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X-Ray: What are those circles near the big toe?

Dr. Samuel Kellner often gets this question when reviewing X-rays with his patients. These circle shaped masses near the big

X-Ray: What are those circles near the big toe?


When reviewing X-rays with patients, I often get asked: what are those two circle shaped masses near my big toe? This question gets asked anxiously as if something may be wrong with their foot. However, it would be more concerning if these bones were not present as everyone is born with them.

These are called sesamoid and they perform a specific function: to act as a pulley system. This gives a mechanical advantage to stabilizing the big toe on the ground, and aids with propulsion of the foot when walking or running. 

Embedded within a flexor tendon that attaches under the big toe, the sesamoid bones have cartilage on their deep surface and serve as part of the big toe joint. It is quite a complex joint. 

Most people are much more familiar with the patella, or knee cap, which serves the quadricep tendon in the same way, to extend our knee joint more efficiently. It’s just that the sesamoid bones are not as noticeable.



All things that have a function can have dysfunction as well. “Sesamoiditis” is a common inflammatory condition of either or both of these bones. There is typically an underlying cause to why these might become inflamed. 

Overuse, impact injury, certain foot types, and poor movement patterns are most typical. Furthermore, repetitive stress injury to either of these bones can lead to arthritis or fracture of a sesamoid. 

If you are having pain in the ball of the foot near the big toe, sesamoiditis could be the culprit. A thorough history, examination and x-rays are necessary to provide the appropriate diagnosis and treatment plan. 

Call 508-757-4003 or text 508-625-7775 for an appointment in Worcester and Westborough. Same day visits might be available.


Dr. Sam Kellner Dr. Samuel Kellner is a foot and ankle surgeon at Central Massachusetts Podiatry, in Worcester and Westborough. Dr. Kellner is dedicated to helping his patients heal from foot injuries that stop them from daily activities. He also plays basketball and likes to spend his free time with his wife, infant son, and two cats.

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