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Superomedial calcaneonavicular ligament

The superomedial calcaneonavicular ligament, part of the spring ligament complex, is a strong fibroelastic band connecting the sustentaculum tali of the calcaneus to the navicular bone. It plays a critical role in supporting the head of the talus and maintaining the medial longitudinal arch of the foot.

This ligament is clinically significant because it forms the primary static stabilizer of the medial arch. Injury or degeneration contributes to adult-acquired flatfoot deformity (posterior tibial tendon dysfunction).

Synonyms

  • Superomedial portion of the plantar calcaneonavicular ligament

  • Spring ligament (superomedial component)

  • Medial calcaneonavicular ligament

Origin, Course, and Insertion

  • Origin: Medial surface of the sustentaculum tali of the calcaneus

  • Course: Runs forward and slightly medially, curving around the head of the talus

  • Insertion: Medial surface of the navicular bone, blending with fibers of the deltoid ligament

Relations

  • Superiorly: Head of the talus (rests upon the ligament)

  • Inferiorly: Plantar calcaneonavicular ligament complex and soft tissues of sole

  • Medially: Tibialis posterior tendon and deltoid ligament

  • Laterally: Talonavicular joint capsule

  • Anteriorly: Navicular bone

  • Posteriorly: Sustentaculum tali of the calcaneus

Function

  • Medial arch support: Primary static stabilizer of the medial longitudinal arch

  • Talus stabilization: Prevents inferior displacement of the talar head

  • Load distribution: Transfers forces between calcaneus, talus, and navicular bones

  • Synergy: Works with the posterior tibial tendon and plantar fascia to maintain normal foot biomechanics

Clinical Significance

  • Degeneration/tears: Weakening leads to collapse of the medial longitudinal arch (flatfoot)

  • Adult-acquired flatfoot deformity: Often due to combined spring ligament and posterior tibial tendon dysfunction

  • Chronic insufficiency: Leads to valgus deformity, midfoot instability, and pain along medial ankle

  • Imaging role: MRI is essential for detecting partial or complete tears, degeneration, and associated talonavicular subluxation

MRI Appearance

  • T1-weighted images:

    • Normal: ligament appears as a low-to-intermediate signal band connecting calcaneus to navicular

    • Degeneration: thickened ligament with intermediate signal intensity

    • Tears: discontinuity or focal hyperintense gaps

  • T2-weighted images:

    • Normal: ligament is dark (low signal), slightly darker than on T1

    • Pathology: partial or complete tears show bright hyperintense signal within the ligament

    • Edema and joint effusion appear as bright signals adjacent to ligament

  • STIR:

    • Normal ligament: low signal

    • Degeneration/tears: hyperintense bright signal indicating fluid or inflammation

  • Proton Density Fat-Saturated (PD FS):

    • Normal: thin, dark band with sharp borders

    • Tears: bright signal clefts or diffuse thickening

    • Very sensitive for detecting subtle sprains and early degeneration

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal or no enhancement

    • Pathology: enhancement along torn fibers or inflamed periligamentous tissues

    • Helpful in distinguishing scar tissue from recurrent ligament injury

CT Appearance

Non-Contrast CT:

  • Normal ligament: thin soft-tissue density difficult to differentiate from capsule

  • Indirect signs: widening of talonavicular joint, abnormal talar head positioning

  • Chronic degeneration: may show calcification within ligament fibers

Post-Contrast CT (standard):

  • Ligament visualization still limited

  • Surrounding soft-tissue inflammation or synovitis may be inferred

  • Bony alignment changes (talonavicular subluxation) often more apparent than the ligament itself

MRI image

Superomedial calcaneonavicular ligament (spring ligament complex) axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Superomedial calcaneonavicular ligament sagittal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000