Definition: Sesamoiditis is the term used to describe inflammation of the tendons surrounding the sesamoid bones in the ball of the foot, under the big toe.
Nearly every bone in the human body is connected to another bone by way of a joint, but in the hand, knee, and foot there are some bones that are instead embedded in tendons or muscles. In the foot there are two, occasionally just one, very small sesamoid bones in the flexor brevis muscle and its associated tendons. The flexor brevis muscle is used to bend (flex) the big toe. The bones are found close together, but unconnected. The sesamoid bones act as pulleys: because of their presence, the tendon is unable to completely flatten and therefore slides over the bones, providing a more consistent pull on the toe. Their position means that the sesamoid bones in the foot bear considerable weight when a person is standing, walking, running, squatting or jumping. They are thus subject to stress and vulnerable to damage, particularly among groups of people such as runners and dancers.
Causes: Injury: Sudden trauma or repetitive stress can cause injury to the tendons around the sesamoid bones, or a fracture of the bones themselves. Injury triggers a painful inflammatory response. The onset of sesamoiditis is usually gradual and often caused by an increase in the level or intensity of activity.
Structural factors: The risk of developing the condition is increased if you have high arches, which cause more weight to be born by the balls of the feet. Your sesamoid bones may be larger than normal, in which case they bear extra weight during each step. If the fatty pad on the ball of your foot is thin, there is less protection for the bones. If the first metatarsal (the long bone in the foot that connects to the first big toe bone) is naturally positioned pointing slightly downwards, the sesamoids will be lower and therefore subject to more weight and pressure during walking. Overpronation, a condition where the foot rolls inwards excessively, also results in extra pressure on the sesamoids.
Lifestyle: If your activities and lifestyle regularly include running, dancing, squatting for extended periods, wearing high heels for extended periods, or other situations in which your big toe is flexed upwards and weight is being placed on the ball of the foot, you are at risk of developing sesamoiditis.
Age: Osteoporosis may weaken the sesamoid bones, leaving them more vulnerable to fracture, and osteoarthritis can trigger the growth of bone spurs, which can irritate and inflame the surrounding tendons.
Symptoms: Injury to tendons can cause quite severe pain. With a trauma, the pain will be immediate and localized under the big toe on the ball of the foot. Repetitive stress injury will cause gradually developing pain that starts as a mild ache and tenderness to pressure. The pain will be worse when walking barefoot or wearing thin-soled shoes, but will be better with rest and elevation. As the condition worsens, pain will become more constant and is often experienced as intense throbbing. The big toe joint may be stiff, and there may be some swelling or bruising. Moving the toe upwards will make the pain worse.
Diagnosis: Your doctor will ask you questions relating to your symptoms, any trauma to the foot, and more general questions about your lifestyle, particularly any sports or activities that you engage in.
You will have a physical examination of the foot, during which the doctor may manipulate the big toe to locate the area of pain and which movements make the pain worse. He or she will also assess the degree of flexibility of the toe.
X-rays of the foot will be taken. Occasionally an X-ray of the unaffected foot will also be taken, for comparative purposes. X-rays clearly show bones, and therefore are a useful tool in the diagnosis of sesamoiditis. Sometimes an X-ray is inconclusive, in which case a bone scan may be performed.
Treatment: Conservative (non-surgical) treatment is usually successful, but in cases where such measures have failed to provide relief, surgery can be performed to pare or remove the sesamoid bones. Surgery can lead to other, related problems, so is only performed if absolutely necessary.
For sesamoiditis without a bone fracture, the following measures should help:
Avoid any activity that worsens the pain.
Rest the foot by limiting weight-bearing activities and perhaps using a crutch when walking.
Take over-the-counter pain medication such as acetaminophen (Tylenol), ibuprofen (Advil), or aspirin, as directed.
Ice the foot by crushing ice in a bag, wrapping the bag in a towel, and applying to the ball of the foot. Keep the ice in position for as long as is comfortable, and repeat several times a day when the pain is acute.
The big toe can be taped into a slightly downward position, to relieve stress on the sesamoid tendons.
Wear shoes that are long enough and that have cushioned soles and low heels. Try inserting a cushioning pad (dancer’s pad) inside the shoe, placed under the sesamoid bones. In some cases wearing a shoe with stiff soles may be more comfortable.
Your doctor may administer a corticosteroid injection to relieve pain and inflammation. This often provides immediate relief from symptoms.
Your doctor may recommend that you wear a brace on the lower leg for 4-6 weeks.
Custom orthotics will redistribute weight away from the sesamoid bones and can be worn with cushioning pads.
If the sesamoid bone has been fractured it is more likely that you will need to wear a brace for a few weeks. The big toe may be taped in order to restrict movement of the joint while the bone heals. Orthotic inserts and cushioned pads can reduce the weight borne by the sesamoids.
Prognosis: With time and careful treatment your symptoms of sesamoiditis should disappear. To avoid recurrence of the condition, wear orthotics in your shoes, minimize time spent wearing high heels, and be careful not to overdo activities that trigger pain.
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