The talocalcaneal interosseous ligament is a strong broad ligament occupying the tarsal sinus and canal between the posterior and anterior subtalar joint facets, running obliquely from the talus (above) to the calcaneus (below). It is one of the strongest hindfoot ligaments and the primary stabiliser of the subtalar joint against excessive tilting. Together with the cervical ligament, it occupies the sinus tarsi.
Primary stabiliser of the subtalar joint, preventing excessive talocalcaneal inversion, eversion, and rotatory displacement between the talus and calcaneus.
The talocalcaneal interosseous ligament is the central stabilising structure of the subtalar joint and its disruption produces subtalar instability. Complete disruption requires severe mechanism beyond typical ankle sprains. In sinus tarsi syndrome, both this ligament and the cervical ligament may be involved. During subtalar arthroscopy and posterior subtalar joint injection, the sinus tarsi is identified and instrumented with knowledge of this ligament's oblique course through the tarsal canal. Subtalar arthrosis secondary to calcaneus fracture may involve interosseous ligament calcification.
Calcaneus fractures that cross the posterior facet disrupt the talocalcaneal interosseous ligament, producing subtalar instability in addition to articular incongruity; ORIF restoring the posterior facet and ligament tension is the standard for displaced intraarticular fractures, with subtalar arthrodesis reserved for severe comminution.
