Do I Suffer From Accessory Navicular Syndrome

Overview
The accessory navicular is an extra piece of bone or cartilage just above the arch on the inside of the foot. It sits next to the navicular tarsal, which gives it its name, where the posterior tibial tendon attaches to the bone before continuing to the underside of the arch. The little bone is a congenital anomaly, you are born with it. If the extra tissue doesn?t cause any problems, you may never know it is there. You can, however, develop the painful condition called accessory navicular syndrome. This occurs when the extra bone or the posterior tibial tendon surrounding it becomes irritated. Trauma from a sprain, friction from footwear, and overuse can all inflame the tissues.



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
Not everyone who has an accessory navicular will develop these problems. When problems do occur, they may begin in early adolescence. The obvious indication is a painful bump on the inside of the foot, which hurts to touch, and causes problems that gradually become worse, and which are aggravated by activity, walking, etc., leading to all the problems discussed here. Pain may be worse towards the end of the day, and continue into the night. Among adults, symptomatic accessory navicular is more common in women than in men, with onset typical at 40 years of age or greater. Among symptomatic children, the mean age of onset for maels is 6 years, and for females, 4.5 years. In general, symptoms may occur between 2 and 9 years of age.

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
Initial treatment is conservative. With the first episode of symptoms, a medial heel wedge, anti-inflammatories, and physical therapy can be helpful. If very painful, a cast or boot may be needed for a short period time before the wedge and physical therapy can be initiated. Very rarely is a steroid injection warranted or recommended. As the pain improves, patients can resume activities. For a minority of patients, an arch support or custom orthotic can help to take some of the extra pressure off of the accessory navicular and the posterior tibial tendon.



Surgical Treatment
If non-operative treatment fails to relieve the patient’s symptoms, surgical intervention may be warranted. The standard operative treatment of an accessory navicular is a Kidner procedure. However, if surgery is undertaken it is important that it address the underlying source of the patients pain.