Extra Bone In Foot Accessory Navicular

Overview
An accessory navicular is defined as an extra bone in the foot, and oftentimes it causes moderate to severe discomfort. Depending on the severity, your doctor may recommend a non-surgical treatment to alleviate the pain, or surgery if treatment doesn?t decrease symptoms.



Causes
Like all painful conditions, ANS has a root cause. The cause could be the accessory navicular bone itself producing irritation from shoes or too much activity. Often, however, it is related to injury of one of the structures that attach to the navicular bone. Structures that attach to the navicular bone include abductor hallucis muscle, plantar calcaneonavicular ligament (spring ligament) parts of the deltoid ligament, posterior tibial tendon.

Symptoms
The catalyst for symptoms might be some sort of injury (such as a broken or sprained ankle), excessive activity, or irritation from where shoes are rubbing on the bony prominence the accessory navicular makes. These can irritate the bone, or make the tendon it?s embedded in (the posterior tibial tendon, remember?) inflamed and sore. Because the tendon is compromised in its ability to support the arch, accessory navicular syndrome almost always leads to flat feet, which is one very obvious symptom.

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
Initial treatment is conservative. With the first episode of symptoms, a medial heel wedge, anti-inflammatories, and physical therapy can be helpful. If very painful, a cast or boot may be needed for a short period time before the wedge and physical therapy can be initiated. Very rarely is a steroid injection warranted or recommended. As the pain improves, patients can resume activities. For a minority of patients, an arch support or custom orthotic can help to take some of the extra pressure off of the accessory navicular and the posterior tibial tendon.



Surgical Treatment
Once the navicular inflammation has lessened it is not necessary to perform surgery unless the foot becomes progressively flatter or continues to be painful. For these children, surgery can completely correct the problem by removing the accessory navicular bone and tightening up the posterior tibial tendon that attaches to the navicular bone. The strength of this tendon is integral to the success of this surgery as well as the arch of the foot. Following surgery the child is able to begin walking on the foot (in a cast) at approximately two weeks. The cast is worn for an additional four weeks. A small soft ankle support brace is then put into the shoe and worn with activities and exercise for a further two months.