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Topic

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Base of first metatarsal bone

The base of the first metatarsal bone is the proximal expanded end of the first metatarsal, forming a key structural component of the medial column of the foot. It plays an essential role in load transmission during gait and forms important articulations within the tarsometatarsal (Lisfranc) joint complex.

It is a crucial anatomical landmark in foot biomechanics, trauma assessment, surgical planning, and cross-sectional imaging of the foot.

Synonyms

  • Proximal end of the first metatarsal

  • First metatarsal base

Location

  • Situated in the medial aspect of the forefoot

  • Proximal end of the first metatarsal bone

  • Anterior to the medial cuneiform

  • Medial to the second metatarsal base

  • Forms part of the tarsometatarsal (Lisfranc) joint

Anatomical components

  • Proximal articular surface:

    • Articulates with the medial cuneiform

  • Lateral facet (variable):

    • May articulate with the second metatarsal

  • Non-articular surfaces:

    • Serve as attachment sites for ligaments and tendons

  • Osseous structure:

    • Cortical shell with underlying cancellous bone

Relations

Anteriorly:

  • Shaft of the first metatarsal

Posteriorly:

  • Medial cuneiform bone

Medially:

  • Soft tissues of the medial foot border

Laterally:

  • Second metatarsal base

  • Intermetatarsal ligaments

Inferiorly (plantar):

  • Peroneus longus tendon groove and insertion nearby

Superiorly (dorsal):

  • Dorsal tarsometatarsal ligaments

X-ray appearance

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

  • Base: Seen as the proximal broadened end of the first metatarsal

  • Articulation: Clear joint space with the medial cuneiform

  • Cortical margins: Smooth and well-defined

  • Alignment: Forms part of the medial Lisfranc alignment

CT appearance

Non-contrast CT:

  • Base: Well-defined osseous structure with clear articular surfaces

  • Cortical margins: Sharp and intact

  • Trabecular pattern: Normal cancellous bone

  • Joint assessment: Excellent visualization of the first tarsometatarsal joint

  • Alignment: Accurate evaluation of medial column architecture

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Marrow of the base: High signal intensity

  • Articular surface: Well delineated against joint space

T2-weighted images:

  • Cortex: Low signal

  • Joint fluid: High signal outlining the base

  • Surrounding ligaments: Low-to-intermediate signal

STIR:

  • Fat suppression: Uniform marrow fat suppression

  • Base margins: Clearly visualized

  • Joint recesses: High signal from fluid

Proton density fat-saturated (PD FS):

  • Bone marrow: Suppressed fat signal

  • Joint fluid: Bright signal

  • Ligaments and tendon insertions: Well delineated as low-signal structures

MRI image

Base of first metatarsal bone mri anatomy labelled image-img-00000-00000

CT VRT 3D image

Base of first metatarsal bone