The sesamoids are two tiny round bones situated under the base of the big toe and embedded in a tendon leading to it. Their function is to allow the big toe to move up and down during walking and to absorb impact as the foot strikes the ground. Sesamoiditis is usually caused by repetitive, excessive pressure on the forefoot which leads to the surrounding tissues becoming irritated and inflamed. It is a common problem among ballet dancers and in people who have a rigid, highly arched foot. Any activity, which places constant pressure on the ball of the foot, can cause sesamoiditis. Occasionally the cause of pain could be due to fracture of the sesamoids but this is rare.
Sesamoiditis causes pain in the ball of the foot, especially on the inner (medial) side, usually with a gradual onset. The pain may be constant or just occur during weight-bearing activity and may be accompanied by swelling around the big toe joint. A fracture of one or both sesamoid bones is usually the result of an injury involving a sudden and heavy impact to the ball of the foot and pain is immediate.
It is important to off-load pressure from the ball of the foot around the sesamoids. This can usually be achieved with a specially designed pad or modified shoe. Inflammation and swelling can be treated with ibuprofen or a similar anti-inflammatory.
Treatment for a fractured sesamoid involves rest and immobilisation for 6-8 weeks.