Accessory and Sesamoid Bones in the Body: A study on their Size and Presence

Abstract

Aim: Accessory and sesamoid bones are hidden anatomical structures that fulfil a wide variety of functions in the human body. Therefore, studying the nature, formation and dimensions of these structures is of great importance for the medical literature. In our study, we aimed to measure the presence and area (size) of these ossicles.
 Material and Method: Our study was performed retrospectively on the images of individuals who applied to Ordu University and whose radiological images were obtained. The presence of accessory and sesamoid ossicles (present/absent) and their sizes (measured using the PACS system) were evaluated on radiographs and CT images. The results of the ossicles were divided into gender, age, and bilateral groups. Statistical analyzes were performed with the SPSS program. 
 Results: The most common and largest accessory ossicles in the foot were os peroneum (18.2%), os naviculare accessoria (17.4%), os trigonum (12.1%) and os intermetatarsarum (7.8%). Sesamoid ossicles at the level of the first metatarsophalangeal joint of the foot and the first metacarpopgalangeal joint of the hand were found to be 100% common. The second most common sesamoid bone in the hand and foot was at the fifth mtp (22.22%) and mcp (68.53%) joints. In the hand, the most common accessory ossicles were os triangulare (6.08%), os radiale externum (2.60%) and os centrale (1.73%). Accessory ossicles (fabella: 19%, cyamella: 17.5%) were found in 25.5% of the knee.
 Conclusion: Accessory and sesamoid ossicles are most commonly found in the hand, foot, and knee. The presence and size of these ossicles can be both beneficial and harmful. Sesamoids provide mechanical benefit, whereas accessory ossicles can be mistaken for fractures and may lead to unnecessary medical conditions. Knowing the dimensions of these ossicles allows them to be clinically differentiated from avulsion fractures.