A sesamoid is a bone embedded in a tendon. In the foot, the sesamoids are two pea-shaped bones located in the ball of the foot, beneath the big toe joint. A fracture in a sesamoid bone can be either acute or chronic. An acute fracture is caused by trauma and produces immediate pain and swelling at the site of the break. A chronic fracture is a stress fracture usually caused by repetitive stress or overuse. Sesamoiditis is an overuse injury involving chronic inflammation of the sesamoid bones and the tendons involved with those bones caused by increased pressure. Often, sesamoiditis is associated with a dull, longstanding pain beneath the big toe joint. The pain comes and goes, usually occurring with certain shoes or certain activities..