Bone marrow edema is seen along the syndesmotic joint of os naviculare with the native navicular.
Os naviculare is an accessory ossicle. It may form a fibrocartilagenous joint with the navicular bone, which may become inflamed.
The three types of os naviculare include small sesamoid bone in the tibialis posterior tendon (Type I, os tibiale externum), larger triangular shaped bone that forms a fibrocartilagenous pseudojoint with the navicular (Type II) and prominent navicular tuberosity (Type III). Type II and Type III accessory navicular bones are more likely to become symptomatic.
Kidner procedure published in 1929 by Dr. Frederick C. Kidner (1879-1950) consists of excision of the accessory navicular bone and re-attachment of tibialis posterior tendon on the plantar surface of the navicular.
Kidner FC: The pre-hallux (accessory scaphoid) in its relationship to flat-foot. J BoneJoint Surg 571:831, 1929