CorpusHuman Anatomy
SkeletalJoint

Subtalar joint

Articulatio subtalaris

Also known as: talocalcaneal joint, transverse tarsal joint, Chopart joint, inversion, eversion

The synovial joint between the talus and the calcaneus where, together with the transverse tarsal joint, inversion and eversion of the foot take place.

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Overview

Anatomically, the subtalar joint is the articulation between the posterior facet of the talus and the posterior articular surface of the calcaneus — a plane synovial joint with its own capsule. Clinically, the term often includes the anterior talocalcaneonavicular joint (talar head with the middle/anterior calcaneal facets, the navicular and the spring ligament). The two are separated by the tarsal canal and sinus tarsi, which contain the strong interosseous talocalcaneal ligament and the cervical ligament.

The transverse tarsal (midtarsal, Chopart) joint — talonavicular plus calcaneocuboid joints — lies in front and works with the subtalar joint. The combined movements are inversion (sole faces medially; with supination and adduction) and eversion (sole faces laterally; with pronation and abduction). They allow the foot to adapt to uneven ground; when the joints are "unlocked" (pronated) the foot is a flexible shock absorber, and when "locked" (supinated) it becomes a rigid lever for push-off.

Invertors: tibialis anterior and tibialis posterior; evertors: fibularis longus, brevis and tertius. Range: inversion ≈20–30°, eversion ≈5–15°.

Location

Below the ankle joint, between the talus and the calcaneus.

Parts & subdivisions

  1. Posterior talocalcaneal (subtalar) joint
    Posterior facets; own capsule.
  2. Talocalcaneonavicular joint
    Talar head with calcaneus, navicular and spring ligament.
  3. Transverse tarsal (Chopart) joint
    Talonavicular + calcaneocuboid joints; amputation plane.
  4. Interosseous talocalcaneal ligament
    In the sinus tarsi; strongest bond between talus and calcaneus.

Anatomy

Articulations

Talus ↔ calcaneus (posterior facet); talus ↔ calcaneus, navicular and spring ligament (talocalcaneonavicular).

Ligaments

Interosseous talocalcaneal, cervical, lateral and medial talocalcaneal ligaments; plantar calcaneonavicular (spring) ligament; bifurcate ligament.

Function

  • Inversion and eversion of the foot
  • Adapts the foot to uneven surfaces
  • Converts rotation of the leg into pronation/supination of the foot during gait

Clinical significance

Subtalar arthritis and fusion

Post-traumatic arthritis after calcaneal fractures causes pain walking on uneven ground; treated by subtalar arthrodesis, which preserves ankle dorsiflexion and plantarflexion but abolishes inversion–eversion.

Sinus tarsi syndrome

Persistent lateral hindfoot pain and instability after inversion sprains, from injury to the ligaments within the sinus tarsi.

Test yourself

In a typical inversion sprain of the ankle, which ligament is usually torn first?
  1. Deltoid ligament
  2. Calcaneofibular ligament
  3. Anterior talofibular ligament
  4. Posterior talofibular ligament

Answer: Anterior talofibular ligament

The anterior talofibular ligament is the weakest lateral ligament and is taut in plantarflexion, so it is the first to tear in inversion–plantarflexion injuries; the calcaneofibular ligament tears next; the posterior talofibular ligament is rarely involved.

More skeletal system questions

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.