Summary Tarsal Tunnel Syndrome is a compressive neuropathy of the tibial nerve at the level of the tarsal tunnel which can lead to pain and paresthesias of the plantar foot. Diagnosis can be suspected clinically with burning plantar foot pain with a positive Tinel's sign over the tibial nerve. EMG/NCS can help confirm the diagnosis. Treatment is an initial trial of pain management and orthotics. Operative tarsal tunnel release is indicated in patients with persistent symptoms who fail nonoperative management. Etiology Mechanism types of impingment intrinsic ganglion cyst tendonopathy tenosynovitis lipoma/tumor peri-neural fibrosis osteophytes extrinsic shoes trauma anatomic deformity (tarsal coalition, valgus hindfoot) post-surgical scaring systemic inflammatory disease edema of the lower extremity cause of impingement able to be identified in 80% of cases Anatomy Posterior tarsal tunnel an anatomic structure defined by flexor retinaculum (laciniate ligament) calcaneus (medial) talus (medial) abductor hallucis (inferior) contents include tibial nerve posterior tibial artery FHL tendon FDL tendon tibialis posterior tendon Tibial nerve has 3 distal branches medial plantar lateral plantar medial calcaneal the medial and lateral plantar nerves can be compressed in their own sheath distal to tarsal tunnel bifurcation of nerves occurs proximal to tarsal tunnel in 5% of cases Anterior tarsal tunnel flattened space defined by inferior extensor retinaculum fascia overlying the talus and navicular contents include deep peroneal nerve and branches EHL EDL dorsalis pedis artery Presentation History may have previous trauma or surgery Symptoms pain pain with prolonged standing or walking often vague and misleading medial foot pain sharp, burning pains in the foot numbness intermittent paresthesias and numbness in the plantar foot may present as part of the "heel pain triad" posterior tibial tendon deficiency (adult-acquired flatfoot), plantar fasciitis, tarsal tunnel syndrome believed to be due to loss of static and dynamic stabilizers of the medial arch and susequent traction neuropathy on the tibial nerve Physical exam tenderness of tibial nerve (tinel's sign) sensory exam equivocal pes planus muscle wasting of foot intrinsics abductor digiti quinti or abductor hallucis pain with dorsiflexion and eversion of the ankle compression test plantar flexion and inversion of ankle digital pressure over tarsal tunnel highly senstitive and specific Imaging Radiographs weight-bearing radiographs provide osseous structure MRI may be helpful to rule out accessory muscle or soft-tissue tumor Studies EMG positive finding include distal motor latencies of 7.0 msec or more prolonged SENSORY latencies of more than 2.3 msec sensory (SAP) more likely to be abnormal than motor decreased amplitude of motor action potentials of abductor hallucis or abductor digiti minimi Diagnosis history is often most useful diagnostic aid Treatment Nonoperative lifestyle modifications, medications indications usually ineffective medications anti-inflammatory medications SSRIs have been used bracing orthosis or foot wear changes to address alignment of hindfoot can try a period of short-leg cast Operative surgical release of tarsal tunnel indications after 3-6 months of failed conservative management and compressive mass (ganglion cyst) identified positive EMG reproducible physical findings outcomes best results following surgery are in cases where a compressing anatomic structure (ganglion cyst) is identified and removed traction neuritis does not respond as well to surgery Technique Tarsal Tunnel Surgical Release approach identify the nerve proximally decompression layers that must be released include flexor retinaculum deep investing fascia of lower leg superficial and deep fascia of abductor hallucis Complications Recurrence usually caused by inadequate release repeat tarsal tunnel release not recommended Prognosis Results vary between 50-90% success Worse results with 'double crush' injuries and post-operative scarring Revision surgery less successful than index operation