The forefeet are the main weight-bearing areas of the foot. They incur the greatest amount of impact and shear force when we walk and run, and they are the source of much of our foot pain.
The sesamoids are two pea-shaped bones on the bottom of the feet, under the first metatarsal heads (bones in the foot), behind the big toe joints.. They help support the body weight and elevate the bones of the big toe. They act like pulleys by providing a smooth surface over which the tendons move. This action enhances the tendons’ ability to convey muscle forces in walking and running.
While most bones in the human body are connected to each other at joints, the sesamoids are not connected to any other bones; instead, they are connected to the tendons. When the sesamoids become irritated or inflamed, the result is sesamoiditis, which actually is a form of tendinitis. Sesamoiditis is usually characterized by a dull, persistent pain in the affected area. The pain comes and goes, depending on your footwear and level of activity.
Related Foot Conditions
Two conditions may occur in conjunction with sesamoiditis:
- Turf Toe - an injury of the soft tissue around the big toe joint, characterized by sharp pain and swelling. It often happens when the big toe joint is extended beyond its normal range of movement during sports that require quick moves on rigid surfaces. The condition affects the entire toe joint and limits its range of motion.
- Metatarsalgia - generalized pain in the ball of the foot. It occurs in the same area of the foot as sesamoiditis but is typically the result of pressure, trauma or repetitive damage to the heads of the metatarsal bones. Sesamoiditis and metatarsalgia may be mistaken for one another or may occur simultaneously.