How To Maximize Outcomes In Tarsal Tunnel Surgery

Author(s): 
By Stephen L. Barrett, DPM, MBA, CWS

As with any peripheral nerve surgery, tarsal tunnel surgery is demanding and can sometimes be excessively difficult. Additionally, one may not have a full appreciation of the outcome until some point in the postoperative period — if at all — when the nerve has had adequate time for recovery and/or regeneration.

Sadly, there are many misnomers in podiatric medicine and surgery. For example, the nomenclature of “tarsal tunnel syndrome” implies that the site of chronic nerve entrapment is at the level of the tarsal tunnel, which actually resides beneath the laciniate ligament or flexor retinaculum at the level of the medial ankle. In reality, this is rarely a source of entrapment.

It would be more accurate to clarify this condition as “multiple nerve entrapment at the medial ankle” as this condition almost always involves entrapment of the medial and lateral plantar nerves, and frequently involves the medial calcaneal nerve as well. Anatomically, the tarsal tunnel is the area proximal to the superior edge of the conjoined edges of the deep and superficial fascia of the abductor hallucis muscle. This is where the medial and lateral plantar nerve tunnels begin. It is analogous to the human forearm wrist fascia in the upper extremity. It is well known in carpal tunnel surgery that the median nerve is rarely entrapped at this level but actually occurs distally beneath the volar carpal ligament.

There are many small factors that contribute to and differentiate successful “tarsal tunnel surgery” versus those surgical interventions that may not be ultimately successful or, in some cases, are detrimental for the patient. Most of these factors can be boiled down into three areas: preoperative considerations and diagnosis; intraoperative surgical technique; and postoperative management.

A Guide To Essential Preoperative Considerations
Diagnosing this condition can sometimes be difficult and confusing for the physician. Patients occasionally have nebulous descriptions, which many times do not fit with the clinician’s clinical perspective or ideation. It is not unusual for the patient to complain of a wide array of symptoms during their history of present illness.

Tarsal tunnel syndrome is frequently associated with other lower extremity pathology such as recurrent Morton’s neuroma. It may be masked by other pathology such as heel pain that is attributed only to plantar fasciosis.1

Heel pain is the most common reason a patient seeks podiatric care and the percentage of patients with nerve entrapment can be very high. Rose, et al., showed that nerve entrapment occurred in 72 percent of 97 patients who presented with heel pain.2 We have seen the same presentation with involvement of the medial calcaneal nerve, with or without additional entrapment of the nerves in the medial ankle.

When one obtains a history of present illness, there are key statements that should raise some flags for physicians. These statements include: “It gets worse throughout the day,” “it hurts at night — even when I am not on it,” “the orthotic makes it worse” and “there is a full feeling in my ankle.” It is also not unusual for patients to say they have heel pain but the pain has a different nature than when they were first treated for their plantar fasciosis. Any of these telling statements by the patient should clue the practitioner into expanding the investigation not only to ascertain nerve entrapment but also to identify potential systemic disease, which could be the etiology of the patient’s condition.

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