Pain in the ball of the foot, especially at the base of the big toe may be due to sesamoiditis. The term sesamoiditis is a general description for any irritation of the sesamoid bones. Sesamoid bones are very small, about the size of a kernel of corn and very unique. Most bones in the human body connect to each other at joints, but the sesamoid bones found underneath the base of the big toe do not connect to any other bone. Instead, they connect only to tendons. This allows the bones to act like a pulley and provide a smooth surface on which tendons can slide. The kneecap (or patella) is another example of a sesamoid bone. The two sesamoids found underneath the big toe are arranged side by side and known as the Tibial and Fibular Sesamoid.
Just like any other bone, sesamoids can break. A break in a bone is called a fracture and can lead to immediate pain. But again, sesamoids are not like typical bones. The tendons surrounding the sesamoids may become irritated or inflamed causing a pain that will slowly rise as the inflammation increases. This is a form of tendinitis and is common in young people who engage in physical activity like running or dancing.
During examination, a podiatrist will look for tenderness at the sesamoid bones. They may manipulate the bone slightly or ask the patient to bend and straighten the big toe. X-rays are commonly used to determine if the bones are fractured. Treatment of sesamoiditis is generally nonoperative and involves controlling the pain, icing the sole of the affected foot, and reducing activity. Additional measures may be used such as changing the type of shoe worn, using a cushioning pad, or an injection of steroid medication to reduce swelling.