COXA VARA literally translates to a decrease in the angulation of the top part of the femur bone. Typically, the angle between the neck (which is the part of the femur between the long straight portion and the ball portion) of the femur and the shaft of the femur is 135 degrees. In coxa vara, this angle is typically defined as being < 120°. There are multiple causes of coxa vara. There is a true congenital type that a child may be born with, it may be associated with other disorders, such as congenital femoral deficiency, or it may the consequence of another more global problem, such as osteogenesis imperfecta, fibrous dysplasia, or multiple hereditary exostosis.