When is surgery indicated for posterior tibial nerve entrapment?

Updated: Oct 15, 2019
  • Author: Minoo Hadjari Hollis, MD; Chief Editor: Thomas M DeBerardino, MD  more...
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Answer

Surgical release is indicated for refractory cases of posterior tibial nerve entrapment (tarsal tunnel syndrome) and for most cases with space-occupying lesions. In patients with proximal or distal posterior tibial nerve entrapment, this has an 80-90% likelihood of improving or resolving the symptoms.

The location of the release is partially dependent on the location of entrapment. Most cases, however, call for a full release of the posterior tibial nerve and of the lateral plantar nerve and its branches. The skin is marked for the proposed skin incision. For proximal entrapment, the incision is started 2 cm proximal to the medial malleolus, approximately halfway between the medial malleolus and the Achilles tendon. It is extended distally and plantarly, directly superficial to the course of the posterior tibial nerve.

A full release includes release of the flexor retinaculum overlying the nerve, starting proximal to the medial malleolus and moving distally to include release of the deep fascia of the abductor hallucis. The neurovascular bundle is posterior to the flexor digitorum brevis. Typically, medial and lateral plantar nerves branch at the level of the medial malleolus. It is best to identify the posterior tibial nerve proximally and follow it distally.

All sources of potential impingement are released from the medial and lateral plantar nerves. The medial calcaneal branches are quite variable and should be watched for closely. A large number of vessels are encountered routinely, and some crossing veins may need to be ligated.

It is important to ensure full release of the lateral plantar nerve and its first branch. The superficial and deep fascia of the abductor hallucis is released as the nerve is followed distally. Partial release of the plantar fascia is usually necessary for full visualization. No consensus exists in the literature about the necessary amount of plantar fascia release.

The extent of the plantar fascia release may be dictated partially by the arch height, and a full release may be indicated in patients with a cavus foot, whereas a minimal release could be considered in patients with flatfoot. Retraction of the abductor hallucis and the flexor digitorum brevis allows good visualization of the lateral plantar nerve and its first branch. The usual course of the lateral plantar nerve is just anterior to the heel pad.

As the lateral plantar nerve is followed, any compressive fascial bands are cut. The fascia of the quadratus plantae is also identified and released if it is noted to cause any compression by the medial edge of the quadratus plantae fascia on the first branch of the lateral plantar nerve. In cases of associated space-occupying lesions, the incision is modified as necessary for complete excision of the tumor.

Bipolar electrocautery and surgical loupe magnification are necessary for optimal visualization. Handling of the nerve should be minimized. Often, large varicosities are present that should be considered part of the underlying compressive etiology. Care must be taken to avoid injury to these large vessels, which can compromise visualization and can cause intraoperative and postoperative bleeding and postoperative scarring. The medial plantar nerve is fully released. The tourniquet is released before closure to ensure that no major bleeding occurs.

The plantar skin incision is reapproximated without the use of subcutaneous sutures. Reapproximating the subcutaneous tissues and the skin closes the medial segment of the incision. A bulky soft-tissue dressing is then applied, and range-of-motion exercises are encouraged.


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