dancers) - Prolonged standing on hard surfaces - Ill-fitting footwear compressing the medial ankle

## Conservative Treatment (First-Line — 85-90% Success) **1. Biomechanical Correction:** - Custom orthotics for flat feet — the MOST important intervention when pes planus is present; controls pronation and reduces nerve stretch - Medial arch support insoles for milder cases - Proper footwear with structured medial support **2. Activity Modification & Rest:** - Reduce prolonged standing and high-impact activities - Cross-training with non-weight-bearing exercise (swimming, cycling) - Workplace modifications for standing occupations **3. Anti-Inflammatory Measures:** - NSAIDs (ibuprofen, naproxen) for 2-4 weeks during acute flares - Ice application to the medial ankle — 15-20 minutes, 3-4x daily - Topical anti-inflammatory gels directly over the tarsal tunnel **4. Corticosteroid Injection:** - Ultrasound-guided injection into the tarsal tunnel provides 60-75% relief - Can be both diagnostic and therapeutic - Repeat injections limited to 2-3 per year to avoid tendon weakening **5. Physical Therapy:** - Tibial nerve gliding exercises (neural mobilization) - Calf stretching and ankle mobility work - Intrinsic foot muscle strengthening (toe curls, towel scrunches) ## Surgical Treatment (10-20% of Cases) **Tarsal tunnel release (decompression):** - Indicated after 3-6 months of failed conservative treatment - Flexor retinaculum is surgically released to decompress the nerve - Space-occupying lesions removed simultaneously - Success rate: 75-85% — but declines significantly if surgery is delayed beyond 12 months - Recovery: 6-12 weeks non-weight-bearing, then gradual return over 3-6 months