The sustentaculum tali is a horizontal shelf-like projection from the medial surface of the calcaneus that supports the middle articular facet of the talus and carries the groove for the flexor hallucis longus tendon on its inferior surface. The spring ligament attaches along its anterior margin. The sustentaculum is one of the strongest and most cortically dense parts of the calcaneus and serves as the primary fixation point in calcaneal fracture surgery.
The sustentaculum tali is critical in calcaneal fracture surgery as it remains attached to the talus through strong ligaments and does not significantly displace even in severe fractures; it therefore provides a reliable reference landmark for reduction. A sustentaculum screw directed from the lateral calcaneus into the sustentaculum is biomechanically the strongest fixation point in calcaneal plating. Sustentaculum tali fractures can compress the FHL tendon in its groove causing triggering, pain, and limited hallux flexion.
In displaced intra-articular calcaneal fractures, the sustentaculum tali remains in anatomical position due to its strong ligamentous attachments, providing the key landmark for reduction of the fractured lateral wall; a sustentaculum-directed screw anchors the plate construct.
Sustentaculum tali fractures or post-traumatic exostosis impinge on the flexor hallucis longus tendon in the sustentacular groove, causing hallux flexor triggering and posteromedial ankle pain reproduced by resisted hallux plantarflexion, treated by tendon sheath release or sustentaculum trimming.
