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Inferoplantar longitudinal calcaneonavicular ligament

The inferoplantar longitudinal calcaneonavicular ligament (spring ligament) is the most important component of the spring ligament complex of the foot. It spans between the sustentaculum tali of the calcaneus and the plantar surface of the navicular bone. This ligament plays a critical role in maintaining the medial longitudinal arch of the foot, supporting the head of the talus, and stabilizing the talonavicular joint.

It is thick, fibrocartilaginous, and reinforced superiorly by the tibialis posterior tendon and inferiorly by the plantar aponeurosis. Injury or laxity of this ligament contributes to adult-acquired flatfoot deformity and progressive collapse of the medial arch.

Synonyms

  • Plantar calcaneonavicular ligament

  • Spring ligament (inferoplantar longitudinal component)

  • Medial arch support ligament

Origin, Course, and Insertion

  • Origin: Anterior margin of the sustentaculum tali of the calcaneus

  • Course: Runs forward and slightly medially, forming a broad fibrocartilaginous band beneath the talar head

  • Insertion: Plantar surface of the navicular bone

Relations

  • Superiorly: Head of the talus (directly supported by the ligament)

  • Inferiorly: Plantar aponeurosis and abductor hallucis muscle fibers

  • Medially: Tibialis posterior tendon (reinforcing fibers)

  • Laterally: Articular capsule of the talonavicular joint and other components of the spring ligament complex

Function

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

  • Talar support: Acts as a sling supporting the head of the talus

  • Joint stabilization: Stabilizes the talonavicular and subtalar joints during gait

  • Load distribution: Reduces stress on cartilage and adjacent ligaments of the medial foot

Clinical Significance

  • Ligament tears/laxity: Major cause of adult-acquired flatfoot deformity

  • Degeneration: Common in middle-aged patients, often with posterior tibial tendon dysfunction

  • Symptoms: Medial foot pain, collapse of arch, valgus deformity of hindfoot

  • Imaging importance: MRI is the gold standard for evaluating spring ligament pathology; CT useful for chronic degeneration, calcification, and associated deformities

  • Surgical role: Repair or reconstruction is critical in flatfoot correction procedures

MRI Appearance

  • T1-weighted images:

    • Normal ligament: low-to-intermediate signal intensity (dark band)

    • Clearly defined against adjacent bright fat

    • Tear/degeneration: thickening, irregularity, or intermediate hyperintense signal

  • T2-weighted images:

    • Normal ligament: low signal, slightly darker than on T1

    • Tears: focal or diffuse bright hyperintense signal within ligament fibers

    • Chronic degeneration: heterogeneous signal with partial discontinuity

  • STIR:

    • Normal: hypointense

    • Pathology: bright hyperintense edema or fluid signal indicating ligament tear or inflammation

  • Proton Density Fat-Saturated (PD FS):

    • Normal: uniform dark band

    • Tear/degeneration: linear or irregular bright hyperintensity, especially at calcaneal or navicular attachment

  • T1 Fat-Sat Post-Contrast:

    • Normal: minimal or no enhancement

    • Pathologic ligament: diffuse or patchy enhancement from inflammation or scarring

    • Post-surgical repair: enhancing scar tissue around ligamentous plane

CT Appearance

Non-Contrast CT:

  • Normal ligament: thin, soft-tissue density band between sustentaculum tali and navicular (poorly visualized)

  • Pathology: calcification or ossification within ligament in chronic degeneration

  • Indirect signs: collapse of medial arch, subluxation of talonavicular joint

Post-Contrast CT:

  • Limited role; ligament itself shows little contrast uptake

  • May demonstrate surrounding inflammatory or degenerative changes

MRI image

Inferoplantar longitudinal calcaneonavicular ligament axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Inferoplantar longitudinal calcaneonavicular ligament coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000_00001

MRI image

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