Sunday, March 4, 2018

Accessory Navicular Bone

See the "bump" on the left foot?
A patient messaged me recently regarding pain in the left foot. This patient guessed that it might be due to an accessory navicular bone there. The patient had been doing a little more running and weight training in the gym recently and the left foot started hurting. A medial heel wedge recommended by a podiatrist didn't help. Neither did anti inflammatory medication provided by the doctor.

Our feet sometimes give even the most careful athlete/ runner problems. The so called accessory navicular  or "extra foot bone" can sometimes cause a lot of pain and discomfort.

All of us have a navicular bone on the inner part of our foot, near to the center of the arch. Not everyone has an accessory navicular though. I've actually had quite a number of patients complain of pain there. These patients tend to be more active and athletic, although some are not active at all. They often tend to have a little bump in this part of the arch.

Actually I, too have an accessory navicular bone in just my left foot, which so far thankfully hasn't given me any problems. 

This extra bone is usually not noticed until adolescence as the accessory navicular bone starts to calcify. It is then that the bump in the inner aspect of the arch gets noticed. For most people, it never gives any problems. For some, after an injury which often involves a twist, a stumble or fall, the accessory navicular bone becomes painful.

The accessory navicular bone is often attached to the posterior tibial muscle tendon. This muscle is involved when you push off your foot while walking or running. The same muscle that causes the dreaded shin splints. It helps keep the foot aligned and lifts up your arch. Hence you get pain when the tibialis posterior gets irritated from too much contact in the arch area.

My patient had the accessory navicular bone in the right foot surgically removed 30 years ago. Strangely enough, the foot only started hurting after a twisted ankle. My patient wasn't keen on surgery this time as the patient felt that after removing that extra bone, weight bearing on that side seemed altered and was never the same again.

The patient felt that removing the accessory navicular bone threw "the balance" off in the entire right side thereafter. (Surgical intervention requires the accessory navicular bone to be excised and reattachment of the posterior tibial tendon to the navicular).

I asked my patient to come in to our clinic to let me assess it. It was the accessory navicular bone causing her pain.

After treating my patient, the pain subsided . My patient then sent me a picture of the left foot the next day.

Have a look when I put both pictures together. Of course I didn't managed to "get rid" of the accessory navicular bone. The bump just doesn't look as obvious. But I definitely made my patient able to run again.

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