Sometimes, feet do weird things. For instance, about 10% of the general population?s feet have decided that having an extra bone in the mix is a really great idea. This extra bone (or sometimes a bit of cartilage), is called an accessory navicular. It shows up in a tendon called the posterior tibial tendon (which is a fancy name - but just remember, it helps support the arch of the foot) on the middle of the inside of the foot, just above the arch. This extra little bone is present from birth, so it?s not something that?ll suddenly grow later in life. Now, accessory navicular syndrome is when that extra bone starts causing issues with your shoe-wearing, or even the shape and function of your foot. It?s the syndrome you want to worry about, not necessarily the extra bone itself.
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.
A visible bony lump on the inner part of the foot, towards the middle, just above the arch of the foot. Redness, swelling, and sensitivity of the bony prominence. Pain or throbbing in the middle of the foot and the arch. Difficulty with foot movement and activity. Possible skin callous or skin irritation caused by footwear rubbing over the lump. Not everyone who has an accessory navicular will develop these problems. When problems do occur, they may begin in early adolescence. The obvious indication is a painful bump on the inside of the foot, which hurts to touch, and causes problems that gradually become worse, and which are aggravated by activity, walking, etc., leading to all the problems discussed here. Pain may be worse towards the end of the day, and continue into the night.
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 - http://tiffanyholmquist.wordpress.com/2015/03/19/adult-aquired-flat-foot... and plantar fasciitis, it?s important to seek treatment.
Non Surgical Treatment
Initial treatment is conservative. With the first episode of symptoms, a medial heel wedge, anti-inflammatories, and physical therapy can be helpful. If very painful, a cast or boot may be needed for a short period time before the wedge and physical therapy can be initiated. Very rarely is a steroid injection warranted or recommended. As the pain improves, patients can resume activities. For a minority of patients, an arch support or custom orthotic can help to take some of the extra pressure off of the accessory navicular and the posterior tibial tendon.
If non-surgical treatment fails to relieve the symptoms of accessory navicular syndrome, surgery may be appropriate. Surgery may involve removing the accessory bone, reshaping the area, and repairing the posterior tibial tendon to improve its function. This extra bone is not needed for normal foot function.