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Tarsal Sinus

sinus tarsi

The tarsal sinus (sinus tarsi) is the cone-shaped space between the talus and calcaneus, formed by the sulcus tali superiorly and the sulcus calcanei inferiorly. It contains the interosseous and cervical talocalcaneal ligaments, a fat pad, blood vessels, and proprioceptive nerve endings. The tarsal sinus communicates laterally with the tarsal canal medially.

Anatomical Data

Structure & Landmarks

Articulations	Not a bone, the inter-tarsal space between the talus and calcaneus
Landmarks	Palpable as a depression anterior to the lateral malleolus between the talus and calcaneus Direct tenderness in this region is the cardinal sign of sinus tarsi syndrome
Ossification	Not a bone. The tarsal sinus is the inter-tarsal space between the talus and calcaneus.

Clinical Relevance

Clinical Notes

Sinus tarsi syndrome from ligament disruption and synovitis within the tarsal sinus produces lateral hindfoot pain reproduced by direct palpation in the sinus and by hindfoot inversion. MRI identifies the pathological ligament signal change and synovitis. Corticosteroid injection into the sinus provides diagnostic confirmation when it relieves the pain and is also therapeutic in the short term.

Palpation

Find the front edge of the lateral malleolus and move just forward of it onto the top of the outer midfoot. The soft hollow there is the opening of the sinus tarsi; it deepens when the foot is turned inward. Tenderness here suggests subtalar or sinus tarsi problems.

Pathology

Common Injuries & Conditions

Sinus Tarsi Syndrome

Persistent lateral hindfoot pain over the sinus tarsi after ankle sprains, often with a sense of instability, from injury to the interosseous ligaments and synovium.

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