04/02/2026
Ever spotted this small, round bone near the cuboid on foot imaging? 👀
That’s the Os Peroneum — a normal accessory ossicle embedded within the peroneus longus tendon. Visible beautifully on X-ray, CT, and MRI, this little structure plays an important role in lateral foot mechanics!
Though usually harmless, it can be involved in Painful Os Peroneum Syndrome (POPS), especially in runners and athletes. 🏃♂️⚽
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📸 Modalities:
1️⃣ X-ray – shows a small, well-corticated rounded bone near the lateral aspect of the cuboid.
2️⃣ CT – gives excellent cortical detail and helps differentiate from fractures.
3️⃣ MRI – ideal for checking tendon pathology, marrow edema, or surrounding inflammation.
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🩻✨ Radiologist’s Point of View:
The Os Peroneum lies within the peroneus longus tendon as it courses around the lateral cuboid. It’s a normal anatomic variant, but becomes clinically significant when associated with tendon tears, fractures of the ossicle, or lateral foot pain. ⚠️
📌 On X-ray: Appears as a small oval/round well-corticated ossicle near the cuboid.
📌 On CT: Defines cortical integrity and rules out multipartite ossicles vs. acute fracture.
📌 On MRI:
Look for bone marrow edema,
Peroneus longus tendinopathy,
Tendon tears,
Surrounding soft tissue inflammation — key features in Painful Os Peroneum Syndrome.
Understanding this tiny structure helps avoid misdiagnosis and ensures accurate MSK reporting! 🧠💡
Radiology always shows more than meets the eye! ✨
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