| Introduction |
 A compressive neuropathy caused by compression of the tibial nerve- 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
- Prognosis
- results vary between 50-90% success
- worse results with 'double crush' injuries and post-operative scarring
- revision surgery less successful than index operation
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| Anatomy |
- Tarsal tunnel
- an anatomic structure defined by
- flexor retinaculum (laciniate ligament)
- calcaneus (medial)
- talus (medial)
- abductor hallucis (inferior)
- contents of tarsal tunnel 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
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| 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
- 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
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| Imaging |
- Radiographs
- weight-bearing radiographs provide osseous structure
- MRI
- may be helpful to rule out accessory muscle or soft-tissue tumor
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| 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
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| Treatment |
- Nonoperative
- lifestyle modifications, medications
- indications
- 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
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| 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
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| Complications |
- Recurrence
- usually caused by inadequate release
- repeat tarsal tunnel release not recommended
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