Sesamoiditis is an inflammatory condition of the 1st metatursal phalangeal joint that is seen commonly in athletes. It is especially prevalent in runners, tennis players, basketball players and ballet dancers. The seamoid bones are two small bones embedded in the tendon of the flexor hallucis brevis muscle just under the base of the big toe joint. Acting as a pulley for the tendon, the sesamoids help the big toe move normally and provide leverage when the big toe “pushes off” during walking and running. Sesamoiditis can be due to injury to the sesamoid bone (stress fracture) or injury to the flexor hallucis brevis muscle (tendonitis). Patients often present with pain and swelling at the ball of the foot. The condition is diagnosed by careful palpation of the various structures surrounding the 1st metatarsal phalangeal joint. X-Rays are necessary to see if there is a fracture. Approximately 10% of patients have a bipartite sesamoid bone. Patients with a bipartite sesamoid bone meaning they have an extra sesamoid bone are more likely to develop sesamoiditis. Treatment consists of rest, immobilization with a removable walking cast, cortisone injections, antiflammatory medications, physical therapy and orthotics. Occasionally surgical excision of the sesamoid bone is necessary.