Tarsal Tunnel Syndrome

Definition

 

Entrapment neuropathy of posterior tibial nerve within the tibial tunnel

 

Anatomy

 

Taral Tunnel

 

Flexor Retinaculum 

- medial malleolus to posterior calcaneum

 

Tarsal tunnel

- roof is flexor retinaculum

- tibia anteriorly

- talus and calcaneum laterally

 

Contents

- T. Post

- FDL

- Posterior tibial artery, tibial nerve

- FHL

 

Tibial nerve

- 3 terminal branches

- medial and lateral plantar

- medial calcaneal

- usually divide within tunnel

 

Aetiology

 

Specific cause identified in 60% cases

 

Idiopathic 

- 40% cases

- most common

 

Post-traumatic

- scarring after sprain

- bony prominence 2° calcaneal fracture

 

Inflammatory 

- RA

- tenosynovitis

 

SOL

- tumours

- ganglion of tendon sheath

- lipoma

- neurilemmoma (Schwannoma) 
- varicose veins

- medial talo-calcaneal bar

 

Accessory muscles

- FDL

 

History

 

Diffuse pain plantar aspect

- burning, tingling or numbness

- 1/3 have proximal radiation to leg

 

Aggravated by activity

 

Examination

 

Tenderness over Tarsal Tunnel

 

Positive Tinel's sign    

 

Palpate for thickening or swelling (cyst, ganglion etc)

 

Usually no sensory loss or weakness 

 

May see wasting of abductor hallucis

 

NCS 

 

At best 90% accurate

- Prolonged sensory conduction time in 75%

- Prolonged motor latency in 50%

- conduction velocity of CPN done to exclude peripheral neuropathy

 

MRI

 

MRI positive in 85% 

- FHL synovitis, dilated veins, mass, fracture, scar, etc

- 25% have contralateral MR findings with no symptoms

 

Diagnosis

 

At least 2 of

- Hx of tingling & burning

- positive tinels

- positive NCS

 

DDx

 

Local

- plantar fasciitis

- fracture

- tenosynovitis

 

Neurological

- peripheral neuritis

- diabetic neuropathy

- leprosy

- neurilemmoma

- neuroma

- spinal compression

 

Management

 

Non-operative

 

Of little benefit

- try NSAIDs

 

Operative

 

Surgical release by division of Flexor Retinaculum

 

Incision 

- 10 cm proximal to medial malleolus

- curved distally to TNJ

 

Release

- flexor retinaculum

- proximal investing fascia

- individual tendon sheaths / tibialis posteror in separate sheath

- abductor hallucis fascia

 

Follow and release both plantar nerves

- protect medial calcaneal branch

- runs off lateral plantar

 

Post op

- NWB for 3/52

 

Results

 

75% success if no underlying causes