Subtalar

Subtalar refers to the subtalar region of the hindfoot, most often the subtalar joint (talocalcaneal joint), the articulation between the talus and the calcaneus. It is part of the hindfoot complex that also includes the talonavicular joint and contributes to the foot’s ability to adapt to uneven surfaces as well as to invert and eversion during gait.

Anatomy of the joint involves three articular facets on the inferior surface of the talus (anterior, middle, posterior) that articulate with corresponding facets on the superior surface of the calcaneus. The posterior facet is the largest. Stability is provided by a set of talocalcaneal ligaments, including the interosseous talocalcaneal ligament within the tarsal sinus, and the cervical, posterior talocalcaneal, and other supporting ligaments. The joint is closely related to the talocalcaneonavicular complex.

Biomechanics and function: The subtalar joint primarily enables inversion (supination) and eversion (pronation) of the hindfoot, with movement coupled to the adjacent talonavicular joint. Its oblique axis allows complex, triplanar motion that accommodates uneven terrain and contributes to the foot’s overall pronation-supination during the gait cycle.

Clinical relevance: Subtalar pathology includes arthritis, instability, and coalition, a congenital fusion between the talus and calcaneus that can limit motion. Subtalar fusion (arthrodesis) may be indicated for persistent pain or instability. Imaging, including X-rays, CT, and MRI, aids diagnosis and treatment planning.

Pathology and management vary with age, activity, and overall hindfoot alignment, but the subtalar joint remains central to hindfoot motion and stability.