Presentation
Ankle twist and pain.
Patient Data
Age: 30 years
Gender: Male
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No fractures detected.
A well-corticated bony fragment is seen anterior to the medial malleolus.
Incidental accessory navicular type 2.
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Zoomed images on the ankle showing the bone fragment related to medial malleolus.
Case Discussion
The observed ossicle related to the medial malleolus is likely representing an unfused secondary ossification center of the medial malleolus. It appears as a rounded ossicle related to the anterior tip of the medial malleolus 1.
Related pathology is called osteochondrosis of the medial malleolus or traction apophysitis of the accessory ossification center of the medial malleolus 2.
Differential diagnosis includes:
- os subtibiale: usually rounded, larger than 4 mm, and projects posteriorly
- medial malleolus avulsion fracture: usually occurs as a chip fracture, with a rough cortical outline facing medial malleolus and not corticated
- post-traumatic ossification of the deltoid ligament complex 3
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