Accessory Ossicles in the Region of the Foot and Ankle: An Epidemiologic Survey in a Jordanian Population

Abstract

Background and Objectives: The incidence of accessory bones in the region of foot and ankle is quite variable between studies and are often confused with avulsion fractures in trauma patients with musculoskeletal injuries. The aim of this study was to assess the incidence of accessory ossicles of the foot and ankle according to gender, side and coexistence, and to determine how frequently accessory ossicles were misdiagnosed as avulsion fractures. Materials and Methods: Oblique and/or lateral foot radiographs of 1000 adult patients referred from emergency departments to foot and ankle clinic were retrospectively reviewed for the presence of accessory ossicles. The Kappa statistic was used in order to assess the validity of radiographic interpretation for the presence of these bones. Results: Accessory ossicles were detected in 40.2% of the radiographs. The incidence rates for the accessory ossicles in order of frequency were: Os trigonum (15.4%), accessory navicular (13.7%), os peroneum (11.5%), os vesalianum (1.1%), os supranaviculare (0.7%), os subfibulare (0.6%), os talotibiale (0.4%), os calcaneus secundarius (0.3%), os supratalare (0.3%), os infranaviculare (0.3%), os intermetatarseum (0.2%), and os subtibiale (0.1%). Coexistence of two or three ossicles in the same foot was observed in 4.4% of the cases, mostly coexistence with os peroneum (2.9%), followed by accessory navicular (1.6%). 2.7% of accessory ossicles were initially misdiagnosed as avulsion fractures at emergency departments. Interrater agreement over identification of different accessory ossicles was found to be reasonably reliable, with a Kappa greater than 0.80 for all assessed bones. Conclusions: In clinical practice, a thorough knowledge of normal anatomical variants is essential to facilitate appropriate diagnosis and treatment and can help to prevent diagnostic errors.

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

“…Although we reported a high rate of accessory ossicles in our study, we identified at least one accessory ossicle in 52.18% (60/115). In studies in the literature, this rate was reported as 18.3%, 26.1% and 40.2% with different rates (14)(15)(16)(17).…”

“…This variation should be noted as it may have radiographic appearances similar to a fracture of the posterior talar process (20). Its frequency varies between 1-25% in the literature (7,(14)(15)(16)(17)21). Candan B. et al evaluated the diameters of os trigonum on radiological images and showed its mean length as 10.21 mm and mean width as 6.53 mm.…”

Os Intermetatarseum: A Rare Variation of Great Relevance

“…It is a relatively uncommon anatomical variation, with a reported prevalence of around 0.1 % to 12.5 % in the general population (van Aswegen et al, 2020;Kalbouneh et al, 2021). While often asymptomatic, the os intermetatarseum can be associated with pain and other symptoms that can significantly affect quality of life (de Oliveira et al, 2018).…”

Imaging of Bone Anatomical Variants Around the Foot and Ankle

“…The most common accessory bones of the foot and ankle are the os trigonum, the accessory navicular (type 2 is the most common of the three types), and the os intermetatarseum. 3,10 Sesamoids differ anatomically. Sesamoid bones reduce friction and protect tendons; their clinical importance becomes clear during acute trauma or in the differential diagnosis with fractures.…”

“…The most common accessory bones of the foot and ankle are the os trigonum, the accessory navicular (type 2 is the most common of the three types), and the os intermetatarseum. 3 10…”