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Ankle joint

The ankle joint (talocrural joint) is a synovial hinge joint formed by the distal tibia and fibula articulating with the talus. It is the main joint of the ankle region, permitting dorsiflexion and plantarflexion, while subtalar and midfoot joints allow inversion and eversion. The ankle joint is stabilized by strong medial and lateral collateral ligaments, and surrounded by multiple tendons essential for movement.

Articulations

  • Superiorly: Tibial plafond (distal tibia)

  • Laterally: Lateral malleolus of fibula

  • Inferiorly: Trochlear surface of the talus

Ligament Attachments

  • Medial (Deltoid ligament complex): Tibiotalar (anterior & posterior), tibionavicular, tibiocalcaneal

  • Lateral ligament complex: Anterior talofibular (ATFL), posterior talofibular (PTFL), calcaneofibular ligament (CFL)

  • Syndesmotic ligaments: Anterior and posterior tibiofibular ligaments stabilize distal tibiofibular articulation

Tendon and Muscle Relations

  • Anteriorly (extensor group): Tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius

  • Posteriorly (flexor group): Tibialis posterior, flexor digitorum longus, flexor hallucis longus, Achilles tendon (gastrocnemius + soleus)

  • Laterally (peroneal group): Fibularis longus and brevis tendons

  • Medially: Tibialis posterior tendon passes behind medial malleolus (Tom, Dick, Harry mnemonic with vessels/nerves)

Nerve Supply

  • Deep peroneal nerve: Supplies anterior compartment & ankle capsule

  • Tibial nerve: Posterior compartment & ankle capsule

  • Sural nerve: Lateral cutaneous contribution

  • Saphenous nerve: Medial cutaneous contribution

Arterial Supply

  • Anterior tibial artery → dorsalis pedis

  • Posterior tibial artery branches

  • Peroneal artery branches

  • Anastomotic network forms malleolar arterial circle around ankle

Venous Drainage

  • Superficial veins: Great and small saphenous veins

  • Deep veins: Accompany anterior tibial, posterior tibial, and peroneal arteries

  • Drain into popliteal vein

Function

  • Primary movement: Dorsiflexion and plantarflexion

  • Stability: Maintains tibiofibular–talar congruency via ligamentous and bony support

  • Load transmission: Transfers body weight from tibia/fibula to talus and foot

  • Dynamic support: Provided by surrounding muscles and tendons

Clinical Significance

  • Fractures/dislocations: Common in high-energy trauma, e.g., Weber & Lauge-Hansen classification patterns

  • Sprains: Most frequent musculoskeletal injury, especially ATFL tears

  • Arthritis: Post-traumatic osteoarthritis is common

  • Osteochondral lesions: Often at talar dome

  • Imaging role: MRI detects soft-tissue/ligament tears, CT provides fracture detail

MRI Appearance

  • T1-weighted images:

    • Cortical bone: uniform low signal (dark)

    • Marrow of tibia, fibula, and talus: intermediate-to-high signal depending on fat content

    • Ligaments: low-signal bands; sprains show thickening, partial discontinuity

    • Fractures: low-signal linear defects across bone

  • T2-weighted images:

    • Cortical bone: low signal (dark rim)

    • Marrow: intermediate-to-high depending on fat vs edema

    • Edema and effusion: bright hyperintense

    • Cartilage defects: focal bright signal changes with thinning

  • STIR:

    • Normal bone marrow: dark

    • Fractures, edema, soft-tissue injury: bright hyperintense

  • Proton Density Fat-Saturated (PD FS):

    • Normal: uniform low signal in cartilage/ligaments

    • Tears: bright linear/irregular hyperintense lines in ligaments

    • Excellent for subtle ATFL/CFL tears and cartilage damage

  • T1 Fat-Sat Post-Contrast:

    • Normal bone: mild enhancement

    • Synovitis, inflammatory arthritis: enhancing synovium

    • Osteochondral lesions: rim enhancement around necrotic area

MRI Arthrogram Appearance

  • Contrast outlines ankle joint capsule and cartilage

  • Ligamentous tears: contrast leaks into surrounding tissues

  • Osteochondral lesions: contrast pools in talar dome defects

  • Enhances detection of small cartilage fissures

CT Appearance

Non-Contrast CT:

  • Cortical bone: high-density bright outline

  • Fractures: sharply delineated

  • Subchondral sclerosis, osteophytes seen in degenerative cases

  • Excellent for assessing fracture alignment

Post-Contrast CT (standard):

  • Rarely used for joint evaluation directly

  • May demonstrate associated soft tissue inflammation

CT Arthrogram Appearance

  • Contrast fills ankle joint space

  • Cartilage defects: contrast penetration into subchondral bone

  • Ligament tears: contrast extravasation at disrupted fibers

  • Particularly useful when MRI contraindicated

CT VRT 3D image

Ankle joint 3d vrt image

MRI image

Ankle joint MRI coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

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

CT image

Ankle joint ct axial

CT image

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