Sesamoiditis of the foot is an inflammation of the sesamoids, the two tiny bones located on the underside of your forefoot—one on each side of the base of the big toe. Sesamoid bones, unlike other bones in the body, are not connected to neighboring bones by a joint.

They are held in place by tendons within muscles. These bones are tiny, about the size of a pea, and they are essential to normal foot function.

They modify pressure when standing and walking, and they diminish friction in the soft tissues under the toe joint with movement of the big toe.

The tissues surrounding the sesamoid bones can become inflamed for many reasons. Sesamoiditis is considered an overuse injury because it often results from repeated toe movements, as when dancing and running. Stress fractures of the sesamoid bones can also cause sesamoiditis.

Although sesamoiditis used to be a rare cause of foot pain and disability, it has become more common in recent years, and it is sometimes reported in young athletes, who are now participating in sports at earlier ages and with higher levels of intensity.

If you think you may have sesamoiditis, it is important to have your foot evaluated by a podiatrist or orthopedist. Fortunately, nonsurgical treatment is often successful.

What Are The Common Causes of Sesamoiditis?

Sesamoiditis is characterized by chronic inflammation of the sesamoid bones and their surrounding tendons. The injury occurs most often in ballet dancers, baseball catchers, and runners.

The condition may be precipitated by a sudden and excessive upward bending force on the big toe or other type of foot trauma. The type of shoes you wear can aggravate sesamoiditis if they cause misalignment of the sesamoid bones.

High-heeled shoes, for instance, can cause the feet to become imbalanced or too flexible. This may place excessive pressure on your sesamoid bones and increase the risk of fracture.

Symptoms of Sesamoiditis to Watch For

Most people with sesamoiditis have pain under the great toe on the ball of the foot. The pain is felt most when the forefoot is flexed, such as when you are walking and your back foot pushes off so you can take your next step.

Pain caused by an overuse injury usually develops gradually and worsens over time. The pain may be intermittent and intensify when wearing certain shoes or engaging in certain activities. You may also notice swelling and bruising, especially if sesamoiditis occurs in association with an injury or stress fracture.

Some people complain of numbness or difficulty bending and straightening the great toe.

In those who put off seeking medical attention, sesamoiditis may lead to gait changes, such as limping to avoid walking on the painful area. Gait changes can in turn lead to other problems in the joints of the knee, hip, and lower back.

How is Sesamoiditis Diagnosed?

Your physician will ask you for a complete medical history and a description of your current symptoms. He or she will examine your foot for any abnormalities or signs of injury or infection, and evaluate your other foot for comparison.

The goal of the foot examination is to determine whether certain toe movements produce pain and whether any part of the foot is tender to the touch.

To accomplish this, your physician will attempt to reproduce the pain by manipulating the foot and bending the great toe upward, or by asking you to bend and straighten your toes.

Often an x-ray of the forefoot is required to make a correct diagnosis. The x-ray can be helpful in identifying the presence of a fracture. In some cases, the x-ray will reveal a sesamoid bone that looks like it is divided into two or more separate bones.

This is normal.

If you have a fracture of the sesamoid bone, the edges of these bone pieces may appear jagged rather than smooth, which is generally how they appear on x-rays. Your physician may also request an x-ray of your opposing foot.

When x-ray findings are inconclusive, further testing with a bone scan may be considered.  The intravenous agents used during a bone scan accumulate in areas where bone tissue is stressed. Other imaging tests, such as magnetic resonance imaging, may also be useful.

How is Sesamoiditis Treated?

While conservative therapies for sesamoiditis are usually effective, they can take some time to work. This is because every time you stand or walk, you put pressure on your feet.

So it is impossible to avoid all aggravating activities until the foot heals completely. Your podiatrist or orthopedist will be able to tell you more about the frequency and duration of various recommended therapies. In general, conservative therapies for sesamoiditis include:

• Discontinuation of the aggravating activity.
• Use of over-the-counter pain medications and non-steroidal, anti-inflammatory drugs, such as ibuprofen and aspirin.
• Applying ice to the sole of the foot.
• Wearing shoes with soft soles and low heels.
• Fitting shoes with a cushioning pad of dense foam rubber to relieve stress.

If you have severe pain, your doctor may recommend cortisone injections to reduce inflammation, or he may recommend the use of a removable brace on the leg for four to six weeks in order to foster healing of the bones and reduce inflammation.

Most patients with sesamoiditis will not require surgery. If the condition fails to resolve after conservative therapy, several procedures may be considered. These include:

• Bone removal to remove part or all of one sesamoid bone. Removing both sesamoid bones is typically avoided because the toe muscles will not be able to function as normal.
• Scraping of extra tissue in patients with chronic plantar keratosis (a deep callus that develops beneath the sesamoid bones).
• Bone graft for patients with nonunion stress fractures. A bone graft may help the parts of the bone heal together.

What You Should Do After Sesamoiditis Treatment

Overuse injuries can recur. To prevent a future episode of sesamoiditis, it is important to return to activity gradually and continue wearing a cushioning pad under the sesamoids to support them.

Avoid vigorous activities for several weeks to allow pain and inflammation to subside. When possible, avoid movements that put your weight on the balls of the feet.

Simple modifications to your footwear may be all that is needed to help you resume normal walking. Some patients may benefit from a four- to six-week course of physical therapy to help resume normal function. It can take several months for the condition to completely resolve.