Neuroanatomical basis for the tarsal tunnel syndrome

Abstract

Background: The results of surgical treatment for tarsal tunnel syndrome have been suboptimal, especially in the absence of space-occupying lesions. We attribute this to a poor understanding of the detailed anatomy of the `tarsal tunnel' and potential sites of nerve compression.

Methods: This study involved the dissection of 19 cadaveric feet. All findings and measurements were documented with digital photography and digital calipers.

Results: This study demonstrated three well-defined, tough fascial septae in the sole of the foot. In addition to the flexor retinaculum and the abductor hallucis, two of these septae represented potential sites of compression of the posterior tibial nerve and its branches. The medial plantar nerve may be entrapped under the medial septum. However, in 16 of 19 feet, the medial plantar nerve did not traverse beneath the septum. The lateral plantar nerve traversed beneath the medial septum in all specimens. The nerve to abductor digiti minimi may be trapped under the medial and intermediate septum.

Conclusion: We detailed the anatomical relationship of the nerve branches relative to the fibrous septae and found that the medial plantar nerve did not traverse a septae in all specimens.

Clinical relevance: We believe better understanding of the anatomical relationships of the tarsal tunnel and a clear communication system among anatomists, neuroradiologists and foot and ankle surgeons will facilitate accurate preoperative localization of the site of nerve compression possibly leading to better outcomes.