What Is The Sesamoid Bone?

Suresh Sivacolundhublog

What Is The Sesamoid Bone

Unless you’ve studied anatomy or had a sesamoid injury, it’s unlikely that you’ll have heard of the sesamoid bone before. The sesamoid bone is a short bone that develops in some tendons (where they cross the ends of long bones).
Unlike standard bones, which connect via joints, they connect to muscles via tendons. Due to their small size and critical function (in our body’s biometrics and range of motion), injuries are not all that uncommon.
If you suspect that you’ve sustained an injury to a sesamoid bone in your foot, book an appointment with The Foot Clinic today. Our team of experienced podiatrists treat all things feet and may be able to assist.

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Where Would I Find the Sesamoid Bone?

There are actually four sesamoid bones commonly found in the adult human body. These include:

  • Two patellas (in the quadriceps tendon at the knee, also known as the kneecaps).
  • Two pisiforms (in the flexor carpi ulnaris tendon, at the base of each index finger).

Sesamoid bones can also form on the tarsal, metatarsal or even the incus bone (inside the ear), but this can vary from person to person.

How Do Sesamoid Bones Form?

Beyond the four sesamoid bones commonly found in the knees and hands, additional bones are often formed in response to added strain on muscles and tendons. They begin as cartilaginous nodules, with most sesamoid bones undergoing some ossification during pre-puberty and further ossification during puberty.

Sesamoid bones tend to appear much earlier in females than they do in males.

Lack of bone formation often indicates a delay in puberty. As such, these bones may be useful in monitoring the progression of puberty in children and adolescents.

    What Do Sesamoid Bones Actually Do?

    They are meant to relieve tension within muscles and tendons by redistributing weight and force across them (therefore protecting tendons from excessive wear, strain and injury).

    Sesamoid bones also act as a spacer, changing the angle of a tendon before it reaches its attachment point.

    How Can Sesamoid Bones Be Injured?

    When talking about sesamoid bones, specifically in the feet, there are a few ways they can be injured.

    They can sometimes be fractured from a direct blow when jumping. Stress fractures, however, are more common - these result from chronic repetitive trauma during certain activities (such as dancing or long-distance running). Medial sesamoids in the big toe are fractured most often, but fractures can also occur to sesamoids in the other toes.

    Sesamoid fractures are sometimes confused with toe fractures. This can be because extending the toe and standing on tiptoes can be painful. One way to tell the difference is the location of pain or tenderness – when a sesamoid fracture is the culprit, tenderness is generally located beneath the metatarsal head (directly below the sesamoid), and swelling is minimal.

    How Are Sesamoid Fractures Diagnosed?

    X-rays are usually required to diagnose a sesamoid fracture. As the bone is so small, it may actually take a few weeks of symptoms before stress fractures are visible on an x-ray. If no fracture is present initially, you may be sent for more x-rays in 2 to 3 weeks' time to get a better picture of what’s going on.

    How Are Sesamoid Fractures Treated?

    There are actually several treatment options available for sesamoid bone fractures. Rest is very important and may require you to be non-weight bearing (either partial or complete, depending on symptoms). Other treatments may include:

    • Immobilisation of the foot, using either a well-padded walking cast or a hard-soled shoe (in some cases, a moulded orthotic may be used). This will be combined with a ‘donut’ or ‘C’ pad over the sesamoid area.
    • A cast for three to four weeks, after which time you will likely be switched to a firm shoe with a donut pad for the following four to six weeks.

    Stress fractures may take between 3 and 6 months to heal. If the pain persists beyond six months, further treatment may be required.

    Walking on Sunshine with The Foot Clinic

    Although sesamoid bones are not present in the feet of every single person, we have seen our fair share of injuries and fractures at The Foot Clinic. If you have injured your toe and find extending or bending it to be quite painful, book an appointment with one of our podiatrists today.

    If it is determined that you have sustained a sesamoid fracture, we aim to advise a treatment plan to see you back on your feet.