What is a Sesamoid Bone?

Sesamoid bones are bones located within a tendon that assist with gliding and power transmission. The knee cap is the largest sesamoid in the body. Two small sesamoid bones are located at the base of the big toe joint and they are called the tibial and fibular sesamoids (they are about the size of a lima bean). The anatomy in this area is intricate as there are many ligaments and muscle attachments to these small bones. They are generally tough little bones that carry weight on every step we take.

What is Sesamoiditis?

These small bones are subject to a lot of stress. When they are inflamed it is called sesamoiditis. This is a very common condition. Sesamoiditis can be confused with sesamoid fracture. To confuse the matter, the sesamoid bones can have variable anatomic shape or comprised of two bone parts with connecting cartilage (called a bipartite sesamoid).


  • Pain and swelling underneath the big toe joint.
  • Symptoms generally worse when weightbearing.
  • Localized swelling may be present.
  • Pain with bending of the big toe joint. 


X-rays are taken initially. Sesamoiditis is often diagnosed by ruling out more serious conditions. Other conditions include arthritis, stress fractures, fractures, and less commonly avascular necrosis(dead bone) of the sesamoid bones. An MRI and/or bone scan can be helpful at ruling out these other pathologies.


The treatment for sesamoiditis focuses on reducing pressure on the sesamoids and improving biomechanics. Custom orthotics play a key role in taking stress off of the sesamoid bones and rebalancing the foot. Additionally a shoe with a stiff sole and rocker bottom is very effective when paired with an orthotic. Icing and anti-inflammatory medication can be helpful. Sometimes a mild steroid injection will be recommended.

Is Surgery Needed?

Usually surgery for sesamoiditis is not recommended. If there is a nonhealing fracture or avascular necrosis of a sesamoid, then the sesamoid may be removed.  If at all possible this procedure should be avoided because it can cause deformity of the big toe as it destabilizes the big toe joint complex. However if removing a sesamoid is necessary, the surgeons at Ankle and Foot Clinics Northwest use surgical techniques to optimize your outcome.

If you believe you may have a sesamoid condition, we recommend you schedule an evaluation.

We are your Northwest foot and ankle experts.  We have treated patients thoughout Puget sound and across Snohomish and Skagit counties. Our Arlington office sevices the northern counties including  Lake Stevens, Darrington, Mount Vernon, Marysville, Anacorties, Whidbey Island, and Bellingham.

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