Abstract: Objective To investigate a method to distinguish avulsion fracture from sesamoid,accessory bone,and permanent osteoepiphyte. Methods Fourteen cases of suspicious avulsion fractures of articular portion of tubular bones were reviewed. Direct/indirect signs and the injury mechanism of avulsion fractures were analyzed and compared with permanent osteoepiphyte,sesamoid and accessory bones for their morphological characteristics. Results There are two cases of permanent osteoepiphytes,three cases of sesamoids,and three cases of accessory bones. These cases were characterized by smooth edges,contiguous bony cortex,without swelling of the surrounding soft tissue or obvious image changes after consecutive radiography. Conclusion It is fundamental in image analysis to distinguish avulsion fracture from physiological small osteoepiphyte,sesamoid bone,and aberrant accessory bone.

Key words: avulsion fracture, permanence osteoepiphysis, sesamoid, accessory bone, image observation