Cacomelia is a birth defect that occurs in one or more
limbs (arm or leg). Cacomelia is due to a disturbance
during the development of the embryo. An embryo is a
fertilized egg from the time of conception until the 8th
week of pregnancy. Perhaps the most well-known type
of cacomelia is club foot. Club foot is a birth defect
involving one or both feet in which in which the affected
foot appears rotated internally at the ankle.
Clubfoot is a type of cacomelia.
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Another form of cacomelia is metatarsus adductus, in which the toes and forefoot are
pointed inwards and the sole of the feet appear bean-shaped. This is believed to be
caused by the baby being in the breech position in the womb, in which the legs or buttock
(s) are positioned to come out first during delivery instead of the head.

Another form of cacomelia is congenital vertical talus, in which the bottom of the foot is
stiff, has no arch, and usually curves which is often referred to in appearance as a rocker
bottom. It is a rare cause of flat feet and can lead to serious disability and discomfort.
Sometimes birth defects can be caused by medication taken during pregnancy. For
example, thalidomide was an anti-nausea and sedating drug known to cause shortening in
one or more limbs, with the arms being more frequently affected.

Cacomelia comes from the Greek word "kakos" meaning "bad," and the Greek word
"melos" meaning "limb." Put the two words together and you have "bad limb."
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