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Talocalcaneal interosseous ligament

The talocalcaneal interosseous ligament (TCIL) is a strong band of fibrous tissue that occupies the sinus tarsi, binding the talus to the calcaneus. It is a key stabilizer of the subtalar joint, resisting abnormal rotational and translational forces. The ligament consists of thick oblique fibers, extending across the sinus tarsi, and works synergistically with the cervical ligament to provide dynamic hindfoot stability.

The TCIL is clinically relevant because injury or degeneration contributes to chronic subtalar instability, sinus tarsi syndrome, and hindfoot pain. It is often damaged in ankle sprains, subtalar dislocations, or repetitive overuse injuries.

Synonyms

  • Interosseous talocalcaneal ligament

  • Sinus tarsi ligament

  • Subtalar interosseous ligament

Origin, Course, and Insertion

  • Origin: Groove of the talus within the sinus tarsi

  • Course: Thick, oblique fibers extend laterally across the sinus tarsi

  • Insertion: Sulcus of the calcaneus, directly opposite the talar groove

Relations

  • Superiorly: Neck of talus and body of talus

  • Inferiorly: Upper surface of calcaneus

  • Anteriorly: Cervical ligament

  • Posteriorly: Posterior talocalcaneal joint capsule

  • Laterally: Sinus tarsi fat pad

  • Medially: Deep subtalar joint structures

Function

  • Stabilization: Provides primary ligamentous support for the subtalar joint

  • Restriction of motion: Limits excessive inversion and eversion between talus and calcaneus

  • Load distribution: Maintains talocalcaneal articulation during weight bearing

  • Synergistic role: Works with cervical ligament for hindfoot stability

  • Clinical marker: Injury contributes to chronic ankle instability and sinus tarsi syndrome

Clinical Significance

  • Injury mechanism: Commonly injured in severe inversion ankle sprains and subtalar dislocations

  • Degeneration: Weakening and thickening seen in chronic instability or sinus tarsi syndrome

  • Symptoms: Hindfoot pain, instability, difficulty walking on uneven ground

  • Surgical relevance: Reconstruction or stabilization may be required in chronic subtalar instability

  • Imaging role: MRI best for evaluation; CT useful for osseous relations and indirect findings

MRI Appearance

  • T1-weighted images:

    • Normal ligament: low signal (dark band) across sinus tarsi

    • Surrounded by intermediate to bright fat signal in sinus tarsi

    • Partial tear: irregular thickening with patchy intermediate signal

    • Complete tear: discontinuity with high-signal gap

  • T2-weighted images:

    • Normal ligament: low signal, darker than on T1

    • Injury: hyperintense signal at ligament substance or attachments

    • Associated findings: subtalar joint effusion, sinus tarsi edema

  • STIR:

    • Ligament normally dark

    • Hyperintense bright signal indicates edema, tear, or inflammation in acute injuries

  • Proton Density Fat-Saturated (PD FS):

    • Normal: dark band with uniform low signal

    • Tears: focal or diffuse bright signal extending into ligament fibers

    • Best sequence for subtle sprains and partial-thickness injuries

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal to no enhancement

    • Pathology: enhancing thickened ligament in chronic inflammation or postoperative scar tissue

CT Appearance

Non-Contrast CT:

  • Ligament not well visualized due to soft tissue density

  • Indirect signs: widening of sinus tarsi, subtalar malalignment, associated fractures

Post-Contrast CT (standard):

  • Limited direct visualization of ligament

  • Adjacent inflammatory or postsurgical soft tissue changes may show enhancement

MRI images

Talocalcaneal interosseous ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Talocalcaneal interosseous ligament coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Talocalcaneal interosseous ligament coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001