Accessory Navicular


Accesory Navicular

  • This anatomic variant consists of an accessory ossicle located at the medial edge of the navicular
  • Accessory ossicles are derived from unfused ossification centers.
  • 90% bilateral
  • It is most commonly symptomatic in the 2nd decade of life and causes medial foot pain
  • Symptomatic in <1% of patients.


  • Type I occurs primarily as a round sesamoid within the substances of the distal posterior tibial tendon.

It is rarely associated with symptoms.

Small, 2–3-mm sesamoid bone in the PTT; referred to AS “os tibiale externum”


  • Type II is associated with a synchondrosis within the body of the navicular at risk for disruption either from traction injury or shear forces in the region.

Larger ossicle than type I

Secondary ossification center of the navicular bone

Most common variety (50%)


  • Type III, also known as a navicular beak or a cornuate navicular occurs with fusion of the accessory navicular bone to the body of the navicular.


Clinical Features:

–         Pain may begin after wearing ill-fitting shoes, with weight bearing activities or athletics, or after trauma to the foot.

–         Tenderness over the medial aspect of the foot and over the accessory navicular bone.

–         Secondary Achilles tendon contracture can occur

–         Flatfoot is common and with severe flatfoot, lateral pain may occur secondary to impingement of the calcaneus against the fibula.


–         AP, lateral, internal oblique and external oblique

–         The accessory ossicle may be best visualized on the internal oblique view(reverse oblique view)




•   Conservative measures: Shoe-wear modification, including use of a softer, wider shoe,  NSAIDS

•   Medial arch support for flatfoot.

•   A below knee cast may be worn for 3 -6 weeks for persistent symptoms

•   Surgery maybe employed for persistent pain not responding to conservative measures

•    Kidner’s procedure: Consists of excising the accessory navicular and rerouting the tibialis posterior tendon into a more plantar position.

•    Kidner’s operation will not correct sag at the metatarsocuneiform joint.

•   Severe flatfoot deformity with lateral impingement symptoms may require concomitant osteotomy of the calcaneus and/or medial column of the foot to improve alignment and decrease mechanical stress of the PTT insertion.


  1. Sella EJ, Lawson JP, Ogden JA. The accessory navicular synchondrosis. Clin Orthop Relat Res 1986;209:280–285

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