Does Accessory Navicular Syndrome Merit Surgery

Overview
The accessory navicular is an ossicle, or extra bone located medially to the navicular. Depending on the type, or stage, it may be connected to the navicular by a fibrous union, via a type of joint called a synchrondrosis. In those who have this extra bone, it is present at birth, but it starts as soft cartilage and then begins to ossify (turn into bone) at around age nine. Some sources believe that, in about half of those who have it, the bone will fuse to the navicular in late adolescence, but it is not clear that this actually happens.



Causes
Just having an accessory navicular bone is not necessarily a bad thing. Not all people with these accessory bones have symptoms. Symptoms arise when the accessory navicular is overly large or when an injury disrupts the fibrous tissue between the navicular and the accessory navicular. A very large accessory navicular can cause a bump on the instep that rubs on your shoe causing pain.

Symptoms
Many people have accessory (?extra?) naviculars (figure 1) - a prominent extra bone extending from the navicular bone. Most accessory naviculars are completely asymptomatic. However, some individuals will develop pain on the inside of their midfoot. Pain may occur from the pressure of the shoe fit ware against the prominence, irritating either the bone itself or the fibrous junction where the accessory bone meets the regular navicular. Alternatively, the fibrous junction or interface may become painful as a result of tension applied by the posterior tibial tendon through its connection or insertion at that site. Often, individuals will be asymptomatic for years, however, a new pair of shoes or a change in their activity level can cause symptoms. The accessory navicular itself typically develops during adolescence, when the two areas of the navicular bone fail to fuse together.

Diagnosis
Your doctor will diagnose an accessory navicular by examining your child?s foot. Your physician may also obtain x-rays to confirm the accessory navicular and to rule out other conditions.

Non Surgical Treatment
Treating accessory navicular syndrome is focused on relieving symptoms. Some treatment methods are Icing to reduce swelling. Immobilization with a cast or walking boot to reduce inflammation and promote healing. Medications to reduce pain and inflammation. Physical therapy to strengthen muscles. Orthotics to support the arch. Surgery may be needed to remove the accessory bone and reshape the area if other methods are not successful.



Surgical Treatment
The above non-surgical options should be enough to treat accessory navicular syndrome. If they fail, a surgery would be necessary to remove the extra bone that has been causing the problems. The most common procedure for this condition is known as the Kidner procedure where a small incision is made over the navicular bone. The accessory navicular is identified and dissected free from the posterior tibial tendon. The posterior tibial tendon is then reattached to the remaining navicular bone.