Conditions and Treatments - Tarsal Tunnel Syndrome ׀ by Sarah Meuler, DPT

Tarsal tunnel syndrome (TTS) is the compression and entrapment of the posterior tibial nerve in the tunnel beneath the flexor retinaculum along the medial side of the ankle. Tarsal tunnel syndrome is not as common as carpal tunnel syndrome but clinical presentations of the syndrome are quite similar. Tarsal tunnel syndrome is also commonly referred to as tibial nerve dysfunction.

Anatomy
The tarsal tunnel is formed by the medial malleolus, calcaneus and talus and is deep to the deltoid ligament and flexor retinaculum. The tibial nerve is derived from the more proximal sciatic nerve and innervates the deep muscles of the posterior compartment of the leg. The tibialis posterior, flexor digitorum longus and flexor hallucis longus join with the tibial nerve and tibial artery to pass through the tarsal tunnel into the medial foot. In the foot the tibial nerve branches into the medial and lateral plantar nerves and provides sensation to the sole of the foot, lateral heel and plantar aspect of the toes. (1)

Cause and Diagnosis of Tarsal Tunnel Syndrome
Compression of the tibial nerve within the tarsal tunnel may be caused by swelling after trauma, a space- occupying lesion, inflammation, valgus deformity or chronic inversion of the ankle (2). TTS may also be more common in people with rheumatoid arthritis secondary to the joint inflammatory nature of the disease (3). Individuals with TTS may complain of pain and sensation changes to the sole and toes of the foot as well as pain to the medial aspect of the ankle and medial malleolus. Pain typically is exacerbated by long periods of standing and walking and is more commonly felt at night (2). Acute TTS can commonly be mistaken for plantar fasciitis and careful examination of symptoms is needed to be able to properly treat the individual's functional deficits. Untreated, chronic TTS can lead to muscular weakness of the foot. The table below is found in Magee's Orthopedic Physical Assessment (2) and can assist a physical therapist in differentially diagnosing plantar fasciitis vs. tarsal tunnel syndrome.

Table 13-14 (2)

Differential Diagnosis of Plantar Fasciitis and Tarsal Tunnel Syndrome

Treatment
With proper assessment and evaluation, physical therapists can properly treat TTS without expensive testing such as a nerve conduction study, electromyography or MRI. Examination of the foot should include observation of ankle anatomy and biomechanics, strength and sensation testing. Individuals with TTS may present with decreased light touch sensation to the sole of their foot along the tibial nerve distribution. In more advanced cases, inversion and plantar flexion strength may be diminished. Treatment should focus on decreasing the inflammatory response with modalities and increasing function with manual therapy and therapeutic exercise. In a patient with pes planus or increase pronation, treatment should focus on strengthening and correction of the over-pronation to decrease stress on the tibial nerve. In a literature review by Ahmad M, et al., decompression surgery may be beneficial for a patient that is not responding to conservative treatment (4). Also, in the case of a space occupying lesion, further testing may be indicated to assess the amount of tibial nerve compression within the tarsal tunnel. If left untreated, TTS can cause nerve fibrosis and this may lead to a poor outcome even with decompression surgery (4). Physical therapists can play a major role in identifying and treating tarsal tunnel syndrome to prevent further functional limitations and allow each individual to return to their previous level of functioning.