Accessory navicular: A heritable accessory bone of the human foot

✍ Scribed by A. M. Offenbecker; D. T. Case

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 146 KB
• Volume: 22
• Category: Article
• ISSN: 1047-482X
• DOI: 10.1002/oa.1193

✦ Synopsis

Abstract

The accessory navicular is a supernumerary bone of the human foot located medial to the navicular tuberosity and represents a secondary center of ossification that has failed to fuse to the main body of the navicular. Three forms of the accessory bone have been identified: Type I is an independent ossicle that is often embedded within the tibialis posterior tendon; Type II is a triangular accessory bone that attaches to the navicular tuberosity by means of a cartilaginous or fibrocartilaginous bridge; and Type III represents a fused Type II, which forms a hook‐like protuberance extending from the tuberosity. The Type II accessory navicular is the most common of the three forms and is the most readily identifiable in skeletal material since it causes the navicular tuberosity to become abnormally flattened and porous. The purpose of this study was to describe the various manifestations of the accessory navicular in dry bone, to present and compare frequency data for several skeletal populations, and to consider questions of laterality and sex bias in trait expression. In total, the skeletons of 497 Danes, 460 Euro‐Americans, 300 African Americans, 100 Japanese, and 205 Europeans were examined for the presence of the Type II accessory navicular. Overall frequencies for the five groups ranged from 2% in the African American sample to 5% in the Japanese sample. Since several family pedigrees have documented the accessory navicular as being an inherited skeletal defect, the relatively low frequency found in the present study makes this trait a potentially useful indicator of genetic relatedness within archaeological cemeteries. In addition, the trait was found to occur more often unilaterally than bilaterally and there was nearly equal incidence among males and females. Copyright © 2010 John Wiley & Sons, Ltd.