Tarsal Tunnel Syndrome



Tarsal tunnel syndrome is a set of symptoms caused by entrapment of the posterior tibial nerve, and/or its branches, within the tarsal tunnel. It is analogous to carpal tunnel syndrome in the hand but much less common.

It is an important differential diagnosis to consider in the presentation of “heel pain”.  Classically patients present with pain, numbness or paraesthesia around the posteromedial and plantar aspects of the foot.



The tarsal tunnel Is a fibro-osseous tunnel located around the posteromedial hindfoot. Its boundaries are:

  • Floor: medial walls of distal tibia (medial malleolus), talus and calcaneum
  • Roof: flexor retinaculum – bridging from the calcaneum onto the medial malleolus

Contents – from medial to lateral:

  • tibialis posterior tendon
  • flexor digitorum longus tendon
  • posterior tibial artery and vein
  • tibial nerve
  • flexor digitorum hallucis

(Mnemonic: Tom, Dick and A Very Nervous Harry)

*awaiting image upload*

Reproduced from Yang et al

The tibial nerve is a direct branch of the sciatic nerve. After crossing the popliteal fossa, it passes under the tendinous arch of the soleus muscle. It runs deep to soleus and above FHL. It then courses anterior to FHL tendon and into the tarsal tunnel. After the tunnel it branches into the medial and lateral plantar nerves. This bifurcation has been reported to occur prior to the tunnel in approximately 5% of the population.

These nerves supply sensation to the plantar aspect of the foot. The medial plantar nerve supplies the medial 3 and half digits and the remainder by the lateral plantar nerve. Motor branches supply the intrinsic muscles of the foot:

  • Medial plantar:
    • abductor hallucis
    • flexor digitorum brevis
    • flexor hallucis brevis
    • single medial lumbrical
  • Lateral plantar:
    • quadratus plantae
    • abductor digiti minimi
    • lateral three lumbricals
    • plantar and dorsal interossei

A third branch of the tibial nerve, the medial calcaneal nerve, pierces the flexor retinaculum to supply sensation to the medial aspect of the heel. This nerve can vary by branching prior to the tunnel and running over the retinaculum.



Causes can be split into:

  • Intrinsic:
    • osteophytes
    • tendinopathies or tenosynovitis
    • space occupying lesions (e.g. varicose veins, ganglions, lipoma, neuroma, tumour)
    • local trauma with secondary scarring, adhesion and perineural fibrosis
  • Extrinsic:
    • direct trauma to the nerve (incl iatrogenic e.g. calc osteotomy)
    • hindfoot malignment – varus or valgus
    • lower limb oedema – secondary to heart failure, pregnancy, lymphatic obstruction
    • systemic arthropathies
    • arterial insufficiency or diabetes leading to neural ischaemia



The mainstay of diagnosis is careful history taking and clinical examination.

History: patients often complain of pain and/or paraesthesia localised to the posteromedial hindfoot, which radiates into the plantar aspect of the foot. Symptoms are often exacerbated by exercise, constrictive footwear and can occur at night-time.

Clinical examination: tenderness and irritability along the tibial nerve within the tarsal tunnel. Tinel’s testing over the nerve in the tunnel is positive if it reproduces the symptoms. Provocation manoeuvres have been described by dorsiflexing and everting the foot or plantar flexing and inverting with compression of the tunnel. In more longstanding cases weakness may be demonstrated in abduction of the hallux or little toe.



Plain weight-bearing radiographs are often useful to look for signs of hindfoot mal alignment, osteophytes, signs of previous trauma and tarsal coalitions.

Ultrasound can delineate the anatomy of the nerve and highlight any compressive pathology such as ganglions, tenosynovitis, vascular abnormalities and tumours.

MRI can show space occupying lesions and can also trace the nerve through the tunnel and distally. It can also show signs of intrinsic muscular atrophy (of e.g. abductor hallucis / abductor digiti minimi) which can occur with prolonged compression of the motor branches.

Nerve conduction studies including EMG can be useful in diagnosing the condition. It can also guide the clinician to other differential diagnoses if there are patterns of peripheral neuropathy or myopathy or more proximal compressive neuropathy. However, a normal test does not exclude a compression of the posterior tibial nerve, due to the rate of false negatives.


Non-operative management

This is the mainstay of treatment and may include:

  • anti-inflammatory medication
  • activity modification
  • orthoses
  • physiotherapy

If an underlying cause such as an inflammatory arthropathy is identified, then onward referral to rheumatology is indicated.

Ultrasound-guided local anaesthetic and steroid injections can help both diagnostically and therapeutically.


Operative management

Surgery may be considered if all non-operative measures have been exhausted and symptoms persist, although studies have shown better outcomes if performed within 12 months of symptom onset.

Surgical decompression is most commonly carried out via an open approach, centred over the flexor retinaculum, midpoint between medial malleolus and inferior calcaneum. Care needs to be taken to release the retinaculum down to the abductor hallucis and then careful blunt dissection to expose the tibial nerve and free it from the retinaculum along its course (in a similar fashion to carpal tunnel decompression). Decompress the overlying fascia as the nerve branches into the medial and lateral plantar nerves. Follow each branch down to the heel. Extend the dissection distally under abductor hallucis as this is a common site of compression of Baxter’s nerve (inferior calcaneal nerve - the first branch of the lateral plantar nerve).

Look for signs of interneural fibrosis and consider decompression of the circumferential fibrosis under magnification if appropriately trained.

The best surgical outcomes are reported when the tarsal tunnel syndrome is secondary to compressive pathology such as ganglion cysts. The surgical management of tarsal tunnel has a  wide-ranging success rate of 45%- 96%.

In summary, the main indications and guidance for surgery are:

  • Clinical history suggestive of tarsal tunnel syndrome with positive Tinel’s sign
  • Definite point of entrapment of the nerve secondary to space-occupying lesion
  • Non-operative measures which do not provide benefit should not be protracted and delay surgical decompression to avoid potential irreversible changes to the nerve



Compression of which structure causes plantar heel pain and isolated weakness of little toe abduction?

  1. 1st branch Medial plantar nerve
  2. Medial calcaneal nerve
  3. Sural nerve
  4. 1st branch Lateral plantar nerve
  5.  Tibial nerve

Which structure is compressed in tarsal tunnel syndrome?

  1. Superifical peroneal nerve
  2. Dorsolateral cutaneous nerve of superifical peroneal nerve
  3. Tibial nerve
  4. Sural nerve
  5. Deep peroneal nerve



  • M. Ahmad et al. Tarsal tunnel syndrome a literature review. Foot and Ankle Surgery 18 (2012) 149–152
  • Sammarco GJ, Chang L. Outcome of surgical treatment of tarsal tunnel syndrome. Foot Ankle Int 2003;24(2):125–31
  • Yang et al. Fine dissection of the tarsal tunnel in 60 cases. Sci Rep 7, 46351 (2017)