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 Where is the Achilles heel? 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
The syndrome may result from any of the following, previous trauma such as a foot or ankle sprain. Chronic irritation from shoes or other footwear causing friction against the bone. Strain from overuse or excessive activity.Symptoms
The symptoms of accessory navicular syndrome commonly arise during adolescence, when bones are maturing and cartilage fuses into bone. In other instances, symptoms do not appAccessory Navicularear until adulthood. The signs and symptoms include a visible bony prominence on the midfoot the inner side of the foot above the arch. Redness or swelling of the bony prominence. Indistinct pain or throbbing in the midfoot and arch during or after physical activity.Diagnosis
It is important to examine the posterior tibial tendon and measure the extent of pain to this tendon proximal to the navicular bone. You can clinically determine the amount of posterior tibial tendon involvement by assessing the degree of swelling, pain on palpation and strength. To evaluate the patient?s strength, have the patient stand and balance on one foot along with rising up on his or her toes.Non Surgical Treatment
In order to strengthen your muscles to prevent further injury and to provide support to the foot, your podiatrist may also outline a physical therapy routine and prescribe orthotics. Orthotics will provide support to the arch of your foot, although they must be carefully crafted in order to make room for that pesky extra bone you?ve got poking about.Surgical Treatment
The original procedure advocated by Kidner involved shelling out of the accessory navicular bone from within the insertional area of the posterior tibial tendon and rerouting this tendon under the navicular bone in hopes of restoring a normal pull of this tendon. When treating younger children, history has shown us that simply shelling out of the accessory navicular bone from within the tendon and remodeling the tuberosity of the navicular bone can give you satisfactory results.
In general, you want to reserve advancement of the posterior tibial tendon for adults or those who have a more significant flatfoot deformity. You may also use this approach after determining that quality custom orthotics are only resulting in a slight decrease of symptoms.