The navicular bone: what every sufferer must know

The amazing foot

The human foot provides structural support for the body, makes ambulation possible, bears the weight of the body, and endures the stress of everyday and athletic activities like running, jumping, lifting, and much more. It’s a complex structure with 33 joints and more than 100 muscles, tendons, and ligaments. Amazingly, each foot contains 26 bones which comprise ¼ of the bones in the body.

The accessory no one wants

Some members of the population—7-19%—are gifted with an extra bone located on the inner side of the foot just above the arch. This bone, the accessory navicular, os tibial externum, is present at birth.

Since the accessory navicular bone is not part of the normal structure of the foot, it can become a problem that turns into a chronic syndrome when the bone and posterior tibial tendon are aggravated.

The dawning of distress

The redness, irritation, and soreness often appear in patients between ages 8 and 15 when the bones are maturing and the cartilage is developing. Athletics and activities become more strenuous, the feet suffer, and the top of the foot where the bone is protruding hurts. The condition can be aggravated in patients with flat feet. The pain can also manifest in adulthood.

Causes of the inflammation

Trauma/foot or ankle sprain
Irritation from shoes or other footwear rubbing against the extra bone
Activity or overuse

Get your symptoms checked by a professional

If you or your adolescent suffer from these symptoms, make an appointment at American Foot for a checkup:
- A visible bony prominence on the inside of the midfoot just above the arch
- Redness and swelling of the bony prominence
- Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity

Diagnosing the syndrome

To diagnose accessory navicular syndrome, the Doctor at American Foot will ask about symptoms and conduct a full evaluation of foot structure, joint and muscle strength, and range of motion. He or she may press the bony prominence to gauge the degree of pain. X-rays are used to confirm the diagnosis. An MRI or other advanced imaging tests may be used to further evaluate the condition.

Non-surgical treatment approaches

There is a variety of non-surgical treatments that could help relieve the symptoms of accessory navicular bone syndrome:

Rest—avoid strenuous activity
Immobilize—a cast or removable walking boot forces rest and allows the inflammation to diminish
Ice—reduces swelling. Do not put ice directly on the skin.
Medicate—over-the-counter medication such as ibuprofen (NSAIDs), may be prescribed to reduce pain and inflammation. Some cases, may require treatment with steroids.
Physical therapy—strengthens the muscles and helps decrease inflammation. Beneficial exercises learned in therapy can help prevent symptoms from recurring.
Orthotic devices—provide support for the arch and relieve pressure that may cause inflammation.

With diligent care, the foot pain can subside; however, since the bone is still in place, it can become sore and tender again. If pain returns or persists, surgery may be indicated.

The surgical route

After careful consultation, your doctor at American Foot will conduct surgery on the accessory navicular bone. Surgical recovery time varies with each patient. Generally, after surgery the patient wears a cast for about 3 weeks and graduates to a cast boot walker. Physical rehabilitation begins at approximately 4-6 weeks or when the patient is able to walk in tennis shoes. Typically, in about 3 months the patient is able to resume normal activity.