The Prevalence of Accessory Ossicles, Sesamoid Bones, and Biphalangism of the Foot and Ankle: A Radiographic Study

Abstract

Background: Accessory ossicles, sesamoid bones, and biphalangism of toes are the most common developmental variations of the foot. These bones may be associated with painful syndromes; however, their clinical importance is not well understood because the reported prevalence varies widely. Therefore, we aimed to investigate these variants in Turkish subjects. Methods: A total of 1651 foot radiographs were retrospectively assessed. Radiographs of feet were examined regarding the prevalence, sex, and bilaterality of accessory ossicles, sesamoid bones, and biphalangism in Turkish subjects. Results: Accessory ossicles (26.1%) and sesamoid bones (8%) were detected. The most common accessory ossicles were os trigonum (9.8%), accessory navicular bone (7.9%), and os peroneum (5.8%). Also, we detected os supratalare (0.48%), os calcanei secundarium (0.42%) os subfibulare (0.42%), os supranaviculare (0.36%), os vesalianum (0.30%), os subtibiale (0.24%), os intermetatarseum (0.12%), and os subcalcis (0.12%). We observed bipartite hallux sesamoid in 1.8% and interphalangeal sesamoid bone of the hallux in 0.7% of radiographs. Incidences of metatarsophalangeal sesamoid bones were found as 0.6%, 0.06%, 0.6%, and 5.8% in the second, third, fourth, and fifth digit, respectively. We observed biphalangeal toe in 0.5%, 1.7%, 3.5%, and 37.6% in the second, third, fourth, and fifth toe, respectively. Conclusion: This study is the first detailed report on the incidence of the most common variants of the foot and ankle in a wide-ranging patients’ series in Turkish subjects. Our study’s findings will contribute to reducing misdiagnosis. Clinical Relevance: The results of this study may provide anatomical data that could help clinicians in the diagnosis and management of disorders that present with pain and discomfort in the feet. Knowledge of these variants is important to prevent misinterpreting them as fractures.

Knowing Your Accessory Foot Ossicles and Avoiding Misdiagnoses: A Case Report of Painful Os Vesalianum Pedis

“…As described earlier os vesalianum pedis is a rare accessory ossicle and an even rarer symptomatic one [1].…”

“…Os vesalianum pedis was first illustrated in the 16th century [2] and named after its illustrator, Vesalianum, in the 20th century [3]. This accessory ossicle is located proximal to the base of the fifth metatarsal within the peroneus brevis tendon [1]. Its prevalence is usually between 0.1% and 0.5%, but some series report prevalence as high as 6% [4][5][6].…”

“…Its prevalence is usually between 0.1% and 0.5%, but some series report prevalence as high as 6% [4][5][6]. Even though some authors often describe it as bilateral [7], a radiographic study including more than 1500 radiographs, didn't find any patient with bilateral os vesalianum pedis [1]. Similar to other accessory ossicles, os vesalianum pedis is mainly asymptomatic and found incidentally on radiographs, usually after an acute injury [7].…”

“…The foot and ankle are very prone to anatomic variations, either accessory ossicles, bipartitions, or coalitions [ 1 ]. According to a recent study, the prevalence of foot accessory ossicles can be as high as 26% [ 2 ].…”

“…Similar to other accessory ossicles, os vesalianum pedis is mainly asymptomatic and found incidentally on radiographs, usually after an acute injury [ 7 ]. However, in a few patients, this accessory ossicle can be the source of lateral foot pain [ 1 ]. The differential diagnosis of this condition is the Jones fracture (a fracture through the metaphyseal-diaphyseal junction of the fifth metatarsal); pseudo-Jones fracture (fifth metatarsal proximal tubercle avulsion); and in the pediatric population, Iselin’s disease (fifth metatarsal traction apophysitis) and the mere presence of the growth plate.…”