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Base of distal phalanx of great toe

The base of the distal phalanx of the great toe (hallux) is the proximal portion of the terminal phalanx forming the articular interface with the head of the proximal phalanx. It plays a crucial role in the stability and motion of the interphalangeal joint of the great toe and contributes significantly to weight-bearing and push-off during gait.

It is an important anatomical landmark in foot anatomy, sports medicine, trauma assessment, and forefoot imaging.

Synonyms

  • Proximal base of the distal phalanx of the hallux

  • Base of terminal phalanx of the great toe

Location

  • Situated at the proximal end of the distal phalanx of the hallux

  • Distal to the proximal phalanx

  • Forms the distal articular surface of the interphalangeal joint

  • Located medial to the distal phalanges of the lesser toes

  • Superficial and subcutaneous on the dorsal and medial aspects

Anatomical components

  • Articular surface:

    • Proximal concave surface articulating with the head of the proximal phalanx

  • Osseous structure:

    • Cortical shell with cancellous interior

  • Soft tissue attachments:

    • Joint capsule of the interphalangeal joint

    • Collateral ligaments

    • Flexor hallucis longus tendon insertion (distal phalanx, close to base)

  • Nail complex (distal relation)

Relations

Proximally:

  • Head of the proximal phalanx of the great toe

Distally:

  • Shaft and tuft of the distal phalanx

  • Nail bed and nail plate

Dorsally:

  • Extensor hallucis longus tendon insertion (via dorsal hood)

Plantarly:

  • Flexor hallucis longus tendon (in close proximity/insertion distally)

Medially:

  • Skin and subcutaneous tissues

Laterally:

  • Interphalangeal joint capsule and collateral ligaments

X-ray appearance

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

  • Base: Proximal articular surface of the distal phalanx

  • Cortical outline: Smooth and well-defined

  • Joint relationship: Clearly seen articulating with proximal phalanx

  • Best seen on: Lateral and oblique views

CT appearance

Non-contrast CT:

  • Base of distal phalanx: Well-defined proximal articular surface

  • Cortical margins: Sharp and intact

  • Trabecular pattern: Normal cancellous bone

  • Joint space: Clearly visualized

  • Spatial detail: Excellent depiction of articular contour

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Marrow of distal phalanx: High signal

  • Articular surface: Clearly delineated

  • Joint capsule: Thin low-signal outline

T2-weighted images:

  • Cortex: Low signal

  • Joint fluid: High signal within the interphalangeal joint

  • Surrounding soft tissues: Intermediate-to-high signal

STIR:

  • Fat suppression: Uniform suppression of marrow fat

  • Joint and periarticular tissues: Bright signal

  • Base margins: Well visualized against suppressed marrow

Proton density fat-saturated (PD FS):

  • Bone marrow: Fat suppressed

  • Joint fluid: High signal

  • Collateral ligaments: Low-signal linear bands

MRI image

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

CT image

Base of distal phalanx of great toe ct

CT VRT 3D image

Base of distal phalanx of great toe 3d