Extra Bone In Foot Accessory Navicular

Overview
The accessory navicular also termed the os navicularum or os tibiale externum - is an extra bone or piece of cartilage on the inner side of the foot above the arch that attaches to the posterior tibial tendon within this area. This extra bone, present at birth, is not part of the normal bone structure and found in approximately 10% of the population. Some people with an accessory navicular may be unaware of the condition if symptoms are never experienced. But accessory navicular syndrome is a painful condition caused by aggravating the bone, the posterior tibial tendon or both.\Accessory navicular syndrome is an irritation of the accessory navicular and/or posterior tibial tendon. This irritation can be caused by shoe rubbing, trauma, excessive activity, or overuse and can cause problems with the shape and function of your foot. Many people with this disorder also have flat feet which puts more strain on the posterior tibial tendon. Some people are born with an accessory Navicular because during development, the bones of the feet sometimes develop abnormally causing the extra bone to form on the inside of the foot.



Causes
Accessory navicular syndrome as it is called can result from a number of causes, excess or overuse syndrome as seen in an athlete. Trauma to the foot as in an ankle sprain or direct trauma to the navicular bone. chronic irritation from shoes rubbing against the extra bone, over time, may cause pain. Excessive pronation which strains the attachment of tibialis posterior muscles into the navicular bone. Keep in mind, the larger the actual accessory bone, the greater the chance of it becoming an issue.

Symptoms
The majority of people with an accessory navicular experience no symptoms, since, for the most part, the little extra bone simply isn?t large enough to cause problems. Unfortunately, some people lose on ?accessory navicular roulette,? and the bone begins to mess things up with the foot. These problems usually show up sometime in adolescence, when bones and cartilage in the body are settling into their final shapes (although occasionally people make it all the way through childhood, only to start experiencing discomfort and pain in adulthood).

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
Most cases of accessory navicular syndrome may be treated conservatively with some sort of immobilization. This should allow the fibrous tissue between the two bones to heal. If a patient is extremely flat footed (pronated) then I lean more towards an orthotic than a boot as my main goal is to keep the patient's foot from flattening out too much and thus reduce the strain on the two bones. Supplementation with ice, oral anti-inflammatory medication. If the patient is athletic sometimes we can keep them active with an orthotic, but other times they have to give up their sport for a period of time to allow the condition to heal.



Surgical Treatment
If conservative measures do not seem to help, however, you may need to have surgery to make adjustments to the bump. This could include reshaping the little bone, repairing damage to the posterior tibial tendon, or even removing the accessory navicular altogether.