Accessory ossicles of the foot—an imaging conundrum

  • Shuyi GuoEmail author
  • Yet Yen Yan
  • Sonia Shu Yi Lee
  • Tien Jin Tan
Pictorial Essay


Various anatomical variations can be found in the foot and ankle, including sesamoid bones and accessory ossicles. These are usually incidental findings and remain asymptomatic; however, they may cause complications resulting in painful syndromes or degenerative changes secondary to overuse or trauma. They can also lead to fractures or simulate fractures. These complications are challenging to diagnose on radiographs. Advanced imaging with US, CT, MRI, or Tc-99m bone scan is useful for definitive diagnosis. This study aims to illustrate how imaging modalities can be used to diagnose complications of common sesamoids and accessory ossicles of the ankle and foot (hallux sesamoids, os trigonum, accessory navicular, os supranaviculare, os peroneum, os intermetatarseum, and os calcaneus secundarius) and demonstrate the imaging differences between fractures and their mimics.


Sesamoids Accessory ossicles Radiography Ultrasound Computed tomography Magnetic resonance imaging 


Authors’ contributions

All authors have made substantial contributions to the conception and design of the study, or acquisition of data, or analysis and interpretation of data, drafting the article or revising it critically for important intellectual content, and final approval of the version to be submitted.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© American Society of Emergency Radiology 2019

Authors and Affiliations

  1. 1.Department of RadiologyChangi General HospitalSingaporeSingapore

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