Presentation
Bicycle vs tree - painful and swollen right ankle
Patient Data
Age: 40 years
Gender: Male
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Small well corticated bony fragments lies at the anterior aspect of the medial malleolus.
Marked soft tissue swelling over the lateral malleolus with a small bony fragment and increased lucency at the tip which is suspicious for an avulsion fracture. Alignment is normal.
Case Discussion
The differential diagnosis for this bony fragment at the medial malleolus includes:
- fracture - unlikely as non-tender and well corticated
- prior trauma - if prior history of trauma
- os subtibiale - lies in association with the posterior colliculus; this ossicle lies in relation to the anterior colliculus
- unfused malleolar accessory ossification center - smaller than os subtibiale, more rounded and lie anteriorly
Given appearances and history an unfused malleolar accessory ossification or old avulsion fracture are favored.