Sesamoiditis is an inflammation of the sesamoid bones in the forefoot (two pea-shaped bones located in the ball of the foot). Most bones in the human body are connected to other bones through joints. Sesamoid bones are not connected to any other bones or joints, but instead are either connected to tendons or embedded in muscle. These two sesamoids are located side by side under the base of the big toe. They act as a pulley by providing a smooth surface for the tendons (tough fibrous bands connecting muscles to bones) to slide over. This, in turn, increases the ability of the tendons to transmit muscle force and also helps to flex the big toe. The sesamoids also assist with balance and weight-bearing function. Sesamoiditis refers to multiple conditions affecting the sesamoids tendons complex.
Sesamoiditis can be determined by its gradual onset, unlike other foot problems with symptoms that come on quickly. The most common symptoms of sesamoiditis include:
- Pain – Mainly underneath the big toe on the ball of the foot. Your pain most likely will develop gradually over time, and is related to weight bearing on the area.
- Swelling and bruising – These symptoms may or may not be present.
- Bending difficulty – It can be difficult and painful trying to bend and extend your big toe.
Every time you push off your foot to take another step, the sesamoid bones are involved. As the sesamoids become more irritated over time, damage to cartilage can occur, leading to arthritis. Rarely, fractures can occur.
Sesamoiditis is classified as a form of tendonitis, due to the placement of the sesamoid bones inside the tendons. These risk factors can cause sesamoiditis:
- Increase in activity – This is the main cause of sesamoiditis. A sudden increase in your exercise routine or sports training can aggravate the sesamoid bones.
- Activities that cause repetitive impact on the balls of your feet – Sesamoiditis is very common in ballet dancers, baseball catchers and track runners.
- Bony feet – If you have bony feet, you may not have enough fat to help protect the sesamoids from impact. People with high arches in their feet tend to put most of their pressure on the balls of their feet.
Your doctor will gather your entire medical history and follow up with a thorough physical exam. During the exam your doctor will ask you where you feel the most pain and which activities you are doing when the pain is at its worst. X-rays also will be used to locate and identify the problem. If the expected result is sesamoiditis but it fails to appear on an X-ray, your doctor will most likely order a bone scan or MRI to be sure.
Treatments for sesamoiditis normally do not consist of any operative procedures. The treatments generally range from decreasing activity to wearing orthotics or braces.
The multidisciplinary team of foot experts at Northwell Health Orthopaedic Institute treats sesamoiditis as well as a broad range of foot and ankle conditions that can occur at any stage of life.