Tarsal Tunnel Syndrome/Posterior Tibial Nerve Entrapment

A peripheral compression neuropathy that results in foot pain and paresthesias along the medial and plantar aspects of the foot and toes secondary to posterior tibial nerve entrapment in the tarsal tunnel (1)[C]

Synonym(s): Posterior tibial nerve entrapment

Space-occupying lesions (eg, ganglion or lipoma)

Local trauma

Scar tissue

Abnormal foot/ankle mechanics (eg, excessive pronation)

Hindfoot deformities (eg, heel valgus or varus)

Repetitive activity

Weight gain

Lower extremity edema

Previous foot or ankle surgery

Accessory muscles (eg, accessory soleus)

Hypertrophic flexor retinaculum

Osteophytes/bone spurs

Varicose veins

Fat pad dysfunctions

Systemic diseases (eg, diabetes)

Tarsal tunnel is a fixed anatomic space bordered by the calcaneus and talus superiorly, inferiorly, and laterally and by the flexor retinaculum medially. The flexor retinaculum (or laciniate ligament) runs obliquely from posterior to anterior and forms the roof of the tunnel.

Structures passing through the tunnel include the tibialis posterior, flexor digitorum longus, and flexor hallucis longus tendons, as well as the posterior tibial artery, veins, and tibial nerve.

Tibial nerve branches at various locations through the tunnel, forming the medial and lateral plantar nerves, along with the medial calcaneal nerve. The medial and lateral plantar nerves then enter their own tunnels.

The medial plantar nerve runs deep to the abductor hallucis and flexor hallucis longus muscles.

The lateral plantar nerve passes directly through the abductor hallucis muscle.

Medial calcaneal nerve pierces through the flexor retinaculum to the medial side of the heel, providing sensory innervation to the posterior and medial heel.

Tarsal tunnel can be viewed as an upper tunnel or a lower tunnel, which are different clinical entities based on nerve branching locations.

Tarsal tunnel syndrome presents with a nonspecific, highly variable clinical picture.

History of trauma or repetitive activity (eg, running)

Numbness, tingling, and burning to the medial aspect and sole of the foot; can include calf symptoms and radiation to the toes

Foot cramping

Prolonged standing or walking often exacerbates the symptoms.

Habit of removing shoes to obtain relief

Patients lack morning pain and often lack heel pain.

Nocturnal pain may awaken the patient, especially after excessive activity.

Rest and lower extremity elevation are often helpful in relieving the symptoms.

Numbness/tingling that progresses to a burning sensation at the plantar aspect of the foot; intermittent initially; can become constant

Plantar foot pain accentuated by walking and foot dorsiflexion

Nocturnal pain often relieved with walking

Pain worse at the end of the day

Occasional fusiform swelling over the nerve course

Motor weakness or loss as late finding: Poor prognostic indicator

Muscle fasciculations

Tenderness distal or proximal to area of entrapment (Valleix sign)

Inspect for biomechanical abnormalities such as excessive heel varus or valgus positioning.

Observe for swelling.

Observe for toe contractures, which can occur late.

Palpate for soft tissue thickening or lesions.

Light touch–induced paresthesias

Diminished 2-point discrimination often occurs early.

Diminished pinprick sensation to plantar foot

Intrinsic muscle weakness, although possibly present, is difficult to assess.

Atrophy of abductor hallucis or abductor digiti minimi as a late finding

Percussion sign (Tinel sign)

Cuff sign: Pain with pneumatic pressure device around leg

Dorsiflexion-eversion test: Pain elicitated when placing the foot in maximum dorsiflexion and eversion and then maximally dorsiflexing the metatarsophalangeal joints and holding this position for 5–10 s (sensitivity of 97%, specificity of 100%) (3)[A]

Plantar fasciitis

Calcaneal bursitis

Tendinitis/tenosynovitis [flexor hallucis longus (FHL), posterior tibialis tendon (PTT), flexor digitorum longus (FDL)]

S-1 radiculopathy

Peripheral vascular disease, including popliteal artery entrapment

Peripheral neuropathy

Systemic disease (eg, Reiter disease, rheumatoid arthritis, gout) (4)[C]

Bony abnormalities (eg, degenerative changes, previous fractures)