Tarsal Tunnel Release (Posterior Tibial Nerve Decompression)

Indication. Tarsal tunnel syndrome that has failed a 3-6 month trial of conservative care — burning, tingling or numbness in the plantar foot (medial plantar, lateral plantar or calcaneal distribution), worse with standing, walking and prolonged weight-bearing, frequently nocturnal (it wakes the patient), and relieved by rest, elevation and shoe modification. Make the diagnosis on clinical grounds first. The bedside signs are a Tinel's sign posterior to the medial malleolus with distal radiation (the Valleix phenomenon), a positive dorsiflexion-eversion test (maximal passive ankle dorsiflexion plus eversion reproduces symptoms — it stretches the nerve beneath the laciniate ligament), and in chronic disease diminished two-point discrimination on the plantar foot and intrinsic muscle atrophy. Confirm with electrodiagnosis, but treat the patient. Motor nerve conduction showing prolonged distal motor latencies of the medial and lateral plantar nerves (over 6.2 ms is abnormal), reduced or absent plantar sensory action potentials, and denervation potentials in abductor hallucis and flexor digitorum brevis support the diagnosis — but a normal study does not exclude it, and abnormal studies do not reliably predict outcome. Relative indications include acute (traumatic) tarsal tunnel syndrome, an identifiable space-occupying lesion (ganglion, varicosities, lipoma, accessory muscle) on imaging even before a full conservative trial, post-traumatic compression from a calcaneal or pilon malunion, and symptomatic post-surgical scarring. Who not to operate on. Avoid surgery when the true diagnosis is a systemic or proximal problem:

The patient factors that decide success. Surgery is most rewarding when a definable, mechanical cause is present and the patient is otherwise well; it is least rewarding when the symptom source is systemic.

Consent specifically for the incision behind the malleolus, possible saphenous or calcaneal nerve numbness or a painful neuroma, wound problems over the thin medial malleolar skin, haematoma, and the realistic expectation that nerve recovery is gradual over many months and that success is not guaranteed (a good or excellent result in roughly 44-85 percent depending on the series). Setup. Supine with a bump under the ipsilateral hip to internally rotate the leg and bring the medial ankle into view, the foot over the end of the table so the ankle can be manipulated, a thigh tourniquet (inflate to 250-300 mmHg), and loupe magnification (2.5x to 3.5x) — identifying and protecting the nerve and its branches is the whole game.

The goal: expose and decompress the posterior tibial nerve along its entire course from 8 cm above the medial malleolus to the navicular tuberosity, through all three zones — the proximal and distal flexor retinaculum and the abductor hallucis origin — while protecting the artery, the vein and every nerve branch, excise any space-occupying lesion, and confirm with a dynamic check that the nerve glides freely before you close.

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Rehabilitation | Phase | Timing | Immobilisation | Therapy | |-------|--------|----------------|---------| | 1 | 0-2 weeks | Below-knee backslab, non-weight-bearing; drain out at 24-48 hours when under 30 mL/day | Elevation, ice, neurovascular checks; finger and toe active motion only | | 2 | 2-6 weeks | Remove backslab and sutures at week 2; CAM boot or ankle brace | Touch-down to partial then full weight-bearing; gentle active ankle and toe ROM. No passive stretching (nerve irritation) | | 3 | 6-12 weeks | Wean to a supportive shoe; full weight-bearing | Proprioception (balance board), theraband resistance, intrinsic foot strengthening (towel curls, marble pickup) | | 4 | 3-6 months | Supportive footwear with arch support | Walking program, gradual return to activity; avoid high-impact work until the nerve has recovered | Nerve recovery is slow and reassuring. Symptoms may worsen briefly after surgery (manipulation), then improve gradually over 3-6 months. Sensory recovery precedes motor recovery, and a positive Tinel's that migrates distally as the nerve regrows is a good sign. Full recovery can take 12 months. Review at 2 weeks (wound), 6 weeks (progress), 3 months (symptoms), 6 months (repeat EMG/NCS if no improvement) and 1 year (final outcome).

Epidemiology. Tarsal tunnel syndrome is uncommon relative to carpal tunnel syndrome. It is most frequent in adults in the fourth to sixth decades and shows a slight female predominance. A structural or space-occupying cause — ganglion, talocalcaneal coalition, varicosities, accessory muscle, tumour or post-traumatic deformity — is found in a large proportion of surgical cases; truly idiopathic compression carries a more guarded prognosis. Outcomes. Reported complete symptom relief ranges from about 44 percent (Pfeiffer and Cracchiolo, a sobering benchmark) to 85 percent objective relief (Gondring), the variability reflecting patient selection. Across series, outcomes are best when a definite compressing lesion is identified and addressed early, and worst in idiopathic disease, diabetes, bilateral symptoms and worker's compensation cases. Revision surgery succeeds in roughly 50-60 percent — materially lower than primary release. Surgical anatomy — boundaries and contents. The tarsal tunnel is a fibro-osseous canal posterior to the medial malleolus. Its deep floor is the medial malleolus, the posterior talus, the sustentaculum tali and the medial calcaneus; its superficial roof is the flexor retinaculum (laciniate ligament) running from the medial malleolus to the calcaneus, with superficial and deep layers. From anterior to posterior it contains the tendons of tibialis posterior and flexor digitorum longus, the posterior tibial artery and its venae comitantes, the tibial nerve, and the flexor hallucis longus tendon — Tom Dick ANd Very Nervous Harry. Surgical anatomy — the nerve and its branches. The posterior tibial nerve enters the tunnel about 8 cm proximal to the malleolus, running between FDL and FHL, posterior to the vessels and anterior to FHL. It trifurcates at or just distal to the malleolus into three branches, each of which must be individually decompressed:

The abductor hallucis. Taking origin from the medial calcaneal tubercle and the medial plantar fascia, it forms a fibrous arch over the medial plantar nerve — the anatomical basis of distal tarsal tunnel syndrome and the reason its release is the single most important and most-missed step. Key evidence. The clinical diagnostic framework and the recommendation to operate after failed conservative care come from Cimino's foundational review. Kinoshita's dorsiflexion-eversion provocation test — positive in affected feet and negative in every normal foot — underpins both bedside diagnosis and the intra-operative dynamic check. Daniels' cadaveric work showed the tibial nerve is most tensioned by combined dorsiflexion-eversion, the biomechanical rationale for that test. Outcomes data (Takakura; Pfeiffer and Cracchiolo; Gondring) consistently show that an identifiable lesion treated early does best. For failed primary surgery, Barker, Rosson and Dellon demonstrated that systematic neurolysis of every branch in its own tunnel offers meaningful relief, but coexisting radiculopathy or neuropathy predicts a poor result.