Sesamoiditis in the Foot
Sesamoiditis. Most of the bones found in the body are connected to each other through joints. Some bones exist only within tendons or muscles and have no direct connection to joints. These types of bones are known as sesamoids. Examples of other sesamoid bones in the body include the kneecap and the shoulder blade. Their function is to allow a muscle to form an angle with the associated joint for an improved pulley action.
Foot Sesamoiditis: The sesamoids that can cause foot pain are found in sole of the ball of the foot under the big toe. They exist in a tightly bound together pair – one called the medial sesamoid and the other the lateral sesamoid. When a sesamoid becomes inflamed, the condition is known as sesamoiditis. It can be very painful on the inner aspect of the ball of the foot as shown in the diagram.
Sesamoids act like pulleys and provide a mechanical advantage to improve the leverage of the muscle working on the big toe joint, which in turn allows the tendons greater strength to contract muscles. When the big toe and foot are totally flat to the ground, the sesamoids are in their ‘start position’ at the ankle end of their range where there is a little depression for them to sit in. When the toe is fully bent – like the back foot when you are taking a long step with the other foot – the sesamoids are dragged forward to their ‘end position’, where again there is a place for them to sit. Most people with sesamoiditis develop the condition because their big toe doesn’t bend efficiently and drags the sesamoid bones only half way forward. In this position, they get stood on, which shouldn’t happen despite their location on the ball of the foot. The bone then can become bruised from this repeated trauma.
Sesamoid injuries are generally well treated with orthotics in your shoes to correct the big toe function. Treating sooner rather than later is a good idea as the condition can be hard to shift once it becomes established. Treatment of sesamoiditis tends to take a little longer than other conditions as the healing of these bones is slow due to their position inside the sesamoid apparatus. This is a gristle- like complex that limits blood flow to the area.
Signs and Symptoms of sesamoiditis
- Pain under the great toe in the ball of the foot
- Aggravation of pain when walking, running or weight bearing
- Lack of swelling or bruising
- Possible difficulty and pain in bending or straightening the great toe
- Often the point of pain is difficult to locate when you are pressing the area.
Who gets Sesamoiditis?
This condition is most common in ballet dancers, runners and baseball catchers. It is also common in people who have bony feet, arthritis, osteoporosis, high arched feet, very flat feet and forefoot runners. As discussed above, problems with the big toe joint, including bunions, hallux limitus and arthritis can particularly predispose a person to this condition.
Treatment of sesamoiditis
Treatment for sesamoiditis typically involves resting the area and avoiding activities that aggravate the pain. Strapping and ice and may be useful when first diagnosed to help relieve pain. Anti-inflammatory drugs typically don’t help as much as you might expect due to the limitation in blood flow to carry them to the affected area.
Often, a full length orthotic is used to help offload the sesamoids and deflect pressure away from the area. If the condition has been caused by another problem; such as pes cavus (high arched) or pes planus (low arched) feet, bunions or a reduced fat pad; orthotics are essential for treating the underlying condition.
Failing conservative treatments, injections of steroids or surgery may be required.