Accessory Ossicles and Sesamoid Bones: Spectrum of Pathology and Imaging Evaluation

Dr. Kalantari; Dr. Seeger; Dr. Chow; Dr. Motamedi


Appl Radiol. 2007;36(10):28-37. 

In This Article

Abstract and Introduction

The authors describe a spectrum of accessory ossicle and sesamoid pathology and suggest appropriate imaging modalities. While they are considered to be normal anatomic variants, accessory ossicle and sesamoid bones may help to identify the source of patient symptomatology. The recognition of key imaging findings can help radiologists determine whether or not clinical symptoms are associated with these structures.

Accessory bones, or ossicles, are considered to be normal anatomic variants. Sesamoid bones are ovoid nodular bones, often small, found embedded within a tendon or joint capsule. Although accessory ossicles and sesamoid bones are generally considered clinically insignificant anatomic variations, they can become symptomatic. Traumatic conditions include acute fracture, stress fracture, and pseudarthrosis. Neoplastic and arthritic conditions are also encountered, as well as inflammatory and degenerative disorders.

This article reviews a spectrum of accessory ossicle and sesamoid pathology and provides guidelines for the preferred imaging modality for the suspected abnormality. We discuss some of the more commonly symptomatic bones, namely the os acromiale, os styloideum, metacarpal and hallux sesamoids, patella, os trigonum, os calcaneus secundarius, accessory navicular, os peroneum, and os intermetatarseum.


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