Extra Bone In Foot Accessory Navicular

Overview
Accessary bone syndrome affects overpronators because of irritation in this area. Improper fitting shoes can also irritate the area. When pain becomes such that it changes running form or becomes intolerable, something needs to be done. Surgery alone without addressing causative factors is useless. Pain returns and new cartilage returns in the tendon, and the inflammation causes pain.



Causes
An injury to the fibrous tissue connecting the two bones can cause something similar to a fracture. The injury allows movement to occur between the navicular and the accessory bone and is thought to be the cause of pain. The fibrous tissue is prone to poor healing and may continue to cause pain. Because the posterior tibial tendon attaches to the accessory navicular, it constantly pulls on the bone, creating even more motion between the fragments with each step.

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
Plain x-rays are used to determine the size of the accessory navicular. There are three main types of accessory navicular bones: a small bone embedded within the nearby posterior tibial tendon; a triangular shaped bone connected to the navicular by thick cartilage; and a large prominent navicular tuberosity thought to represent an accessory navicular that has fused to the navicular. If the status of the posterior tibial tendon needs to be assessed or if other problems are suspected, (ex. Navicular stress fracture) it may be necessary to perform an MRI. Although this is not considered routine, an MRI may be helpful in identifying the degree of irritation. An MRI would demonstrate fluid or edema that may accumulate in the bone as a result of the irritation.

Non Surgical Treatment
In order to strengthen your muscles to prevent further injury and to provide support to the foot, your podiatrist may also outline a physical therapy routine and prescribe orthotics. Orthotics will provide support to the arch of your foot, although they must be carefully crafted in order to make room for that pesky extra bone you?ve got poking about.



Surgical Treatment
If non-operative treatment fails to relieve the patient’s symptoms, surgical intervention may be warranted. The standard operative treatment of an accessory navicular is a Kidner procedure. However, if surgery is undertaken it is important that it address the underlying source of the patients pain.