Congenital Foot Deformities in Children

What You Need To Know

Understanding accessory navicular syndrome and how it affects your child’s foot.

Accessory Navicular Syndrome in Children

The accessory navicular (os navicularum or os tibiale externum) is an extra bone or 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 what is called accessory navicular syndrome. An accessory navicular is congenital, meaning it is present at birth, and it is not part of normal bone structure.

People who have an accessory navicular are often unaware of the condition if it causes no problems. However, some develop a painful condition when the bone or posterior tibial tendon are aggravated. Many people with accessory navicular syndrome also have flat feet (fallen arches). A flat foot puts more strain on the posterior tibial tendon, which can produce inflammation or irritation of the accessory navicular.

Adolescence is a common time for symptoms to first appear, when bones are maturing and cartilage is developing into bone. Sometimes symptoms do not occur until adulthood. Signs include a visible bony prominence on the midfoot, redness and swelling, and vague pain or throbbing in the midfoot and arch, usually during or after activity.

Symptoms can result from trauma such as a foot or ankle sprain, chronic irritation from footwear rubbing against the extra bone, or excessive activity or overuse. If your child is showing foot pain or a noticeable bump along the arch, schedule an evaluation so we can examine the foot and determine the right course of care.

Diagnosis and Treatment Options

To diagnose accessory navicular syndrome, your doctor will ask about symptoms and examine the foot, looking for skin irritation or swelling. The doctor may press on the bony prominence to assess the area for discomfort. Foot structure, muscle strength, joint motion, and the way the patient walks may also be evaluated. X-rays are usually ordered to confirm the diagnosis, and an MRI or other advanced imaging may be used if pain or inflammation continues.

The goal of nonsurgical treatment is to relieve symptoms. Immobilization in a cast or removable walking boot allows the affected area to rest and decreases inflammation. Ice, applied as a bag covered with a thin towel (never directly on the skin), helps reduce swelling. Oral nonsteroidal anti-inflammatory drugs such as ibuprofen may be prescribed, and in some cases oral or injected steroids may be used with immobilization.

Physical therapy may be prescribed, including exercises to strengthen the muscles and decrease inflammation, which may also help prevent recurrence. Over-the-counter or custom orthotic devices that fit into the shoe provide arch support and may help prevent future symptoms.

If nonsurgical treatment fails to relieve symptoms, surgery may be appropriate. Surgery may involve removing the accessory bone, reshaping the area, and repairing the posterior tibial tendon to improve its function. This extra bone is not needed for normal foot function, and we will guide your child through each step of care and recovery.