Extra Bone In Foot Accessory Navicular

Overview
The accessory navicular is an ossicle, or extra bone located medially to the navicular. Depending on the type, or stage, it may be connected to the navicular by a fibrous union, via a type of joint called a synchrondrosis. In those who have this extra bone, it is present at birth, but it starts as soft cartilage and then begins to ossify (turn into bone) at around age nine. Some sources believe that, in about half of those who have it, the bone will fuse to the navicular in late adolescence, but it is not clear that this actually happens.



Causes
It is commonly believed that the posterior tibial tendon loses its vector of pull to heighten the arch. As the posterior muscle contracts, the tendon is no longer pulling straight up on the navicular but must course around the prominence of bone and first pull medially before pulling upward. In addition, the enlarged bones may irritate and damage the insertional area of the posterior tibial tendon, making it less functional. Therefore, the presence of the accessory navicular bone does contribute to posterior tibial dysfunction.

Symptoms
Symptoms of this syndrome would include redness, swelling and tenderness over the navicular bone. The navicular bone is located on the inside of the foot approximately midway between the ankle bone and big toe joint. It will tend to be worse after activity and can be aggravated by those that wear very dressy shoes as opposed to casual shoes like sneakers. In other words, the flatter or less supportive the shoe, the greater the chance for pain.

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
The goal of non-surgical treatment for accessory navicular syndrome is to relieve the symptoms. The following may be used. Immobilization. Placing the foot in a cast or removable walking boot allows the affected area to rest and decreases the inflammation. Ice. To reduce swelling, a bag of ice covered with a thin towel is applied to the affected area. Do not put ice directly on the skin. Oral nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be prescribed. In some cases, oral or injected steroid medications may be used in combination with immobilization to reduce pain and inflammation. Physical therapy may be prescribed, including exercises and treatments to strengthen the muscles and decrease inflammation. The exercises may also help prevent recurrence of the symptoms. Custom orthotic devices that fit into the shoe provide support for the arch, and may play a role in preventing future symptoms. Even after successful treatment, the symptoms of accessory navicular syndrome sometimes reappear. When this happens, non-surgical approaches are usually repeated.



Surgical Treatment
If all nonsurgical measures fail and the fragment continues to be painful, surgery may be recommended. The most common procedure used to treat the symptomatic accessory navicular is the Kidner procedure. A small incision is made in the instep of the foot over the accessory navicular. The accessory navicular is then detached from the posterior tibial tendon and removed from the foot. The posterior tibial tendon is reattached to the remaining normal navicular. Following the procedure, the skin incision is closed with stitches, and a bulky bandage and splint are applied to the foot and ankle. You may need to use crutches for several days after surgery. Your stitches will be removed in 10 to 14 days (unless they are the absorbable type, which will not need to be taken out). You should be safe to be released to full activity in about six weeks.