Accessory ossicles

Last revised by Andrew Murphy on 21 Jan 2024

Accessory ossicles are secondary ossification centers that remain separate from the adjacent bone. They are usually round or ovoid in shape, occur in typical locations and have well-defined smooth cortical margins on all sides.

In most cases, they are congenital in origin, although they may occur as a result of trauma or local degenerative disease 2.

The significance of accessory ossicles is their potential to mimic avulsion fractures.

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Cases and figures

  • Figure 1: the foot
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  • Figure 2: accessory ossicles of the foot
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  • Figure 3: accessory ossicles of the foot
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  • Case 1: fabella
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  • Case 2: os triangulare
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  • Case 3: os trigonum
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  • Case 4: os subepicondylare mediale
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  • Case 5: Os calcaneus secundarius & os intermetatarseum
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