Os peroneum with os tibiale externum

Case contributed by Dr Pir Abdul Ahad Aziz


Patient with a history of diabetes presents with pain in the plantar foot.

Patient Data

Age: 50 years old
Gender: Female

Reduced bone density of tarsal bones is noted with well preserved joint space.

Os peroneum and os tibiale externum are noted.

Annotated image

A green circle has been placed around the os peroneum.

Case Discussion

Geist classification:

Type 1 accessory navicular bone also known as os tibiale externum

2-3 mm sesamoid bone embedded within the distal portion of the posterior tibial tendon
no cartilaginous connection to the navicular tuberosity and may be separated from it by up to 5 mm
accounts for 30% of accessory navicular bones
usually asymptomatic

Type 2 accessory navicular bone

accounts for ~55% (range 50-60%) of all accessory navicular bones
triangular or heart-shaped
typically measures around 12 mm
connected to the navicular tuberosity by a 1-2 mm thick layer of either fibrocartilage or hyaline cartilage
eventual osseous fusion to the navicular tuberosity may take place

Type 3 accessory navicular bone

an especially prominent navicular tuberosity called a cornuate navicular
thought to represent a fused type 2 and is occasionally symptomatic as a result of painful bunion formation over the bony protuberance

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Case information

rID: 42488
Published: 24th Jan 2016
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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