Tarsal Tunnel Syndrome Treatment & Management

A positive history combined with supportive physical findings (see Presentation) and positive electrodiagnostic results (see Workup) makes the diagnosis of tarsal tunnel neuropathy highly likely. Patients with a high likelihood of nerve compression generally have a good clinical result after surgical decompression of the tibial nerve. It is important to note, however, that the absence of positive electrodiagnostic results does not rule out the possibility that decompression may be successful in treating the symptoms of tarsal tunnel syndrome.

Surgery is contraindicated in patients who are not medically stable enough to undergo this elective procedure. In addition, appropriate medical workup should be initiated in patients who may have medical comorbidities that may preclude the performance of surgical decompression.

Several conditions may mimic or coexist with tarsal tunnel neuropathy. Surgical treatment may depend on an accurate determination of the conditions that are similar to tarsal tunnel syndrome but do not improve after surgical decompression (see DDx).

Some concern exists regarding whether decompression of the tibial nerve in patients with marked pes planovalgus deformity may cause a deleterious effect because decompression of the medial retinacular compartment may be associated with an increase in nerve tension. Questions arise regarding whether a joint stabilization procedure may be a necessary adjunct in determining long-term postoperative success. To the authors' knowledge, no studies have been performed to assess the long-term efficacy of decompression and stabilization, decompression and orthoses management, and decompression alone.

Tibial nerve entrapment is common in diabetics, causing neuropathic complainst and sensory disturbances. It has been suggested that surgical treatment of tarsal tunnel syndrome may help prevent diabetic foot disease and thus reduce the risk of amputation. ^[20]  

Medical therapy for tarsal tunnel syndrome may consist of local injection of steroids into the tarsal canal. An acceptable conservative approach in the early treatment of tarsal tunnel neuropathy includes the use of local anesthetics and soluble steroids, which may aid in the reduction of the patient's pain. These therapies may occasionally produce complete relief of symptoms, but they must be performed judiciously, in that improper placement of syringe needles can cause additional nerve injury. Physical therapy may be of some value in reducing local soft-tissue edema, thereby easing pressure on the compartment.

Also, in symptomatic patients who exhibit a contracture of the gastrocnemius muscle of the triceps surae, stretching exercises that are designed to improve the flexibility of the gastrocnemius should be initiated. In cases in which the patient has a pes planovalgus foot type, a well-designed foot orthosis may reduce tension on the tibial nerve by decreasing the load on the medial column. This is accomplished by providing a medial longitudinal posting on the orthotic for both the hindfoot and forefoot.

The use of night splints with the foot in plantarflexion and varus may be considered in patients with a valgus foot. This modality has not been shown to have long-term efficacy in well-controlled comparison studies with outcome measures, but it is commonly used in clinical practice. ^[21]

When conservative therapy fails to alleviate the patient's symptoms, surgical intervention may be warranted. Space-occupying masses require removal. Numerous reports exist of neurilemoma of the tibial nerve, which may have be removed. A thorough knowledge of the local anatomy is a prerequisite before release of the affected nerve is attempted.

External neurolysis of the nerve may be necessary if surgical exploration demonstrates adhesions or scar tissue as the cause of the nerve impingement. Moreover, if scarring or entrapment encapsulates the nerve tissue, in addition to external neurolysis, a release of the epineurium is warranted.

The tarsal tunnel is amenable to decompression via an endoscopic technique. ^[22] A retractor-integrated endoscope can be used to create a space by retracting the soft tissues and to visualize and manipulate the target structures. Krishnan reported a case series where he used an endoscopic technique in the tarsal tunnel in 24 patients (6 females, 18 males; age range, 28-82 years; mean age at surgery, 54.6 years) with tarsal tunnel syndrome. ^[23]  All cases were unilateral.

