Skeleton deformed by Rickets, 1879. Rickets is a disorder caused by a deficiency of vitamin D, calcium, or phosphate. Rickets leads to softening and weakening of the bones and is seen most commonly in children 6-24 months of age. Photo: The Burns Archive
Polydactyly is a medical term used to describe extra fingers on the hands or toes on the feet. The extra fingers or toes may be small and non-functional, or they may be fully formed with bones and skeletal connections. Extra digits can exist in different places on the hands and feet. Polydactyly often occurs bilaterally (on both hands or both feet), or it may occur on just one hand or foot. Similarly, a person may have extra digits on just the hands, just the feet, or other combinations.