Type Ii Accessory Navicular Bone

Overview
The navicular bone is located on the top of the foot near the arch. People who have this extra bone can feel a bump or bony protuberance on the top of the foot above the arch. While the bone itself does not cause pain, accessory navicular syndrome can develop when the bone and/or nearby tendon is irritated. The navicular bone is attached to muscles, ligaments and the posterior tibial tendon. Since ligaments and tendons have poor blood supply and don?t heal easily, any irritation to the surrounding structures can develop into a painful condition.



Causes
This painful foot condition is caused by an extra bone in the foot called the accessory navicular. Only about 10% of people have this bone (4 to 21%), and not all of them will develop any symptoms. The navicular bone is one of the normal tarsal bones of the foot. It is located on the inside of the foot, at the arch.

Symptoms
Adolescence is a common time for the symptoms to first appear. This is a time when bones are maturing and cartilage is developing into bone. Sometimes, however, the symptoms do not occur until adulthood. The signs and symptoms of accessory navicular syndrome include a visible bony prominence on the midfoot (the inner side of the foot, just above the arch) Redness and swelling of the bony prominence. Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity.

Diagnosis
To diagnose accessory navicular syndrome, medical staff ask about the patient?s activities and symptoms. They will examine the foot for irritation or swelling. Medical staff evaluate the bone structure, muscle, joint motion, and the patient?s gait. X-rays can usually confirm the diagnosis. MRI or other imaging tests may be used to determine any irritation or damage to soft-tissue structures such as tendons or ligaments. Because navicular accessory bone irritation can lead to bunions, heel spurs and plantar fasciitis, it?s important to seek treatment.

Non Surgical Treatment
If the foot becomes painful following a twisting type of injury and an X-ray reveals the presence of an accessory navicular bone, your doctor may recommend a period of immobilization in a cast or splint. This will rest the foot and perhaps allow the disruption between the navicular and accessory navicular to heal. Your doctor may prescribe anti-inflammatory medication. Sometimes an arch support can relieve the stress on the fragment and decrease the symptoms. If the pain subsides and the fragment becomes asymptomatic, further treatment may not be necessary.



Surgical Treatment
If conservative measures do not seem to help, however, you may need to have surgery to make adjustments to the bump. This could include reshaping the little bone, repairing damage to the posterior tibial tendon, or even removing the accessory navicular altogether.