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ACCESSORY NAVICULAR

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.

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)
• 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

Solutions:

Arch Supports:

• Bio-Orthotics Winstep or Sundance exercising support with metatarsal lift
• Lower and thinner arch support with longitudinal and metatarsal support, such as the Bio-Orthotics Journey or Silhouette, for use when shoes cannot accommodate the Winstep or Sundance exercising support
• For children, use scaphoid pads until they reach the size for the smallest prefabricated arch support

• Extra depth shoes with
• Straight last
• Firm heel counter
• Connecting shanks
• Extended medial counter
• Mild rocker soles
• For exercise, wear shoes with titanium springs 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

Activities:

• Regular stretching program for gastrocnemius and soleus muscles, Achilles tendon and arch structures
• Rotate weight bearing exercises, such as walking or jogging, with non-weight bearing exercising, such as swimming or bicycling