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Calcaneus

The calcaneus, or heel bone, is the largest tarsal bone and forms the foundation of the rearfoot. It articulates with the talus superiorly and the cuboid anteriorly, transmitting weight from the talus to the ground. The calcaneus provides attachment for the Achilles tendon, numerous ligaments, and intrinsic foot muscles, playing a key role in locomotion and balance.

Fractures of the calcaneus, often caused by axial loading (e.g., falls from height), are among the most disabling injuries of the foot due to joint involvement and risk of subtalar arthritis.

Joints

  • Subtalar joint: Superior articulation with talus (posterior, middle, and anterior facets)

  • Calcaneocuboid joint: Anterior articulation with cuboid

  • Talocalcaneonavicular joint: Supports midfoot stability (via talar head resting on calcaneus and navicular)

Ligament Attachments

  • Medial side: Deltoid ligament (via sustentaculum tali), spring ligament complex

  • Lateral side: Calcaneofibular ligament, lateral talocalcaneal ligament

  • Inferior side: Long plantar ligament, short plantar ligament (plantar calcaneocuboid)

  • Posterior side: Plantar fascia originates at medial tubercle

  • Talocalcaneal ligaments: Interosseous and cervical ligaments stabilize subtalar joint

Tendon and Muscle Attachments

  • Posterior: Achilles tendon inserts on calcaneal tuberosity

  • Inferior: Plantar fascia originates at medial calcaneal tubercle

  • Medial: Flexor hallucis longus tendon passes through groove on sustentaculum tali

  • Lateral: Peroneal tendons (fibularis longus and brevis) pass posterior to lateral malleolus along calcaneal surface

  • Muscles: Abductor hallucis, abductor digiti minimi, quadratus plantae, extensor digitorum brevis arise from calcaneus

Nerve Supply

  • Medial calcaneal branches: From tibial nerve (heel and plantar surface)

  • Lateral plantar nerve: To intrinsic muscles

  • Sural nerve: Lateral heel sensation

Arterial Supply

  • Posterior tibial artery branches: Medial and lateral calcaneal arteries

  • Peroneal (fibular) artery branches: Lateral calcaneal contributions

  • Dorsalis pedis contributions: Small branches to anterior calcaneus

Venous Drainage

  • Drains into posterior tibial and peroneal veins

  • Communicates with plantar venous plexus

Function

  • Acts as the primary weight-bearing bone of the heel

  • Provides attachment for Achilles tendon and plantar fascia

  • Contributes to lever arm for gait propulsion

  • Forms structural base for subtalar and calcaneocuboid joints

Clinical Significance

  • Fractures: Commonly due to axial trauma; intra-articular extension may involve subtalar joint

  • Osteomyelitis: Can occur in diabetics or post-trauma

  • Plantar fasciitis: Medial calcaneal tubercle is common site of pain

  • Stress fractures: Seen in athletes and military recruits

  • Heel spurs: Bony projections at calcaneal tuberosity associated with plantar fasciitis

MRI Appearance

  • T1-weighted images:

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

    • Cortical bone: uniform low signal (dark rim)

    • Fractures: linear low-signal lines

    • AVN or infection: diffuse low-signal marrow changes

  • T2-weighted images:

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

    • Cortical bone: dark low signal

    • Edema or fracture: bright hyperintense signal

    • Osteomyelitis: focal high signal in marrow with adjacent soft tissue changes

  • STIR:

    • Normal marrow suppressed (dark)

    • Fractures, marrow edema, or osteomyelitis: bright hyperintense signal

  • Proton Density Fat-Saturated (PD FS):

    • Normal: homogeneous low-intermediate signal marrow

    • Pathology: bright signal abnormalities reveal stress fractures, edema, infection

  • T1 Fat-Sat Post-Contrast:

    • Normal: homogeneous mild enhancement of marrow

    • Infection: heterogeneous enhancement with adjacent soft tissue involvement

    • AVN: lack of enhancement in necrotic zone with rim enhancement

MRI Arthrogram Appearance

  • Contrast outlines subtalar and calcaneocuboid joint surfaces

  • Osteochondral lesions: contrast tracks into defects of calcaneal facets

  • Useful for evaluation of subtalar cartilage damage in trauma

CT Appearance

Non-Contrast CT:

  • Best modality for cortical bone

  • Fractures: sharply defined cortical breaks, intra-articular extension clearly visible

  • Cortical bone: high-density sharply outlined rim

  • Stress fractures: fine sclerotic lines or cortical breaks

  • Chronic changes: sclerosis, subchondral collapse, calcaneal spur formation

CT Arthrogram Appearance

  • Contrast highlights subtalar and calcaneocuboid articular surfaces

  • Cartilage defects appear as contrast-filled clefts

  • Helps evaluate subtalar joint integrity and osteochondral lesions when MRI is contraindicated

CT VRT 3D image

Calcaneus bone 3d image ct

MRI image

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

CT image

Calcaneus ct axial

CT image

Calcaneus sagittal ct cross sectional anatomy AI enhanced radiology image-img-00000-00000