An accessory navicular bone is a common finding on many foot x-rays. Most accessory naviculars are asymptomatic. However, in some patients the prominent bone on the inside of foot will create discomfort, which leads to difficulty with shoe fitting. Alternatively, the fibrous union between the navicular bone and the ?extra? accessory part may become irritated and cause discomfort. Diagnosis is completed through physical examination and plain x-rays of the foot. Treatment is usually non-operative, often including a change in shoe wear and activity modification. However, patients that have ongoing symptoms once non-surgical treatments are tried, often consider surgery to remove the prominent accessory navicular and, if necessary, reattach the posterior tibial tendon.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.SymptomsWhat do you do when your Achilles tendon hurts
? are the signs/symptoms of Accessory Navicular Syndrome? Pain in the foot following trauma (such as after an ankle sprain) Chronic irritation from shoes or other footwear rubbing against the bone. A visible bony prominence on the inner side of the foot just above the arch. Redness and swelling of that area. Vague pain or throbbing in the arch mostly occuring during or after periods of physical activity. Symptoms appear most often during adolescence, but some may not occur until adulthood.Diagnosis
Plain x-rays are used to determine the size of the accessory navicular. There are three main types of accessory navicular bones: a small bone embedded within the nearby posterior tibial tendon; a triangular shaped bone connected to the navicular by thick cartilage; and a large prominent navicular tuberosity thought to represent an accessory navicular that has fused to the navicular. If the status of the posterior tibial tendon needs to be assessed or if other problems are suspected, (ex. Navicular stress fracture) it may be necessary to perform an MRI. Although this is not considered routine, an MRI may be helpful in identifying the degree of irritation. An MRI would demonstrate fluid or edema that may accumulate in the bone as a result of the irritation.Non Surgical Treatment
Rest is the most important factor in relieving your pain. You may need to immobilize your foot to allow the affected tissues to rest enough that they can heal. Icing the area will help decrease any inflammation and swelling. Our staff may recommend anti-inflammatory medications as well. Most likely you will need to change your footwear-and possibly add orthotics-to accommodate your bony prominence and relieve strain in the midfoot. Sometimes physical therapy may be able to help strengthen tissues and prevent additional injuries.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.