Large Accessory Navicular Bone

Overview
As many as 14% of people have an ?accessory? or extra bone or piece of cartilage on the inner side of the foot. An accessory navicular is an inborn condition that affects only a minority of the population. It is not part of normal bone structure and therefore is not present in most people. It may be found when the foot is x-rayed for other reasons, or when irritation develops. Patients may not be aware of it until a change in their activity, growth spurt or new footwear creates friction. Most cases of accessory navicular syndrome are treated conservatively.



Causes
It is commonly believed that the posterior tibial tendon loses its vector of pull to heighten the arch. As the posterior muscle contracts, the tendon is no longer pulling straight up on the navicular but must course around the prominence of bone and first pull medially before pulling upward. In addition, the enlarged bones may irritate and damage the insertional area of the posterior tibial tendon, making it less functional. Therefore, the presence of the accessory navicular bone does contribute to posterior tibial dysfunction.

Symptoms
Symptoms of accessory navicular syndrome often appear in adolescence, when bones are maturing. Symptoms include A visible bony prominence on the midfoot, Redness and swelling, Vague pain or throbbing in the arch, especially after physical 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
Using PRP treatments, orthotics, proper running shoes and physical therapy should do the trick. No long recovery, no long down time. My runners and athletes are usually back to their sport pain free within a month. The key is eliminating the syndrome, not the bone (or cartilage).



Surgical Treatment
Fusion of the accessory navicular to the navicular with screws is required when there is a large accessory navicular bone and removal of this bone would reduce the articular surface of the Navicular to the talus (coxa pedis). Fusion will relieve pain without disrupting the tibialis posterior tendon insertion nor narrowing talar head support. In most instances, a patient’s recovery will be as follows. 0-6 weeks: Immobilization (in case or cast boot) non-weight-bearing or touch weight-bearing. 6-10 weeks: Increasing activity in a cast boot. Physical therapy to work on strength and balance. Full recovery after 9 weeks-2 months. In some patients (where the posterior tibial tendon is still intact and functioning) the treating surgeon may allow weight-bearing as tolerated in a cast boot immediately after surgery.