Sesamoid Bones: What are they?

X-ray of foot with bunion highlighting the sesamoid bones

If you ever get a trivia question asking how many bones are in a foot, the answer they are looking for is 26 bones (though some only have two versus three in their 5th toe, so 25). But is that necessarily true?  Well for sake of the basic trivia question that answer would suffice, however, when a foot and ankle surgeon evaluates your foot, there are two very important bones that are often not mentioned in normal foot anatomy. These two bones bring the total number of bones in your foot to 28 bones. These two bones are called the tibial and fibular sesamoid bones and are not just an anomaly, but normal anatomical structures found in everyone’s foot. These two pea shaped bones are found underneath the “big toe” joint and act like a pulley for the tendons to help move the big toe up and down. These two bones can be equated to the patella in your knee that helps your knee bend.  They also act to help absorb weight placed in the ball of the foot during activities. Since sesamoids are bones, they can be subject to injuries just like any other bone. Common pathology of these small bones includes, fracture, inflammation/sesamoiditis, turf toe, and angular deformities of the big toe. These two bones can be very problematic in another way as they are supplied with very small blood vessels leading to often painful process called avascular necrosis (AVN) where the bone does not adequate blood flow and can start to “die” in a sense. Common injuries to the sesamoids include, direct trauma to the bottom of the foot, hyperextension or hyperflexion of the big toe, jumping off something and landing on the ball of your foot and even wearing high heeled shoes can cause problems. The symptoms that a patient may experience would be that of sharp or achy pain, swelling, pain with direct touch of the bone, pain with walking or activity, and pain with moving the big toe. As foot and ankle surgeons we seek to treat these injuries with a multi-modal protocol depending on if the injury is acute or chronic. With acute injuries we look to initially off-load the foot the best as possible with either a stiff-soled shoe and an appropriate insert, or a walking boot. Next, when the swelling the pain have started to calm, we can often transition someone into a stability walking shoe and a custom orthotic to help mechanically off-loading the bones to aid in continued healing and prevent reinjury. These injuries can often take much more time to heal secondary to the level of impact they face with daily walking and standing and can become chronic problems.  With chronic pain and swelling resulting from a previous injury, fracture or maybe AVN we begin to look at more invasive treatment types such as steroid injections or removal of the sesamoid bone completely. One new innovative treatment of both acute and chronic sesamoid injuries is the use of the new MLS Class IV Laser at Foot and Ankle Center of Iowa. We feel that this modality can be a great adjunct to the mentioned non-surgical treatments for many acute or chronic injuries including sesamoid injuries, restoring blood flow to the area and reducing pain and inflammation. You can schedule your consultation by calling us at 515-639-3775 or schedule online here: https://www.footanklecenteriowa.com/