Presentation
Medial ankle pain at the area of medial malleolus bilaterally, more on the left side, increased on effort.
Patient Data
Age: 12 years
Gender: Male
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Bilateral well-corticated bony fragment inferior to the medial malleolus.
Case Discussion
Given the bilaterality and clinical presentation, Os subtibiale is favored than unfused malleolar accessory ossification or old avulsion fracture.
Os subtibiale is a normal variant where an accessory ossicle is noted inferior and anterior to the medial malleolus. It should be differentiated from unfused accessory ossification center of the medial malleolus, that appears smaller, rounded with well-defined shape and more anterior in position.