Most bones in the human body are connected to each other at joints. But there are a few bones that are not connected to any other bone. Instead, they are connected only to tendons or are embedded in muscle. These are the sesamoids. The kneecap is the largest sesamoid in the body. Two other very small sesamoids bones which are about the size of a small frozen pea are found in the underside of the forefoot near the great toe, one on the outer side of the foot and the other closer to the middle of the foot.
The sesamoid is embedded in the flexor tendon it has an articulation with the adjacent metatarsal bone. During movement the sesamoid actually glides with the tendon.
Sesamoids act like pulleys and help stabilize the flexor tendon stopping it from deviating. They provide a smooth surface over which the tendons slide, thus increasing the ability of the tendons to transmit muscle forces.
The sesamoids in the forefoot also assist with weight bearing and help elevate the bones of the great toe. Like other bones, sesamoids can fracture. Additionally, the tendons surrounding the sesamoids can become irritated or inflamed. This is called sesamoiditis and is a form of tendinitis. It is common among ballet dancers, runners and wicket keepers.
- Pain is focused under the great toe on the ball of the foot. With sesamoiditis, pain may develop gradually; with a fracture, pain will be immediate.
- Swelling and bruising may or may not be present.
- You may experience difficulty and pain in bending and straightening the great toe.
During the examination, the Podiatrist will look for point tenderness at the sesamoid bones this may involve slight manipulation the bone, you might be asked to bend and straighten the toe. Intensifying pain with bending the big toe is a diagnostic feature.
Your Podiatrist will often request X-rays of the forefoot to ensure a proper diagnosis.
In many people, the sesamoid bone nearer the center of the foot (the medial sesamoid) has two parts (bipartite). Because the edges of a bipartite medial sesamoid are generally smooth, and the edges of a fractured sesamoid are generally jagged, an X-ray is useful in making an appropriate diagnosis. Your Podiatrist may also request X-rays of the other foot to compare the bone structure. If the X-rays appear normal, the Podiatrist may request a bone scan.
Treatment is generally non-operative. However, if conservative measures fail, your Podiatrist may recommend surgery to remove the sesamoid bone.
What you can do?
- Stop the activity causing the pain.
- Take aspirin or ibuprofen to relieve the pain (always seek the advice of your GP or pharmacist prior to taking such drugs for the first time).
- Rest and ice the sole of your feet. Do not apply ice directly to the skin, but use an ice pack or wrap the ice in a tea towel.
- Wear soft-soled, low-heeled shoes. Stiff-soled shoes like clogs may also be comfortable.
- Use a felt cushioning pad to relieve stress.
- Return to activity gradually, and continue to wear a cushioning pad of dense foam rubber under the sesamoids to support them. Avoid activities that put your weight on the balls of the feet.
- Tape the big toe so that it remains bent slightly downward (plantar flexion).
- Try an off the shelf foot orthotic such as the Active-8 Enhancer orthotic, designed to off load the sesamoid apparatus.
- Your Podiatrist may recommend an injection of a cortico steroid medication to reduce swelling.
- If symptoms persist, you may need to wear a removable air cast foot brace for four to six weeks.
A Fractured Sesamoid
- You will need to wear a stiff-soled shoe or an air cast brace.
- Your Podiatrist may strap the joint to limit movement of the big toe.
- You may have to wear a J-shaped felt pad around the area of the sesamoid to relieve pressure as the fracture heals.
- Pain relievers such as aspirin or ibuprofen may be recommended.
- It may take several months for the discomfort to subside.
- Orthotic devices such as the Active-8 Enhancer orthotic often help off load the area and reduce pain levels as the fracture heels.
What treatments are available?
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