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Talocalcaneal joint

The talocalcaneal joint, also called the subtalar joint, is formed between the talus and calcaneus. It lies inferior to the talus and superior to the calcaneus, playing a crucial role in hindfoot motion, shock absorption, and adaptation to uneven ground. It allows inversion and eversion of the foot, complementing dorsiflexion and plantarflexion at the ankle joint.

This joint is stabilized by multiple strong ligaments and surrounded by tendons that provide dynamic support. Pathology of the talocalcaneal joint is common in trauma, arthritis, and coalition syndromes.

Articulating Surfaces

  • Talus: Three facets (posterior, middle, anterior) on the inferior surface of the talus

  • Calcaneus: Three corresponding facets (posterior, middle, anterior) on the superior surface of the calcaneus

Ligament Attachments

  • Interosseous talocalcaneal ligament: Strong band within sinus tarsi; key stabilizer

  • Cervical ligament: Lateral stabilizer of sinus tarsi

  • Medial talocalcaneal ligament: Medial stabilization between talus and calcaneus

  • Lateral talocalcaneal ligament: Reinforces lateral capsule

  • Posterior talocalcaneal ligament: Supports posterior aspect of joint

  • Spring ligament complex (plantar calcaneonavicular): Functionally supports talar head at subtalar articulation

Tendon and Muscle Relations

  • Posterior: Achilles tendon, plantaris tendon

  • Medial: Tibialis posterior, flexor digitorum longus, flexor hallucis longus

  • Lateral: Peroneus longus and brevis tendons, extensor digitorum brevis muscle overlying sinus tarsi

  • Anterior: Extensor tendons crossing ankle into foot

Nerve Supply

  • Tibial nerve branches: Supply medial and posterior aspects of subtalar joint

  • Deep peroneal nerve: Anterior contributions

  • Sural nerve: Lateral sensory contribution

Arterial Supply

  • Posterior tibial artery: Via artery of tarsal canal

  • Dorsalis pedis artery: Via artery of sinus tarsi

  • Peroneal artery: Lateral contributions

  • Clinical note: Dual supply is important in surgical planning and AVN prevention

Venous Drainage

  • Venous plexuses drain into posterior tibial, dorsalis pedis, and peroneal veins

Function

  • Inversion and eversion: Primary axis of hindfoot motion

  • Shock absorption: Adapts foot to uneven terrain

  • Stability: Works with ankle and midtarsal joints for balance

  • Load transfer: Shares weight-bearing between talus and calcaneus

Clinical Significance

  • Subtalar arthritis: Secondary to trauma, inflammatory arthropathy, or coalition

  • Fractures: Calcaneal and talar fractures often disrupt subtalar joint

  • Coalition syndromes: Fibrous, cartilaginous, or bony fusions restrict motion

  • Instability: Ligamentous injury can cause chronic hindfoot instability

  • Imaging role: MRI/CT vital for evaluating fractures, arthritis, coalition, and instability

MRI Appearance

  • T1-weighted images:

    • Cortical bone: uniform low signal (dark rim)

    • Marrow: intermediate-to-high signal depending on fat content

    • Fractures: linear low-signal defects through facets

    • Arthritis: joint space narrowing, low-signal subchondral sclerosis

  • T2-weighted images:

    • Normal marrow: variable intermediate-to-high signal

    • Cortical bone: consistently low signal (dark)

    • Arthritis/edema: bright hyperintense marrow signal beneath subchondral bone

    • Joint effusion: hyperintense within joint space

  • STIR:

    • Normal marrow suppressed (dark)

    • Bone marrow edema, effusion, or coalition appear bright hyperintense

  • Proton Density Fat-Saturated (PD FS):

    • Normal facets: smooth dark cortical outline with intermediate marrow

    • Tears or inflammation: bright signal in ligaments, joint capsule, or marrow

    • Excellent for detecting interosseous ligament injury and early arthritis

  • T1 Fat-Sat Post-Contrast:

    • Normal: mild homogeneous enhancement of synovium

    • Arthritis/synovitis: thickened, enhancing synovium

    • Post-traumatic lesions: enhancing granulation tissue vs non-enhancing necrosis

MRI Arthrogram Appearance

  • Contrast outlines subtalar joint spaces

  • Coalition: absence of contrast flow across fused facets

  • Osteochondral defects: contrast pools in subchondral irregularities

CT Appearance

Non-Contrast CT:

  • Cortical bone: bright, dense high attenuation

  • Excellent for subtalar fractures and coalition

  • Arthritis: joint space narrowing, sclerosis, and osteophytes

  • Coalition: osseous bridging in middle facet common

CT Arthrogram Appearance

  • Contrast delineates posterior, middle, and anterior facets

  • Osteochondral lesions: contrast extends into defects

  • Coalition: lack of contrast across fused joint surfaces

  • Superior to plain CT for cartilage surface evaluation when MRI is contraindicated

CT VRT 3D image

Talocalcaneal joint (subtalar joint) 3d

MRI image

Talocalcaneal Joint (Subtalar Joint) MRI sagittal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Talocalcaneal joint (subtalar joint) sagittal CT cross sectional anatomy radiology image-img-00000-00000