Prevalence and distribution of sesamoid bones and accessory ossicles of the foot as determined by digital tomosynthesis

Abstract

We previously reported that digital tomosynthesis (DTS) is a reliable tool for evaluating bony structures of the hand. The current study aimed to identify the prevalence and distribution of sesamoid bones and accessory ossicles of the foot using DTS and to compare the results to those of conventional radiography (CR). Foot images (DTS, 213; CR, 44) of 213 patients taken at a tertiary hospital were retrospectively reviewed. Sesamoid bones were identified in the metatarsaophalangeal (MTP), distal interphalangeal (DIP) and interphalangeal (IP) joints of the great (I), second (II), third (III), fourth (IV), and fifth (V) toes. Accessory ossicles were observed in the midfoot and hindfoot. The mean number of sesamoid bones and accessory ossicles was 3.9 ± 1.3 for the left foot and 3.7 ± 1.0 for the right foot on CR; and 3.9 ± 1.4 for the left foot and 3.9 ± 1.3 for the right foot on DTS. Sesamoid bones were observed in MTP I (100%), MTP II (5%), MTP III (2%), MTP IV (2%), MTP V (14%), and IP (68%) on CR. Sesamoid bones were observed in MTP I (100%), MTP II (8%), MTP III (1%), MTP IV (2%), MTP V (25%), and IP I(65%) on DTS. Among accessory ossicles, the most common bone identified was os tibiale externum (23% on CR and 33% on DTS) andos peroneum (14% on CR and 21% on DTS), and os trigonum (32% on CR and 0.5% on DTS). DTS was useful for finding sesamoid bones and accessory ossicles, although there were some limitations in observing the hindfoot.