Bowleg refers to an outward curving, or bowing, of the legs. It is due to a deformity of the knees.
During infancy, bowleg is normal. The condition usually corrects itself over the first few years of life. In an adult with bowleg, the knee alignment is not normal. The lower leg curves outward from the thigh, moving the knees farther apart.
The deformity can result from arthritis that affects the inside of the knee more than the outside. This causes wearing of the inner joint cartilage and bone. The problem can also come about when a fractured leg bone heals with an outward curvature. An injury to the growth plate of a child's knee joint, particularly on the inside, can lead to unbalanced growth of the bone. This can also cause the legs to bow. Bowlegs are associated with rickets as well. Rickets is a childhood bone disease that stems from a lack of vitamin D in the diet.