How do you tell tarsal tunnel syndrome apart from plantar fasciitis?

Both cause pain in the sole, but tarsal tunnel syndrome is dominated by numbness, tingling, and burning, and usually lacks the sharp first-step pain in the morning and is not limited to the inner heel. A positive Tinel sign (tapping the medial ankle triggering radiating numbness and tingling) can serve as a clinical clue for differentiation, and ultrasound and nerve conduction studies can also help distinguish the two.

Which groups are more prone to tarsal tunnel syndrome?

Athletes, people who stand or walk for long periods, those with a history of ankle sprain or local trauma (up to 43% of patients have a related history of injury), and people with flatfoot or heel valgus are at higher risk. Diabetes, lower-limb edema, and weight gain also increase the risk.

Does tarsal tunnel syndrome always require surgery?

Not necessarily. Conservative treatment (orthotic insoles, stretching, anti-inflammatory painkillers, neuropathic medication, ultrasound-guided corticosteroid injection) is the first-line option. Surgical decompression is considered only when conservative treatment fails or nerve damage has already appeared; research indicates that if surgical intervention is delayed by more than 10 months, nerve recovery may be slower.

Stepping Out of Foot Pain: Tarsal Tunnel Syndrome (TTS) Symptoms, Diagnosis, and Treatment Options

Epidemiology

Reported epidemiological figures vary widely. The condition is relatively uncommon, and clinicians tend to have a lower index of suspicion for it, which can lead to missed or mistaken diagnoses. Some podiatric physicians consider TTS fairly common, whereas most neurologists and electrophysiologists regard it as fairly rare.
Female patients outnumber male patients.
It is common in athletes and in people who stand for long periods.
Up to 43% of patients have a history of trauma, including events such as ankle sprains.

Pathophysiology

The tarsal tunnel is formed by the distal tibia in front, the talus and calcaneus laterally, and the flexor retinaculum (laciniate ligament) medially; the flexor retinaculum forms the roof of the tunnel.
The structures within the tarsal tunnel include the tibial nerve, the tibial artery and veins, the flexor hallucis longus (FHL), the flexor digitorum longus (FDL), and the tibialis posterior tendon. The posterior tibial nerve passes between the FDL and FHL muscles and then bifurcates within the tarsal tunnel to form the medial plantar nerve and the lateral plantar nerve. In 5% of people, the bifurcation occurs proximal to the tarsal tunnel.
Within the tarsal tunnel, the tibial nerve branches into the medial plantar nerve, the lateral plantar nerve, and the medial calcaneal nerve.
- The medial plantar nerve is responsible for sensation over the medial sole and the first three and a half toes, and supplies motor function to the first plantar muscle, the abductor hallucis, the flexor digitorum brevis, and the flexor hallucis brevis.
- The lateral plantar nerve is responsible for sensation over the lateral heel and the last one and a half toes, and supplies motor function to the flexor digitorum brevis, the quadratus plantae, and the abductor digiti minimi.
- The medial calcaneal nerve is responsible for sensation over the posterior and medial heel. The medial calcaneal nerve usually branches from the posterior tibial nerve proximal to the tarsal tunnel and provides sensory innervation to the posteromedial heel. In 25% of patients, this nerve branches from the lateral plantar nerve or lies on the surface of the flexor retinaculum.
Tarsal tunnel syndrome can be classified as proximal or distal according to the site of compression, depending on whether the tibial nerve itself (proximal) or its terminal branches (distal) is compressed. The cause may be intrinsic or extrinsic and may involve one or more of the three nerve branches (calcaneal nerve, medial plantar nerve, and lateral plantar nerve).
Anatomically, both the posterior tibial nerve and artery show some variation, which may be related to the development of TTS, but more research is needed.
Based on the location of the bifurcation point, the posterior tibial nerve has four types of branching patterns.
- Type I: the bifurcation point of the posterior tibial nerve lies proximal to the tarsal tunnel; this occurred in 11 of 60 cases (18.33%).
- Type II: the bifurcation lies at the upper border of the tunnel; there were 3 cases (5%).
- Type III: this pattern is the most common. The bifurcation lies within the tunnel; there were 42 cases with this pattern, a proportion of 70%.
- Type IV: that is, distal to the tunnel. There were 4 cases with this pattern, accounting for 6.67% of patients.
The posterior tibial artery divides into two main branches, the medial and lateral plantar arteries, each closely accompanied by veins on both sides. The bifurcation points of the posterior tibial artery all lie within the tarsal tunnel, and there are two types of branching patterns.
- Type I: the bifurcation point of the posterior tibial artery lies within the tarsal tunnel, close to the proximal end, about 71.67%.
- Type II: the bifurcation point lies in the distal portion of the tarsal tunnel. A total of 28.33%.

Risk factors

Reduced volume or increased pressure within the tarsal tunnel
Local tissue overgrowth (such as the flexor retinaculum or abductor hallucis)
Compressive lesions (such as ganglion cysts, lipomas, or bone spurs)
Tenosynovitis
Local trauma
Prior surgery
Scar tissue formation
Foot or ankle abnormalities (such as flatfoot)
Heel deformity (such as heel valgus or varus)
Repetitive activity
Weight gain
Lower-limb edema
Variant accessory muscles (such as an accessory tibialis posterior)
Systemic disease (such as diabetes)

History

The clinical presentation of tarsal tunnel syndrome (TTS) is variable and nonspecific.
It may be related to trauma or to repetitive activity (such as running).
There is numbness, tingling, and burning over the medial foot and sole, and symptoms may extend to the calf or toes.
There may be a cramping sensation in the mid-arch, usually unilateral.
Symptoms gradually worsen over the course of the day; prolonged standing or walking aggravates them, while rest relieves them.
Patients may get into the habit of taking off their shoes to ease discomfort.
There is usually no morning pain and no marked heel pain.
Nighttime pain after excessive activity may wake the patient.

