What is the main ligament of the subtalar joint?

What is the main ligament of the subtalar joint?

• A. Deltoid ligament
• B. Interosseous talocalcaneal ligament
• C. Calcaneofibular ligament
• D. Spring ligament

Answer: (B)

The key idea is that the primary stabilizer of the subtalar joint is the interosseous talocalcaneal ligament. It sits in the tarsal sinus between the talus and calcaneus and acts as the main restraint to movement between these two bones. Because it lies right between the talus and calcaneus, it provides the strongest intrinsic support for hindfoot alignment and limits excessive inversion or eversion at the subtalar joint, helping to define the joint’s axis of motion. The other ligaments listed belong to different structures: the deltoid ligament stabilizes the medial ankle mortise, the calcaneofibular ligament stabilizes the lateral ankle, and the spring ligament supports the arch and the talonavicular joint rather than serving as the main subtalar stabilizer.

The key idea is that the primary stabilizer of the subtalar joint is the interosseous talocalcaneal ligament. It sits in the tarsal sinus between the talus and calcaneus and acts as the main restraint to movement between these two bones. Because it lies right between the talus and calcaneus, it provides the strongest intrinsic support for hindfoot alignment and limits excessive inversion or eversion at the subtalar joint, helping to define the joint’s axis of motion.

The other ligaments listed belong to different structures: the deltoid ligament stabilizes the medial ankle mortise, the calcaneofibular ligament stabilizes the lateral ankle, and the spring ligament supports the arch and the talonavicular joint rather than serving as the main subtalar stabilizer.