Dr. Kirby demonstrates the gliding articular motions of the talus and calcaneus during subtalar joint pronation and supination.
The maximally pronated position of the subtalar joint occurs when the lateral process of the talus drops down into the floor of the sinus tarsi of the calcaneus and is stopped by interosseous contact forces. Subtalar joint supination causes an increase in the volume of the sinus tarsi since the lateral process of the talus is moving away from the floor of the sinus tarsi of the calcaneus.
Sinus tarsi syndrome occurs when the interosseous compression forces between the lateral process of the talus and the floor of the sinus tarsi of the calcaneus are increased in patients with more severe medial subtalar joint axis deviation and/or with painful scar tissue within the sinus tarsi from inversion ankle sprains or other traumatic pathologies.