Physical examination

Numbness and tingling of the sole, intermittent at first and possibly becoming persistent later, and can turn into a burning sensation.
Pain in the sole worsens with walking and with dorsiflexion of the foot.
Nighttime pain often eases after walking.
Pain worsens toward the end of the day.
Fusiform swelling along the nerve path is occasionally seen; in later stages, muscle weakness or loss may appear, with a poor prognosis.
When tapping over the tarsal tunnel, pain may radiate upward to the mid-calf (Valleix phenomenon).
The examination should look for biomechanical abnormalities of the foot, such as excessive foot eversion or inversion.
Look for swelling or toe contracture (which may appear in later stages).
Light touch provokes paresthesia, and pinprick sensation on the sole is reduced.
Intrinsic muscle weakness may be present but is hard to assess; atrophy of the abductor hallucis or abductor digiti minimi is a late finding.
Tinel sign: tapping over the tarsal tunnel provokes paresthesia; specificity is 70% to 90%.
Cuff sign: a pressure cuff on the leg provokes pain.
Dorsiflexion-eversion test: the foot is placed in maximal dorsiflexion and eversion, then the metatarsophalangeal joints are maximally dorsiflexed and held for 5 to 10 seconds to provoke pain; positive in 82% of TTS patients.
Trepman test: maximal plantar flexion and inversion.
Triple compression test: a combination of the Tinel test and the Trepman test, held for 30 seconds.

Diagnostic tools

Initial workup may use X-ray to rule out morphological or structural abnormalities.
Ultrasound can assess whether the cross-sectional area of the tibial nerve is enlarged. Studies show that a cross-sectional area ratio within the tarsal tunnel greater than 1 (sensitivity 74%, high specificity) may suggest tarsal tunnel syndrome. This examination can also assess soft-tissue structures and help evaluate the posterior tibial nerve and its bifurcation.
MRI is the standard for evaluating compression caused by abnormal muscles, ganglion cysts, or tumors, but its sensitivity for diagnosing TTS is not high. It may help exclude or confirm other causes of a patient’s symptoms.
Electrophysiological studies can rule out a double crush syndrome caused by an upstream neuropathy.
Electromyography (EMG) is used to assess motor latency, but it has a higher false-positive rate when evaluating the intrinsic foot muscles.
Nerve conduction studies (NCS) help improve sensitivity for evaluating sensory and motor action potentials, but they are usually used as an adjunct to diagnosis because they often produce false-negative results.

Initial treatment

Conservative treatment is the preferred approach, including:
Soft-tissue physical therapy modalities, including ultrasound, iontophoresis, phonophoresis, and electrical stimulation, may help reduce pain.
Local anesthetics and corticosteroid injections can also be used to relieve pain and confirm the diagnosis; a ganglion cyst can be aspirated under ultrasound guidance.

Short-term medication

Anti-inflammatory painkillers (NSAIDs)
Corticosteroid injection
Tricyclic antidepressants can be used to treat chronic pain
Vitamin B complex supplementation may help nerve repair

Additional treatment

Other non-surgical treatments include ice application, relative rest, and reducing local pressure from shoes or clothing.
Custom arch-support orthotic insoles and orthopedic shoes can be used to correct biomechanical abnormalities and reduce pressure.
A medial heel wedge or heel cup may reduce nerve traction by inverting the heel.
A night splint can be tried.
Stretching and strengthening exercises for the lower-limb and foot muscles, strengthening of the tibialis posterior, and kinesiology taping can improve foot stability by supporting the arch and reducing the biomechanical stress in this region.

Surgery

Surgery involves releasing the flexor retinaculum from its proximal attachment near the medial malleolus down to where it supports the calcaneus; reported success rates range from 44% to 96%.
Patients with a positive Tinel sign before surgery usually respond better to surgical decompression than those without.
Younger patients, and patients with shorter-duration symptoms, early diagnosis, a clear cause, and no prior ankle pathology, also respond better to surgery.
If non-surgical treatment fails, surgical treatment is considered, including:
- Decompression of the tibial nerve and its branches within the tarsal tunnel
- Flexor retinaculum release
- Abductor hallucis fascia release
- Cryosurgery (though more research is still needed to support it)
Postoperative physical therapy aims to control pain, swelling, and inflammation.

Follow-up

Perform regular sensory testing and examination to monitor changes in the patient.
If surgical intervention is delayed by more than 10 months, the outcome of nerve recovery may be worse.
Without treatment, patients may be at risk of permanent nerve damage, leading to persistent pain, motor deficits, plantar ulceration, or complex regional pain syndrome.
If symptoms recur after surgical release, it is usually related to inadequate decompression at the initial operation.

Prognosis

The prognosis is related to early intervention in treatment and adherence to the rehabilitation program.
Early surgical intervention can improve nerve compression and persistent symptoms caused by intrinsic factors.
Most patients achieve good results with non-surgical treatment; however, when symptoms persist, surgery is associated with about a 90% rate of symptom improvement in the studies.

References

Tarsal Tunnel Syndrome | Musculoskeletal Key
Sci Rep. 2017 Apr 11;7:46351
Healthcare (Basel). 2024 Oct 17;12(20):2071.