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Medial malleolus

The medial malleolus is the distal projection of the tibia on the medial side of the ankle. It plays a key role in stabilizing the ankle joint, serving as an attachment site for the deltoid ligament complex and forming the medial buttress of the ankle mortise.

It is clinically significant as a common site of fracture in ankle injuries and is vital in maintaining ankle stability. Because of its close relation to important tendons and vascular structures, trauma here may cause both bony and soft-tissue complications.

Joints

  • Contributes to the talocrural (ankle) joint, articulating with the medial surface of the talus

Ligament Attachments

  • Deltoid ligament (medial collateral ligament): attaches strongly to the medial malleolus and consists of:

    • Anterior tibiotalar ligament

    • Tibionavicular ligament

    • Tibiocalcaneal ligament

    • Posterior tibiotalar ligament

Tendon and Muscle Relations

  • Posterior to medial malleolus (in tarsal tunnel):

    • Tibialis posterior tendon

    • Flexor digitorum longus tendon

    • Flexor hallucis longus tendon (passes slightly posterior-lateral)

  • Medial to malleolus: Covered by retinacula and subcutaneous tissue

  • Anteriorly: Related to saphenous vein and nerve

Nerve Supply

  • Tibial nerve: passes posterior to medial malleolus in the tarsal tunnel, innervates ankle and foot joints

  • Saphenous nerve: provides cutaneous supply anterior to malleolus

Arterial Supply

  • Posterior tibial artery: main vascular supply posterior to malleolus

  • Anterior tibial artery branches: contribute anteriorly near joint capsule

  • Medial malleolar branches: small direct branches from anterior and posterior tibial arteries

Venous Drainage

  • Great saphenous vein: runs anterior to medial malleolus

  • Posterior tibial vein tributaries: pass posterior to malleolus

  • Dorsal venous arch connections drain into great saphenous vein

Function

  • Provides medial stability to the ankle mortise

  • Serves as attachment point for deltoid ligament

  • Guides tendons in the tarsal tunnel for smooth ankle and foot motion

Clinical Significance

  • Fractures: Common in rotational ankle trauma, often part of bimalleolar or trimalleolar fractures

  • Ligament injuries: Deltoid ligament rupture may accompany fractures or dislocations

  • Tarsal tunnel syndrome: Compression of tibial nerve posterior to malleolus

  • Surgical importance: Internal fixation in ankle fractures requires protection of neurovascular and tendon structures

MRI Appearance

  • T1-weighted images:

    • Cortical bone: low signal (dark rim)

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

    • Fracture: linear low-signal line with surrounding intermediate signal change

  • T2-weighted images:

    • Cortical bone: uniformly dark (low signal)

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

    • Bone edema or fracture: bright hyperintense signal

    • Deltoid ligament: normally low signal, tears show thickening or bright signal

  • STIR:

    • Normal marrow suppressed (dark)

    • Fracture lines, edema, and bone bruise appear bright hyperintense

  • Proton Density Fat-Saturated (PD FS):

    • Normal marrow: uniform dark with cortical low signal

    • Pathology: bright signal abnormalities at fracture or ligament attachment sites

MRI Arthrogram Appearance

  • Contrast outlines the ankle joint capsule near the medial malleolus

  • Ligament tears: contrast leaks into disrupted fibers

  • Osteochondral defects of talus adjacent to medial malleolus become more conspicuous

CT Appearance

Non-Contrast CT:

  • Provides excellent cortical detail of medial malleolus

  • Fractures: sharply defined cortical disruptions visible

  • Cortical bone: very high density with sharp margins

  • Marrow changes less well assessed compared to MRI

CT VRT 3D image

Medial malleolus 3d

MRI image

Medial malleolus MRI axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Medial malleolus MRI coronal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image

Medial malleolus MRI sagittal cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

CT image

Medial malleolus ct axial