The accessory navicular is an extra bone in the foot that is located on the inner side of the foot, near the arch. It is also known as os tibiale externum or os naviculare accessorium.
The accessory navicular bone is not present in all individuals and is considered a variation in foot anatomy. It develops during childhood and is usually fused with the navicular bone by the age of 14, although in some people it may remain separate.
In some cases, the accessory navicular can cause pain and discomfort, especially when there is excessive pressure or stress on the foot. This condition is known as accessory navicular syndrome and may cause swelling, redness, and difficulty walking or standing.
Treatment for accessory navicular syndrome may include rest, ice, physical therapy, or the use of orthotic devices to support the foot.
In severe cases, surgery may be necessary to remove the extra bone or correct any associated deformities.