Accessory ossicles

Last revised by Joachim Feger on 4 Sep 2023

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: accessory ossicles of the foot
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  • Figure 2: 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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