Most people have 26 bones in their foot however some people have more bones in their feet. These extra bones are referred to as accessory bones. The navicular bone, one of the bones located at the instep of the middle of the foot, is an example of an extra bone people are born with. The navicular bone is very important as the tibilias posterior tendon which has a very important role while walking inserts into the navicular.
When you have this bone next to the navicular it’s called the accessory navicular bone. During the growth process, the navicular and the accessory navicular never fuse into one solid bone, but remain connected by fibrous tissue or cartilage.
When does the accessory navicular bone become problematic?
Most of the time this condition does not cause any pain to people and they live their whole lives without any knowledge of this extra bone in their foot. In some cases the accessory navicular bone can be palpated easily inside the arch of the foot and a bony prominence may be present. The pain can occur from this bony prominence causing friction on the inside of the shoes. In some cases redness and swelling may occur in this area and the patient is unable to wear shoes.
Orthotics to off load pressure from the accessory navicular can be very effective. Other treatments include injection therapy to reduce inflammation. Prolotherapy is an injection technique that works to strengthen these ligament, tendon, and muscle attachments by causing a mild anti-inflammatory response in the tissues. Prolotherapy supports the body’s normal healing response to injury.