Fibrous and membranous tissues of the tarsal tunnel; quantitative 3D anatomy using a digital microscribe

Purpose The aetiology of tarsal tunnel syndrome is not always clear. Treatment commonly involves a single release of the flexor retinaculum, but post-operative outcomes are not always successful. This may be due to the lack of understanding the tissues that may compress the neurovasculature. The aim of this study was to define the tissues that separate the contents of the tarsal tunnel. Methods Feet from embalmed body donors ( n = 15; mean age = 83.9 ± 10.2 years; female = 9, male = 6) were examined. One underwent magnetic resonance imaging. All were dissected and modelled in virtual three-dimensional space. Results The tarsal tunnel was divided into at least five spaces by a fibrous skeleton, formed by septae that were much thicker than previously understood. Conclusion These data strongly suggest that the fibrous skeleton may compress the neurovasculature and may need to be considered in the diagnosis and management of tarsal tunnel syndrome. Surgically, this may more precisely inform which tissues need to be targeted for tarsal tunnel release.