Exercises For Accessory Navicular Syndrome

Overview
Accessory navicular describes the presence of an extra bone growth center on the inside of the navicular and within the posterial tibial tendon that attaches to the navicular. The primary symptom from this additional bony prominence is pain and tenderness. This congenital defect (present at birth) is thought to occur during development when the bone is calcifying. Because this accessory portion of the bone and the navicular never quite grow together, it is believed that, over time, the excessive motion between the two bones results in pain.



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 hammer toe surgeries tibial tendon.

Symptoms
It?s common for any symptoms to present during adolescence, when bones are maturing, though problems may not occur until adulthood. You may notice a bony prominence on the inner side of the midfoot. There may or may not be redness and swelling around this bump, especially if it rubs against footwear. You may be prone to blisters or sores in the area. Pain generally involves a vague ache or throbbing in the midfoot and arch as well, especially when you?re active. Many people with this syndrome develop flat feet, too, which can create additional strain in the foot.

Diagnosis
Usually, you will only need an X-ray to determine the size or type of the accessory navicular bone or the amount of medial navicular tuberosity hypertrophy. Be cognizant of stress fractures which may be duplicated as a hairline fracture or increased calcification. When treating children, always look for avascular necrosis of the navicular (Kohler?s disease). An X-ray of this condition will reveal a flattening of the navicular along with increased bone density.

Non Surgical Treatment
Treatment of the accessory navicular begins with rest, which may include activity modification or temporary immobilization in a boot or a brace. Once the inflammation subsides the foot needs to be supported. The support consists of a specially designed orthotic arch support. Occasionally, the orthotic will dig into the edge of the accessory navicular bone under the arch of the foot. This is very uncomfortable. For this reason the orthotic support needs to be carefully made. The orthotic support will help control (but not cure) the flat foot and will often decrease the inflammation on the navicular.



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.