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Talocalcaneonavicular joint

The talocalcaneonavicular joint (TN joint) is a complex, ball-and-socket articulation of the hindfoot. It consists of the head of the talus (ball) fitting into a socket formed by the calcaneus, navicular, and plantar calcaneonavicular (spring) ligament. This joint is crucial for foot mobility, inversion-eversion, and load transfer between hindfoot and midfoot.

It forms part of the transverse tarsal joint (Chopart joint), along with the calcaneocuboid joint, and contributes to subtalar mechanics.

Joints Involved

  • Head of talus articulates with:

    • Navicular bone (anteriorly)

    • Anterior and middle calcaneal facets (inferiorly)

    • Plantar calcaneonavicular ligament (spring ligament) (inferoinferiorly)

Ligament Attachments

  • Plantar calcaneonavicular (spring) ligament: Supports talar head from below and prevents medial collapse

  • Talonavicular capsule and ligaments: Enclose articulation with navicular

  • Interosseous talocalcaneal ligament: Between talus and calcaneus, stabilizing subtalar component

  • Bifurcate ligament: Stabilizes navicular and calcaneus anteriorly

Tendon and Muscle Relations

  • Medial: Tibialis posterior tendon inserts into navicular, supporting spring ligament and talar head

  • Superior: Extensor tendons cross dorsally over navicular (EHL, EDL, tibialis anterior)

  • Inferior/plantar: Flexor hallucis longus and flexor digitorum longus pass nearby in the tarsal tunnel

Nerve Supply

  • Tibial nerve branches: Medial plantar and lateral plantar nerves (via articular twigs)

  • Deep peroneal nerve: Provides articular branches anteriorly

  • Sural nerve: Minor contributions laterally

Arterial Supply

  • Posterior tibial artery: Via artery of tarsal canal and deltoid branches

  • Dorsalis pedis artery: Via artery of tarsal sinus

  • Peroneal artery branches: Contribute laterally

Venous Drainage

  • Venous return via posterior tibial, dorsalis pedis, and peroneal veins

Function

  • Mobility: Provides a ball-and-socket mechanism for hindfoot inversion/eversion

  • Load transfer: Distributes forces from talus to calcaneus and navicular

  • Stability: Spring ligament prevents talar head collapse and medial arch flattening

  • Kinematics: Critical in Chopart joint motion for walking and running

Clinical Significance

  • Injury: TN joint dislocations and ligament tears cause instability

  • Flatfoot deformity: Spring ligament failure leads to collapse of medial longitudinal arch

  • Arthritis: Post-traumatic and degenerative arthritis common in hindfoot

  • Coalitions: Talocalcaneal coalition restricts joint mobility and causes pain

  • Imaging: MRI is best for soft tissue/ligamentous injuries, CT for coalition and bone detail

MRI Appearance

  • T1-weighted images:

    • Joint surfaces: low-signal cortical bone with intermediate marrow signal (depending on fat content)

    • Ligaments (spring, interosseous): low-signal bands

    • Effusion: intermediate-to-high signal in joint recesses

  • T2-weighted images:

    • Joint cartilage: intermediate-to-high signal

    • Effusion/synovitis: bright hyperintense

    • Bone marrow edema: bright signal within talus, calcaneus, or navicular

    • Ligament tears: focal discontinuity with bright signal gap

  • STIR:

    • Suppresses normal marrow fat (dark)

    • Highlights edema, effusion, or ligament injury as hyperintense

  • Proton Density Fat-Saturated (PD FS):

    • Normal ligaments: low dark signal

    • Tears: bright linear or irregular signals disrupting ligament continuity

    • Useful for detecting spring ligament degeneration

  • T1 Fat-Sat Post-Contrast:

    • Normal: mild homogeneous synovial enhancement

    • Pathology: intense enhancement in synovitis, inflammatory arthritis, or post-traumatic change

MRI Arthrogram Appearance

  • Contrast outlines talonavicular joint and subtalar recesses

  • Cartilage defects: Contrast penetrates subchondral lesions

  • Ligament tears: Contrast pools along disrupted spring ligament or capsule

  • Helps confirm small osteochondral lesions of talar head

CT Appearance

Non-Contrast CT:

  • Excellent cortical detail of talus, calcaneus, and navicular

  • Detects coalitions, subchondral sclerosis, osteophytes, and fractures

  • Spring ligament indirectly assessed by talar head uncovering

CT Arthrogram Appearance

  • Contrast fills the TN joint recesses

  • Cartilage defects: Contrast extends into fissures of talar head or navicular

  • Ligament tears: Contrast leaks into disrupted capsule or spring ligament

  • Helpful for osteochondral lesions and coalition assessment when MRI is contraindicated

CT VRT 3D image

Talocalcaneonavicular joint 3d

MRI image

Talocalcaneonavicular joint MRI axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Talocalcaneonavicular joint MRI sagittal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Talocalcaneonavicular joint sagittal CT cross sectional anatomy radiology image-img-00000-00000

X Ray image

Talocalcaneonavicular joint