Overview
Some people have more bones in their feet than others. Actually, it?s not all that uncommon to have extra bones in the feet. These extra bones area called accessory bones. The navicular bone, one of the small bones located at the instep or arch of the middle of the foot, is an example of an extra bone people are born with. It?s called the accessory navicular bone. During the maturation process, the navicular and the accessory navicular never fuse into one solid bone, but remain connected by fibrous tissue or cartilage. It is estimated that 4-14% of the population are born with an accessory navicular bone.
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
Perhaps the most common of the extra bones in the foot, the accessory navicular bone is estimated to be present in 7 to 19 percent of the population. Zadek and Gold maintained that the bone persisted as a distinct, separate bone in 2 percent of the population. Also be aware that the accessory bone normally fuses completely or incompletely to the navicular. It is this incomplete fusion which allows for micromotion, which, in turn, may cause degenerative changes that can also contribute to the pain.
Diagnosis
To diagnose this disorder doctors often ask questions relating to symptoms, evaluate the foot by pressing on different areas to evaluate discomfort, watch the patient walk, evaluate foot structure, and most likely take x-rays.
Non Surgical Treatment
Non-surgical treatments are enough to cure the symptoms caused by the accessory navicular. The treatment options include Immobilization, a cast or a walking boot is usually used to immobilize the foot so that the inflammation and pain are alleviated quickly due to the rest that the foot gets. Apply ice bags or wrap the ice in a towel and apply it on the aching region to alleviate inflammation. Orthotic devices that can be fit into the shoes are prescribe to keep the symptoms from resurfacing. Exercises are helpful for strengthening the muscles, which would not only help alleviate inflammation but also keep the symptoms from appearing again. NSAIDs and steroids may be prescribed as per the need of the patient to ease the pain and inflammation.
Surgical Treatment
The Kidner procedure involves resecting the prominent accessory navicular and ensuring that the posterior tibial tendon is still attached to the bone. Often the prominent bone can simply be shelled out from its position relative to the posterior tibial tendon, which leaves the tendon intact. However, if the tendon is loose and floppy once the extra bone has been removed, suturing or tother is required as a means of attaching it into the remaining navicular bone.