Question: what is type 1 os naviculare?
Answer: type 1 accessory navicular bone (os tibiale externum, os naviculare secundarium) 2-3 mm sesamoid bone embedded within the distal portion of the posterior tibial tendon. no cartilaginous connection to the naviculam tuberosity and may be separated from it by up to 5 mm. accounts for 30% of accessory navicular bones.