Tarsal Tunnel Syndrome: Expanding the Paradigm on Etiology and Treatment

Recent research has challenged the traditional understanding of tarsal tunnel syndrome (TTS), finding that compression of the tibial nerve at the level of the high ankle—a distance of 10–16 cm proximal to the laciniate ligament—is a common component of TTS. We have published and/or had research accepted for publication on this subject. Our work establishes that a tibial nerve compression at the level of the high ankle is common, occurring in more than half of all people with clinical findings of TTS (Figure 1).^1-3 This research has also found that a significant proportion of people with the clinical presentation of TTS that had a high tibial nerve entrapment did not have an entrapment at the level of the laciniate ligament.  

The clinical findings of TTS go back to 1918 when Malaise first described the symptoms.⁴ In 1962, Keck⁵ defined the term tarsal tunnel syndrome as a compression of the tibial nerve by the laciniate ligament, and two years later McGill noted an additional component is entrapment of the nerve and/or its branches under the abductor hallucis muscle and its fascia.⁶ Compression of the tibial nerve at the level of the high ankle was not recognized until Baxter noted it in 1995, describing the tibial nerve as entrapped in the fascia of the lower fibers of the gastrocnemius muscle.⁷ Later, Mackinnon and Yee described this nerve compression as entrapped by the fascia of the lower leg and ankle.⁸

Segura first recognized that entrapment of the tibial nerve at the level of the high ankle could be a common occurrence when the author employed an “inching” technique in electrodiagnostic (EDX) testing in addition to conventional EDX techniques.⁹ The inching approach was established more than 50 years ago in the evaluation of cubital tunnel syndrome, and physicians later employed it to assess carpal tunnel syndrome.^10,11 The method involves stimulation of the nerve in question at short segments along its course and allows for improved localization of any focal slowing.

In people with a clinical suspicion of TTS this inching approach occurred in 2-cm segments along the tibial nerve from 10–16 cm proximal to (or above) the abductor hallucis muscle (Figure 2).^1–3 In patients presenting with TTS, the tibial nerve was entrapped 53%–76% of the time, with 24% of these patients not having EDX evidence of compression at the laciniate ligament. Aspects of our research also found significant correlation between the presence of this entrapment and obesity, diabetes, and peripheral neuropathy. 

Clinical Pearls for the Treatment of Tarsal Tunnel Syndrome

Physicians evaluating patients with clinical findings of TTS should evaluate the tibial nerve at the high ankle for signs of entrapment (eg, test for a provocative sign or Tinel’s sign), and when sending patients for EDX testing, have the neurophysiologist perform inching or short-segment nerve testing along the tibial nerve at the level of the high ankle (ie, 10–16 cm from the abductor hallucis muscle).

With failure rates for TTS surgery ranging from 4–56%,¹² surgeons need to consider the presence of a high tibial nerve entrapment. Given that a proportion of patients with the clinical findings of TTS only have entrapment of the tibial nerve at the high ankle, not the laciniate ligament, a surgeon who overlooks this entrapment creates the possibility that their surgical decompression may not provide the patient with any improvement. Raikin and Minnich noted this scenario in 2003, recognizing failure to decompress the tibial nerve at the high ankle as a cause of failed TTS surgery.¹³

Last, surgeons should be aware that the laciniate ligament may not be compressing the tibial nerve, and in such cases the
ligament may not need to be released, allowing for a less invasive surgical intervention.

In Conclusion

This research suggests physicians and neurophysiologists involved in the diagnosis and treatment of TTS should use an expanded paradigm, wherein they consider the presence of a tibial nerve entrapment at the level of the high ankle. The authors believe this approach will result in improved surgical outcomes, and may lead to new conservative treatments for TTS.

Dr. Nirenberg is a Fellow of the Association of Extremity Nerve Surgeons, has been in practice for over 32 years and serves on the editorial board of the Journal of the American Podiatric Medical Association.

Dr. Segura has over 40 years’ experience in neurology, and he has fellowship training in neuromuscular diseases and electrodiagnostic testing.

References

1.    Segura RP, Nirenberg, MS. High tibial nerve entrapment: a common component of tarsal tunnel syndrome. J Am Podiatr Med Assoc. Forthcoming.
2.    Segura RP, Nirenberg MS. Prevalence of obesity in high tarsal tunnel syndrome: a cross-sectional study. J Am Podiatr Med Assoc. 2023;113(4):22-056. doi:10.7547/22-056
3.    Segura RP, Nirenberg, MS. An investigation of common anatomic sites of tibial nerve compression in persons with clinical findings of tarsal tunnel syndrome. J Am Podiatr Med Assoc. Forthcoming.
4.    Patel AT, Gaines K, Malamut R, et al. Usefulness of electrodiagnostic techniques in the evaluation of suspected tarsal tunnel syndrome: an evidence-based review. Muscle Nerve. 2005;32(2):236-240. doi:10.1002/mus.20393
5.    Keck C. The tarsal-tunnel syndrome. J Bone Joint Surg. 1962;44(1):180-182.
6.    McGill D. Tarsal tunnel syndrome. Proceed Royal Soc Med. 1974;1125-26.
7.    Baxter DE. Functional nerve disorders. The Foot and Ankle in Sport. Mosby;1995:9-21.
8.    Mackinnon SE, Yee A. Tarsal Tunnel Release. Surgical Education/Learn Surgery. Washington University School of Medicine in St. Louis. Published Oct. 8, 2011. Accessed Oct. 31, 2024.
9.    Segura RP. Incidence of Tarsal Tunnel Syndrome in a Diabetic Population: Redefining Topographic and Electrophysiologic Correlates. Presented at: 13th World Congress on Pain. Montreal, Quebec, Canada. 2010.
10.    Kimura J. A method for determining median nerve conduction velocity across the carpal tunnel. J Neurol Sci. 1978;38(1):1-10. doi:10.1016/0022-510x(78)90240-x
11.    Miller RG. The cubital tunnel syndrome: diagnosis and precise localization. Ann Neurol. 1979;6(1):56-59. doi:10.1002/ana.410060113
12.    Yalcinkaya M, Ozer UE, Yalcin MB, Bagatur AE. Neurolysis for failed tarsal tunnel surgery. J Foot Ankle Surg. 2014;53(6):794-798. doi:10.1053/j.jfas.2014.05.012
13.    Raikin SM, Minnich JM. Failed tarsal tunnel syndrome surgery. Foot Ankle Clin. 2003;8(1):159-174. doi:10.1016/s1083-7515(02)00161-4