What is the Accessory Navicular bone?
|The Accessory Navicular bone is sometimes called an os naviculare or os tibiale externum and is a extra bone situated adjacent to the navicular bone.|
What is Accessory Navicular Syndrome?
Accessory Navicular syndrome is a painful problem caused by an accessory navicular bone.
This condition usually presents during teenage years. This is a time when bones are maturing and cartilage is developing into bone. Sometimes, however, the symptoms do not occur until adulthood. The signs and symptoms of accessory navicular syndrome include:
- A visible bony prominence on the midfoot (the inner side of the foot, just above the arch)
- Redness and swelling of the bony prominence
- Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity
Ultrasound examination at The Foot and Ankle Centre can assist in diagnosing this problem.
Causes of Accessory Navicular Syndrome
Some people will have always had this extra bone present in their foot but certain factors may cause to bone to become symptomatic including:
- Trauma – acute trauma to the bone can cause irritation
- Footwear – Chronic irritation from shoes or other footwear rubbing against the extra bone
- Flat feet- The accessory navicular bone is often situated in the tendon of tibialis posterior. Having a flat foot puts more strain on the posterior tibial tendon, which can produce inflammation or irritation of the accessory navicular bone
|Accessory Navicular bone often lies in the tendon of tibialis posterior||In a flat foot the tendon of tibialis posterior works a lot harder|
Treatment of Accessory Navicular Syndrome
Treatment of accessory navicular bone depends on the cause of the irritation. If the cause of irritation is from footwear then footwear adjustment may be necessarily in these cases.
Most cases of accessory navicular syndrome are seen in those with flat feet. The flat foot posture increases the activity of tibialis posterior which causes irritation of the extra ossicle. Treatment in these cases needs to reduce the activity of tibialis posterior.
- Orthotics with a medial rearfoot post –There are a number of different orthotic designs available for flat feet. Most orthotic designs are simply arch supports.
These are not ideal for the flat foot, often only irritating the arch of the foot.
For this particular problem a rear foot orthotic is ideal
- Lace up ankle brace
When symptoms do not resolve with conservative management surgical excision of the extra ossicle may be necessary.