Accessory Navicular Bone

What Is the Accessory Navicular?

The accessory navicular (os navicularum) is an extra bone or piece of cartilage located on the inner side of the foot just above the arch. It is incorporated within the posterior tibial tendon, which attaches in this area and can lead to Accessory Navicular Syndrome. 

An accessory navicular is congenital (present at birth). It is not part of normal bone structure and therefore is not present in most people.  

What Is Accessory Navicular Syndrome?

People who have an accessory navicular often are unaware of the condition if it causes no problems. However, some people with this extra bone develop a painful condition known as accessory navicular syndrome when the bone and/or posterior tibial tendon are aggravated. 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.

Signs & Symptoms of Accessory Navicular Syndrome

Adolescence is a common time for the symptoms to first appearSometimes, 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
• Pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity

Diagnosis of  Accessory Navicular Syndrome

X-rays are usually ordered to confirm the diagnosis. If there is ongoing pain or inflammation, an MRI or other advanced imaging tests may be used to further evaluate the condition.

MANAGEMENT

Nonsurgical Treatment

The goal of nonsurgical 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 Fomentation: 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.
• Medications. Oral nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be prescribed
• Physical therapy. 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.
• Orthotic devices. Custom orthotic devices that fit into the shoe provide support for the arch and may play a role in preventing future symptoms.

Surgery

If nonsurgical treatment fails to relieve the symptoms of accessory navicular syndrome, surgery may be appropriate.

Surgery

1. Kidner Procedure : Removal of extra bony piece and reattach the tibialis posterior tendon to the native bone and the put it into cast or walker boot.
2. Fusion of accessory navicular bone: Instead of removal of extra bone,  bone piece margin will be prepared and then bony piece fixed with native bone with screw fixation for the purpose of fusion.
3. Medial Displacement calcaneum Osteotomy: This is the recent advance in addition to the treatment of accessory navicular fusion. This osteotomy decrease the tension of repair.thus,it will help to augment the whole procedure success.