Anatomy
- Larger division of the sciatic nerve, L4 to S3
- Superficial to popliteal vessels, then deep to the soleus arch
- Runs with posterior tibial vessels between FDL and FHL
- Divides into medial and lateral plantar nerves in the tarsal tunnel
- Medial calcaneal branch supplies the heel
- Supplies calf muscles, tibialis posterior, FDL, FHL and sole intrinsics
- Tarsal tunnel order, tibialis posterior, FDL, artery and veins, nerve, FHL
Aetiology
- Knee dislocation, less often than common peroneal nerve
- Tibial fractures and deep posterior compartment syndrome
- Penetrating trauma
- Iatrogenic in posterior knee, ankle and medial calcaneal surgery
- Popliteal cysts, ganglia and nerve sheath tumours
Clinical Features
- Complete lesion loses plantarflexion, toe flexion and inversion
- Toe clawing and calcaneus gait
- Plantar sensory loss is most disabling, causing neuropathic ulceration
- Tarsal tunnel syndrome is compression beneath the flexor retinaculum
- Tarsal tunnel causes include ganglia, varicosities, accessory muscles, hindfoot valgus and fracture scarring
- Burning plantar pain, worse standing and at night
- Tinel sign and positive dorsiflexion eversion test
- Baxter nerve compression causes medial heel pain mimicking plantar fasciitis
Investigations
- Nerve conduction less sensitive than at the wrist
- Ultrasound or MRI for space-occupying lesions
Management
- Observe closed traction injuries with serial examination and electrophysiology
- Explore open injuries, repair clean lacerations and graft gaps
- Protective footwear and orthoses for persistent deficit
- Tendon transfers have a limited role
- Tarsal tunnel starts with orthoses, neuropathic agents and occasional injection
- Release the flexor retinaculum and abductor hallucis fascia
- Release less predictable than carpal tunnel, best with a discrete lesion
Prognosis
- Recovers better than common peroneal repair
- Better blood supply, more connective tissue and shorter distance to targets
- Protective sensation is the main goal
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.