In approximately 10% of the population, an extra bone is developed in front of the ankle at the navicular bone. This is called an accessory navicular. When it is small, it does not cause symptoms. In about half the cases, it fuses to the navicular bone with no problem by adolescence. In others, it becomes symptomatic in adulthood or after an injury disrupts the fibrous tissue that attaches the accessory to the navicular. It is sometimes equated to posterior tibial tendon dysfunction (PTTD) or tarsal coalition. Both are discussed in their own sections.
The extra bone can be uncomfortable if it is large enough to rub on shoes. In addition, the feet associated with the accessory are usually flat and the combination of these conditions is what usually causes those with it to seek treatment.
Other names or similar foot conditions:
- Flat feet
- Sometimes equated to posterior tibial tendon dysfunction (PTTD) or tarsal coalition
- Kohler’s disease
Symptoms:
- Pain, tenderness, or irritation on or around the top of the instep at the location of the navicular bone
- Pain may increase with activity or tight shoes
Signs to look for:
- Swelling and obvious difference from other foot
- Flat foot or feet
Possible Causes:
- Is usually found in the genetic flatfoot
- Can be related to repeated strains and sprains of the foot
Goals:
- Create an arch that will correct motion of foot while walking
- Reduce pressure and friction at the navicular
- Restore alignment to the ankle, top of the foot and knees
How We Help:
Arch Supports:
- BioOrthotics exercising support with metatarsal lift
- Lower and thinner arch support with longitudinal and metatarsal support for use when shoes cannot accommodate the BioOrthotics exercising support
- For children, use scaphoid pads until they reach the size for the smallest prefabricated arch support
Shoes:
- Extra depth, double or triple depth shoe with high toe box, firm heel counter, rocker sole and connecting shank with straight last
- Straight last
- Smart shoes, including heel to toe rockers, negative heel shoes and shoes with titanium springs
- Avoid flip-flops. Only wear sandals with a back and only the Orthaheel, Alegria or Aetrex brand
- Wear heels or pumps minimally at most
- Go barefoot on a minimal basis only
Other:
- If accessory navicular is large enough, shoe may need a donut hole device or to be modified to reduce rubbing
- Try different ways of lacing shoes that avoid or reduce rubbing at the prominence
Activities:
- Rotate weight bearing exercises, such as walking or jogging, with non-weight bearing exercising, such as swimming or bicycling
This information does not constitute a diagnosis of your condition and does not take the place of a doctor’s care. The information has been compiled from sources available to the general public and referenced below. Copyright 2007-2010 Carole Romig
Sources Image: Eorthopod.com, Footandankle.mdmercy.com Text: Footandankle.mdmercy.com, Dynomed.com, Allaboutmydoc.com