Of the 24 patients, 10 had posttraumatic tarsal tunnel syndrome and 14 were idiopathic (1 had been operated for tarsal tunnel syndrome on the same side 3 years earlier; in this case, therefore, only a part of the nicely healed scar was reopened). ^[23] Twenty-one patients had the classic presentation of tarsal tunnel syndrome, three had the distal variant, and two had the algetic form. With regard to concomitant diseases, 13 patients had diabetes mellitus, two had polyneuropathy, and five had peripheral vascular occlusive disease.

Evaluation of the results was conducted according to Bishop's five-scale system (excellent/very good/good/moderate/poor) adapted to tarsal tunnel syndrome. ^[23] Follow-up ranged from 6 months to 6 years (mean, 2.5 years). Results were represented for the latest follow-up documentation. Of the 24 patients, eight had excellent results, 10 very good, four good, and two poor (both of whom had relapses). Of the 13 patients with concomitant diseases, all but two improved; however, only one had excellent results, whereas six had very good results, four good, and two poor. Protective sensation recovered in all patients.

An ultra-minimally invasive approach to decompression of the tibial nerve under ultrasonographic (US) guidance has been described and found to be effective. ^[24]

Preparation for surgery

The patient may be placed in either the supine or the lateral recumbent position to facilitate exposure of the medial aspect of the operative foot. Use of a pneumatic tourniquet is recommended.

Operative details

A curved incision should be made approximately 1 cm posterior to the distal tibia and carried in the plantar direction, paralleling the shaft and malleolus and curving gradually toward the sustentaculum tali. (See the image below.) Miniopen approaches using a smaller incision have also been described. ^[25]

The retinaculum should be identified and carefully released in its entirety. The posterior tibial nerve should be identified, visualized, and left undisturbed along the course until its bifurcation at the porta pedis. Care should be exercised to avoid cutting the small calcaneal branches that arise from the posterior tibial nerve; these branches are often surrounded by fatty tissue and may be difficult to easily visualize. (See the image below.)

The medial plantar branch of the posterior tibial nerve should be identified and traced along the margin of the flexor sheath of the hallucis longus. The lateral branch should be followed distally and the deep fascia of the abductor hallucis released. Any fibrous bands that are noted to be constricting the nerves should be carefully released.

After release, all the branches of the tibial nerve should be lying free of any fascial covering. The tourniquet should be deflated to observe for and control bleeding. A layered closure should be performed, including the subdermal layer but not the flexor retinaculum. The skin may be closed with sutures or staples; a drain is not necessary. In a tarsal tunnel release, a layer closure of the wound should be performed by taking care not to reapproximate the extensor retinaculum, because this is the most common cause of the entrapment neuropathy.

A mild compression dressing and the initial immobilization should be applied with slight inversion to the affected area by using a splint for 3 weeks of nonweightbearing. After the splint is discontinued, the patient may begin joint mobilization and a graduated return to weightbearing.

Because of the anatomy of the affected region, several complications of compression release surgery may arise, most of which can be minimized with meticulous dissection and careful identification of the local anatomy.

Laceration of the nerve or posterior artery could have significant deleterious effects on foot function. A failure to adequately release the retinaculum along its entire course may lead to poor postoperative results. This is the most likely etiology of surgical failure.

Additionally, associated plantar fasciitis may be a cause of persistent pain in the medial heel region after decompression, which may have be addressed separately. A case study by Kim and Dellon demonstrated that a neuroma of the distal saphenous nerve may need to be considered as a causative factor if pain continues after surgical release. ^[26]

The patient should be nonweightbearing for a period of 3 weeks to allow for proper healing. Early mobilization should be initiated to decrease the formation of scar tissue, which may itself contribute to compression neuropathy. The use of surgical shoe aids to help reduce pressure on the surgical site is recommended. Formal physiotherapy may be helpful for the patient to regain strength and motion and for the relief of residual pain.

After suture removal, the patient should be able to resume the use of soft shoes, taking care to avoid shoes that may cause pressure or irritation of the surgical site. In patients who have a pes planus foot type, insole orthoses should be considered to stabilize the medial column.