Can Orthotics Have An Impact On Tarsal Tunnel Syndrome?
In a review of the literature and their clinical experience, these authors discuss the pathomechanics of tarsal tunnel syndrome, keys to the differential diagnosis and the role of functional foot orthotics in treating the condition.
Keck coined the phrase “tarsal tunnel syndrome” in a 1962 case report of an Army recruit who experienced numbness, a pins and needles sensation, and burning on the plantar surface of the feet.1 This eventually progressed to complete anesthesia during basic training. While rest relieved the pain initially, the patient went on to have weakness and dysfunction in multiple intrinsic foot muscles. Percussion to the neurovascular bundle could reproduce symptoms. Conservative care included bed rest and whirlpool massage during a hospital admission.
When there was no improvement, the treating physician quickly entertained surgery and identified a constricted and compressed posterior tibial nerve in its compartment within the tarsal tunnel. The physician released the nerve from beneath the flexor retinaculum, relieving the symptoms.
The author made several important points in this case report.1 He stated that tarsal tunnel syndrome, in most cases, was probably much more common and simply misdiagnosed and therefore mistreated. Keck added that “poor foot structure” in the general population, unlike the athletic army recruits, could be a cause of the pain. He concluded that this is likely a larger problem than perceived since the general population would stop being active to relieve the pain, which would result in under-reporting of a larger problem.
Many clinicians, including us, exhaust conservative care prior to entertaining surgery. The diagnosis and care of tarsal tunnel syndrome is no different. A recent literature search on PubMed limited to the phrase “tarsal tunnel syndrome” published in the last 10 years yielded 154 articles. Unfortunately, none of these articles document the effectiveness of functional foot orthotic devices in the care of tarsal tunnel syndrome. However, multiple articles list orthotic therapy as an option of care based on the goal of holding the foot and ankle in a more neutral position to relieve tension on the nerve and therefore decrease pain.2-4
Accordingly, we will carefully explain the reasons why we believe functional foot orthotics can have an impact on tarsal tunnel syndrome. It is important to understand the anatomy of the region of the tarsal tunnel and the mechanics of your patient’s foot, and how they relate to the symptoms before considering any treatments, including orthotic therapy.
We will also review other diagnoses that can mimic tarsal tunnel syndrome and how to confirm a tarsal tunnel syndrome diagnosis prior to any treatment decisions. Finally, we will review the parameters that one should consider when writing the most effective orthotic prescription to address the pain associated with this condition.
Defining Tarsal Tunnel Syndrome
Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve and its branches.2,3,5 It typically presents as diffuse plantar foot pain, burning, tingling or even numbness, which may radiate proximally or distally from the posteromedial ankle. There is a positive Tinel’s sign upon percussion of the nerve with possible altered sensations.6 Patients may also present with weakness in the lateral plantar intrinsic muscles with an inability to spread the toes on the affected side.7,8 Confirmation of sensory loss and diminished muscle function with nerve conduction studies is valuable in diagnosing these patients. One may also exacerbate the symptoms with eversion and dorsiflexion of the subtalar–ankle joint complex in a pronated position to create tension on the nerve.