The first metatarso-sesamoid joint.

The first metatarso-sesamoid joint is separately identified from the first metatarso-phalangeal joint and its anatomical characteristics are described from a study of one hundred anatomical specimens of normal adult and children's feet and two hundred radiographs of patients' feet. The author finds that the metatarso-sesamoid joint is assymmetrical both in children and adults, the medial surface being larger than the lateral. The medial sesamoid lies centrally, and the lateral sesamoid lies laterally, under the head of the first metatarsal. A knowledge of the shape and function of this joint is important in understanding the pathology as well as the therapeutic indications of various conditions of forefoot imbalance, mainly of hallux valgus.