Will Accessory Navicular Syndrome Always Require Surgery

Overview
When there is injury to the muscle, fibrous tissue, or soft tissue of the navicular and the accessory navicular bones, symptoms will arise. This injury allows excessive movement between the bones. Fibrous tissue, ligaments and tendons have poor blood supply and are prone to poor healing. Often, this extra navicular bone lies near or attaches to the posterior tibial tendon. (See figure.) When the posterior tibial muscle contracts with movements such as foot inversion or plantar flexion, the posterior tendon moves and the accessory navicular bone moves. This can cause severe pain in those with Accessory Navicular Syndrome. It can become disabling to patients because the posterior tibial tendon attached to the navicular bone is responsible for supporting the medial arch during standing, walking and running. Activities which most of us do daily!



Causes
This painful foot condition is caused by an extra bone in the foot called the accessory navicular. Only about 10% of people have this bone (4 to 21%), and not all of them will develop any symptoms. The navicular bone is one of the normal tarsal bones of the foot. It is located on the inside of the foot, at the arch.

Symptoms
A visible bony lump on the inner part of the foot, towards the middle, just above the arch of the foot. Redness, swelling, and sensitivity of the bony prominence. Pain or throbbing in the middle of the foot and the arch. Difficulty with foot movement and activity. Possible skin callous or skin irritation caused by footwear rubbing over the lump. 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.

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
For less severe symptoms, decreasing or modifying activity, such as avoiding aggravating activities, may suffice. Ice and NSAIDS can be used to help control pain. An arch support or an orthotics may help to stabilize the arch during this time. When rubbing on the bump causes pain, a doughnut pad can be worn. Exercises to increase range of motion and improve movement should still be used.



Surgical Treatment
If non-surgical treatment fails to relieve the symptoms of accessory navicular syndrome, 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.