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Base of proximal phalanx of great toe

The base of the proximal phalanx of the great toe (hallux) forms the proximal articular portion of the proximal phalanx and participates in the first metatarsophalangeal (MTP) joint. It is a key bony structure involved in weight bearing, propulsion during gait, and stability of the medial forefoot.

It is an important landmark in foot anatomy, sports medicine, podiatry, and forefoot imaging.

Synonyms

  • Base of hallux proximal phalanx

  • Proximal articular base of the great toe phalanx

Location

  • Situated in the medial forefoot

  • Distal to the head of the first metatarsal

  • Proximal to the shaft of the proximal phalanx

  • Forms the phalangeal component of the first MTP joint

  • Medial to the lesser toe phalanges

Anatomical components

  • Articular surface:

    • Concave surface for articulation with the first metatarsal head

  • Cortical shell with cancellous core

  • Capsuloligamentous attachment sites:

    • Joint capsule

    • Medial and lateral collateral ligaments

  • Plantar attachments:

    • Plantar plate

    • Tendinous insertions via flexor hallucis brevis sesamoid apparatus

Relations

Proximally:

  • Head of the first metatarsal

Distally:

  • Shaft of the proximal phalanx

Plantar:

  • Plantar plate

  • Sesamoid complex (via flexor hallucis brevis)

Dorsal:

  • Extensor hallucis longus tendon

Medial and lateral:

  • Collateral ligaments of the first MTP joint

X-ray appearance

Plain radiographs (AP, oblique, and lateral foot views):

  • Base: Seen as the proximal expanded portion of the proximal phalanx

  • Articular surface: Smooth concave margin facing the metatarsal head

  • Joint alignment: Forms the phalangeal component of the first MTP joint

  • Cortical outline: Sharp and well-defined

CT appearance

Non-contrast CT:

  • Base: Well-defined bony structure with clear cortical margins

  • Articular surface: Smooth, concave contour

  • Trabecular pattern: Normal cancellous bone

  • Joint relationship: Accurately demonstrates congruency with first metatarsal head

  • Utility: Excellent for assessing fine osseous detail

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Marrow within base: High signal intensity

  • Articular surface: Well delineated against joint space

T2-weighted images:

  • Cortex: Low signal

  • Joint fluid: High signal outlining the articular surface

  • Adjacent soft tissues: Intermediate-to-high signal

STIR:

  • Fat suppression: Uniform suppression of marrow fat

  • Joint space: Bright signal

  • Capsule and tendons: Clearly visualized

Proton density fat-saturated (PD FS):

  • Bone marrow: Suppressed fat signal

  • Joint fluid: High signal

  • Collateral ligaments and plantar plate: Seen as low-signal structures against bright fluid

MRI image

Base of proximal phalanx of great toe mri anatomy labelled image-img-00000-00000

CT image

Base of proximal phalanx of great toe ct

CT VRT 3D image

Base of proximal phalanx of great toe