What is the accessory navicular?
• The accessory navicular (os navicularè / os tibiale externum) is an extra bone/cartilage located on the inner
side of the foot just above the arch. Normally but not always it is incorporated within the posterior tibial
tendon, which attaches in this area.
How is it commonly injured?
Because of its exposure on the inside of the foot, this accessory can be aggravated by :
Chronic friction/irritation from footwear
Overuse the tibias posterior tendon from excessive foot hyper pronation
Classification and Signs and Symptoms of this injury
Often there is a visible bump on the inside of the arch as seen in the picture here.
Sometimes this bump can become intensely painful to push on and it enlarges due to the progression of the
injury and is swollen and red
This can ache, throb and occasionally reduce the power of the tibias posterior muscle during testing.
Diagnosis of this injury normally happens with a plain Xray
Current management techniques
Reduce all friction and pressure to these areas of the foot
Taping and padding of the arch can reduce tibialis posterior tension
Physical Therapy - this must include soft tissue massage to the tibias posterior muscle and strengthening
Orthotics - Custom foot orthoses may also provide relief
Medications - Oral non-steroidal anti-inflammatory drugs may be prescribed
Surgery - if conservative measures fail there are surgical procedures to remove the accessory bone