The sesamoid bones of the hand and their pathology.

Three cases of sesamoid bone pathology are presented, including two cases of sesamoid fracture and a case of sesamoid periostitis. The literature is reviewed. Sesamoid bones probably function in the body as pulleys. Most people have five sesamoid bones in each hand. Two at the thumb metacarpophalangeal joint, one at the interphalangeal joint of the thumb, one at the metacarpophalangeal joint of the index finger on the radial side, and one at the metacarpophalangeal joint of the little finger on the ulnar side. Sesamoid bones have been seen with periostitis in Reiter's syndrome. The medial sesamoid bone of the thumb metacarpophalangeal is frequently enlarged in acromegaly. The sesamoid bones of the thumb have been fractured or trapped inside the joint during injury to the thumb metacarpophalangeal joint. The treatment of disabling pain in a sesamoid bone is enucleation of the bone.