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Subtalar joint

The subtalar joint, also known as the talocalcaneal joint, is a complex synovial joint formed between the talus and calcaneus. It plays a crucial role in hindfoot motion, particularly inversion and eversion, allowing the foot to adapt to uneven surfaces and maintain balance during gait.

It is an important anatomical and biomechanical component of the ankle–hindfoot complex and a key focus in orthopedic evaluation and imaging.

Synonyms

  • Talocalcaneal joint

  • Subastragalar joint

Location

  • Situated in the hindfoot

  • Between the inferior surface of the talus and the superior surface of the calcaneus

  • Inferior to the ankle (tibiotalar) joint

  • Posterior to the talonavicular joint

  • Lies deep to the sinus tarsi and tarsal canal

Anatomical components

  • Articular surfaces:

    • Posterior, middle, and anterior talocalcaneal facets

  • Joint capsule:

    • Surrounds each articular facet

  • Sinus tarsi and tarsal canal:

    • Interosseous spaces between talus and calcaneus

  • Ligamentous supports:

    • Interosseous talocalcaneal ligament

    • Cervical ligament

    • Medial, lateral, and posterior talocalcaneal ligaments

Relations

Superiorly:

  • Talus

Inferiorly:

  • Calcaneus

Anteriorly:

  • Talonavicular joint

Posteriorly:

  • Posterior talar process

Laterally:

  • Sinus tarsi

Medially:

  • Tarsal canal

X-ray appearance

Plain radiographs (lateral and hindfoot views):

  • Subtalar joint space: Seen between talus and calcaneus

  • Posterior facet: Best appreciated on lateral view

  • Joint alignment: Normally parallel articular margins

  • Subtle contours: Often partially obscured due to overlapping bones

CT appearance

Non-contrast CT:

  • Articular surfaces: Clearly delineated talar and calcaneal facets

  • Joint space: Uniform and well-defined

  • Cortical margins: Sharp and smooth

  • Subtalar alignment: Accurately assessed in axial and coronal planes

  • Osseous anatomy: Excellent visualization of posterior, middle, and anterior facets

MRI appearance

T1-weighted images:

  • Articular cartilage: Intermediate-to-low signal

  • Subchondral bone marrow: High signal

  • Joint space: Low signal without fluid prominence

T2-weighted images:

  • Joint fluid: High signal within the subtalar joint

  • Articular cartilage: Intermediate signal

  • Surrounding soft tissues: Intermediate-to-high signal

STIR:

  • Fat suppression: Uniform across marrow

  • Joint fluid and recesses: Bright signal

  • Sinus tarsi contents: Well visualized

Proton density fat-saturated (PD FS):

  • Joint fluid: High signal

  • Cartilage and ligaments: Well-defined against suppressed marrow

  • Interosseous talocalcaneal ligament: Low-signal band within the tarsal canal

CT VRT 3D image

Subtalar joint 3d

MRI image

Subtalar joint mri anatomy labelled image-img-00000-00000

MRI image

Subtalar joint mri anatomy labelled image-img-00000-00000_00001