Extra Bone In Foot Accessory Navicular

Overview
The bones of the foot occasionally develop abnormally in a child and an extra bone called an accessory navicular is present towards the inside of the foot, in front of the ankle. This bone is present in approximately 10% of the general population but not large enough to cause symptoms in the majority of these individuals. The extra bone lump present in childhood can be quite uncomfortable because it rubs on shoes. In addition, the feet associated with the accessory navicular are invariably flat. If the child is active and involved in various athletic activities, this will aggravate the inflammation of the tendon that attaches to the accessory navicular. This tendon is called the posterior tibial tendon and is responsible for maintaining the strength of the arch of the foot. The flat-footedness associated with the accessory navicular usually brings the child for treatment.



Causes
This can result from any of the following. Trauma, as in a foot or ankle sprain. Chronic irritation from shoes or other footwear rubbing against the extra bone. Excessive activity or overuse. Many people with accessory navicular syndrome also have flat feet (fallen arches). Having a flat foot puts more strain on the posterior tibial tendon, which can produce inflammation or irritation of the accessory navicular.

Symptoms
One obvious problem with the accessory navicular is that it may be large and stick out from the inside of the foot. This can cause it to rub against shoes and so become quite painful. The fibrous connection between the accessory navicular and the navicualar, as well, is easy to injure, also leading to pain. This is kind of like a fracture, and such injuries cause the bone to move around too easily, leading to pain with activity. When the connection between the bones is injured in this way, the two bones do not always heal properly, so pain may continue unabated.

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
Fortunately, surgery is not the only answer when it comes to relieving symptoms of accessory navicular syndrome. The physician may recommend wearing a cast or walking boot for a period of time so the foot can recover from the inflammation. Ice may be used to relieve swelling, too, although it should be wrapped to avoid direct contact with the skin.



Surgical Treatment
The above non-surgical options should be enough to treat accessory navicular syndrome. If they fail, a surgery would be necessary to remove the extra bone that has been causing the problems. The most common procedure for this condition is known as the Kidner procedure where a small incision is made over the navicular bone. The accessory navicular is identified and dissected free from the posterior tibial tendon. The posterior tibial tendon is then reattached to the remaining navicular bone.