Congenital Foot Deformities in Children

What You Need To Know

Understanding congenital foot conditions like accessory navicular syndrome in children.

Understanding Congenital Foot Deformities

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. It is not part of normal bone structure and is not present in most people.

People who have an accessory navicular are often unaware of the condition if it causes no problems. However, some develop a painful condition known as accessory navicular syndrome when the bone or posterior tibial tendon becomes aggravated. This can result from trauma, such as a foot or ankle sprain, chronic irritation from shoes rubbing against the extra bone, or 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. Adolescence is a common time for symptoms to first appear, as bones are maturing and cartilage is developing into bone. Sometimes, symptoms do not occur until adulthood.

Signs and symptoms include a visible bony prominence on the midfoot, redness and swelling of that prominence, and vague pain or throbbing in the midfoot and arch, usually during or after activity. If your child shows any of these signs, an evaluation with a podiatrist can confirm the diagnosis and guide the right care plan.

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 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 if pain or inflammation continues, an MRI or other advanced imaging may be used.

The goal of nonsurgical treatment is to relieve the symptoms. Immobilization in a cast or removable walking boot allows the affected area to rest and decreases inflammation. Ice, applied with a thin towel between the pack and skin, helps reduce swelling. Oral nonsteroidal anti-inflammatory drugs such as ibuprofen may be prescribed, and in some cases oral or injected steroid medications are used with immobilization to reduce pain.

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

If nonsurgical treatment fails to relieve the symptoms, surgery may be appropriate. Surgery may involve removing the accessory bone, reshaping the area, and repairing the posterior tibial tendon. This extra bone is not needed for normal foot function, so children can expect to return to activity once healing is complete.