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Topic

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Trochlea of talus

The trochlea of the talus is the superior, dome-shaped articular surface of the talus that articulates with the distal tibia and fibula to form the talocrural (ankle) joint. It plays a central role in ankle stability and motion, transmitting body weight from the leg to the foot while allowing controlled dorsiflexion and plantarflexion.

It is a critical structure in ankle biomechanics, orthopedic assessment, trauma evaluation, and cross-sectional imaging.

Synonyms

  • Talar dome

  • Trochlear surface of the talus

Location

  • Situated on the superior aspect of the talus

  • Interposed between the medial and lateral malleoli

  • Inferior to the tibial plafond

  • Superior to the talar body

  • Forms the roof of the talus within the ankle mortise

Anatomical components

  • Articular cartilage covering the trochlear surface

  • Medial and lateral trochlear margins:

    • Lateral margin is broader and more prominent

  • Anterior portion:

    • Wider than the posterior portion

  • Subchondral bone plate

  • Underlying cancellous bone of the talar body

Relations

Superiorly:

  • Tibial plafond

Medially:

  • Medial malleolus

Laterally:

  • Lateral malleolus

Inferiorly:

  • Body of the talus

Anteriorly:

  • Neck of the talus

Posteriorly:

  • Posterior process of the talus

X-ray appearance

Plain radiographs (AP, mortise, and lateral ankle views):

  • Trochlea: Appears as a smooth, curved radiopaque articular surface

  • Joint space: Uniform and symmetric with the tibial plafond

  • Best visualized on: Mortise view

  • Surface contour: Convex superior outline

CT appearance

Non-contrast CT:

  • Trochlea: Well-defined curved articular surface

  • Subchondral bone: Clearly visualized

  • Cortical margins: Smooth and continuous

  • Spatial assessment: Excellent for evaluating contour, symmetry, and articular congruity

  • Relationship with tibial plafond and malleoli: Precisely demonstrated

MRI appearance

T1-weighted images:

  • Subchondral bone: High signal marrow beneath low-signal cortical plate

  • Articular cartilage: Low-to-intermediate signal thin layer

  • Trochlear contour: Clearly delineated

T2-weighted images:

  • Articular cartilage: Intermediate-to-high signal

  • Joint fluid: High signal outlining the trochlear surface

  • Subchondral bone: Low-to-intermediate signal

STIR:

  • Fat suppression: Uniform in talar marrow

  • Articular surface: Well visualized against suppressed marrow

  • Joint fluid: Bright signal

Proton density fat-saturated (PD FS):

  • Cartilage: High signal relative to suppressed marrow

  • Subchondral bone: Low signal

  • Joint space: High signal

  • Excellent contrast for delineating cartilage and articular margins

CT VRT 3D image

Trochlea of talus

MRI image

Trochlea of talus mri anatomy labelled image-img-00000-00000

MRI image

Trochlea of talus mri anatomy labelled image-img-00000-00000_00001