What Is Accessory Navicular Syndrome

Overview
Some people, possibly beginning in early adolescents, but perhaps later, can develop a painful bump on the side of their foot. The pain may be worse after athletic activity or just normal walking, and walking itself may become painful. This pain may become constant, but it will tend to improve with continued rest. Depending on the size of the bump, it may rub against shoes, or cause pain if the bump is hit by something. Over time, the arch of the foot may be lost and a flat food will develop.



Causes
An injury to the fibrous tissue connecting the two bones can cause something similar to a fracture. The injury allows movement to occur between the navicular and the accessory bone and is thought to be the cause of pain. The fibrous tissue is prone to poor healing and may continue to cause pain. Because the posterior tibial tendon attaches to the accessory navicular, it constantly pulls on the bone, creating even more motion between the fragments with each step.

Symptoms
Adolescence is a common time for the symptoms to first appear. This is a time when bones are maturing and cartilage is developing into bone. Sometimes, 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. Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity.

Diagnosis
An initial assessment is an orthopaedic office begins with a thorough history and complete physical exam, including an assessment of the posterior tibial tendon and areas of tenderness. Associated misalignments of the ankle and foot should be noted. Finally, weight-bearing x-rays of the foot will help in making the diagnosis. Sometimes, an MRI may be needed to see if the posterior tibial tendon is involved with the symptoms or getting more clarity on the anatomy of the accessory navicular.

Non Surgical Treatment
The goal of non-surgical 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. 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. Oral nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be prescribed. In some cases, oral or injected steroid medications may be used in combination with immobilization to reduce pain and inflammation. Physical therapy may be running sock recommendations prescribed, including exercises and treatments to strengthen the muscles and decrease inflammation. The exercises may also help prevent recurrence of the symptoms. Custom orthotic devices that fit into the shoe provide support for the arch, and may play a role in preventing future symptoms. Even after successful treatment, the symptoms of accessory navicular syndrome sometimes reappear. When this happens, non-surgical approaches are usually repeated.



Surgical Treatment
The original procedure advocated by Kidner involved shelling out of the accessory navicular bone from within the insertional area of the posterior tibial tendon and rerouting this tendon under the navicular bone in hopes of restoring a normal pull of this tendon. When treating younger children, history has shown us that simply shelling out of the accessory navicular bone from within the tendon and remodeling the tuberosity of the navicular bone can give you satisfactory results.
In general, you want to reserve advancement of the posterior tibial tendon for adults or those who have a more significant flatfoot deformity. You may also use this approach after determining that quality custom orthotics are only resulting in a slight decrease of symptoms.