Tarsal tunnel syndrome is an entrapment of the posterior tibial nerve or one of its branches within the tarsal canal by the flexor retinaculum, the fibro-osseous tunnels, or the deep fascia.1-4 Sixty to 80 percent of cases have a specific cause of compression and there are multiple factors.5
• A tumor within the tarsal canal that puts pressure on the nerve
• Fracture of the calcaneus with a fragment compressed against the nerve
• Severe pronation that stretches the soft tissue and compresses the nerve
• Enlarged blood vessels (i.e. varicose veins)
• Bone abnormalities
• Generalized leg edema
• Metabolic disorders such as diabetes
Tarsal tunnel syndrome has a number of symptoms.1-3 Patients may say they have pain at the bottom of the foot and inside of the ankle that they characterize as burning, shooting, searing, stabbing, tingling or numbing. This pain is aggravated by activity and relieved by rest.
Other symptoms of tarsal tunnel syndrome include:
• tenderness with palpation over the tarsal tunnel
• sensory loss in the areas that the posterior tibial nerve supplies
• muscle weakness and atrophy in severe cases
Keys To Diagnosis And Treatment
The keys to diagnosing the condition are a good history and physical exam. Two key diagnostic markers are a positive Tinel’s sign and sensory loss in nerve distribution. To conduct the dorsiflexion-eversion test, dorsiflex the ankle approximately 15 to 20 degrees and attain 10 degrees of eversion. Have the patient extend the toes at the metatarsophalangeal joint.These maneuvers increase stress along the structures at the medial ankle, causing pain.5
X-rays can help you determine if there is any osseous or structural deformity. The use of magnetic resonance imaging (MRI) can identify any possible soft tissue mass. Some consider nerve conduction studies the gold standard of diagnosis.
Conservative treatments include controlling the inflammation via non-steroidal anti-inflammatory drugs (NSAIDs) or local steroid injections, immobilization, orthoses to control the function of the foot, physical therapy and iontophoresis.1,2,6
In the presence of a fracture or some identified tumor, one should immediately bypass conservative therapy and explore surgical options.1,2,4,6,7 Decompression of the tarsal tunnel consists of releasing certain soft tissue structures to reduce pressure on the nerve or nerves. The three big components to the release are release of the flexor retinaculum, release of the deep fascia and release of the posterior tibial nerve and its branches from any surrounding tissue that may be compressing them. Note that the first two components are the more traditional components with the third being a necessity for proper decompression.3
Following surgical correction, patients may expect to be on crutches with no weightbearing on the involved foot for four to six weeks.1,2 It is important to communicate to the patient that tarsal tunnel can recur.
1. Coughlin MJ, Mann RA, Saltzman CL. Surgery of the Foot and Ankle, eighth edition, volume 1. Elsevier, Philadelphia, 2007.
2. Banks AS, Downey MS, Miller SJ. McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, third edition, volume 2. Lippincott, Williams and Wilkins, Philadelphia, 2001.
3. Singh G, Kumar VP. Neuroanatomical basis for the tarsal tunnel syndrome. Foot Ankle Int. 2012; 33(6):513-18.
4. Sung KS, Park SJ. Short-term operative outcome of tarsal tunnel syndrome due to benign space-occupying lesions. Foot Ankle Int. 2009; 30(8):741-5.
5. Alshami AM, Babri AS, Souvlis T, Coppieters MW. Biomechanical evaluation of two clinical tests for plantar heel pain: the dorsiflexion-eversion test for tarsal tunnel syndrome and the windlass test for plantar fasciitis. Foot Ankle Int. 2007; 28(4):499-505.
6. Lau JT, Daniels TR. Tarsal tunnel syndrome: a review of the literature. Foot Ankle Int. 1999; 20(3):201-9.
7. Gondring WH, Trepman E, Shields B. An outcomes analysis of surgical treatment of tarsal tunnel syndrome. Foot Ankle Int. 2003; 24(7):133-8.