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Calcaneonavicular ligament (Bifurcate ligament)

The calcaneonavicular ligament, also known as the bifurcate ligament, is a strong Y-shaped ligament of the midfoot. It originates from the anterior process of the calcaneus and splits into two distinct bands: the calcaneonavicular ligament (medial limb) and the calcaneocuboid ligament (lateral limb). This bifurcation gives it its characteristic "Y" shape.

It plays a key stabilizing role in the Chopart joint (transverse tarsal joint complex), specifically supporting the articulation between the calcaneus, cuboid, and navicular bones. Due to its anatomic position and strong attachments, it is a critical stabilizer of the midfoot but is also prone to injury in inversion ankle sprains.

Synonyms

  • Bifurcate ligament

  • Y-shaped ligament of Chopart joint

  • Dorsal calcaneonavicular ligament (medial limb)

Origin, Course, and Insertion

  • Origin: Anterior process of the calcaneus

  • Course: Runs anteromedially and anterolaterally as two separate bands forming a Y-shape

  • Insertion:

    • Medial limb (calcaneonavicular): dorsal surface of navicular bone

    • Lateral limb (calcaneocuboid): dorsal surface of cuboid bone

Relations

  • Superiorly: Extensor digitorum brevis muscle and overlying tendons

  • Inferiorly: Capsule of the calcaneocuboid joint and calcaneus

  • Medially: Navicular bone and talonavicular capsule

  • Laterally: Cuboid bone and peroneus longus tendon groove

Function

  • Midfoot stabilization: Provides critical support to the transverse tarsal joint complex

  • Joint reinforcement: Strengthens the calcaneonavicular and calcaneocuboid articulations

  • Prevents abnormal displacement: Limits excessive motion of the navicular and cuboid relative to the calcaneus

  • Weight transfer: Assists in maintaining foot stability during gait and weight bearing

Clinical Significance

  • Injury: Often injured in inversion ankle sprains due to its attachment at the anterior calcaneal process

  • Avulsion fractures: May be associated with avulsion of the anterior calcaneal process, sometimes confused with fracture of calcaneus or cuboid

  • Midfoot instability: Laxity or rupture contributes to instability of the Chopart joint

  • Surgical relevance: Important landmark in midfoot surgeries and Chopart joint stabilization procedures

  • Imaging importance: Injuries may be missed on radiographs; MRI and CT provide optimal visualization

MRI Appearance

  • T1-weighted images:

    • Normal ligament: low signal intensity (dark band) connecting calcaneus to navicular and cuboid

    • Acute tear: discontinuity or focal intermediate-to-bright signal replacing ligament fibers

    • Surrounding fat planes: bright, aiding delineation

  • T2-weighted images:

    • Normal ligament: low signal (dark), more conspicuous against fluid background

    • Injury: bright hyperintense signal indicating edema, partial tear, or rupture

    • Better sensitivity for detecting associated bone marrow edema at calcaneus, cuboid, or navicular

  • STIR:

    • Ligament normally dark

    • Tears or sprains: hyperintense edema within ligament or surrounding soft tissue

    • Highlights associated bone contusions or joint effusion

  • Proton Density Fat-Saturated (PD FS):

    • Normal ligament: thin dark band

    • Tear: bright linear or irregular signals disrupting the band

    • Particularly effective for identifying subtle sprains and partial-thickness tears

  • T1 Fat-Sat Post-Contrast:

    • Normal ligament: minimal enhancement

    • Injured ligament: surrounding enhancement due to inflammation or synovitis

    • Chronic degeneration may show diffuse thickening with patchy enhancement

CT Appearance

Non-Contrast CT:

  • Ligament itself poorly defined due to soft-tissue density

  • May show calcification or ossification in chronic degeneration

  • Avulsion fractures of anterior calcaneal process are well seen

Post-Contrast CT:

  • Minimal role for direct visualization of ligament

  • Surrounding soft-tissue inflammatory changes may show enhancement

MRI images

Calcaneonavicular ligament (Bifurcate ligament) axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI images

Calcaneonavicular ligament (Bifurcate ligament) coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000