Multipartite hallux sesamoid

Dr Henry Knipe et al.

Multipartite hallux sesamoids are a commonly seen normal variant, present in up to 33% of hallux sesamoids. They are more commonly bipartite than tripartite. 

The medial (tibial) sesamoid is more likely to be multipartite than the lateral (fibular) sesamoid because it more commonly has more than one ossification centre. Bipartite hallux sesamoids are bilateral in ~70% (range 50-85%) of cases. 

Differential diagnosis

The principal differential diagnosis is a hallux sesamoid fracture. It can be difficult to differentiate because bipartite hallux sesamoids are more likely to fracture than complete hallux sesamoids. Features that support a bipartite over a fractured sesamoid include:

  • transverse lucency
  • smooth, well-corticated margins
  • sum of the two parts is greater than the adjacent (and hopefully normal) sesamoid
Lower limb anatomy
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Article information

rID: 24082
Section: Anatomy
Synonyms or Alternate Spellings:
  • Bipartite hallux sesamoid
  • Tripartite hallux sesamoid
  • Multipartite hallux sesamoid bones
  • First metatarsal multipartite sesamoid
  • Bipartite hallux sesamoids
  • Tripartite hallux sesamoids

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Cases and figures

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    Bipartite seasmoid
    Case 1: left medial bipartite hallux seasmoid
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    Case 2
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