Type Ii Accessory Navicular Bone

Overview
The human body is rarely the same from person to person. Some things stay the same, like the function of the internal organs. Even when structures are similar, however, little variations, like extra bone tissue, can make a significant difference in the body. Having small, extra bones is not as uncommon as you might think. Sometimes, though, these additional tissues can cause painful problems, as with accessory navicular syndrome.



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
Most people born with this bone begin to experience the symptoms (if at all any) in adolescence. Some may not develop any symptoms until adulthood. The symptoms are a visible abnormal protrusion in the mid-foot, swelling and redness of the protrusion, pain in the mid-foot after performing an activity.

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
Treatment of the accessory navicular begins with rest, which may include activity modification or temporary immobilization in a boot or a brace. Once the inflammation subsides the foot needs to be supported. The support consists of a specially designed orthotic arch support. Occasionally, the orthotic will dig into the edge of the accessory navicular bone under the arch of the foot. This is very uncomfortable. For this reason the orthotic support needs to be carefully made. The orthotic support will help control (but not cure) the flat foot and will often decrease the inflammation on the navicular.



Surgical Treatment
If conservative care does not alleviate the problem then surgical intervention should be considered. 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.