Fibrous and muscular components of the tarsal tunnel roof; a quantitative 3D anatomical study using dissection and a digital microscribe.

PURPOSE: There is no gold standard technique to diagnose and treat tarsal tunnel syndromes. This is due to the lack of consensus on the structures that form the roof of the tarsal tunnel. The flexor retinaculum is consistently stated to form the roof, but there is no clear understanding of the anatomy (borders, spatial relations) of this fibrous tissue. This makes the surgical release inconsistent, and potentially incomplete, when treating tarsal tunnel syndrome. METHODS: The aim of this study was to accurately describe the roof of the tarsal tunnel. Feet of embalmed Body Donors (n = 15; mean age = 84.64 ± 11.21 years; F = 7, M = 7; L = 10, R = 5) were analysed. They were dissected and modelled in virtual three-dimensional space. The relations and dimensions of all tissues were measured. RESULTS: The roof was formed by both the flexor retinaculum and the abductor hallucis (AbH) muscle (n = 15), and a lateral fascia of the AbH muscle (n = 11). The tarsal tunnel roof was consistently formed by both fibrous and muscular tissues. CONCLUSION: These data strongly suggest that this unique, multi-tissue organisation of the roof, needs to be further assessed when surgically decompressing the contents of the tarsal tunnel. This may inform more accurate techniques for tarsal tunnel release.